combination treatment in autoimmune diseases

W.B. HARRISON B. A. C. DIJKMANS (Eds.) Combination Treatment in Autoimmune Diseases

Springer-Verlag Berlin Heidelberg GmbH

W.B. HARRISON B. A.C. DIJKMANS (Eds.)

Combination Treatment in Autoimmune Diseases

With 13 Figures and 37 Tables

Springer

Dr. W. B. HARRISON Novartis Pharmaceuticals, Australia Pty. Ltd. Waterloo Road 54 North Ryde, NSW 2113 Australia

Prof. Dr. B.A.C. DIJKMANS Vrije Universiteit Academic Hospital Department of Rheumatology P.O. Box 7057 1007 MB Amsterdam The N etherlands

ISBN 978-3-642-07704-3

Library of Congress Catalog ing in-Publication Oata applied for Combination treatment in autoimmune diseases: with 37 tab les / W. B. Harrison; B. A. C. Oijkmans (ed.). -

ISBN 978-3-642-07704-3 ISBN 978-3-662-04759-0 (cBook) DOI 10.1007/978-3-662-04759-0

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Contents

I General Section

Combination treatment in autoimmune diseases - Introduction. W.B. HARRISON and B.A.C. DIJKMANS

Combination therapy for autoimmune diseases: the rheumatoid arthritis model. . . . . . . . . . . N. FATHY, D.E. FURST

3

5

Methodology of combination trials. . . . . . . . . . . . . . . . . . . . . . . .. 27 M. BOERS

Regulatory aspects of evaluating combination treatments in autoimmune diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 35 P. KURKI

New therapies in development for autoimmune diseases: their rationale for combination treatment. . . . . . . . . . . . . . . . . . . .. 43 V. STRAND

Combination therapy: the risks of infection and tumor induction . . . . .. 63 D.E. YOCUM

II Disease specific section

Combination treatment in autoimmune diseases: Systemic lupus erythematosus .......... . 75 G. MORONI, O. DELLA CASA ALBERIGHI, C. PONTI CELLI

Combination therapy in autoimmune disease: vasculitis . . . . . . . . . . .. 91 D. CARRUTHERS, P. BACON

Combination therapies for systemic sclerosis. . . . . . . . . . . . . . . . . . . 109 c.P. DENTON, C.M. BLACK

Therapy of Sjogren's syndrome ........................... 131 N.M. MOUTSOPOULOS, H.M. MOUTSOPOULOS

VI Contents

Spondylarthropathies: options for combination therapy ......... 147 A.M. VAN TUBERGEN, R.B.M. LANDEWE, S.VAN DER LINDEN

Combination therapy in rheumatoid arthritis. S. Binghman, P. Emery

III Futurology

. ........ 165

What will treatment of autoimmune diseases entail in 20lO? .......... 187 T.W.J. HUIZINGA, F.e. BREEDFELD

Stem cell transplantation for autoimmune diseases ............... 193 J. MOORE, P. BROOKS

Part I General section

Combination treatment in autoimmune diseases -Introduction

W.B. Harrison, B.A.C. Dijkmans

During the last decade intervention has been instituted for all kinds of diseases -even in a premorbid state, as early as possible, to control the activity of the disease, to avoid further damage and to maintain quality of life. Apart from the principle 'Treat now, not later", emphasis is laid on aggressive initial therapy. These adagia have influenced in recent times all fields of medicine, from oncology to infectious diseases and also - the topic of the present edition - the "autoimmune diseases". As an example of the latter, rheumatoid arthritis (RA) demonstrates how the attitude of physicians has been changed.

From an expectant point of view in the eighties (primum nil nocere) the attitude has been changed, as we approached and entered the new millennium, to initial aggressive therapy especially in patients with a poor prognosis. Despite the advance of instituting monotherapy with a single optimised disease-modifying anti-rheumatic drug (DMARD) - with methotrexate as prototype agent in RA - adequate disease remission is not often achieved, and adverse events may well prevent the use of higher dosages of the single agent in question. Therefore, the next step was to combine two or more DMARDs. The choice of combining DMARDs can be purely practical and based upon the anti-rheumatics most used in daily practice, for instance methotrexate and sulphasalazine. The choice of combining drugs can be influenced by different toxicity patterns to avoid cumulative toxicity. More theoretically determined considerations led to combinations of DMARDs with expected clinical beneficial effects based on their supposed mode of action.

Theoretical considerations can lead - even with the limited number of DMARDs available - to an almost infinite number of combination strategies. Boers and, in another paper, Fathy and Furst outline possible strategies based on primary choice between maximisation of efficacy and minimisation of toxicity, and illustrate strategies with examples from trial experience in the field of RA.

This issue consists of contributions from the most prominent experts in this field. In the first section the general principles of combination treatment are discussed, from rationale and methodology to benefits of risks in daily practice.

The second section concerns specific diseases. It is striking that, although there is so much experience with combining DMARDs in RA, for several other autoimmune diseases combination therapy has not yet been developed. Denton and Black, on the

4 W.B. Harrison, B.A.C. Dijkmans

other hand, are able to add a refreshing new meaning to the term "combination therapy" in systemic sclerosis by pointing out the aetiologies beyond those caused by immunopathology, and dealing with combinations of therapy to address issues beyond immunotherapy.

The last section is devoted to the future and we hope to come back in 2010 with an issue which will look back and determine whether the predictions of Brooks and Moore as well as those of Huizinga and Breedveld have come true.

Combination therapy for autoimmune diseases: the rheumatoid arthritis model

N. Fathyl, D.E. Furst2

I Assiut University Hospital, Seattle, Washington, USA 2 Virginia Mason Research Center, Seattle, Washington, USA

Introduction

Rheumatoid arthritis (RA) is not necessarily a benign disease and many patients have a poor outcome as joint damage results in functional decline. Those patients who are rheumatoid factor (RF) positive, have early active disease and have early erosions on X-ray also have a shortened life span [98, 100, 109]. Since RA frequently affects patients during their most productive years, disability can result in major economic loss, especially within 10 years of disease onset [99]. In the most recent comprehensive economic study in the United States, the total (direct and indirect) cost of arthritis, including RA and osteoarthritis, was nearly $65 billion. Accordingly, the impact of RA and osteoarthritis on resource utilization is enormous [130]. The total yearly direct costs for RA alone in the United States, based on a national community-based sample, are estimated to be $15 billion [130].

With this in mind, it would be useful to have predictors of potentially destructive disease. Luckily, there appear to be predictors of such destructive disease, and these include:

I. High disease activity and severity (including extra-articular features such as nodules, a high number of swollen and tender joints, and low functional status).

2. RF positivity and elevated acute-phase reactants 3. Conventional radiographic erosions early during the course of RA (it may be that

in the future, imaging techniques such as MRI may replace conventional radiographic techniques, but the meaning of the changes that are seen on MRI are not yet understood [19, 31, 55,101].

In this sub-group of patients, joint damage begins to occur in the first 3 years of disease [9, 31, 35] and, in the context of the complexity of the pathogenesis of RA, there has been a tendency to initiate early aggressive therapy. Despite early initiation of disease-modifying anti-rheumatic drug (DMARD) monotherapy, results are not satisfactory as patients still experienced poor long-term outcomes, while at the same

Correspondence to: Daniel E. Furst, Virginia Mason Research Center, 1201 9th Ave, Seattle, WA 98101, Washington, USA

6 N. Fathy, D.E. Furst

time not being able to continue DMARD therapy secondary to toxicity [49, 198, 110]. As monotherapy is not sufficiently efficacious, it is reasonable to consider combination DMARD therapy as a potentially more effective approach to RA. The approach is similar to that used in some malignant diseases where agents with different mechanisms of action inhibit different pathogenetic pathways and early combination therapeutic intervention may significantly improve prognosis. In fact, the results of a few combination studies for RA showed that such therapy may reduce joint damage, improve the patients' function and improve their quality of life [101]. Theoretically, combination therapy may result in synergistic or at least additive effects, which may improve the efficacy of any single DMARD, suppress disease activity before irreversible joint damage occurs and decrease DMARD toxicity by decreasing the dose of any single DMARD.

If one is to consider combination DMARD therapy, a rational basis for these combinations of DMARD should be established. The combination of DMARD mechanisms of action, DMARD kinetics and DMARD toxicity is such a rational framework. This framework could be used to:

1. Help treat individual patients not responding to the usual, proven DMARD combinations.

2. Help predict synergistic and non-overlapping combinations of DMARD, thus supplying a theoretical background to design new therapeutic strategies for RA (this may save time and money as new studies are designed)

3. Provide ideas for future research.

It must be realized, however, that this approach is limited by our lack of knowledge of the exact mechanisms of action of DMARDs, insufficient knowledge of their kinetics and, even, an incomplete understanding of the long-term toxicities of these medications.

In the above context, we present a rational approach to the use of combination DMARD therapy and compare the theoretical results to existing data on combination therapy to test the practicality of this approach. The mechanisms of the commonly used DMARD are described, the kinetics of these drugs explicated, and the overall toxicities of the DMARDs outlined. Finally, we compare the direct costs of these regimens, realizing that this cost analysis leaves out significant toxicity costs, indirect costs, etc. While TNF blocking agents and MTX are more effective than some DMARDs, and DMARDs such as minocyc1ine, hydroxychloroquine and auranofin are generally considered to be somewhat less effective than other DMARDs, no actual review of the comparative efficacy of these compounds is undertaken [77].

DMARDs mechanisms of action (Table 1)

Methotrexate

Methotrexate (MTX) was first used in the treatment of RA in 1951 [49]. It is the medication to which other agents are usually added in different combination regimens and, by many, is considered to be the "basic/background" DMARD [82].

The mechanism of action of low-dose MTX in RA is not completely understood. Its therapeutic effect may be due to anti-folate activity, immunomodulating effects, immunosuppressive properties, anti-inflammatory effects or the combination of all these factors [125].

Combination therapy for rheumatoid arthritis 7

Table 1. Mechanisms of action of DMARDs

AZA Cyclo D-Pen Gold HCQ/ Lef MTX Mino SSZ TNF-sporin CQ blockers

T cell inhibition:

CD8+ CD4+ IL-2 IL-6 IL-8 IL-IO Interferon-y

B cell inhibition:

Ig synthesis Natural killer

cell inhibition Prostaglandin inhibition Phospholipase A2

Macrophage inhibition:

iNOS TNF-a (TM/IV) TNF-a (Oral) IL-I

Antigen processing:

Activator protein-I activity

Polymorphonuclear leukocyte inhibition:

Phagocytosis Lysosomal enzyme release Chemotaxis Oxygen radical inhibition DHODH AICAR and DHFR MMPI (collagenase) Oxygen radical

scavenging/release p53-mediated apoptosis

+

+

+

+

+ +

+

+

+

+

+ + +

±

±

±

+

+

+

+

+

+

+

+

+ + +

+

+

+ + +

+

+

+

+ + +

+ +

+

+

+

+

+ +

+

+

+ + +

+

+ +

+

+

+ + + +

+

+

+

±

+

+

+

+

±

+ +

+ +

± ±

DMARD, Disease-modifying anti-rheumatic drug; AZA, azathioprine; D-Pen, D-penicillamine; HCQ/CQ, hydroxychloroquine; lef, leflunomide; Mino, minocycline; ssz, sulfasalazine; TNF, tumour necrosis factor; IL, interleukin; Ig, immunoglobulin; iNOS, inducible nitric oxide synthetase; TNF-a, tumor necrosis factor-a; 1M/IV, intra-muscular, intravenous; DHODH, dihydro orotate dehydrogenase; AICAR, aminoimidazole carboxamide ribonucleotide transformylase; DHFR, dihydrofolate reductase; MMPI, metal!oproteinase inhibitor

After MTX enters cells, it binds to and inactivates dihydrofolate reductase (DHFR), This, in turn, inhibits thymidylate synthetase and purine synthesis which, thereafter, suppress DNA, RNA and other protein synthesis. 7-Hydroxymethotrexate also has some of these effects, although its affinity for some of the enzymes inhibited


by MTX is less than the parent compound. Another metabolite of MTX, its intracellular polyglutamate, also affects these enzymes. MTX, even at very low concentrations, effectively inhibits 5-aminoimidazole carboxamide ribonucleotide transformylase (AICAR), through AICAR enhancement of adenosine release. Adenosine release suppresses polymorphonuclear function as measured by chemotaxis, protease activity and leukotriene-B4 production [16]. Although a direct effect on B cell function is possible, the decrease in IgM RF synthesis seen after MTX may be a secondary effect [94]. MTX, 7-hydroxymethotrexate and their polyglutamates accumulate in cells, also resulting in the inhibition of T cell and macrophage function [13, 40]. MTX decreases concentrations of soluble interleukin-2 (IL-2) receptor through an effect on polyamine synthesis and decreases IL-I secretion as well as having effects on secondary IL-6 and IL-8 secretion. A recent investigation found that low-dose MTX strongly suppresses the production of TNF-a [56, III J. Suppression of the IL-6 decreases reactive oxygen species in the synoviocyte and this may playa fundamental role in the anti-inflammatory effect of MTX in RA [14, 70, 71, 117].

Finally, MTX inhibits neovascularization [20], which may play an important role in decreasing the chronic inflammatory process.

Gold

Gold salts are administered either orally (auranofin) or intramuscularly (aurothiomalate or aurothioglucose).

Gold salts accumulate intracellularly via a sequence of ligand and exchange reactions involving sulfhydryl groups on the cell surface. Low concentrations of injectable gold can inhibit the binding of transcription factor activator protein-l (AP-I), so gold may regulate gene expression leading to decreased production of several cytokines (including IL-l a, IL-I~, IL-6 and TNF) as well as metalloproteinases, thus having a major effect on inflammation [11, 23, 531. Aurothiomalate decreases the number of monocytes and the expression of the major histocompatibility complex class II molecules on monocytes [29]. Other effects, some of which may be "downstream effects", include decreased RF levels in serum, decreased endothelial expression of neutrophil adhesion receptors and, consequently, decreased neutrophil recruitment into the joints [15, 95]. Finally, gold salts inhibit phagocytosis and lysosomal enzyme activity of polymorphonuclear cells. From the numerous apparent effects of gold salts that have been published, one would have to conclude that the major and most important mechanisms of gold effects have not yet been delineated.

Hydroxychloroquine and chloroquine (antimalarials)

Antimalarials enter the cells and accumulate in acid vesical environments, such as lysosomes and the Golgi apparatus l18, 126]. Because antimalarials have an alkaline pH, they change the pH of the environment in the lysosomes and the Golgi apparatus. This, in turn, changes the functions of these organelles. Since lysosomes and golgi apparatae exist in many cell types, the antimalarials can potentially change the functions of lymphocytes, macrophages, fibroblasts and polymorphs. Decreases in protease function and release and inhibition of antigen processing of monocytes and macrophages have been documented after antimalarials in vitro, as has been suppres-


sion of IL-6 release from T cells and monocytes, IL-l and TNF-a release, and trapping of free radicals [7, 20, 33, 43].

D-Penicillamine

Like many DMARDs, the precise mechanism of D-penicillamine is unknown. Its main anti-rheumatic action may be through its effect on thiol groups. D-PenicilIamine can reduce thiol cross-linking and oxidization. Depending on its oxidation state and metabolism, D-penicillamine can affect the cell surface receptor sulfhydryl groups of T lymphocytes, natural killer (NK) cells and monocytes [54, 85, 119]. One of the in vitro mechanisms of action of D-penicillamine may be similar to that of gold salts, as D-penicillamine inhibits the DNA binding of the transcription factor AP-I. Inactivation of AP-l reduces the expression of various cytokines and metalloproteinases as well as cell adhesion molecules [23,53].

Cyclosporin A

Cyclosporin A ultimately inhibits IL-2 secretion [127]. The effect is mediated through inhibition of a nuclear transcription factor via complexes of cyclosporin A and cyclophilin (a cytoplasmic housekeeping protein), which then binds calcineurin (an intracellular phosphatase) [40, 121]. These steps inhibit amplification of the cellular immune response, thus inhibiting the production of IL-2 and IL-2 receptor. As both IL-2 synthesis and IL-2 receptor production are inhibited, secondary B cell functions, interferon-gamma production and NK cell activity are decreased. TNF-a is also said to be affected. T cells that are already activated are not affected, and T cell-independent functions such as macrophage response to lymphokines and T cell responses independent of T cell antigens are not impaired.

SulJasalazine

Sulfasalazine (SSZ) is split, in the colon, into equimolar amounts of its main metabolites, sulfapyridine (SP) and 5-aminosalicylic acid (5-ASA). SSZ exerts an immunomodulatory activity via suppression of the inflammation in the gastrointestinal tract, where SSZ, SP and 5-ASA concentrations are very high. In contrast to the relatively clear effect of SSZ in inflammatory bowel disease, the source of anti-rheumatic activity of SSZ is still unclear [23, 115]. 5-ASA alone has little effect in RA. SP, SSZ, or both, are probably required for maximal effect in RA. In RA patients who responded clinically to SSZ, B cell proliferation was inhibited using a phytohemagglutinin-proliferative response ex vivo [107]. SSZ inhibits the proliferation of synoviocytes and reduces the release of IL-lj3 and IL-6 [4]. 5-ASA scavenges oxygen radicals in vitro and SSZ lowers prostanoid levels (specifically leukotriene-B4 in polymorphonuclear cells and thromboxane A2 in platelets) [4, 102]. Finally, SSZ suppresses collagenase and stromelysin in rabbit chondrocytes in vitro [91]. Overall, the mechanism of action of SSZ is probably complex, involving both the parent compound and SP, at least in RA. There are probably effects on B cell proliferation, release of interleukins, oxygen radicals and prostanoids, and, perhaps, collagenase and


stromelysin. Since most of these effects are ex vivo, however, no definitive mechanism of action can be ascribed to SSZ, although it has been suggested that SSZ inhibits folate metabolism (particularly through inhibition of DHFR). Folinic acid does not reverse the anti-proliferative effect of SSZ, indicating that the anti-rheumatic effects of SSZ involve different mechanisms [20, 115].

Azathioprine

Azathioprine is biologically inactive until metabolized to 6-thioinosinic acid, primarily in the liver and red blood cells. 6-Thionosinic acid interferes with adenine and guanine synthesis, probably through its effect on 6-thioguanylic acid [40, S3]. Azathioprine is immunosuppressive and inhibits the function of T cells, B cells and NK cells. It reduces B cell proliferation in vitro [1], and also inhibits IgO and IgM production, mixed lymphocyte reactivity, circulating T lymphocytes numbers (especially CDS cell suppression) and IL-2 secretion [I, 40, 74]. Azathioprine also appears to inhibit the functions of NK cells in vitro and ex vivo [17]. Azathioprine does not appear to affect cytokines, except secondarily if the underlying RA improves [7].

Leflunomide

Leflunomide acts through its active hepatic metabolite, A 77-1726, which is a potent inhibitor of dihydro-orotate dehydrogenase (DHODH) [S7]. The inhibition of DHODH decreases rUMP and activates the p53 gene, leading to apoptosis and cell cycle arrest. This may be the ultimate mechanism of action of leflunomide, leading to its beneficial effect in RA [22, 32, 75, 123]. A 77-1726 may also alter the synthesis of cytokines by increasing the mRNA level of IL-J 0 receptor, decreasing IL-S receptor, blocking TNF and nuclear factor KP activation. Leflunomide may even have some anti-inflammatory effect through its inhibition of cyclooxygenase-2 activity [SO].

Minocycline

Minocycline, a semisynthetic tetracycline antibiotic, was initially used to treat RA based on the hypothesis that persistent infection, particularly mycoplasmic infection, may cause RA [10]. It does not, in fact, work as an antibiotic. Minocycline probably acts by inhibiting matrix metalloproteinases [44] and reducing collagenase activity in the synovial tissue [46] (including from neutrophils, macrophages, osteoblasts, chondrocytes, epithelial cells and rheumatoid synoviocytes). It may also reduce bone marrow resorption [120]. Minocycline inhibits interferon-a-stimulated inducible nitric oxide synthase in macrophages, decreases serum of IL-I a and TNF-a levels and suppresses IgM RF [2, 64, 65,112, 122].

TNF blocking agents

lnfliximab and etanercept, approved by the Food and Drug Administration (FDA) in 1995-1999, are examples of a new class of DMARDs that interfere with the action of TNF-a, one of the more important cytokines that promote inflammation [S9].

Combination therapy for rheumatoid arthritis II

lnfliximab is a chimeric (part human and part mouse protein), monoclonal antiTNF antibody, which blocks circulating TNF and cross-links T cells and macrophages so that TNF-mediated actions cannot take place [62, 79].

Etanercept is produced by linking the DNA encoding the soluble portions of the human p75 TNF receptor to the DNA encoding the Fc portion of human IgG. Etanercept competes with the membrane binding site for TNF, thus removing p75 TNF from the circulation.

Pharmacokinetics (Table 2)

Antimalarials

Chloroquine and hydroxychloroquine are approximately 74% bioavailable, with serum half-lives of 6-40 days [86, 118]. They are widely distributed into the tissues, although they have a protein binding of only 16-25% [84]. Most metabolism is via the liver, although up to 25% is renally excreted. Munster et al. [90] correlated the bis-hydroxy metabolites with efficacy and the parent compound with gastrointestinal toxicity.

Azathioprine

Azathioprine and its principal active metabolite (6-MP) are well absorbed and have a half-life of 0.2-1.5 h. The drug is only 30% protein bound and 55-80% is metabolized by the liver to inactive metabolites [92]. Since metabolism is via xanthine oxidase, azathioprine may interact with allopurinol. 6-MP is broken down by thiopurine methyl transferase (TPMT). This transferase is selectively inherited and, in I of 300 persons, exists at extremely low concentrations (or is missing). In TPMT-deficient individuals, the risk of myelosuppression after azathioprine is markedly increased [28].

Cyclosporin A

The absorption of cyclosporin A per se is variable, although a newer formulation (Neoral) is characterized by more consistent absorption; nevertheless, absorption remains low (see Table 2). Grapefruit juice enhances absorption, variably, by up to 62%. Since cyclosporin is metabolized by the CYP 3A enzyme family, interactions with other drugs metabolized by the same family may occur [68, 103]. Ketoconazole and diltiazem compete with cyclosporin for the CYP 3A site and, hence, may reduce the metabolism of cyclosporin [76]. Rifampicin and phenytoin induce cyclosporin metabolism. Azathioprine has been shown to decrease cyclosporine concentrations by about 50% through unknown mechanisms [47].

Gold

Oral gold absorption is approximately 15-25%, with a serum half-life of 15-31 days. Its principal early route of excretion is fecal, although after absorption, excretion is about 50% renal and 50% fecal. Oral gold is highly lipid soluble, accounting for its oral ab-

Tab

le 2

. Pha

rmac

okin

etic

s

Abs

orpt

ion

Cle

aran

ce

Seru

m

(% o

f or

al d

ose)

(m

llh)

el

imin

atio

n tl

/2

(h/d

ays)

Aza

thio

prin

e 80

(6-

MP

) 11

4 (6

-MP)

0.

2-0.

5 h

1.5

(6-M

P)

h

Cyc

losp

orin

e 2

0-5

0

2-3

2

3-7

h

D-P

enic

illa

min

e 4

0-7

0

1-7.

5 h

up t

o 6

days

Gol

d:

thio

mal

ate

1M

0.1-

0.2

5-12

day

s

thio

gluc

ose

1M

3-27

day

s up

to

168

days

aura

nofi

n P

O

15-2

5 15

-31

days

HC

Q

74

6-40

day

s

Lef

luno

mid

e 80

31

15

-27

days

Met

hotr

exat

e 70

(ra

nge

75-1

00)

6-24

h

Min

ocyC

\ine

90

low

15

-20

h

Sul

fasa

lazi

ne

SSZ

: 30

7.

6 h

5-A

SA

: 20

-30

Sul

faph

>70

sTN

F"R

2:F

, 10

02

901 -

10

2 4.

81 -

9.5

2 da

ys

I =et

aner

cept

2=

infl

ixim

ab

PO,

Ora

lly;

1M

, in

tram

uscu

lar;

GI,

gast

roin

test

inal

Vol

ume

of

Tot

al p

rote

in

dist

ribu

tion

bi

ndin

g (l

/kg

) (%

)

30

80 (

6-M

P)

3-5

87

57-9

3

95

95

60

16-2

5

0.13

99

.3

0.4-

0.8

30-5

0

76

7.5

90

3L41

l

Rou

tes

of

elim

inat

ion

20-4

5% r

enal

6% r

enal

. 94

% b

ilar

y

25%

ren

al

60-9

0% r

enal

700/

c re

nal.

30%

liv

er

50%

ren

al,

50%

fec

es

16-2

5% r

enal

43%

ren

al

48-1

00%

ren

al,

30%

bil

iary

10-1

3% r

enal

70-9

0% r

enal

(m

etab

olit

es)

Sit

es o

f m

etab

olis

m

50-8

0% l

iver

Liv

er P

450-

3A

Liv

er

dicy

anog

old

dicy

anog

old

Liv

er

40-5

0% l

iver

Liv

er

Liv

er,

GI

trac

t

N 2: 'Tl '" 8- '::' o rn 'Tl a


sorption. It is distributed into macrophage lysosomes, called "aurosomes" [41,42]. Compared to intramuscular gold, auranofin is much better absorbed orally, undergoes less total body retention, has greater fecal excretion and is subject to less urinary excretion [361.

Intramuscular gold (thiomalate, thioglucose) has a serum elimination half-life of 5-27 days in most cases (up to 168 days for thioglucose); it is highly protein bound and has a total body half-life of approximately 1 year. Both thiomalate and thioglucose are 60-90% renally excreted. Like oral gold, intramuscular gold is distributed into Iysosomes, accounting for its very prolonged total body half-life.

Lejlunomide

Leflunomide clearance is very low, resulting in a prolonged terminal serum half-life of up to 18 days. Its active metabolite has an even more prolonged serum half-life of up to 26 days. Urinary and fecal recovery of the drug at about 1 month are equal, each being 40-50%. Leflunomide is extensively metabolized by the liver and undergoes an enterohepatic recirculation [37]. Cholestyramine can be used to decrease serum half-life to approximately 24 h, thus rapidly removing the drug from the body. Response to leflunomide occurs at a dose of 11 mg/day and response probability is greater with steady-state concentrations of> 13 Ilg/ml [39, 124 J.

Methotrexate

MTX is generally well absorbed (0.73) and its absorption is not materially affected by food, although absorption is highly variable across individuals (25-100%) [52, 59]. MTX has a short terminal half-life of approximately 6 h, although individual patients may have elimination half-lives of up to 24 h. MTX protein binding is 30-50%, so that significant protein binding-drug interactions are unlikely. Approximately 10% of MTX is metabolized to its mildly active 7-hydroxymethotrexate metabolite. Both methotrexate and 7-hydroxymethotrexate are polyglutamated and can remain in cells for prolonged periods of time. MTX is principally excreted by the kidney, although up to 30% may undergo biliary excretion. The MTX area under the curve for a given dose increases with age, from infancy through adolescence [38].

Su(fasalazine

SSZ is cleaved in the colon to SP and 5-ASA. 5-ASA is inactive in RA and SP and the parent compound are thought to be the pharmacologically active moieties r50]. SP is absorbed well, while only 20-30% of 5-ASA is absorbed. The latter two compounds undergo acetylation, a process having genetic polymorphism. This polymorphism influences the rate of SP and 5-ASA elimination [58]. Renal elimination accounts for 70-90% of the drug's excretion with a short serum half-life of about 8 h.

TNF blocking agents

Etanercept is given subcutaneously twice weekly. It has a lag phase to maximum concentration of 1.46 (±0.72) h and a serum half-life of 68±19 h. Drug-drug interactions have not been carefully evaluated [67].


Infliximab is given intravenously with initial dose-loading and then dosing approximately every 8 weeks. Infliximab serum half-life averages 9.5 days. Like etanercept, excretory pathways and drug interactions are not fully elucidated.

Toxicity (Table 3)

The side effects of DMARDs are numerous and vary in severity from minor to fatal. Table 3 outlines the toxicity of DMARDs in general. Below, some more specific DMARD-associated toxicities are explicated.

Methotrexate

Even in the low doses used to treat RA, MTX causes gastrointestinal adverse effects in up to 60% of patients [6]. Often, the substitution of parenteral therapy for oral therapy can decrease that toxicity. Another alternative is the use of folic acid therapy, although recent data have shown that folic acid also decreases the efficacy of MTX [1l3]. While hepatic toxicity, as manifested by abnormal liver function tests, is also common, hepatic cirrhosis is not as common as previously thought. The risk factors for cirrhosis include alcohol consumption and, perhaps, prolonged therapy [69]. The most feared side effect of MTX therapy, acute pulmonary toxicity, is quite rare [12].

Table 3. Toxicity of DMARDs (%)

% AZA CsA DPA Gold HCQ Lefluno- MTX Mino- SSZ sTNF,,-mide cycline R2:Fc

Eyes "I GI tract 9-23 19-45 17 "I 12-35 See below 5-18 13-15 5-12 Nausea 9-23 19-45 7-20 3-13% 10-18 13-15 5-12

or vomiting Diarrhea "I 2-18 1.3 17-27% 5-12 9-11 Hepatic 0-5 0-8 "I "I 5-10% 8-38 ,,2 Renal 50-87 3-7 Fever "I 1.1 Rash 1-6 0-2 5 15-30 3.2 9-12% 1-2 1-10 1-5 Stomal. gingivitis 0-5 0.8 5-10 3-5 6-10 Decreased WBC 4-27 2-6 2 0.5 1-4 1-3 Proteinuria 6-7 3-7 "I CNS 8.0 "I 4-13 + 8-23 Other 1.4 12" 2.2 "Ib 7" 0-5 d l.l +c Decreased PIts 0-5 ,,2 4 3 1-2 "I

When specific data is not available: +, <5%; ++, 6-20%; +++, 21-50%; ++++, >50% Gr, Gastrointestinal; WBC, white blood cell count; CNS, Central nervous system; tPlts, decreased platelets a Loss of taste bMyopathy " Alopecia, neuropathy d For example, pneumonitis, neoplasia e Possible increased infection; rare aplastic anemia or multiple-sclerosis-like syndrome


SulJasalazine

While the side effects of SSZ are relatively mild most of the time, gastrointestinal side effects such as nausea and abdominal discomfort are common [3, 21]. Skin rashes are also common (1-5% of patients). Hematological side effects, including leukopenia, while rare, occur most commonly in the first few months of treatment [81]. As opposed to many medications, SSZ does not appear to affect pregnancy [23].

Antimalarials

Antimalarials (hydroxychloroquine and chloroquine) are considered to be among the least toxic DMARDs. Although gastrointestinal side effects such as nausea, vomiting and epigastric and abdominal pain are common, they do not frequently result in discontinuation of these drugs. Although 18-46% of patients treated with antimalarials developed corneal deposits, this does not affect vision [57]. Retinopathy rarely occurs when these drugs are used at recommended dosages; at present, ophthalmological follow-up in patients using antimalarials is recommended only yearly [106].

Gold

Organic gold compounds (aurothiomalate, aurothioglucose etc.) resulted in discontinuation of drug in 40-50% of patients by 1 year [61]. The most common side effects include dermatitis and stomatitis [96]. Serious but more rare side effects include proteinuria, hematuria, thrombocytopenia, leukopenia and anemia [114]. Rare side effects such as bronchiolitis obliterans have been recorded [129].

Azathioprine

Like other DMARDs, azathioprine can cause significant adverse effects. Immediate reactions such as fever plus liver function abnormalities occur rarely [73]. Bone marrow suppression, particularly leukopenia and thrombocytopenia are of more serious concern [68, 93]. As with many DMARDs, gastrointestinal side effects are relatively frequent [51].

Cyclosporin

In low doses, cyclosporin is also used to treat RA. Unusual side effects such as gingivitis and hirsutism can occur with this drug. A serious side effect includes a decrease in glomerular filtration rate (GFR); this is usually but not invariably reversible, particularly if the dose of cyclosporin is not modified when the GFR decreases [37].

Etanercept

Thus far, etanercept has been associated with relatively few side effects, although concern for an increased incidence of serious infections, autoimmune phenomena


and even neoplasia persists [89]. Among the greater than 100,000 patients who have used etanercept, several cases of a multiple-sclerosis-like syndrome, tuberculosis aplastic anemia, agranulocytosis and granulocytopenias have been reported.

Injliximab

Like etanercept, int1iximab is plagued by worries about infections, particularly tuberculosis. Infections, usually not serious, occurred in 26% of int1iximab-treated patients versus 16% of placebo-treated patients while on a background of MTX therapy (in a 24-week study) [25-27]. Autoimmune disease, although rare, has been recorded in three cases of mild SLE-like disease. Neoplasia, too, is a concern, although its incidence is not apparently increased.

Leflunomide

This DMARD is associated with a significant amount of diarrhea and also seems to be associated with abnormal liver function tests. Mild alopecia has also been noted [88].

Minocycline

Side effects from minocycline include dizziness, rash, headaches. Less common side effects include intracranial hypertension, pneumonitis and acute hepatic injury [24, 45, 48, 72]. Minocycline is associated with sun-sensitivity reactions and has been rarely associated with lupus-like disease. These reactions, as well as occasional liver function test abnormalities, must make one slightly more cautious with minocycline than was previously thought necessary [66,97].

D-Penicillamine

D-Penicillamine is rarely used today because it causes a relatively large number and percent of side effects, with fewer than 40% of patients continuing drugs by the end of I year. These side effects include skin reactions, gastrointestinal side effects, proteinuria, leUkopenia, and thrombocytopenia. Rare polymyositis-like, lupus-like and myasthenia gravis-like reactions have been documented.

Combination therapy

Using the data on the mechanisms of action, pharmacokinetics and toxicity of these DMARDs, one can construct matrices, predicting the interactions between one DMARD and another. In these matrices (Tables 4, 5, 6, 7), an "OK" represents a lack of interactions between one drug and another in a given area. For example, in Table 4, an "OK" between MTX and let1unomide in the kinetics column indicates no known negative kinetic interactions and the possibility of a positive interaction for


Table 4. Methotrexate matrix

Drug Kinetic Mechanism Toxicity

Azathiorine H (-)(GI, L) Cyc1osporin A OK ± (-) (Gr, R) D-Penicillamine OK (-) (R) Gold ± (-) (R) Hydroxychloroquine, chloroquine OK ? OK Leflunomide OK OK (-) (L, GI)

Minocycline OK OK ? Sulfasalazine OK OK (-) (H, GI) TNF-a blocking agents OK OK ?

OK, No interaction; 7, no data; -, potentially harmful interaction; ±, theoretical interaction based primarily on in vitro or non-human data; GI, gastrointestinal; L, liver; H, hematological; R, renal

Table 5. Cyc1osporin A matrix


Azathioprine OK OK OK D-Penicillamine OK OK H(R) Gold OK (-)(R) Hydroxychloroquine, chloroquine OK OK OK Leflunomide ± OK OK Methotrexate OK ± (-) (R, GI)

Minocyc1ine ± OK 7 Sulfasalazine OK OK ? TNF-a blocking agents OK OK 7

OK, No interaction; ?, no data; -, potentially harmful interaction; ±, theoretical interaction based primarily on in vitro or non-human data; Gr, gastrointestinal; L, liver; H, hematological; R, renal

those drugs. A "?" indicates a lack of knowledge with regard to a specific interaction (e.g., MTX and D-penicillamine regarding kinetics in Table 4), a "-" indicates a potentially harmful reaction (e.g., azathioprine and MTX in the toxicity column in Table 4). A "±" bespeaks a theoretical interaction based on in vitro or non-human data, but its relevance in the clinical situation is unlikely (e.g., some potential overlap in mechanisms between MTX and hydroxychloroquine but unlikely regarding TNF inhibition).

Table 4 illustrates the matrix of MTX combined with the other DMARDs. Regarding the combination of SSZ and MTX, for example, an "OK" in two of three columns, and a "-" in one of three columns was found. No overlapping mechanism(s) of action or kinetic are likely at in vivo concentrations, hence the "OK" in the mechanism and kinetic columns. "-" indicates a negative interaction with potential for a synergistic (or additive) toxicity [8, 60]. Based on this analysis, one would not expect additive or synergistic effects when using the drugs together, and a 24-week, double-blind, comparision of 105 patients treated with SSZ, MTX or their combination yielded no additive effect [50].

One "OK", one "-" and a "±" were found for MTX plus cyclosporin (Table 5). However, here, a short-term, double-blind trial of methotrexate plus cyclosporin re-


Table 6. Hydroxychloroquine, chloroquine matrix


Azathioprine OK OK OK Cyclosporin A OK OK ? D-Penicillamine ? OK OK Gold ? ± ? Leflunomide ? OK ? Methotrexate OK ± OK Minocycline ? OK ? Sulfasalazine OK OK OK TNF-a blocking agents OK OK

OK, No interaction; ?, no data; -, potentially harmful interaction; ±, theoretical interaction based primarily on in vitro or non-human data

Table 7. Sulfasalazine


Methotrexate OK OK - (H, GI) Cyclosporin A OK OK ? Hydroxychloroquine, chloroquine OK OK OK Azathioprine ? -(GI) Gold ? ± ? Leflunomide ? OK (-, GI) Minocycline ? OK OK D-Penicillamine OK OK ? TNF-a OK OK ?

OK, No interaction; ?, no data; -, potentially harmful interaction; ±, theoretical interaction based primarily on in vitro or non-human data; Gr, gastrointestinal; H, hematological; R, renal

vealed a 24% and 26% improvement in swollen joint count and tender joint count, respectively, when cyc1osporin and MTX were used together and compared to MTX alone [116]. Since cyc1osporin and MTX have minimally overlapping mechanisms, based only on in vitro data (±), the mechanisms are not likely to interfere with each other. Kinetically, from Table 2, there are not likely to be kinetic interactions (hence "OK"), while overlapping gastrointestinal and hematological toxicities result in a "-" for toxicity. No prediction is possible here, and the design of the quoted study (adding cyc1osporin or placebo to MTX "failures") does not test the question.

Only open studies were found for MTX-intramuscular gold interactions. The combination of methotrexate and intramuscular gold plus other DMARDs was tested in an open prospective trial, involving 271 patients with refractory erosive RA (mean disease duration 9.6/7.7/8.3 years for groups 1-3, see below).Group I, treated with MTX monotherapy (n=97), was compared with group 2, with combination therapy MTXlparenteral gold (n=126) and group 3 with MTX+other DMARD (n=48). For purposes of this manuscript, group 3 is heterogeneous and not useful, so it will be ignored. After 5 years 54% of group 1 and 54% of group 2 patients continued their treatment. All efficacy variables improved significantly (P<O.OOI) in both groups without significant intergroup difference. Improvement of greater than 50% in the


Table 8. Approximate per patient direct costs of DMARD therapy during the first 6 months (modified from [63])

Drug Medication cost Monitoring Toxicity Total 6 months over 6 months

Methotrexate (oral) $180 1712 130 2022 Azathioprine $286 1052 241 1579 Cyclophosphamide $1873 1807 (3680) D-Penicillamine $480 1762 251 2493 Cyclosporin $2737 1710 (4447) H ydroxychloroquine $70 492 102 664 Sulfasalazine $41 528 (569) Gold (oral) $596 2617 86 3999 Gold (1M) $296 4825 276 5399 Etanercept $6000 882 (6882) InfJiximab $10.000· 1199 (11,119) Leflunomide $1230 1712 (2945)

-, 1 element missing; 1M, intramuscular • Costs during second six months substantially less ( ) one element is missing

ESR was achieved in 63% and 68% and, in the swollen joint count, in 70% and 85% of patients after 3 years. Combination therapy of MTX with parenteral gold was no more effective in reducing clinical and biochemical disease activity in patients with long-standing destructive RA than monotherapy. Taking into account the higher disease activity at baseline and the greater X-ray progression before baseline among the patients in the combination group, the MTX matrix would have predicted this result, as gold with MTX would be predicted to have no advantage over MTX alone [104]. Also, the combination of MTX with auranofin did not demonstrate any advantage in efficacy over single drug treatment in 335 patients with active RA who entered into a 48-week, prospective controlled double-blind study [128]. Again, the prediction of the matrix appears to borne out.

No study which directly compares infliximab versus MTX versus their combination has been published. However, a study was performed in which MTX was the background therapy and either infliximab or placebo was added. In this international, double-blind, placebo-controlled phase III clinical trial, 428 patients who had active RA and on stable MTX were randomized to placebo (n=88) or one of four regimens of infliximab at weeks 0, 2 and 6 then every 4 or 8 weeks. At 30 weeks, the American College of Rheumatology (ACR) 20 response criteria, representing a 20% improvement from baseline, were achieved in 53%, 50%, 58%, and 52% of patients receiving 3 mg/kg every 4 or 8 weeks or 10 mg/kg every 4 or 8 weeks, respectively, compared with 20% of patients receiving placebo plus MTX (P<O.OOI for each of the four infliximab regimens vs placebo) (P<O.OOI) [78].

Maini et al. [77] reported an interesting 26-week randomized, controlled trial of patients with active RA receiving low-dose MTX who were randomized to one of three doses of anti-TNF-a (cA2) with or without MTX or intravenous placebo plus MTX, 7.5 mg/week. The study demonstrated efficacy of infliximab at 3 and 10 mg/kg with or without MTX and also showed efficacy for MTX plus 1 mg/kg infliximab, suggesting that this combination appears to be synergistic, prolonging the duration of the 20% response in more than 60% of patients a median of 16.5 weeks


(P<O.OOI) vs placebo. A positive additive or synergistic activity is implied, but not proven, by these studies, giving some general, although weak, support to the matrix prediction.

Like infliximab, no study has compared MTX, etanercept or their combination. A trial similar to the infliximab study was carried out by Bankhurst et al. [5]. Using patients already on background MTX, the 6-month, well-controlled study showed that 71 % of patients in the etanercept plus MTX group had a 20% ACR response versus 27% in the methotrexate plus placebo group. Thirty-nine percent of the patients in the methotrexate plus etanercept group had an ACR50 response compared to 3% of the methotrexate versus placebo group [5]. Again, the MTX matrix would have predicted that this combination would be effective, just as with MTX plus infliximab. However, as in the infliximab study, one must remember that this trial is not a clear test of the hypothesis that the etanerceptlMTX combination is better than either drug alone.

Table 6 displays the matrix using hydroxy chloroquine and chloroquine as the background medication. The large number of cells "?" makes prediction less reliable, but points to numerous areas for research. Perhaps one could surmise that two "OKs"; plus one "?" or three "OKs" would predict synergy or additive effects but, at least for the "OKl?" rows, little confidence is warranted [30]..

Although there have been no double-blind, randomized controlled trials of MTX and hydroxychloroquine!chloroquine, there has been at least one randomized (nonblinded) study. Patients had been treated with MTX but had not achieved remission (>3 tender or swollen joints and ESR >30 or CRP >1.5). They were either assigned to continue MTX or randomized to receive 215 mg/day of chloroquine. Intragroup analysis showed a statistically better response in the MTX plus chloroquine groups according to the number of tender joints (P=0.045) and CRP (P=0.008) at 3 months. The difference between the two groups in the number of tender joints also nearly reached significance at 6 months (P=0.056 [l05]. This study confirms the previous study of this combination by Ferraz et al. [30]. There are, therefore, two studies supporting the use of the combination of MTX plus hydroxychloroquine/chloroquine together, although neither is a double-blind study. It should be pointed out that an observational trial indicated that the combination of hydroxychloroquine plus MTX decreased the incidence of abnormal AST in patients compared to those given MTX alone (5.6% vs 9.3%), although there was no enhanced efficacy when the two drugs were used together [34].

The hydroxychloroquine/chloroquine matrix seems to be the one which is less useful than other matrices. That may be because surprisingly little is known definitively about the mechanism of action and pharmacokinetics of hydroxychloroquine!Chloroquine.

Costs

When one finds combinations of DMARDs which are effective and have acceptable toxicity, one also has to consider the cost of treatment. In fact, the true cost of treatment includes both indirect costs such as "opportunity costs" (lost wages, transportation costs, etc.) and direct costs (drug purchase price, monitoring costs, cost of evaluating and treating toxicities, etc.). Consideration of the costs of treatment is relevant because the use of any particular therapeutic regimen for patients with


chronic disease may represent a significant burden to the patient or to society on a long-term basis.

For simplicity's sake, we will only consider certain direct costs such as the drug purchase price, monitoring costs and the costs of evaluating and treating toxicities (Table 8). Medication costs were obtained from the pharmacy of a multi specialty medical institution in Seattle. The monitoring costs were calculated using charges from local laboratories, and the pattern of monitoring was taken from published recommendations [63]. Paradigms for the diagnosis, evaluation and treatment of specific adverse effects were constructed based on the report of Kavanaugh et al. [63].

It is clear from Table 8 that the total costs are dominated by medication costs during the first 6 months for the TNF blocking agents, while monitoring costs generally predominate during the same period for the other medications.

Although it would be fallacious to simply sum total costs when combining DMARDs (e.g., monitoring costs for gold include all monitoring costs for MTX, so only gold monitoring costs should be accounted if gold and MTX were used together), it is also clear that, for most combinations, the addition of TNF blocking agents will result in major cost increases. Thus, the use of TNF blocking agents must include either significantly improved short-term efficacy and significantly improved quality of life or significantly lower long-term indirect costs. To truly place these compounds in the combination armamentarium, a great deal of long-term data regarding quality of life and ability to function in society will be needed, as will direct comparisons among TNF blocking agents and between TNF blocking agents and other combination DMARDs.

Conclusions

The use of a rational approach to combination therapy requires knowledge of the mechanism(s) of action, pharmacokinetics and toxicity (assuming relatively equivalent efficacy) of component drugs. With that knowledge, rational drug combinations can be formulated. Such formulations can be tested based on studies which have been published. This approach generally supports the above rationale, although the lack of specific knowledge in different areas (e.g., details of mechanism and/or kinetics and/or long-term, rare toxicity) may make them less exact than desirable. The addition of cost considerations to the above areas of uncertainty point to future research needs. Nevertheless, even today, this rational approach to combination therapy can help the clinician devise rational drug combinations to use and, as importantly, decide which drug combinations are best to avoid.

Acknowledgement. This work was partially supported by the Rasmuson Center for Arthritis, Orthopaedics and Musculoskeletal Diseases.

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Methodology of combination trials

M. Boers

Department of Clinical Epidemiology & Biostatistics, University Hospital Vrije Universiteit, Amsterdam, The Netherlands

Abstract. Even with the limited number of antirheumatic agents available, theoretical considerations lead to an almost infinite number of combination strategies. This article outlines possible strategies based on the primary choice between maximization of efficacy or minimization of toxicity. Strategies are illustrated with examples from trial experience in the field of rheumatoid arthritis.

Introduction

Combination therapy is becoming increasingly popular in the treatment of autoimmune diseases. This is a direct result of our modest successes in treating afflicted patients, and our ignorance of the etiology and pathophysiology of these diseases. Specifically in the case of rheumatoid arthritis (RA) physicians have become disenchanted with the classical "pyramidal" approach to therapy, i.e., to start with nonsteroidal anti-inflammatory drugs and progress to increasingly toxic antirheumatic agents in case of insufficient response. Surveys have indicated that many rheumatologists are now routinely using combinations [6] even though the evidence for their efficacy is mostly very tenuous [9]. The most popular strategy is that of "step-up", i.e., adding a second (or third) drug in case of insufficient response. The purpose of this article is to outline the theoretical considerations involved in combination strategies, and to explain strategies in use with examples from the literature on RA.

Objectives of combination therapy

As Fathy and Furst [3] explain elsewhere in this issue, the objective (or rationale) of combination therapy is to achieve a better toxicitylbenefit ratio. This ratio is poor for most antirheumatic drugs, resulting in high proportions of drug discontinuation for either lack of effect, toxicity or both. Improving the toxicitylbenefit ratio can involve

Correspondence to: Maarten Boers, Department of Clinical Epidemiology & Biostatistics, University Hospital Vrije Universiteit, PO Box 7057, 1007 MB Amsterdam, The Netherlands

28 M. Boers

influencing one or both of the factors in the ratio simultaneously. A rational selection of candidates for combinations should emerge from knowledge of the mechanisms of action, both for efficacy and toxicity. Unfortunately, this knowledge is limited, so that clinical research in this field has mostly been characterized by a "trial and error" approach. The main focus of interest has been the improvement of efficacy, as most trials of combination therapy have used full doses of the drugs studied. It must be stressed, however, that efficacy and toxicity are not independent phenomena: except for severe adverse events, patients are more likely to continue a drug that is causing side effects if they experience true benefit. Anecdotal experience with methotrexate in high doses and data from trials that show clear differences in efficacy between the treatment groups (e.g., the COBRA trial [ID support this observation.

As an example of combination therapy where the main objective is to reduce toxicity, the case of high-dose corticosteroid therapy for autoimmune diseases can be mentioned. In this setting "steroid-sparing" regimens are routine, where other immunosuppressives such as azathioprine are added to minimize the cumulative corticosteroid dose. In the case of cyclosporin A full antirheumatic dosing is not possible due to prohibitive renal toxicity; the drug is now increasingly popular in lower doses in combination strategies, especially with methotrexate.

Theoretical considerations

To understand the possible effects of combination therapies compared with single drug strategies it is easiest to invoke a metabolic model. In this model enzymes produce compounds from raw material (Fig I). One compound (D) could be equated with disease processes, another (N) with normal physiological processes. Stimulating enzymes that produce N should have a beneficial result, whereas stimulating enzymes that produce D would lead to exacerbation of disease and side effects. The selectivity of a drug is determined by the overlap between the enzyme pathways, and the number of pathways affected by the drug.

Adding a second drug (let alone a third or more) makes the equation considerably more complex. Both for efficacy and toxicity, the second drug can target the same enzyme, the same pathway but a different enzyme, or a different enzyme. The result can be an addition, competition or synergy of the effects, of the single drug (Fig. 2). In the case of addition, the effect of the combination is exactly the sum of the effects of the single components. In the model this is the case where two drugs each target a different pathway (Fig. 3). In the case of competition the effect of the combination is less than addition, and could theoretically even be less than that of the single component. In the model, this can be the case when two drugs target the same enzyme: each drug separately causes partial stimulation (e.g. 75%), but combining the two cannot result in more than 100% stimulation (Fig. 3). A well-known example from microbiology is the combination of some bacteriostatic and bactericidal drugs: the first stops replication of the organism. If the second drug works only on replicating cells, its effect in combination with the first will be negligible. In the case of synergy, the effect of the combination is more than addition. In the model, this can be the case where two drugs target the same pathway but different enzymes, where each separate enzyme cannot be stimulated completely (Fig. 3). An example (but with inhibition instead of stimulation) is the synergistic effect of sulfamethisoxazole and trimethoprim - both inhibitors of different enzymes in the folic acid synthesis pathway - in

Methodology of combination trials

raw material

29

beneficial products

(physiological processes,

therapeutic effects)

unwanted products

(pathological

processes,side effects)

Fig. 1. Efficacy and toxicity of drug treatment expressed in a (hypothetical ) enzymatic model. Both wanted and unwanted effects are expressed as "products" made from raw material. Production can be through multiple pathways, and each pathway can constitute one or a series of enzymes (larf?e arrows). In this model , drug action (small arrows) is envisaged by stimulation of one or more of these enzymes

effect

I I I I I

addition competition (negative

interaction)

synergy (positive

interaction)

Fig. 2. Addition, competition and synergy of effects in combination therapy

the combination cotrimoxazol. Competition and synergy are also called negative and positive interaction, respectively.

Apart from these theoretical considerations, some attention must also be paid to the difficulties of actually demonstrating the advantages of a combination over its components in a trial. As discussed below, the strategy of application (e.g., simulta-

30 M. Boers

tUg A

qq :>

l:rug B addition

drug:l ! :rug B

:> competition

1 :rug A tUg B

I >C=) synergy

Fig. 3. Addition, competition and synergy in the enzymatic model. Addition: both drugs target different pathways: their effects are independent and the total effect is the sum of the separate effects. Competition: both drugs target the same pathway. If each drug stimulates the enzyme by 75%, administering both drugs will lead to no more than 100% stimulation, i.e. 50'7c less than the arithmetic sum of the separate effects. Synergv: both drugs target ditferent enzymes along the same pathway. For example, the effect of drug A is limited by the activity of the subsequent enzyme in the pathway. Adding drug B stimulates this enzyme, leading to an effect of the combination that is more than the sum of the separate effects

neous from the start or add-on in case of insufficient response) is important. Also, the comprehensiveness of the comparison determines the extent to which conclusions can be drawn. In the case of two drugs, the trial should ideally have three arms: one for the combination and one for each of the components. No genius is required to see the problems expand in trials of mUltiple drug regimens. Finally, most autoimmune diseases do not have one or a few clear-cut outcomes. For example, lupus erythematosus can target many different organs, and drugs may specifically be of benefit in disease of only one organ. Similarly, future drugs may selectively prevent joint damage in rheumatoid or osteoarthritis but fail to improve disease activity. In our theoretical model, this translates to having several "disease compounds" in production instead of just one. Simple models of addition, etc., are then less applicable. In the case of toxicity assessment the same applies because each drug can cause a varied spectrum of side effects in different organs.

Methodology of combination trials 31

= parallel

step-up

step-down (bridge)

sawtooth

parallel/switch

time Fig. 4. Illustration of combination strategies

Strategies with examples

As shown in our updated review [9] (and replicated by Felson et al. [4]), the current literature in RA supports at most an additive effect of certain combinations, notably those including corticosteroids. However, the majority of combinations have not been studied sufficiently for a final verdict, and the majority of published trials show no or only modest gains in efficacy, at the cost of no or modest increases in toxicity (i.e., competition of beneficial and side effects!). Which strategies are available and which have been tried? Theoretically, we can distinguish parallel, step-down (bridge), step-up, saw-tooth, and switch (Fig. 4). Within each strategy, we can distinguish combinations with two or more drugs, and with fixed and variable dose regimens. Many variations on the theme are possible, but the underlying choice is between two principles:

I. Maximum efficacy in the window of opportunity, i.e. , reduces disease activity as quickly and as early as possible; this will preferentially lead to parallel or stepdown strategies

2. Individual tailoring on the basis of prognostic factors and initial response, i.e., limits exposure to potentially toxic (combinations of) drugs; this will preferentially lead to step-up, saw-tooth or switch strategies.

However, there is considerable room for manoeuvre moving from principle to choice of strategy, depending on the decisions made for the components, their dose, and the regimen within the strategy.

32 M. Boers

Parallel

In the parallel strategy the components are started simultaneously, and continued throughout the treatment course. For example, Dougados et al. [2] compared the combination of sulfasalazine and methotrexate against each of the single components. Other examples include a trial of the combination of parenteral gold and hydroxychloroquine [7], or methotrexate and auranofin [11].

Step-down (bridge)

The step-down (bridge) strategy resembles the parallel strategy, but components are stopped with time: this can be fixed by protocol or based on the patient response. When employed with more than two components it is the "reverse pyramid" originally proposed by Wilske and Healey [10]. Van Gestel et al. [8] studied the addition of prednisolone to intramuscular gold in this manner. The dose of prednisone was lowered in several steps before it was completely stopped. The COBRA trial compared the combination of step-down prednisolone, methotrexate and sulfasalazine against sulfasalazine alone [1]. The prednisolone was rapidly tapered from 60 mg/ day in the 1st week to 7.5 mg/day in the 7th week, and held constant thereafter until week 28. At that point, it was tapered and stopped in 6 weeks time by protocol. At week 40, methotrexate was likewise tapered and stopped. The strategy of this trial is a hybrid between step-down and parallel, and clearly demonstrates the difficulty of an exact classification. As a two-arm trial, the design prevented a complete assessment of the relative contributions of the single components in the combination.

Step-up

In the step-up strategy, therapy is started as monotherapy and drug(s) are added in case of insufficient response to therapy, or to limit toxicity. A classical example is initial corticosteroid therapy in autoimmune disease (e.g., polymyositis) to which azathioprine or methotrexate is added with the intention of (partially) replacing corticosteroids.

Saw-tooth

The saw-tooth strategy starts as step-down, but allows reinitiation of stopped components in case of flares. The FinRACo trial [5] compared two strategies: a combination of hydroxychloroquine, sulfasalazine, methotrexate and prednisolone, where some individual components could be tapered and also stopped, and restarted as dictated by disease activity; and a strategy where patients were started on sulfasalazine, prednisolone could be added, and sulfasalazine could be replaced by other drugs (such as methotrexate) according to a specified protocol. The first strategy is saw-tooth, the second step-up or switch (see below). Saw-tooth is also the preferred strategy for many other severe autoimmune diseases with evidence of end organ damage, such as systemic lupus erythematosus and vasculitis, although with limited evidence to support it.

Methodology of combination trials 33

Switch

The switch strategy is the classical pyramid strategy when single drugs are administered. In combination treatments, one of the components can be switched with another drug, while the other component(s) are left untouched.

Conclusions

Theoretical considerations lead to an almost infinite number of combination strategies, even with our limited arsenal of antirheumatic drugs. In each disease, the primary choice is between maximum efficacy and minimum toxicity. This choice determines the most likely strategies that need further research. There is currently not enough evidence to firmly support any strategy. In early RA, developments are in the direction of aggressive early treatment, pointing to a preference of step-down over step-up. In other diseases step-up or saw-tooth strategies are more popular on the basis of clinical experience.

References

I. Boers M, Verhoeven AC, Markusse HM, Laar MA van de, Westhovens R, Denderen JC van, Zeben D van, Dijkmans BA, Peeters AJ, Jacobs P, Brink HR van den, Schouten HJ, Heijde DM van der, Boonen A, Linden S van der (1997) Randomised comparison of combined step-down prednisolone, methotrexate and sulphasalazine with sulphasalazine alone in early rheumatoid arthritis [published erratum appears in Lancet (1998) 351: 220]. Lancet 350: 309

2. Dougados M, Combe B, Cantagrel A, et al. (1999) Combination therapy in early rheumatoid arthritis: a randomised, controlled, double blind 52 week clinical trial of sulphasalazine and methotrexate compared with the single components. Ann Rheum Dis 58: 220

3. Fathy N, Furst DE (2001) Combination therapy for rheumatoid arthritis. Semin Immunopathol 23: (in press)

4. Felson DT, Anderson 11, Meenan RF (1994) The efficacy and toxicity of combination therapy in rheumatoid arthritis. A meta-analysis. Arthritis Rheum 37: 1487

5. Mdttdnen T, Hannonen P, Leirisalo-Repo M, et al (1999) Comparison of combination therapy with single-drug therapy in early rheumatoid arthritis: a randomised trial. Lancet 353: 1568

6. O'Dell J (1997) Combination therapy in rheumatoid arthritis: apparent universal acceptance. Arthritis Rheum 40 [SupplJ: S 119

7. Scott DL, Dawes PT, Tunn E, Fowler PD, Shadforth MF, Fisher J, Clarke S, Collins M, Jones P, Popert AJ, et al (1989) Combination therapy with gold and hydroxychloroquine in rheumatoid arthritis: a prospective, randomized, placebo-controlled study. Br J Rheumatol 28: 128

8. Van Oestel AM, Laan RF, Haagsma CJ, Putte LB van de, Riel PL van (1995) Oral steroids as bridge therapy in rheumatoid arthritis patients starting with parenteral gold. A randomized double-blind placebo-controlled trial. Br J Rheumatol34: 347

9. Verhoeven AC, Boers M, Tugwell P (1998) Combination therapy in rheumatoid arthritis - updated systematic review. Br J Rheumatol37: 612

10. Wilske KR, Healey LA (1989) Remodeling the pyramid - a concept whose time has come. J Rheumatol 16: 565

II. Williams HJ, Ward JR, Reading JC, Brooks RH, Clegg DO, Skosey JL, Weisman MH, Willkens RF, Singer JZ, Alarcon OS, et al (1992) Comparison of auranofin, methotrexate, and the combination of both in the treatment of rheumatoid arthritis. A controlled clinical trial. Arthritis Rheum 35: 259

Regulatory aspects of evaluating combination treatments in autoimmune diseases

P. Kurki

National Agency for Medicines, Helsinki, Finland

Introduction and scope

Thus far, attempts to control major autoimmune diseases by solo therapy have not been very successful in the prevention of end organ damage, Toxicity of long-term solo therapy is a dose-limiting factor with many agents, such as cytotoxic agents, other immunosuppressive agents and corticosteroids [7]. Combination therapies with existing therapeutic agents may be necessary for better control of autoimmune diseases.

Combination treatment is indeed commonly used in autoimmune diseases, especially in the most severe cases, although claims for combination therapy are rarely included in the marketing authorisation of the individual medicinal products. The safety and efficacy of the combination therapy in autoimmune diseases is often based on investigator-driven studies because rare autoimmune diseases and out of patent medicinal products are not attractive for commercial development. The mode of action of the individual components of the combinations is usually poorly known or is very broad, often cytotoxic. The development of these combinations has been largely empirical or has been based on clinical and pharmacokinetic profiles of the individual components [3].

The situation is changing, as new agents, especially anti-rheumatic agents are entering the market and the sponsors are eager to exhaust the full therapeutic potential of their products. Regulatory aspects must be taken into account if the marketing authorisation holders aim to make claims promoting the use of their product in combination with other medicinal products. Some regulatory requirements are also relevant for investigator-driven development of combination therapy since regulatory authorities supervise clinical trials in many countries.

This article focuses on the development of combination therapies in which the individual components interfere with the same features of the disease, such as symptoms and signs of inflammation and/or end organ damage. The development of fixed combinations and concomitant use of drugs for different purposes, as well as the

Correspondence to: Pekka Kurki, Department of Pharmacology, National Agency for Medicines, Mannerheimintie 166, P.O. Box 55, FI-00301, Helsinki, Finland, e-mail: [email protected]

36 P. Kurki

concomitant use of medicinal products with other therapies are outside the scope of this article.

The claim for combination therapy

Usually, the use of a medicinal product in combination with other agents is an extension to the original marketing authorisation for solo therapy. However, it is also possible that a new medicinal product is initially licensed for combination therapy. This may be necessary if the drug is not sufficiently effective alone, e.g. it is targeted only to a specific facet of the disease without affecting others. The combination may be claimed to be more effective or safer than existing solo therapies or existing combinations. There may be other advantages for combination therapy, such as avoidance of drug resistance or production of neutralising antibodies. Usually, the combination is for second line therapy when solo therapy is not effective or is not tolerated.

Role of guidance documents issued by the regulatory authorities

The regulatory authorities, such as the European Medicines Evaluation Agency (EMEA) and the Food and Drug Administration (FDA) in the United States, have issued numerous guidance documents for the development and evaluation of medicinal products. These guidelines are easily found in the web sites of the FDA (http://www-t"da.gov) and EMEA (http://www.emea.eu.int). Some of these guidelines are harmonised through the International Congress of Harmonisation (ICH). The lCH guidelines are recognised by regulatory authorities in North America, Japan, and the European Union. Thus, these guidelines need to be reviewed before planning for the development of combination therapies. There are only a few guidelines addressing combination therapy of autoimmune diseases. However, many guidelines, such as those dealing with statistical analysis, choice of a control group for clinical trials, pharmacokinetics, preparation of study reports, clinical development for medicinal products for children, and good clinical practice (OCP) are essential in the development of combination therapy. It is possible to deviate from the guidelines for good scientific, ethical or practical reasons.

Guidelines for autoimmune diseases and combination therapy: rheumatoid arthritis

Only two guidelines issued by the EMEA or the FDA deal with autoimmune diseases and combination treatment. Both guidelines deal with the development of slow-acting drugs for rheumatoid arthritis (RA).

The European document (Points to consider on clinical investigation of slow-acting anti-rheumatic medicinal products in RA. CPMP/EWP/556/95) states that the aims of the treatment are to relieve pain, improve or sustain function, to decrease inflammatory synovitis, and to prevent structural damage. For this purpose, drugs with different modes of action can be used either alone or in combination. The guideline reflects a situation where monotherapy is used for initial treatment. Combination therapy is considered for those patients in whom monotherapy has failed. Only paral-

Regulatory aspects of evaluating combination treatments in autoimmune 37

leI group design is acceptable as a means of assessing efficacy and safety. Two special study designs are mentioned; head to head comparison of an active substance and add-on to an ongoing active treatment with placebo as a comparator.

The FDA guideline (Clinical development programs for drugs, devices, and biological products for the treatment of rheumatoid arthritis) reflects a slightly different treatment strategy based on methotrexate as the base therapy. The FDA guideline states that it is inevitable that new agents will be used in combination with methotrexate and that the combination with methotrexate should be pursued at least from pharmacokinetic and safety points of view.

This guideline states further that combinations of anti-rheumatic drugs can be used in an attempt to improve outcomes and minimise toxicities. However, it warns that drug interactions may result in increased toxicity, even at lower than previously evaluated doses of either agent. This concern is especially evident for agents that have long half-life or non-selective activity, or for drugs that share common target organ toxicity. Thus, the guideline encourages the applicant to perform preclinical studies to predict clinical safety hazards.

Other guidelines dealing with combination therapy

It is obvious that one approach may not be suitable for all autoimmune diseases. Therefore, guidelines for non-autoimmune diseases may be helpful in understanding the regulatory aspects of different clinical situations. Guidelines for the development of combination therapies for HIV infection and for immunosuppressive treatment of acute transplant rejection may offer solutions for special problems of combination therapy. Only the European guidelines for the development of medicinal products for hypertension and cancer are reviewed here to highlight two situations where different strategies for combination treatment must be applied.

Combinations of medicinal products are commonly used to enhance the efficacy and tolerability of anti-hypertensive therapy. Studying hypertension has at least four major advantages over many other diseases with regard to the clinical development; there are plenty of patients, there is a convenient surrogate marker for efficacy (decrease in blood pressure), and the desired effect is obtained within a short period of time. Furthermore, the efficacy can be evaluated in placebo-controlled trials. Thus, the development of combination therapy for blood pressure should follow the strictest scientific standards that may not be feasible in many autoimmune diseases.

The placebo-controlled factorial study design titrating the doses of the individual components is preferred in the phase II studies. The optimal doses of the individual components are then tested in phase III. Phase III studies must demonstrate superior efficacy as compared to the individual components. Furthermore, the efficacy needs to be shown in patients who do not respond to monotherapy. The safety profile must be acceptable in comparison to the observed clinical benefit.

Cancer represents an example of a group of diseases where the high standards adopted for hypertension cannot always be followed. Combination therapy is the rule in many forms of cancer to obtain an acceptable benefit/risk and to avoid drug resistance. Most new anti-cancer drugs, except those for the last resort treatment, are compared to the best available established combination. In rare diseases, uncontrolled studies may be sufficient to grant a marketing authorisation in "exceptional circumstances" if the substance has "outstanding activity". Of course, relevant his-

38 P. Kurki

torical controls should be used in this situation and additional phase IV studies need to be performed. It is recommended that regulatory authorities be consulted in advance if only uncontrolled trials are planned for marketing authorisation.

When a new drug for cancer therapy advances from the last resort to second- and possibly to the first-line treatment, controlled trials against the established therapy, usually a combination therapy, must be performed. The efficacy of a new drug may be established as an add-on to an established drug or drug combination. The new drug (A) may also be studied as a substitute for another drug (B) in an established combination (e.g. B+C). The appropriate study design is A+C vs B+C. Entirely new combinations may be tested in clinical efficacy trials if appropriate preclinical and phase IIII studies are performed. In this case, the confirmatory trial is performed against an established combination.

Scientific advice

Regulatory guidelines are usually based on experience with previously authorised medicinal products. When the progress of science is rapidly applied to the development of new medicinal products, the existing guidelines may not always be applicable for novel types of combinations. In such a situation, scientific/regulatory advice should be sought. In the United States, scientific and regulatory guidance is built into the Investigative New Drug (IND) license. New questions can also be put to the FDA after marketing authorisation. In Europe, formal scientific advice is available from the EMEA through its scientific committee (CPMP). Two CPMP members and their experts initially review the questions. Their reports are then consolidated and approved by the CPMP. Less formal scientific advice is available through national regulatory agencies.

Most autoimmune diseases are rare. Thus, medicinal products for autoimmune diseases may be eligible for an orphan drug status. An orphan drug status may also be applied for for a drug that is used in combination with other medicinal products provided that the combination offers a substantial benefit to the patient. Both FDA and EMEA will give protocol assistance for trials in rare diseases. The orphan drug legislation is especially useful for organisations that lack resources andlor knowledge in drug development.

Preclinical development of combination therapies

There must be a rationale for the choice of a given combination of medicinal drugs. In general, the combination can only be useful if the mode of action and adverse effect profiles of the individual components are different. This may be demonstrated by in vitro studies and by using relevant animal models [9]. Preclinical studies should clarify whether the combination is synergistic or additive, and give guidance for the dosing in clinical trials. However, synergy observed in vitro or experimentally in vivo, has not always been observed in clinical trials.

The applicant must provide a full package of preclinical documentation for a drug combination if one of its components is a new active substance. It may be appropriate to perform long-term toxicological or carcinogenicity studies if the combination is suspected to have harmful pharmacokinetic interactions or to aggravate known ad-


verse effects of the individual components. Studies on drug resistance may be relevant in autoimmune diseases. Immunogenicity of the biotechnological products may sometimes be reduced if the drug combination is strongly immunosuppressive [6].

Phase I and II clinical studies

Usually, the safety of the individual components must be known before embarking on clinical development of a combination. Initial combination with existing background therapy may be considered in special circumstances and with good preclinical documentation [8]. The pharmacokinetic profile of the individual components as well as their possible pharmacokinetic drug-drug interactions need to be studied. If pharmacokinetic interactions are demonstrated, further studies may be necessary to adjust the dosages or to exclude the clinical significance of the observed interaction. Ideal dose-finding studies may be difficult in autoimmune diseases because of several factors, such as paucity of suitable patients and lack of convenient clinical endpoints or their validated surrogates. As a compromise, studies may allow escalation of the dose of the individual components according to their efficacy and tolerability. In general, the doses of the combination should be below or at the lower end of the therapeutic range established for solo therapy.

Phase III studies: first line therapy

The studies must be properly designed to prove the advantages of the combination over the individual components. If possible, the combination must be compared to its individual components in a randomised clinical trial. A placebo arm will be useful to prevent problems if the performance of the solo therapy arms is in doubt or if one is aiming to demonstrate non-inferiority. Crossover studies are rarely possible in autoimmune diseases in which relapses and spontaneous remissions/improvement are common and a carry-over effect is to be expected. An uncontrolled study design with an initial placebo phase may be considered in very rare autoimmune diseases if the efficacy and safety is supported by data from other indications [2]. Blinding of the patients and treating physicians may not always be possible or feasible in the long term. In such cases, one should perform a blinded evaluation of the primary endpoint(s).

The observed advantage must be clinically significant to justify the use of a combination, especially if the tolerability is worsened or if the need for monitoring is increased. In doubtful cases, a confirmatory trial is needed. It is recommended that the endpoints of the study measure a clinically significant feature of the disease. Ambitious endpoints, such as those measuring end organ damage, are recommended. In such trials, the duration of the treatment needs to be longer than in trials focusing on symptomatic relief. For instance, studies aiming to demonstrate a retardation of joint damage in RA should last at least 12 months. However, a longer follow up is usually needed, possibly as a post-approval commitment, to confirm the duration of the effect and to ensure the long-term tolerability.

Regulatory authorities have made recommendations for suitable endpoints for studies of certain autoimmune diseases, such as RA and related rheumatic conditions. If regulatory guidelines are not available, recommendations of the learned so-

40 P. Kurki

cieties, such as the European and International Leagues Against Rheumatism (EULAR and ILAR) as well as the American College of Rheumatology (ACR) may be followed. Other less formal organisations, such as the Conferences on Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT), have made credible recommendations in this area. If no generally accepted endpoints are available, the validity of the primary endpoints must be demonstrated. Validated combined indices may be superior to individual measurements. If the aim of the combination is to improve tolerability, one should ensure that the efficacy of the new combination is equivalent or at least non-inferior to the standard therapy.

Phase III studies: add-on design

By definition, these studies cannot lead to a first line indication. The patients are chosen on the basis of an insufficient response to a generally recognised base therapy. Patients are then randomised to either placebo or active drug. The add-on strategy has been applied in the development of several combination therapies for rheumatoid arthritis. In these combinations, methotrexate has been the base and other drugs, such as cyclosporin or TNF inhibitors have been added on. In add-on studies, it is crucial that the insufficient response to the maximal recommended and tolerated dose of the base medication has been demonstrated [6]. A practical design will allow dose adjustment of both components in case of tolerability problems. However, dose escalation may lead to difficulties in interpretation of the results.

The add-on study design does not prove that the continuation of the base medication is necessary when the disease activity has been stabilised. This can be addressed in studies where patients who obtained a remission or improvement with the combination are randomised to either continue or discontinue the base medication [I]. In this setting, the ethical problem in treating active disease with placebo is avoided since the study endpoint is reached if relapse occurs.

If the combination has more than two components, the development according to the strictest scientific standards becomes very cumbersome. One possibility is to have a sequential development where combination with two agents is developed first and other agents are added on in a placebo-controlled manner.

Conclusions

The possibilities for rational combination therapy improved with the introduction of new non-cytotoxic drugs with a defined mode of action. The practical difficulties in demonstration of efficacy of combination therapy for autoimmune diseases are qualitatively the same as those for solo therapy [4]. The additional hurdle is due to the study designs. Combinations of new, often biotechnological agents, and old medicinal products have been successfully applied by using the add-on or even the "combo" vs single components design [51. However, it must be realised that scientifically ideal study designs are not always feasible for ethical and logistic reasons. In the field of autoimmune diseases, as for other severe and chronic diseases, compromises have to be made in order not to block the progress in patient care. Experience gained in other areas, such as cancer, acute transplant rejection, and HIV infection, may be helpful. These areas may offer good (and also bad!) examples for the development of


combination treatments in difficult circumstances. The present guidelines for autoimmune diseases are not very helpful for the development of combination therapies. However, regulatory authorities are pleased to offer scientific and regulatory advice for developers of combination therapies on a case by case basis.

Acknowledgements. I am indebted to Dr. Markku Toivonen, M.D. and Prof. Olavi Tokola, M.D. from the National Agency for Medicines as well as to Dr. Kent Johnson from the ED.A. for their helpful comments on drafts of this article. Opinions in this article should not be regarded as otlicial regulatory views of any regulatory body.

References

I. Clegg DO, Dietz F, Duffy J, Will kens RF, Hurd E, Germain BF, Wall B,Wallace DJ, Bell CL, Siekman J (1997) Safety and efficacy of hydroxychloroquine as maintenance therapy for rheumatoid arthritis after combination therapy with methotrexate and hydroxychloroquine. J Rheumatol 24: 1896

2. Feldman BM (2000) Innovative strategies for trial design. J Rheumatol 27 rSuppI58]: 4 3. Furst D (1996) Clinical pharmacology of combination DMARD therapy in rheumatoid arthritis.

J Rheumatol 23 [SuppI44J: 86 4. Johnson K (1996) Efficacy assessment in trials of combination therapy for rheumatoid arthritis.

J Rheumatol 23 [Suppl 441: 107 5. Keystone EC (1999) The role of tumor necrosis factor antagonism in clinical practice. J Rheumatol

26 [Suppl 57]:22 6. Kremer JM (1998) Combination therapy with biologic agents in rheumatoid arthritis: perils and prom

ise. Arthritis Rheum 41: 1548 7. Langford CA, Klippel JH, Balow JE, James SP, Sneller MC (1998) Use of cytotoxic agents and cyclo

sporine in the treatment of autoimmune disease. Part I: Rheumatologic and renal diseases. Ann Intern Med 128: 1021

8. Moreland LW (1996) Initial experience combining methotrexate with biologic agents for treating rheumatoid arthritis. J Rheumatol 23 rSupp1441:78

9. Williams RO (1998) Combination therapy in mice: what can we learn that may be useful for understanding rheumatoid arthritis') Springer Semin Immunopathol 20: 165

New therapies in development for autoimmune diseases: their rationale for combination treatment

v. Strand

Clinical Professor (YCF), Division of Immunology, Stanford University School of Medicine, Portola Yalley, CA, USA

Introduction

Over the past decade, combination therapy has emerged as the preferred treatment for severe as well as early aggressive rheumatoid arthritis (RA). This therapeutic approach has been driven by recognition that RA is not only debilitating disease with significant morbidity, but that it can cause premature mortality. Even though methotrexate (MTX) has become a "gold standard" of therapy, its use rarely results in disease remission. The recent introduction of new treatments which offer significant incremental improvements in both efficacy and tolerability argues strongly for utilization of combination therapy.

A variety of novel agents for treatment of systemic lupus erythematosus (SLE) are currently in clinical trials. Despite challenges posed by this heterogeneous, multisystem disease and limited available clinical trial methodology, recognition of a large unmet therapeutic need has fostered interest in the development of new treatments.

Current scientific and clinical data indicate this to be a particularly opportune time to consider combination therapy in both clinical indications, as well as in other autoimmune disorders including systemic sclerosis (SSc), seronegative spondyloarthropathies and Sjogren's syndrome. Although certain agents could be utilized in both RA and SLE, our ability to target specific biological processes can also lead to the application of opposing therapeutic agents in each disease.

Scientific rationale

The complexities of the immune system pose a significant challenge when attempting to optimize therapeutic benefit and minimize risk. Cytokines have pleiotropic

Correspondence to: Yibeke Strand, Clinical Faculty (YCF), Division of Immunology, Stanford University School of Medicine, 306 Ramona Road, Portola Yalley, CA 94028, USA

44 V. Strand

effects; simultaneous autocrine and paracrine regulation of cytokine expression complicate even the most simplistic understanding of immune regulatory networks. We frequently speak of the "inflammation cascade". Considering many of the agonistic as well as antagonistic, pro- and anti-inflammatory stimuli and responses, "inflammation chaos" may be the better term. Furthermore, understanding immunoregulatory circuitry in animal models may not elucidate mechanisms which predominate in human disease, especially as in vitro and/or ex vivo assays cannot be expected to accurately reflect immune responses occurring in vivo. Down-regulating synthesis and/or secretion of a single cytokine, or intervening at a single point in the inflammation "cascade" may not be sufficient to alter the course of well-established autoimmune disease, especially in heterogeneous human populations.

Theoretically, combination therapy utilizing two or more biological agents in both RA and SLE offers the opportunity to modulate important symptomatic and objective manifestations. Targeting multiple sites in the disease process may amplify as well as prolong these effects. Agents designed to block both T cell activation and T cell-B cell collaboration may be especially useful in early disease; their use in combination may result in long-term benefit, even in established disease.

Clinical rationale

Many observations support the use of combination therapy in RA. Long-term compliance with any disease-modifying antirheumatic therapy (DMARD) is poor. With the possible exception of MTX, most lose efficacy and/or develop toxicity in a majority of patients within several years of treatment. Lessons learned in other disease indications such as cancer, hypertension, congestive heart failure and tuberculosis indicate combination treatment to be more effective than single agents.

The pathophysiology of RA is complex and poorly understood. The inciting event which results in early disease manifestations remains elusive. Mechanisms which may explain initiation of disease appear different from those perpetuating the inflammatory process. Interaction of multiple immune effector mechanisms is believed to result in chronic disease, including: endothelial cell activation, stimulation of angiogenesis; ongoing T cell and B ceIl activation and proliferation; recruitment, activation and proliferation of antigen-presenting cells as weIl as monocyte/macrophages; and persistent cytokine and metalloproteinase secretion with continued auto- and paracrine up-regulation of their expression.

Therapeutic efforts in SLE may result in combination therapy, planned or unplanned. Flares or new organ system involvement occur despite apparent control of mild yet persistent symptoms, requiring increases in corticosteroid doses and/or addition of immunosuppressive medications. Several biological therapies under development as potential treatments for SLE are designed to interfere with specific immune responses, to avoid generalized immunosuppression. These agents are believed to be most beneficial in early disease, where short-term treatment may result in longterm effects. Nonetheless, these interventions could be effective at all stages of disease, especiaIly in combination, and may well be used with background traditional therapies.

New therapies in development for autoimmune diseases

Promising therapeutic agents: rationale for combination therapy

A variety of promising therapeutic agents are under development, designed to:

1. Regulate cytokine production

Blocking proinflammatory cytokines in RA Up-regulating anti-inflammatory cytokines in RA Up-regulating anti-inflammatory cytokines in SLE

2. Interfere with antigen-MHC class II-T cell receptor (TCR) interactions

TCR peptides in RA MHC class II antagonists in RA Oral tolerance in RA and SSc

45

3. Block coactivation signalling: interrupting T cell activationff cell-B cell collaboration

CTLA-4Ig in RA and SLE Anti-CD40 ligand (CD40L) monoclonal antibody (mAb) in SLE and RA Combination anti-CD40L mAb+CTLA4-Ig in SLE

4. Interrupt the inflammatory process

Inhibiting complement activation in RA and SLE Interfering with adhesion molecule expression/function Interfering with chemokine expression/function Inhibiting angiogenesis Altering Fas/Fas ligand (FasL) expression Inhibiting cartilage degradation and bone destruction in RA

It is appealing to think that the mechanistic effects of these new therapies will be sufficiently specific to allow combination use, sequentially as well as simultaneously, or as induction followed by maintenance therapy.

Regulating cytokine production

Immune responses have been categorized as T helper (Th) cell Thl and Th2 dominant. The Thl profile, characterized by IL-2, IL-12, interferon-y (IFN-y) TNF-a and IL-18 production, is dominated by cell-mediated responses, and is considered prominent in RA, acute graft versus host disease [GvHD], Crohn's disease and multiple sclerosis [61]. The Th2 profile, dominated by antibody-mediated responses, includes IL-4, -5, -9, -10 and -13 up-regulation and characterizes SLE, chronic GvHD, and SSc. Although these profiles are based predominantly on murine models, and may not be directly applicable to human disease, they nonetheless help in explaining contrasting responses to immune interventions in different autoimmune diseases.

Data derived predominantly from murine models of autoimmune disease indicate that Thl and Th2 cytokines negatively regulate each other's expression and function, and may have opposing effects [70]. For example, IL-lO and IL-4 suppress Thl responses synergistically, and are anti-inflammatory in collagen-induced arthritis, particularly decreasing cartilage damage [16, 39, 79]. In contrast, administration of IL-10 accelerated onset of disease in the NZB/W murine model of SLE, whereas treatment with anti-IL-1O mAbs delayed onset of glomerulonephritis and increased survival [37].

46 V. Strand

Combination therapy utilizing agents to inhibit IL-l f3 and TNF-a offer a rational and very promising approach to the treatment of active RA, especially in patients with incomplete and/or disappointing clinical responses to the recently introduced therapeutics. Both IL-l f3 and TNF-a are required for commitment and differentiation of fetal thymocytes [106]; mediate host responses to, as well as the effects of, inflammation, and sepsis [9, 17]. In animal models: collagen-induced, streptococcal cell wall- and antigen-induced arthritis, and cytokine-specific-knockout mice, TNFa appears predominantly responsible for systemic symptoms of inflammation and IL-l f3 for perpetuation of synovial cell infiltration with resultant bone and cartilage damage [100]. In transgenic mice that overexpress human TNF-a, IL-l acts in series with TNF-a to mediate the arthritic disease [81]. Combining antagonists to IL-lf3 and TNF-a appear synergistic in both collagen- and adjuvant-induced animal models of arthritis [8, 20].

Gene therapy in animal models of inflammatory arthritis has exemplified the potential synergy of anti-cytokine therapy. In antigen-induced arthritis in rabbits, adenoviral gene transfer of a combination of soluble receptor antagonists of IL-l f3 and TNF-a (sIL-IRI and sTNF-a RI) resulted in additive, if not synergistic effects, in the treated joint and reduced synovitis in the contralateral joint [27].

Blocking proinflammatory ctytokines in RA

Recently, IL-12, IL-15 and IL-18 have been shown to act synergistically with IL-If3 and TNF-a, as pro-inflammatory cytokines in RA, up-regulating Th 1 immune responses.

Anti-IL-I2 mAb

IL-12 is primarily released by antigen-presenting cells in response to immune stimulation [94]. It induces IFN-y production and increases natural killer (NK) and cytotoxic T cell-mediated cytoxicity. Treatment with anti IL-12-mAbs prevents development and progression of collagen-induced arthritis, and abrogates experimental colitis [58,74]. Combination therapy with anti-IL-12 and anti-TNF-a mAbs in collageninduced arthritis resulted in synergistic effects, suggesting a new approach for treating RA, although absolute levels of IL-12 in RA synovium do not appear to be elevated [69]. A human anti-IL-12 mAb is currently in clinical trials in RA and Crohn's disease.

IL- 15 antagonists

IL-15, synthesized by macrophages and fibroblasts, up-modulates Th 1 immune responses. It induces T cell chemotaxis and activation, maturation and isotype switching of B cells, up-regulates NK cell cytotoxic activity, and activates neutrophils. Administration of a soluble fragment of IL-15 receptor significanly prevented collageninduced arthritis clinically and by histological evaluation [86]. These results suggest antagonists to IL-15 could offer therapeutic benefit in RA.

New therapies in development for autoimmune diseases 47

IL-I8 antagonists

Recently, IL-18 has been cloned and shown to have powerful Th I-promoting activities in synergy with IL-12. Pro-IL-18 is cleaved by IL-I [3 converting enzyme (ICE) yielding the active protein, which induces Thl T cell proliferation, IL-2 receptor expression, and IFN-y, TNF-a and granulocyte/macrophage colony-stimulating factor (GM-CSF) production. Elevated levels of IL-18 are present in RA synovium [29]. Structurally, IL-18 resembles IL-I; functionally, it resembles IL-12; acting synergistically with IL-12 and IL-15 it can also independently induce and sustain Th 1 responses via direct effects on synovial macrophages [49]. Antagonists to IL-18 may be beneficial in the treatment of active RA.

Up-regulating anti-inflammatory cytokines in RA

IL-4

IL-4 inhibits monocyte expression of the pro-inflammatory cytokines IL-l [3, TNF-a, IL-6, IL-8, IL-17 as well as synovial cell GM-CSF and matrix metalloproteinase (MMP) production. Although IL-4 administration improved disease manifestations in several animal models of autoimmune disease, phase I trials with recombinant human IL-4 in RA demonstrated little therapeutic benefit [82]. This product is no longer in clinical development.

IL-IO

IL-IO inhibits production of pro-inflammatory cytokines and chemokines [including IL-Ia, IL-l[3, IL-6, IL-8, IL-12, TNF-a, GM-CSF and macrophage inflammatory protein (MIP-I)] by monocytes, polymorphonuclear white cells and eosinophils [44]. Administration of IL-IO ameliorated established collagen-induced arthritis; clinical and histological effects were equivalent to anti-TNF-a mAb treatment. Of interest, combination therapy with IL-4 and IL-I 0 synergistically ameliorated disease in this animal model [95].

The potential role of IL-IO for treatment of RA was suggested by a relative deficiency of IL-I 0 production in patients with active disease. Inhibitory effects of IL-I 0 on cytokine and chemokine production in RA synovial fluid and synovial cell cultures indicated that cell surface receptors for IL-I 0 were not saturated, suggesting a relative IL-IO deficiency. A phase I multicenter, placebo, double-blind randomized controlled trial (RCT) examining daily SQ recombinant human IL-IO in patients with active disease demonstrated decreased peripheral blood mononuclear cell (PBMC) production of IL-I [3 and TNF-a in vitro, following phytohemagglutinin (PHA) stimulation and up-regulated expression of soluble TNF receptors (types 1 and 2) and IL-lra [56]. Combination IL-IO therapy with MTX in patients failing MTX alone showed additive clinical benefit.

Gene therapy introducing IL-4 and/or IL-l 0 expression supports the use of these anti-inflammatory cytokines in the treatment of active RA. Adenoviral-induced expression of ILA in knee joints of mice with collagen-induced arthritis prevented cartilage destruction [54]. Overexpression ofIL-lO induced by gene transfer into human

48 v. Strand

synovial fibroblasts inhibited cartilage degradation in scm mouse recipients [71]. Local as well as systemic introduction of IL-I 0 expression prevented development of collagen-induced arthritis [4,55,99].

Up-regulating anti-inflammatory cytokines in SLE

Anti-IL-10 mAbs in SLE

Serum levels of IL-l 0 are increased in patients with active SLE and correlate with disease activity; increased spontaneous production of IL-IO in PBMC cultures from SLE patients can be further stimulated by immune complexes [77,85]. Interestingly, IL-IO levels are elevated in first degree relatives of SLE patients, as well as in spouses in multi-case families, suggesting environmental factors playa role [2, 32]. These alterations in IL-IO and transforming growth factor-j3 (TGF-j3) regulation are hypothesized to result in accelerated T cell apoptosis and defective T cell regulation of B cell antibody production [3]. Treatment of pre autoimmune NZBIW mice with anti-IL-IO mAbs delayed onset of disease; continuous administration of IL-IO accelerated it [37]. Administration of anti-IL-IO mAbs abrogated anti-double-stranded (ds) DNA antibody production in scm mice injected with mononuclear cells from SLE patients [52]. In a pilot, open label trial, impressive improvements in cutaneous disease were reported in six patients with active, steroid-dependent SLE receiving daily intravenous doses of a murine anti-IL-I0 mAb for 21 days, with variable responses in arthritis, serositis and renal manifestations, and one patient with pancreatitis [51]. Confirmation of these results in an RCT with a human mAb are eagerly awaited.

TGF-{3 in SLE

It has been possible to alter disease course in murine SLE following intramuscular injections of naked DNA encoding various cytokines [18]. Naked DNA encoding TGF-j3 production has successfully treated disease in NZBIW mice [83].

Interfering with antigen (peptide)-MHC class II-TCR interactions

Interventions including immunization with TCR-derived peptides and MHC class II peptides have so far demonstrated modest clinical benefit with little or no clinical toxicity. These interventions remain attractive therapeutic options due to ease of administration and excellent tolerability. Their future use in combination with a wide variety of "background therapies" can be readily envisioned, provided concomitant treatments are specifically targeted and not broadly immunosuppressive. Although the "putative inciting antigen" remains elusive in RA (and SLE), data supporting interventions which interfere with antigen-MHC class 11-TCR interactions in SLE are obviously lacking. Moderately successful clinical interventions in RA require confirmation, and may not be applicable in SLE. Regardless, these therapies could offer significant clinical benefit when utilized in early disease, with little toxicity, and may be synergistic in combination with promising other mechanism specific agents.


TCR peptides in RA

Clonal expansion of antigen-specific arthritogenic T cells has been demonstrated in collagen- and adjuvant-induced arthritis. Immunization with synthetic pep tides based on TCR expressed by antigen-specific T cells prevented or ameliorated disease, presumably by stimulating regulatory T cell subsets [34]. Similar preferential expansion of antigen-specific T cells has been sought in humans, with mixed results. Most published data indicate that synovial T cell infiltrates in RA are heterogeneous. Overexpression of specific TCRs (Vj33, 14, 17) has been demonstrated in synovial cell cultures following IL-2 stimulation [76, 92]. In a placebo RCT, immunization of patients with active RA using Vj33, 14 and 17 TCR peptides (with incomplete Freund's adjuvant) demonstrated clinical benefit compared with control [68]. Recently a multicenter, placebo RCT in 340 RA patients showed modest clinical benefit in those receiving less than 7.5 mg/day prednisone, or with early disease [60]. Further studies are currently underway to confirm and expand these data.

MHC class II antagonists in RA

Administration of anti-MHC class II mAbs to block peptide-MHC binding have improved collagen-induced arthritis, as has immunization with DRbl-derived peptides [25, 101]. The shared DR epitope is present in over 50% of patients with RA. An initial study of DR4IDRI peptide (+alum) immunization in patients with active RA, heterozygous for HLA DR4, suggested clinical efficacy in those receiving injections every 6 weeks as compared with every 8 weeks or placebo treatment [90]. Injections were well tolerated; specific serum reactivity to DR4/DRI peptide was not detected. No biological effects of treatment were evident, as measured by absolute lymphocyte counts and responses to tetanus toxoid booster injections. Additional trials are expected.

Oral tolerance in RA and SSc

Repeated low doses of antigen administered orally or nasally appear to generate antigen-specific hyporesponsiveness, presumably by induction of regulatory Th2 cells and/or release of anti-inflammatory cytokines. Confirmatory data exist in multiple animal models of autoimmune disease, including collagen-induced and adjuvant arthritis [72, 104]. Unfortunately, RCTs utilizing either chicken or bovine collagen preparations in patients with active RA failed to demonstrate convincing efficacy [7, 41]. Recently, McKown et al. [62] published an open label pilot trial in SSc, suggesting that these disappointing results might be attributable to concomitant administration of NSAIDs, thereby preventing establishment of oral tolerance due to loss of an intact gastrointestinal mucosal barrier. An intriguing hypothesis, this warrants confirmation in an RCT, currently underway. If positive, oral (or nasal) tolerance may offer an attractive therapeutic modality in patients with recent onset of disease. Theoretically it could readily be used in combination therapy, with careful consideration in view of the prevalent polypharmacy in RA.

50 V. Strand

Coactivation signal blockade: interrupting T cell activationIT cell-B cell collaboration

Following antigen-MHC class II interaction and subsequent TCR binding, co-stimulatory molecules provide the essential "second signal" for T cell activation, and subsequent T cell-dependent B cell activation and isotype switching. Two important systems have been identified: CD40/CD40L (gp39) and CD28/CTLA4-B7-l/B7-2 interactions.

CD40 is distributed on B cells, dendritic cells, macrophages and endothelial/epithelial cells. CD40 and CD40L knockout mice have defective humoral immunity [31]. CD40 interacts with its ligand, CD40L, expressed by T cells, basophils and eosinophils, when activated. CD40-CD40L interactions result in proliferation and differentiation of B cells [23, 30]. B7-1 and B7-2, expressed on activated B cells, T cells, and antigen-presenting cells, act as counter-receptors for CD28 and CTLA-4. Although CD28 is constitutively expressed on T cells, surface expression of CTLA4 occurs only with T cell activation [50]. CD28 binding to B7-l/B7-2 initiates, whereas CD28-CTLA4 binding down-regulates T cell responses.

Anti-CD40L mAb in SLE

Increased and prolonged expression of CD40L by peripheral T and B cells from patients with active SLE has been demonstrated, as well as up-regulated expression in proximal tubules and glomeruli in patients with renal manifestations [103]. Treatment with anti-CD40L mAbs prevented or improved nephritis in NZBIW mice and collagen-induced arthritis [66]. Importantly, administration of anti-CD40L mAbs preserved renal function in SNFI mice with established nephritis [42].

Two commercial products have been studied in clinical trials in SLE. Following encouraging data in chronic refractory idiopathic thrombocytopenic purpura (ITP) , clinical development of one product was placed on hold, due to reported thromboembolic complications. Yet, preliminary data indicated two- to eightfold decreases in peripheral B cell counts in four of five treated patients with concomitant decreases in the number of anti-ds DNA antibody-producing B cells [13].

Clinical trials in SLE with a second product, well tolerated in phase I trials, were discontinued after data in a phase II trial in 85 patients failed to show significant differences active between active and placebo treatment [14,43].

CTLA-Ig in RA and SLE

A soluble fusion protein of CTLA4 and the Fc portion of IgGI, CTLA4-lg, binds to CD28 with higher affinity, thereby preventing B7-IIB7-2 interactions. Treatment with CTLA4-lg prevents or ameliorates collagen-induced arthritis and nephritis in NZBIW mice [21, 84]. Similarly, adenoviral-mediated gene transfer of CTLA4-Ig to NZBIW F1 mice delayed autoantibody formation and proteinuria [11].

Preliminary data demonstrating a low incidence of GvHD in 5 of 12 patients who engrafted following allogeneic bone marrow transplant and pre-incubation of donor marrow cells with CTLA4-Ig in the presence of irradiated recipient PBMCs are consistent with induction of antigen-specific anergy [33]. Although exciting, these early


data require confirmation. Phase I trials have shown recombinant human CTLA4-lg to have a long plasma half-life of 15-16 days without immunogenicity. Preliminary data in patients with psoriasis treated four times in 1 month demonstrated sequential improvement for as long as 3 months, without abrogation of primary immune responses [1]. Clinical trials in RA are underway; protocols in other autoimmue disease indications are eagerly awaited.

Combination anti-CD40L mAb and CTLA4-Ig therapy in SLE

Both therapeutic interventions are attractive, as they should be applicable to RA as well as SLE, psoriasis and other autoimmune diseases, and easily additive to non-immunosuppressive background therapy. Although blockade of co-activation signals theoretically may be less effective in established disease of long duration, early clinical data suggest that such interventions may be effective at all stages. Preclinical data indicate that brief treatment courses resulting in simultaneous blockade of both coactivation signals may lead to durable clinical responses without immunosuppression. Two weeks of treatment in NZBIW mice at onset of disease, approximately 5 months of age, utilizing combination therapy resulted in long-term benefit [12]. In comparison to similar regimens with anti-CD40L mAb or CTLA4-lg alone versus combination, survival at 15 months was zero, 18% and 70%, respectively. This combination has down-modulated even advanced disease, and offered benefit with repeated administration [96].

Clinical trials continue with CTLA4-lg in RA, and are eagerly awaited in SLE. Initial enthusiasm supporting use of anti-CD40L mAbs has obviously been tempered; nonetheless, it is hoped additional clinical trials will follow.

Interrupting the inflammatory process

Several therapeutic agents have been targeted to interrupt underlying inflammatory processes in RA, SLE and other autoimmune diseases. Although the inciting events and/or mechanisms which lead to persistent inflammation may differ, certain pathophysiological responses appear common. These include: complement activation, upregulation of adhesion molecule and chemokine expression and function, stimulation of angiogenesis and signals leading to apoptosis, such as Fas/FasL expression. Specific to RA and evident in other inflammatory conditions (including aging) are processes which promote cartilage degradation and stimulate bone destruction, contributing to osteoporosis.

Inhibiting complement activation in RA and SLE

The classical and alternate complement pathways are frequently activated in immune complex-mediated diseases such as RA and SLE; they converge at complement 5 (C5) to form pro-inflammatory C5a molecules and the membrane attack complex, C5b-9. Complement activation is a marker of active SLE; normalization of serum complement levels are used to assess treatment responses and predict long-term outcome.

52 V. Strand

An mAb to C5 was designed to bind C5 and inhibit its cleavage to the inflammatory mediators, C5a and C5b [59]. Treatment of NZBIW mice with an mAb to murine C5 delayed onset of disease and prolonged survival [97].

A chimeric mAb composed of murine complementarity determining regions recognizing human C5 engrafted onto a human IgG2 F(ab'h and a human IgG4 Fc region (hgG 1.1 mAb) is in clinical trials in RA and SLE. Treatment resulted in sustained inhibition of complement activation in C5-deficient mice reconstituted with human C5 [98]. In a phase I clinical trial in normal volunteers, anti-C5 mAb administration inhibited serum hemolytic complement activity for 12-24 h in a dose-dependent fashion. Well tolerated in phase I trials in RA, it is currently in evaluation in RA, psoriasis, dermatomyositis, bullous pemphigoid, membranous nephritis and SLE nephritis.

Interfering with adhesion molecule expression/function

Recognizing the critical role played by adhesion molecules in mediating recruitment of leukocytes to sites of inflammation, a variety of therapeutics designed to interrupt their transcription, translation, cell surface expression and/or interaction with specific ligands, are currently under development [67]. These include: mAbs to intercellular adhesion molecule type 1 (lCAM-l) and several integrins and selectins, soluble ICAM-l receptors, soluble VCAM-l, oligosaccharide analogs of E- and L-selectins. Murine mAbs to ICAM-l and LFA-l have ameliorated manifestations of antigen-induced arthritis in rabbits, adjuvant arthritis in rats, and collagen- and proteoglycan-induced arthritis in mice [36,38,40,64]. Preliminary studies have demonstrated delay in development of lupuslike disease in parental mice injected at birth with Fl hybrid spleen cells [63].

A murine IgG2a mAb against ICAM-l was evaluated in open label protocols in patients with RA; improvement was observed in some patients for as long as 3-11 months [46, 47]. Increased circulating numbers of IL-2 receptor-positive (CD25+) CD4 cells suggested that administration of mAb altered lymphocyte recruitment into the synovium. Cutaneous anergy during active therapy, with subsequent reversal, was observed in some patients [15, 87, 88]. Although promising, repetitive treatments with this murine mAb resulted in hypersensitivity reactions.

An antisense oligodeoxynucleotide (ISIS 2302) inhibits ICAM-l expression. Following positive results in patients with steroid-dependent, refractory Crohn's disease, a pilot placebo-controlled trial in RA was initiated [57, 102]. Clinical responses were evident at 4-6 months, following intravenous infusions every other day for 26 days, consistent with a delayed but meaningful treatment effect. Administration of a humanized mAb to the beta2 integrin CD 18 in four of five patients with vasculitis resulted in prompt clinical improvement [53].

Recently, combined administration of mAbs to ICAM-I and CD40L were reported to be synergistic in established collagen-induced arthritis, even reversing clinical manifestations of inflammation in some animals [89]. Combination therapy reduced antibody levels to collagen II, which was not evident in animals receiving either treatment alone.

Interfering with chemokine expression/function

Chemokines include a superfamily of small secreted proteins which are chemoattractant and direct migration of leukocytes to sites of inflammation. Each family has its


own chemotactic "fingerprint", and many are highly expressed in RA synovial tissue (CC family: RANTES, MIB-Ia, MIP-Ib, MCP-I; CXC family: IL-8, GRO-a, ENA-78). Therapies directed against chemokines include inhibitors of chemokine production and agents which interfere with their interaction with specific receptors.

IL-8 induces synovial inflammation when injected into a rabbit knee, and is a potent mediator of angiogenesis [93]. A human mAb to IL-8 is in clinical trials in psoriasis and RA.

Based on preclinical data, several other chemokine inhibitors offer promise in the treatment of RA, SLE and other autoimmune diseases. A polyclonal antibody directed against RANTES, chemoattractant for T lymphocytes and monocytes, improved manifestations of adjuvant-induced arthritis, equipotent with indomethacin [6]. MetRantes, a modified chemokine receptor antagonist that interacts with several CC chemokine receptors, ameliorated collagen-induced arthritis [78]. Passive immunization with mAbs against either MIP-Ia or MIP-2 delayed the onset and reduced severity of collagen-induced arthritis [45]. Monocyte chemoattractant protein I [MCP-I (9-76], a truncated form of MCP-I, a potent antagonist of the chemokine receptor CCR2, prevented onset of arthritis in the MRLllpr murine model of SLE [28].

Inhibiting angiogenesis

Angiogenesis contributes to establishment and maintenance of synovial pannus, production of IL-I, IL-6, IL-8 and vascular endothelial growth factor (VEGF), as well as reactive oxygen species. Identification of multiple mediators stimulating angiogenesis, potentially contributing to the persistent inflammatory process in RA, has offered another important target for treatment. These include platelet-derived growth factor (PDGF), epidermal growth factor (EGF), insulin-like growth factor I (IGF-l), hepatocyte growth factor (HGF), fibroblast growth factors (FGFs) and TGF-f3. VEGF is an endothelial cell selective growth factor, acting synergistically with other chemokines. Effects of angiogenic factors such as VEGF, basic FGF and TGFs are mediated in part by the integrin family of cell adhesion molecules, including aVB3, highly expressed in RA synovium [48].

An early therapeutic approach involved use of AGM-1470, a derivative of fumigillin, which inhibited VEGF and angiogenesis in adjuvant- and collagen-induced arthritis, and was synergistic with Taxol and cyclosporin [75]. A soluble form of the VEGF receptor was effective in treating collagen-induced arthritis [65]. A peptide antagonist of the integrin, aVB3, was effective in treating antigen-induced arthritis, as was an orally active aVB3 receptor antagonist in adjuvant arthritis [5]. Injection of phage expressing an a VB3-binding peptide on its surface selectively homed to inflamed joints and effectively treated collagen-induced arthritis [26]. Together, these data indicate that potent inhibitors of angiogenesis may offer effective treatments for active RA, and could be utilized in combination with agents targeted to other parts of the inflammatory process.

Altering Fas/FasL expression

The final common pathway of inflammation in RA involves invasion of articular cartilage, bone and soft tissues by synovial fibroblasts. These cells have a transformed

54 v. Strand

phenotype with expression of oncogenes [22], and the cytokine milieu induces increased expression of the apoptosis factor Fas/ Apo-l. However, the number of synovial cells undergoing apoptosis appears to be low, suggesting that synovial cell hyperplasia in RA reflects a defect in Fas/FasL interactions rather than expression [73]. Despite data in the mrl/L murine model, apoptosis does not appear altered in SLE, although defective clearance of apoptotic debris by phagocytic cells may explain persistent stimulation by cross-reactive antigenic material.

An interesting treatment approach is to harvest macrophages, genetically alter them in vitro to overexpress FasL and reinject them. Autoreactive T cells then undergo apoptosis when Fas receptors on their cell surfaces engage FasL on these modified antigen-presenting cells. This has produced encouraging results in a murine model of SLE, and a similar mechanism of action has been proposed to explain the efficacy of intravenous IgG infusions [80, 105]. Intra-articular gene transfer of FasL produced an apparent "genetic synovectomy" in collagen-induced arthritis with substantial amelioration of disease, and was similarly effective in SCID mice engrafted with human rheumatoid synovium. Due to enhanced cell surface expression of Fas, rheumatoid synoviocytes are more susceptible to anti-Fas antibody-mediated apoptosis. Administration of anti-Fas mAb ameliorated synovitis in the HTLV-l tax transgenic mouse [24]. Together, these data suggest that therapies targeting Fas or FasL expression may have broad applicability in autoimmune disease.

Inhibiting cartilage degradation and bone destruction in RA

Inhibiting MMP secretion

MMPs are believed to playa major role in mediating cartilage and bone destruction in RA. Separately from the effects of IL-I band TNF-a, long-term contact with activated T cells directly stimulates synoviocytes and synovial macrophage/monocytes to produce MMPs [10]. Unfortunately, several clinical trials with MMP inhibitors in RA and osteoarthritis have been halted recently due to tolerability issues. Next generation products are in early trials; data indicating better therapeutic indices are eagerly awaited.

IL-ll acts synergistically with IL-IO, and stimulates production of the tissue inhibitor of metalloproteinases (TIMP) and down-regulates MMP levels, independent of its effects on TNF-a [35]. IL-ll is effective in treating established collagen-induced arthritis and may, therefore, offer therapeutic benefit in RA.

Inhibiting osteoclast activation: osteoprotegrin

Osteoclast differentiating factor or osteoprotegrin ligand (OPG ligand or RANK ligand) is a recently described TNF-a-related cytokine that regulates osteoclast differentation and activation, as well as T cell/dendritic cell interactions. Produced by activated T cells, up-regulated by IL-l and IL-17, it triggers osteoclastogenesis, acting as the crucial mediator of bone erosions. OPG is a secreted soluble protein which acts as a decoy receptor for OPG ligand, and opposes the stimulation of osteoclast activation and differentiation. In the adjuvant arthritis model, OPG treatment substantially reduced bone and cartilage destruction without significant effects on inflammation


(measured by paw swelling) [19]. These data support use of OPG in the treatment of RA, and potentially other causes/contributors to the development of osteoporosis.

Potential combinations

Table I lists many of the therapeutic interventions currently under consideration for the treatment of RA, SLE and other autoimmune diseases. A variety of combination therapies can be envisioned, targeting different aspects of the inflammatory process. Preclinical and limited clinical trial data suggest that some may be more effective in one clinical indication than another, but all, targeted to specific immune responses,

Table 1. Promising new therapies for autoimmune disease

Regulating cytokine production

Blocking proinflammatory cytokines in RA IL-I~, TNF-a: IL-lra, anti-TNF-a mAb, soluble TNF-a receptors IL-12: anti-IL-12 mAb IL-15 antagonists IL-18 antagonists Synthetic molecules which modulate cytokine expression

MAP kinases p 38 NF-KB inhibitors Capsases: ICE

Upregulating antinflammatory cytokines in RA IL-4 IL-IO

Upregulating antiinflammatory cytokines in SLE Anti IL-IO mAbs in SLE TGF-~ in SLE

Interfere with Ag (peptide)-MHC I1-TCR interactions

TCR peptides in RA MHI class II antagonists in RA Oral tolerance in RA and systemic sclerosis

Coactivation signal blockade: interrupting T cell activation/T cell-B cell collaboration

CTLA-4Ig in RA and SLE Anti-CD40L mAb in SLE and RA Combination anti-CD40L mAb+CTLA4-Ig in SLE

Interrupting the inflammatory process

Inhibiting complement activation in RA and SLE Interfering with adhesion molecule in expression/function Interfering with chemokine expression/function Inhibiting angiogenesis Altering Fas/Fas ligand expression Inhibiting cartilage degradation and bone destruction in RA

Inhibiting matrix metalloproteinase secretion Inhibiting osteoclast activation: osteoprotegrin

RA, Rheumatoid arthritis; IL, interleukin; TNF, tumor necrosis factors; mAb, monocolonal antibody; MAP, mitogen activated protein kinase; NF, nuclear factor; ICE, IL-I ~-converting enzyme; SLE, systemic lupus erythematosus; TGF-~, transforming growth factor-~; Ag, antigen; TCR, T cell receptor

56 V. Strand

promise to be safer, possibly more effective, therapies. Although certain interventions are believed most beneficial in early disease, combination treatment may offer benefit in established long duration disease, with long-term responses.

Gene therapy may offer the best means to use these new biologically derived interventions, singly or in combination, allowing site-specific delivery. Systemic delivery of a modified cell population or even intramuscular introduction of DNA encoding a cytokine product may result in disease specific alterations, without interfering with underlying immune surveillance. Further work to identify and perfect the vectors and methodology enabling such interventions are necessary. Nonetheless, we are uncovering novel ways to "tweak" the immunoregulatory circuitry, thereby downmodulating autoimmune responses without resultant immunosuppression.

The pros and cons of using biological therapie in combination

Preclinical and limited clinical data indicate that targeting multiple sites in the underlying inflammatory process may amplify benefit or convert transient effects into sustained responses. Combinations may be sequential, or simultaneous, based on the use of induction and maintenance therapies in oncology and transplantation. Not only may we envision using these new therapies in combination, it is also easy to imagine "background" treatment with one or more agents, adding others on an as needed basis as "pulse" or "flare" therapy. Potential benefits include improved efficacy and better tolerability. Limitations, including toxicity and cost, are more difficult to quantify.

We have limited experience in evaluating combination therapy. Will we consider additive clinical benefit with equal (or better) tolerability sufficient, or will we require synergistic results without increase in toxicity to rationalize expected increase in cost, difficulty in administration, etc., attendant with these cutting edge treatments?

Additional toxicity may occur when new therapies are used in combination, together or with accepted background treatments. Prior deletion or activation of a cell population may result in more rapid cytolysis and/or cytokine release when a second agent is administered, or exacerbation of other treatment-related toxicities. Or a cell population may be up-regulated in number or function. Combination use may alter immunogenicity of a biological agent or its clearance by the reticuloendothelial system. Transient effects can be sustained, and may abrogate a specific immunoregulatory response. Delayed effects can include infections, malignancy, as well as autoimmune manifestations. Long-term data in large patient cohorts will be required to ascertain if these are treatment related or due to the underlying disease.

Our current biological agents are expensive, predominantly due to manufacturing costs. Newer agents, less expensive, will be required to demonstrate significant clinical risklbenefit profiles of meaningful duration as well as economic benefit [91]. As more biologically based (and orally active) treatments become available, it is possible that the use of combination therapies will be less restricted by cost concerns.

Conclusions

Our newest treatments may be more efficacious in combination with "background" therapy. Regardless, it is unlikely that future therapies will be studied in any other clinical scenario.


Although most therapeutic combinations have yet to be formally studied in clinical trials, we can expect their empirical use in the clinic. As new products are introduced, it will be interesting to see how changes in benefit/risk and cost profiles, as well as treatment regimens, dictate clinically driven preferences for combination therapy. It is therefore prudent to view combined use of promising new therapies in the context of our limited current experience with IL-l and TNF-a inhibitors.

The use of these new agents has revitalized our interest and understanding of the challenges posed to the field of rheumatology. Yet they come at a price. We must therefore use these regimens judiciously, and make every attempt to develop longitudinal databases to study their long-term effects.

As the majority of clinical trials are funded by pharmaceutical and biotechnology sponsors, protocols evaluating combination therapy are likely to be restricted to use of experimental product(s) from a single sponsor or combination use with an approved product. Many new agents may first be used in combination in the clinic, after approval. It will be important to us, as rheumatologists, to develop means whereby combinations of experimental and/or newly approved therapeutics can be evaluated prior to or soon after their entry into the market place.

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Combination therapy: the risks of infection and tumor induction

D.E. Yocum

Arizona Arthritis Center, University of Arizona, Tucson, AZ, USA

Introduction

In 1986, Csuka et al. [9] published the results of an uncontrolled open label study evaluating the efficacy and toxicity of combining azathioprine (AZA), cyclophosphamide (CTX) and hydroxychloroquine (HCQ) in severe rheumatoid arthritis (RA). While the efficacy was impressive with over 50% achieving a remission, the toxicities were overwhelming, with cancer and infections being the most serious. For years clinical researchers have been concerned about infection and malignancies in autoimmune disease, independent of therapy [3, 16,27,28, 31, 35, 39,40,53]. Therefore, there has been cautious use of combination therapies, especially when one of the agents in the combination was a cytotoxic drug.

In the past, little was known about the mechanisms of action of most agents used to treat autoimmune diseases, so that combinations of these agents were based primarily on past clinical experiences. In addition, the use of prednisone both in low and high doses to initiate therapy, as well as to act as a bridge when treatments were changed, was common. Finally, the duration of autoimmune therapies was relatively short «6 months) due to marginal efficacy and/or toxicity. Together, these factors made it difficult to ascribe causality for infections or malignancies to any particular treatment.

Most of the data on combination therapy comes from studies in RA because of the number of available patients and the possibility of using a wide variety of agents. In RA, with the addition of methotrexate (MTX), for which the mechanism of action was better understood, combination therapy grew in popularity and success. In 1990, Wilske and Healy [61] wrote an editorial on combination therapy proposing a new therapeutic approach called the "step-down bridge". Instead of the traditional method of starting slowly with what were considered less toxic therapies such as non-steroidassociated inflammatory drugs (NSAIDs) and then adding disease-modifying antirheumatic drugs (DMARDs), they proposed starting early with combined DMARDs. Interestingly, they avoided cytotoxic drugs as initial therapy. However, this was not

Correspondence to: David E. Yocum, Arizona Arthritis Center, University of Arizona, Tucson, AZ, 85724. USA

64 D.E. Yocum

widely accepted, but with the success of combination MTX and cyclosporin (CsA) presented by Tugwell et al. [52], some basic concepts began to develop. These concepts were put together at the First International Consensus Meeting on Combination Therapy held in Cape Cod in 1995 [62].

In other autoimmune diseases, there is very little information on malignancy and infection with individual agents, much less combination therapy. The purpose of this article is to review the potential risks of infection and malignancy associated with combination therapy. The information presented is based upon the limited data available on each treatment used for autoimmune disease.

Combination therapy objective: avoidance of infection and malignancy

Combination therapy is common in nearly all areas of medicine, especially in patients with recalcitrant disease. The major concept is to enhance efficacy, hopefully synergistically, without increasing toxicity. This is best accomplished by combining medications whose mechanisms of action and side effect profile are different (Table 1). In the past, rheumatologists conducted many combination protocols, but the mechanisms of action of the agents used were either unknown or very broad. In most cases, full doses of each agent were used, thus increasing the risk of side effects. In addition, the trials were usually conducted in patients with long standing and in

Table 1. Mechanisms of action of disease-modifying anti-rheumatic drugs

Immune action AZA CTX HCQ SSZ MTX CSA LEF ENT INFL

T cell inhibition: + + + + + CD4 + + CD8 + + IL-2 + + IL-8 + IL-IO + IFN-y + Lymphotoxin +

B cell inhibition: + Ig syntbesis + + + + NK inhibition +

Prostaglandin Syn: + Macrophage inhibition + + + TNF-a + + + IL-l + + +

Antigen processing: + Activator protein-l NF-K~ + +

PMN inhibition: Phagocytosis Lysosomes release + Chemotaxis +

AZA, Azathioprine; CTX, cyclophosphamide; HCQ, hydroxychloroquine; SSZ, sulphasalazine; MTX, methotrexate; CsA, cyclosporin; LEF, leflunomide; ENT, etanercept; INFL, infliximab

Combination therapy: risks of infection and tumor induction 65

many cases "burned out" disease. Finally, most patients were receiving high doses of steroids.

However, over the last 10 years we have acquired a better understanding of the immunopathogenesis of various autoimmune diseases. In addition, the approval of MTX for use in RA, its use in other autoimmune diseases and the understanding that patients must be treated earlier led to many changes in combination therapy. The efficacy and cost effectiveness of MTX make it the best foundation to which other agents could be added. All major combination trials in the last 5 years have added the investigational drug to MTX medication in patients with a partial response to maximally tolerated doses of MTX. Therefore, by combining drugs with fundamentally different mechanisms of action and different side effect profiles, one should achieve a better response with fewer side effects, which is the ultimate goal of combination therapy.

Morbidity and mortality in autoimmune disease

To assess the potential risks of any therapy in a chronic disease, one needs to have a better understanding of the underlying natural morbidity and mortality of the disease itself. This has been looked at in several studies from different countries over the last 50 years [28, 31, 39]. All of these studies have agreed that patients with major autoimmune diseases have an increased mortality, shortening life by an average of 10 years in some cases. Similarly, these studies agree that two of the major causes of death are infection and the disease itself. The studies have disagreed on the role of malignancies in the increased mortality. The exact role of specific anti-rheumatic agents as a cause of malignancy is not clear.

Risks of infection with autoimmune therapy

Inherent risk of infection

All studies have demonstrated an increased death rate in RA due to infection [31, 53], but the exact figures concerning the type of organism involved vary depending on the study. However, RA patients are especially susceptible to bacterial infections. The major areas of infection are the lungs, urinary tract and joints with sepsis being the ultimate cause of death in most individuals. The rate of infection increases with duration of disease and age.

Similarly, infection is the second most common cause of death in systemic lupus erythematosus (SLE) [39]. In addition to relatively common bacterial infections, patients with SLE appear to be more susceptible to organisms such as tuberculosis, coccidiomycosis, viruses such as herpes and opportunistic infections such as Pneumocystis carinii [15, 33]. These infections may also be harder to diagnose, more severe to treat and prolonged in their course. This increased morbidity and mortality due to infections in SLE is related to one of the many immune abnormalities that the patients display [63]. In fact, in many patients, vaccination is not as effective due to this problem and care should be taken when giving live vaccines.

In other forms of autoimmune disease, such as systemic sclerosis, vasculitis and myositis, the inherent risk of infection does not appear to be increased. However, as discussed below, the risk increases with prednisone and cytotoxic drugs.

66 D.E. Yocum

Infection related to spec!fic and combination agents

It has been difficult to associate anyone agent used in autoimmune disease other than prednisone with the increased rate of infection [48]. Prednisone appears to play at least two roles in this relation. The first is in its suppression of immune function, which makes individuals more susceptible. While prednisone has many immunosuppressive actions, its effects on polymorphonuclear leukocytes (PMNs), macrophages and T lymphocytes are probably central [7,8,43]. At low doses, the effects are marginal, but at high doses, they become much more pronounced. High doses of steroids are associated with serious infections in otherwise normal individuals. The combination of high-dose steroids with other immunosuppressive drugs only enhances this effect. In addition, it appears to mask the symptoms of infection, allowing the process to become advanced and more difficult to treat before it is recognized.

While the overall incidence of infections does not appear to be increased with MTX, an increased rate may be present following major orthopedic procedures [5]. However, while one study suggested an increase, two others did not [34, 42]. An increased rate of infections has not been observed when MTX was used in combination with CsA, sulphasalazine (SSZ), etanercept, infliximab, AZA or leflunomide (LEF) [10,25,52,57,58,60].

CsA has been released for use in transplantation since 1982 and for use in RA since 1995. It is a unique immunomodulatory agent whose primary mode of action is the reversible inhibition of T lymphocyte function by suppressing the transcription of interleukin-2 (lL-2) and gamma-interferon (IFN-y) [441. When used in very high doses in transplantation, it was associated with an increase of herpes zoster infections, but not bacterial infections. There is one reported case of P carinii in a patient with RA, who recovered [36]. When used in combination with MTX, as recommended by the Food and Drug Administration (FDA) there has been no increase in infections reported [52].

LEF, an agent recently released for use in RA, is an isoxazole agent which after absorption is cleaved to its active metabolite, which binds to the enzyme dihydroorotate dehydrogenase, thus inhibiting de novo pyrimidine synthesis (6), Its effects appear to be primarily on rapidly dividing and activated lymphocytes [14]. While it is an immunosuppressive and cytotoxic drug, it has not been associated with an increase in infections [46,47]. However, there have been reported cases of leukopenia [301. When used in combination with MTX in 30 patients with RA in an uncontrolled trial, there was no increase in infections seen over 2 years of therapy [58]. However, this agent has only been available for use for a little over 2 years.

AZA, another agent used in autoimmune disease, has only been associated with herpes zoster infections, especially when used at very high doses or in combination with an alkylating agent [9, 37]. Csuka et al. [9] saw this when AZA was combined with CTX. However, when used in doses of less than 2-3 mg/kg, there appears to be less risk of infection with this agent used alone and in combination.

The alkylating agents nitrogen mustard, CTX and chlorambucil all have significant long-term toxicity including infections, especially when used in higher doses [55]. Except in rare circumstances, nitrogen mustard is no longer used in the therapy of autoimmune disease. Both bacterial and opportunistic infections are associated with the use of these agents [4,49]. P carinii is seen especially when CTX is used in combination with high-dose steroids [15]. Both CTX and chlorambucil have been associated with herpes zoster infections [19, 49), While infections with these agents are


often associated with leukopenia, it may occur in the absence of peripheral blood abnormalities.

The tumor necrosis factor (TNF) antagonists, etanercept and infliximab, were recently released for use in RA. Etanercept has also been approved for use in juvenile rheumatoid arthritis and infliximab for use in fistulous Crohn's disease [12, 23]. Both agents have been used alone and in combination with MTX [25, 571. In fact, infliximab is recommended for use in combination with MTX. Neither agent has been associated with an increase in the incidence of infections. However, there are now reports of cases of reactivated tuberculosis and coccidiomycosis with TNF antagonist therapy (NDA submission to FDA). In addition, the FDA requested that the maker of etanercept warn physicians about reports of serious infections occurring with the use of this agent (personal communication). It appears that there may be an association with the ability to clear serious infections when they occur, although there does not appear to be a higher rate of infections. So far, there have been no reports of increased infections when these agents are used in combination with MTX.

The risk of malignancies in autoimune disease

Inherent risk afmalignancy

There have been a multitude of studies examining the role of malignancy, if any, in the higher mortality rate seen in RA. Only two of these studies have demonstrated an excess of deaths due to malignancy [16, 26]. The others have either shown a deficit or no significant difference between RA and the control population [31,53]. However, there is some evidence that RA patients have an excess risk of developing lymphoproliferative malignancies [16]. While early studies suggested an association, they either did not specify the type of rheumatic disease examined or did not have proper controls. The best evidence came from a large Finnish study of over 46,000 patients extracted from two computerized nationwide registries [161. The study demonstrated an increased incidence of Hodgkin's disease, non-Hodgkin's lymphoma, multiple myeloma and leukemia compared to the general population. While criticized for the purity of the data (no patient was examined to confirm the diagnosis of RA), it is an impressive study. Since then, other smaller studies have confirmed the increased incidence of these same lymphoproliferative malignancies [26].

There does appear to be an increased rate of malignancy in SLE. In a study by Reveille et al. [39], malignancy was the third most common cause of death in patients with SLE over the age of 50 years. This was not the case for patients under the age of 50. Unfortunately, the exact types of malignancy were not noted in the study. In another study by Pettersson et al. [35], the relative risk of malignancy in SLE patients was 2.6 and the risk of non-Hodgkin's lymphoma was 44. No association with therapy or age was found.

There is a group of patients with polymyositis and dermatomyositis with malignancy developing within 2 years of diagnosis [45]. These patients have fewer serological abnormalities and a poorer prognosis compared to other patients with myositis [24]. The most common forms of malignancy in this setting appear to be gastric and ovarian [41, 59]. For dermatomyositis, it is recommended that a work up be done looking for malignancies.

68 D.E. Yocum

Sjogren's disease has been associated with an increased rate of lymphoproliferative malignancies, which not only appear to be more common, but also more difficult to treat. The most frequent lymphomas observed are of the B cell type [17, 27]. There appears to be an association with the monoclonal gammopathy that occurs in Sjogren's disease and these lymphomas [22].

For scleroderma, the frequency of malignancy varies from 3% to 7% [3, 11]. Lung cancer occurs with increased frequency in the setting of longstanding disease with interstitial pulmonary fibrosis [40]. In three studies, there appeared to be a subset of women who developed breast cancer around the time of onset of the scleroderma [11, 40]. However, lymphoproliferative malignancies do not appear to be increased except in the setting of immunosuppressive therapy [29].

Malignancy related to specific and combination agents

Studies have been unable to associate an increased rate of malignancy with most of the therapies used in autoimmune diseases, the exception being the alkylating agents [38, 61]. Bladder cancer and leiomyosarcoma [50, 56] complicate the use of CTX. Efforts to reduce bladder exposure to the drug and its metabolites appear to reduce this problem.

There have been frequent reports of leukemia, lymphoma, solid tumors and chromosomal damage in patients receiving alkylating agents [38,50,51,56,61]. In one report, 38 deaths with 15 malignancies were noted in 131 patients with RA receiving chlorambucil between 1965 and 1973 [38]. Of these 15 malignancies, 7 were lymphoma or leukemia. The prevalence of leukemia in 1,612 patients with RA receiving chlorambucil was 0.74% [20]. Other studies have examined the development of malignancies with the use of CTX in RA. In one study, there was a 4-fold increase of solid tumors and a 16-fold increase in the incidence of lymphoreticular malignancies [2]. Other studies have supported these results. Patients receiving these agents alone or in combination should be warned about this apparent increased risk.

While MTX is a carcinogenic substance, it has been difficult to demonstrate a definite increase in any malignancy in patients with autoimmune disease receiving it. There have been a variety of case reports of individuals developing lymphomas while receiving MTX [1]. However, since lymphomas are reported to be increased in diseases such as RA, Sjogren's disease and SLE, these data are hard to interpret [16, 17,27,35]. They are difficult to ignore, however, when they spontaneously regress when the MTX is withdrawn [21]. There are case reports of Epstein-Barr virus-associated lymphoproliferative tumors associated with MTX and one case associated with the combination of MTX and CsA [13].

Neither Aza nor CsA has been associated with an increase in malignancy when used in autoimmune disease [18, 54]. However, when used at higher doses and in combination with each other and high-dose prednisone in transplantation, there was an increase in both reversible and irreversible lymphoreticular malignancies [32]. Similarly, although it is an immunosuppressive agent, LEF has not been found to be associated with an increase in malignancies [46, 47]. However, due to its potential teratogenic effects, LEF must be discontinued for at least 1 year prior to attempted child bearing. Because of their long-term use in transplantation, at least 1,000 babies have been born to mothers taking Aza and CsA without an increase in abortions or


malformations. There are reports of low birth weights in some of the children. Because of a lack of information in autoimmune disease, caution should be used in discussing these issues with women of child bearing potential.

While one of the potential effects of TNF is to kill certain tumors, there has not been an increase in the incidence of malignancies in patients receiving the TNF antagonists, etanercept and infliximab [25, 57]. In post-marketing analysis, over 100,000 people have received etanercept and over 50,000 have received infliximab. However, both agents have only been on the market for approximately 2 years, so that long-term follow-up is needed to make a final assessment. Both agents have been used in combination with MTX with no apparent increase in side effects, including malignancy [25, 57].

Summary

It is clear that the rate of infection is increased in most of the more serious forms of autoimmune disease and agents such as high-dose steroids and the alkylating agents increase this risk. Other agents such as MTX, CsA, LEF, AZA and the TNF antagonists do not appear to increase the risk of infection given either alone or in combination. Similarly, the risk of malignancy in certain types of autoimmune disease appears increased. However, other than the alkylating agents, none of the agents used appear to increase this risk. The more recently released agents such as CsA, LEF and the TNF antagonists need longer durations of follow-up to substantiate this, however. It is clear that, unless they are absolutely necessary, one should avoid the alkylating agents used either alone or in combination to avoid problems with infection and malignancy. In addition, the use of steroids should be kept as low as possible to avoid infections. It is possible that the use of the more benign agents alone and in combination earlier in the disease course may help to reduce both infection and the incidence of malignancy in the long run.

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ence of methotrexate on the frequency of postoperative infectious complications in patients with rheumatoid arthritis. 1 Rheumatol 20: 1129

43. Schleimer RP, Freeland HS, Peters SP, Brown KE, Ders CP (1989) An assessment of the effects of glucocorticoids on degranulation, chemotaxis, binding to vascular endothelial cells and formation of leukotriene B4 by purified human neutrophils. J Pharmacol Exp Ther 250:598

44. Sigal NH, Dumont Fl (1992) Cyclosporin A, FK-506, and rapamycin: pharmacologic probes of lymphocyte signal transduction. Annu Rev Immunol 10:519

45. Sigurgeirsson B, Lindelof B, Edhag 0, Allander E (1992) Risk of cancer in patients with dermatomyositis or polymyositis. A population-based study. N Engl 1 Med 326:363

46. Smolen lS, Kalden lR, Scott DL, Rozman B, Kvien TK, Larsen A, Loew-Friedrich I, Old C, Rosenburg E (1999) Efficacy and safety of leflunomide compared with placebo and sulphasalazine in active rheumatoid arthritis: a double blind, randomized, multicentre trial. Lancet 353:259

47. Strand V, Cohen S, Schitf M, Weaver A, Fleischmann R, Cannon G, Fox R, Moreland L, Olsen N, Furst 0, Caldwell 1, Kaine J, Sharp 1, Hurley F, Loew-Friedrich I (1999) Treatment of active rheumatoid arthritis with leflunomide compared with placebo and methotrexate. Arch Intern Med 159:2542

48. Stuck AE, Minder CE, Frey Fl (1989) Risk of infectious complications in patients taking glucocorticosteroids. Rcv Infect Dis 11:954

49. Thorpe P, Hassall MB, York lR (1976) Rheumatoid arthritis treatcd with chlorambucil: a five-year follow-up. Med 1 Aust 2: 197

50. Thrasher JB, Miller GJ, Wettlaufer IN (1990) Bladder leiomyosarcoma following cyclophosphamide therapy for lupus nephritis. 1 Urol 143: 119

51. To1chin SF, Winkelstein A, Rodnan GP, Pan SF, Nankin HR (1974) Chromosome abnormalities from cyclophosphamide therapy in rheumatoid arthritis and progressive systemic selerosis (scleroderma). Arthritis Rheum 17:375

52. Tugwell P, Pincus T, Yocum DE, Stein M, Gluck 0, Kraag G, McKendry R, Tever 1, Baker P, Wells G (1995) Combination therapy with cyclosporine and methotrexate in severe rheumatoid arthritis. N Engl 1 Med 333: 137

53. Uddin 1, Kraus AS, Kelly G (1970) Survivorship and death in rheumatoid arthritis. Arthritis Rheum 13: 125

54. Van den Borne BEEM, Landewe RBM, Joukes I (1998) No increased risk of malignancies and mortality in cyclosporine A-treated patients with rheumatoid arthritis. Arthritis Rheum 41: 1930

55. Vignon G, Bied 1 (1971) Comparative study of the various immunosuppressive agents in rheumatoid arthritis. Rev Rhum Mal Osteoartic 38:785

56. Wall RL, Clausen KP (1975) Carcinoma of the urinary bladder in patients receiving cyclophosphamide. N Engl 1 Med 293:271

57. Weinblatt ME, Kremer JM, Bankhurst AD, Bulpitt KJ, Fleischmann RM, Fox RI, Jackson CG, Lange M, Burge 01 (1999) A trial of etanercept, a recombinant tumor necrosis factor receptor:Fc fusion protein, in patients with rheumatoid arthritis receiving methotrexate. N Engl 1 Med 340:253

72 D.E. Yocum

58. Weinblatt ME, Kremer JM, Coblyn JS, Maier AL, Helfgott SM, Morrell M, Byrne VM, Kaymakcian MV, Strand V (1999) Pharmacokinetics, safety, and efficacy of combination treatment with methotrexate and leflunomide in patients with active rheumatoid arthritis. Arthritis Rheum 42: 1322

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Part II Disease specific section

Combination treatment in autoimmune diseases: systemic lupus erythematosus

G. Moroni l , O. Della Casa Alberighi2, C. PonticelJil

I Divisione di Nefrologia e Dialisi, Ospedale Maggiore IRCCS, Milan, Italy 2 Clinical Research & Development, Novartis Pharma AG, Basel, Switzerland

Systemic lupus erythematosus: disease overview

Systemic lupus erythematosus (SLE) is a potentially life-threatening chronic inflammatory disorder characterised by the overproduction of autoantibodies and other immunological abnormalities, which may affect the skin, joints, lungs, heart, serous membranes, nervous system and other organs. Renal involvement is common and can greatly affect the prognosis. Table I summarises its main clinical characteristics.

SLE predominantly affects women: the female:male ratio is about 9: 1 [46] and more than 80% of the cases occur in women during their child-bearing years. Its prevalence is about 40 per 100,000 in North America and Northern Europe. Epidemiological surveys report a considerably greater incidence in black, Hispanic and Asian populations [72]. Its familial occurrence is well documented [I].

The disease is associated with the development of autoantibodies that form complexes with "self-antigens", and lead to inflammation, tissue damage and pain [48]. The most common autoantibodies are those against the components of the cell nucleus (anti-nuclear antibodies), which are found in more than 95% of SLE patients and typically include antibodies to double-stranded DNA (anti-dsDNA) (high titres in 46% of patients).

Nephritis (glomerulonephritis) is a major complication that occurs in up to 50% of patients [62]. Although lupus nephritis is the most likely potential threat to survival in SLE patients, the severity of renal dysfunction varies widely from minor transient abnormalities in laboratory urine tests (asymptomatic lupus nephritis) to acute nephritis and end-stage renal failure «5% of patients). The more severe forms of lupus nephritis (WHO class III focal proliferative lesions, class IV diffuse proliferative lesions, or class V membranous nephropathy) require aggressive treatment. The WHO classification of lupus nephritis [23] is summarised in Table 2.

SLE is characterised by periods of flare (symptom exacerbation) and remission (mainly asymptomatic); the flares may be induced by sun exposure, infections, pregnancy/delivery, poor diet or drug treatment. According to the revised American

Correspondence to: Claudio Ponticelli, Divisione di Nefrologia e Dialisi, Ospedale Maggiore IRCCS, Via della Commenda 15, 20122 Milan, Italy

76 G. Moroni, O. Della Casa Alberighi, C. Ponticelli

Table 1. Summary of the main clinical characteristics of SLE

General

Musculoskeletal

Renal

Dermatological/cutaneous

Cardiac

Pulmonary

Haematological

Neurological

Immunological

Malaise, fatigue, fever, weight loss

Arthralgia, arthritis.,,2 joints (86, 37), myalgia, myositis

Haematuria, proteinuria >0.5 g daily (51,94), nephrotic syndrome, glomerulonephritis

Malar "butterfly" rash (57, 96), discoid rash (18,99), photosensitivity (43, 96), nasal/oral ulcers (27, 96)

Pericarditis (56,86), myocarditis, valvulitis, aseptic endocarditis

Pleuritis (56, 86), pneumonitis, antibiotic-resistant pulmonary infiltrates

Anaemia, leukopenia, lymphopenia, thrombocytopenia (59, 89)

Headaches, seizures and psychosis (20, 98)

Antinuclear antibodies (99, 49); anti-double-stranded DNA antibodies, anti-Sm antibodies, false-positive tests for syphilis, positive LE cell preparation (85, 93)

SLE, Systemic lupus erythematosus Percentage sensitivity and specificity of the revised SLE classification criteria are reported in parentheses. The terms in bold refer to the SLE diagnostic criteria of Tan et al. [78]

Table 2, WHO classification of lupus nephritis (modified from [23])

1. Normal glomeruli A.Nil B. Normal by light microscopy but deposits

on immunofluorescence and electron microscopy

II. Pure mesangiopathy A. Mild hypercellularity (+) B. Moderate cellularity (++)

III. Focal and segmental glomerulonephritis A. Active necrotising lesions B. Active and sclerosing lesions C. Sclerosing lesions

IV. Diffuse glomerulonephritis A. Without segmental lesions B. With active necrotising lesions C. With active and sclerosing lesions D. With sclerosing lesions

V. Diffuse membranous glomerulonephritis A. Pure membranous glomerulonephritis B. Associated with class II lesions (A or B) C. Associated with class III lesions (A, B or C) D. Associated with class IV lesions (A, B, C or D)

VI. Advanced sclerosing glomerulonephritis

Rheumatism Association classification of SLE [78], a diagnosis should be made if at least 4 of the II criteria are serially or simultaneously present during any period of observation. The most sensitive criteria are anti-nuclear antibody positivity, arthritis and immunological disorders, The most specific criteria are discoid rash, neurological disorders, malar rash, photosensitivity, oral ulceration, renal abnormalities and immunological disorders, However, although useful for diagnosis, these criteria are of little help in assessing disease activity,

A number of clinical indices for the assessment of disease activity have been proposed, the most widely used of which are the systemic lupus erythematosus disease

Treatment of SLE and lupus nephritis 77

activity index (SLEDAI) from Toronto [12], the systemic lupus erythematosus activity measure (SLAM) from Boston [51], the British Isles Lupus Assessment Group (BILAG) [76], and the European Consensus Lupus Activity Measurement (ECLAM) [83]. However, although these indices are comparable and reproducible, their criteria for measuring activity in some organ systems may be challenged, and the fact that they have not been longitudinally tested means that their role in clinical trials still has to be established [45].

Treatment of SLE and lupus nephritis

SLE is thought to arise as a result of the polyclonal B-cell secretion of pathogenetic autoantibodies induced by hyperactive helper T cells and the consequent formation of immune complexes that become deposited in sites such as the kidney.

The absence of any universally efficacious treatment suggests that lupus is a heterogeneous disorder whose etiopathogenesis varies in different patient subsets (as in lupus-prone mice). Kidney involvement has a high degree of intra- and inter-individual variability: it may run an indolent course, rapidly progress to renal failure, or be chararacterised by alternating periods of quiescence and exacerbation. It is, therefore, difficult to plan a rigid therapeutic protocol, and so treatment should be based on a careful evaluation of the histological picture at renal biopsy and the monitoring of renal signs, i.e. serum creatinine, proteinuria and urinary sediment. Patients with severe forms of lupus nephritis (class IV or class III nephritis involving many glomeruli) should be treated vigorously particularly when renal biopsy specimens have a high activity index. In milder cases, the disease can usually be controlled by means of non-steroidal anti-inflammatory drugs (NSAID) and anti-malarial agents [49, 58, 60,70,82].

Corticosteroids are the standard treatment for more severe SLE, with the addition of cytotoxic/immunosuppressive agents such as cyclophosphamide (Cyc) or azathioprine (Aza) being reserved for the steroid-resistant cases or the patients in whom steroids need to be used more sparingly and/or those with major organ involvement including deteriorated renal function r 42, 58, 60].

Corticosteroids

These may have a number of effects on inflammation and immunological mechanisms, particularly when intravenously administered at very high doses [49, 65]. Although they have improved the survival of patients with SLE and lupus nephritis, only one study [79] has tried to identify an adequate biological index of individual sensitivity, and so the indications for steroid treatment are based on clinical experience rather than scientific approach.

After the 1964 observation by Pollak et al. [63] that only high-dose prednisone (PDN) could improve the prognosis of diffuse proliferative lupus nephritis, the treatment of reference became PDN 1-2 mg/kg per day for several months until the control of disease activity is established. However, many treated patients still showed progressive disease and others developed devastating steroid-related side effects (hypertension, infections, accelerated atherosclerosis, obesity, diabetes, aseptic bone necrosis, cataracts and myopathy).


After the publication of the paper by Cathchart et al. in 1976 [20], many reports showed the beneficial effects of a short course of intravenous high-dose methylprednisolone (MPO) pulses (generally I g given every day for 3 consecutive days), which can dramatically reverse the extrarenal symptoms of SLE and rapidly improve renal function (particularly in the case of a recent increase in serum creatinine levels), although proteinuria tended to take as long as 6 months to improve [67]. Once remission was achieved, it could be maintained by low-dose oral PON, thus reducing the iatrogenic risk of intensive and prolonged corticosteroid therapy. The side effects of MPO pulses are infrequent and include flushing, tremor, nausea and altered taste; more severe but rare complications include seizures, anaphylaxis, psychosis and cardiac arrhythmia [40, 50, 59, 711.

Immunosuppressive agents

The two most widely used immunosuppressive agents in SLE are Cyc and Aza. Cyc is an alkylating agent that interferes with the fundamental mechanisms of cell growth, mitotic activity, differentiation, and function. Aza blocks purine synthesis and, thus, haIts purine-dependent lymphocyte proliferation.

The efficacy of immunosuppressive agents in lupus nephritis has been evaluated in a number of controlled and uncontrolled studies [16, 26-28, 44, 74, 75, 771. The results of the controlled trials comparing corticosteroids with corticosteroids plus immunosuppressive agents have been conflicting because of the differences in therapeutic schedules and the fact that the individual studies involved small patient numbers. To achieve statistical power, Felson and Anderson [36] pooled the data of eight controlled trials and showed that the risk of renal function deterioration and renal death was significantly lower in the patients receiving immunosuppressive therapy than in those given steroids alone; the cumulative mortality rate for non-renal causes was similar in the two groups.

Two years later, Austin et al. [2] reported the long-term results of a trial in which patients with lupus nephritis were randomly assigned to receive PON alone or PON with monthly pulses of intravenous Cyc, or oral Cyc, or Aza or a combination of Aza and oral Cyc. There were no differences in renal survival in the different groups until the 5th year. After 10 years, the renal survival of the patients given PON alone was significantly worse than that of those given intravenous Cyc, with no significant difference between the latter and the groups given other immunosuppressive regimens. Analysis of serial renal biopsies showed a greater progression of sclerotic lesions in the patients given PON alone than in those given immunosuppressive drugs [5]. The risk of major infections was similar among the treatments groups (14%) with the exception of herpes zoster infection, which was more frequent in patients treated with oral or intravenous Cyc. Hemorrhagic cystitis occurred in 17% of patients treated with oral Cyc alone and in 14% of the patients given Aza plus Cyc, and in no cases of patients receiving intravenous Cyc. Premature ovarian failure developed in about 50% of patients treated with oral or intravenous Cyc or with Cyc plus Aza (71 %, 45% and 53%, respectively). Malignancy was equally distributed between patients who received Aza alone and oral Cyc alone (11 % and 17%) [2J. Although the longterm toxicity is still unknown, Cyc pulses seem to have fewer side effects than oral Cyc but their administration is relatively complex, costly and unpleasant. Further trials at the NIH [15,43] confirmed the validity of intravenous Cyc in lupus nephritis.


Table 3. Meta-analysis of immunosuppressive therapy in lupus nephritis: 12-60 month clinical effective-ness of treatments reaching statistical significance (modified from [8])

Treatment Number Total Total End-stage End stage comparison of patients mortality mortality renal disease renal disease

Absolute Risk Number Absolute Risk Number Difference needed Difference needed (95% CI) to treat (95% CI) to treat

All IS agents with 335 vs IDS 13.2 (2.5-23.9)b 7H 12.9 (2.2-23.6) 7.8 PONa compared with PON alone

IV Cyc with 78 vs 105 19.9 (0.3-39.5) 5.0 16.2 (1.7-31.4) 6.2 PONa compared with PON alone

Combination 257 vs 105 NS NS 16.9 (1.0-32.1) 5.9 of oral Aza, Cyc, and PONa compared with PON alone

Aza, Azathioprine; cr, confidence intervals; Cyc, cyclophosphamide; NS, no significant difference found between treatments; IS, immunosuppressive (agents): oral Aza with PON. oral Cyc with PON, oral Aza, oral Cyc with PON, IV Cye with PON; IV, intravenous; PON, prednisone a Represents treatment with positive direction risk reduction for outcome measured hFor example, patients receiving IS agents with PON had 13.2% lower total mortality than those on oral PON alone. 95% of patients would be estimated to respond in the range of 2.5% to 23.95 hetter than oral PON C Represents the reciprocal of the absolute risk difference. For example, for everyone patient with total mortality outcome in the PON-alone group, 7.6 patients on IS agents with PON would need to be treated before total mortality would be observed (1/0.132=7.6)

A recent meta-analysis of 19 prospective controlled trials [8] has shown that both patient and renal survival are significantly better in patients receiving intravenous eyc or the combination of Aza and oral eye than in those given PDN alone. Once again, there was no difference in patient and renal survival between the immunosuppressive schedules (Table 3). These results underline the effectiveness of regimens based on a combination of corticosteroids and immunosuppressive agents in lupus nephritis and their superiority over corticosteroids alone. Moreover, the use of immunosuppressive agents may allow the sparing of steroids.

It is still unclear which immunosuppressive drug has the best therapeutic index, but the clinical impression is that eyc is more effective in the acute phases of the disease because it is a more powerful inhibitor of B cells than Aza and can rapidly reduce the resynthesis of autoantibodies [181. Experimental studies have also shown that eyc is highly efficacious in murine models of active SLE [73]. However, given the potential risk of oncogenicity (as well as gonadal and bladder toxicity), over-high cumulative eyc doses may be dangerous and the use of intravenous pulses may reduce the cumulative dosage. A single administration of 1,000 mg every month reduces the monthly dose by one-half or two-thirds in comparison with the oral administration of 1-2 mg/kg per day.

Aza seems to be better tolerated in the long term, and may involve a lower risk of neoplasia, and less bladder, gonadal and bone marrow toxicity. For these reasons, some groups now prefer it for long-term treatments [18, 64].


A possible alternative is mycophenolate mofetil (MMF), which blocks the de novo pathway of purine synthesis, the only pathway used by lymphocytes [33J; therefore, the use of MMF in SLE may be rational. Preliminary data relating to a very small uncontrolled study, and the 12-month results of a 6-month regimen of PDN + MMF or Cyc, followed by PDN and Aza are currently available [21, 29]. After 12 months, the two treatment schedules were equally effective in inducing a complete or partial remission (complete remission: 81 % of the MMF patients vs 76% of the Cyc patients; partial remission: 14% in each group). The side effects were not significantly different between the two groups.

A double-blind, randomised, placebo-controlled clinical trial of 41 SLE patients without renal involvement [191 has recently shown that methotrexate (MTX) 15-20 mg/week can control the cutaneous and articular activity of SLE and allow a reduction in the PDN dose.

Cyclosporin

Cyclosporin A (CsA) is a powerful immunosuppressive agent that inhibits the transcription of IL-2 and other cytokines by T helper cells [13, 141. In an experimental model of SLE, CsA prevented the deposition of immune complexes in the kidney and the subsequent development of glomerulonephritis [10]. The positive results also obtained in an experimental model comparing early and advanced stage SLE [11) support the hypothesis that CsA could be effectively used as a steroid sparer even in the earliest stages of active disease [25].

A number of uncontrolled clinical trials involving selected patients with advanced disease refractory to conventional treatments [17, 37, 53, 57, 81], as well as a number of controlled trials in lupus nephritis [3,4,34,47,69,78,80] have been carried out using CsA at doses of ,.;5 mg/kg per day in combination with steroids and/or immunosuppressants over periods lasting for up to 7 years. The positive results did not persist beyond drug discontinuation.

The precise mechanism of action of CsA in SLE is still unknown. The theoretical basis for its use is its capacity to suppress T cell function [54], thus inhibiting the activation of the immune system underlying the disease: in particular, the suppression of the T cell-mediated regulation of B cell activity should be useful in a disease characterised by polyclonal B cell activation [33]. However, it has also been suggested that impaired T cell regulatory function may actually contribute to autoantibody formation [39 J. Furthermore, the clinical significance of autoantibody suppression is debatable given the absence of a reduction in titre in some patients despite clinical improvement.

The data obtained from long-term comparative and non-comparative trials of CsA involving patients with refractory SLE (with the exception of Dammacco's study) are summarised in Table 4. Steroids were the most common form of previous treatment and were also the most common combined therapy; other additional treatments included MTX, Cyc and Aza. All of the studies reported a reduction in disease activity (a decrease in the mean SLEDAI score or in the individual SLEDAI score of the majority of the patients) and/or decreased steroid use after CsA treatment.

The largest group of patients to receive CsA as part of their treatment for refractory SLE was studied by Miescher et al. [57]. Seventy-three patients who had failed to respond well to standard treatment with corticosteroids plus Aza and MTX (protein-


uria >3 gil, persistent disease activity, unacceptable adverse events) received CsA 5 mg/kg per day in combination with steroids and, if needed for additional disease control, MTX or Cyc for an average of 7 years. As shown in Table 4 the combination of CsA and steroids provided sufficient disease control in about 25% of the patients, whereas the addition of MTX or Cyc plus MTX was needed in the others. The overall reduction in both disease activity and steroid use at the end of the treatment was about 75% in comparison with baseline.

Data from a small randomised study comparing the effects of CsA plus PDN with those of PDN alone in patients with a first diagnosis of SLE [24, 25] showed a reduction in PDN use of about one-third in the combination group. The efficacy of 2-year treatment with CsA in 27 refractory SLE patients was evaluated using SLAM [17]: the mean disease activity score significantly decreased after six months of therapy, and this was maintained throughout the study.

The data from specific studies of patients with lupus nephritis are summarised in Table 5. Introduced after induction treatment (i.e. pulse PDN 2-3 mg/kg for 3 days or 1 mg/kg per day PO for 2 months), CsA usually controlled disease activity and, in most cases, allowed a considerable reduction in the dose of concomitant steroids, and led to favourable effects on renal function and a significant reduction in proteinuria of 66-98%. Disease control was maintained for between several months and several years of treatment [4, 30, 35, 68, 69, 80]. CsA-related nephrotoxicity was not a major problem at the doses used (3-5 mg/kg per day).

A small study [4] comparing the effects of the CsA + steroid combination with those of corticosteroids alone demonstrated a significant reduction in proteinuria from baseline after 1 year in the patients receiving the combination.

In a series of 26 lupus nephritis patients receiving 5 mg/kg per day CsA in combination with fluocortolone for 2 years after the unsuccessful administration of fluocortolone and antimetabolites [35], proteinuria was successfully corrected, with a 90% reduction in the patients with proliferative or membranous lupus glomerulonephritis and no significant change in serum creatinine levels. Lasting remission of lupus nephritis was found in three small studies [68, 90, 80]. The benefits of the CSA + corticosteroid combination was also shown in a study of patients with membranous lupus nephropathy, although proteinuria reappeared after drug discontinuation [69].

The effectiveness of I year courses of PDN alone (n=8) versus intravenous Cyc (0.5-1.0 g/m2 every other month, n=6) versus CsA «5 mg/kg per day; n=5) has been tested in membranous lupus nephropathy [3]; all of the patients received PDN every other day. Thirteen patients partially improved to proteinuria levels of <2 glday (PDN, 4/8; Cyc, 5/6; CsA, 4/5) and 11 to <0.5 glday (PDN, 4/8; Cyc, 5/6; CsA, 2/5). Relapses of proteinuria >3.5 glday occurred in 6 patients 13-32 months after at least partial remission (PDN, 114; Cyc, 1/5; CsA, 4/4): the high frequency of relapse after CsA may be explained by the abrupt discontinuation of the drug at month 12 according to the protocol. Additional patient accrual is necessary to define fully the comparative effectiveness of these three drugs in lupus membranous nephropathy.

In a recent study, 40 children with lupus nephritis were randomised to receive CsA or Cyc plus PDN for 1 year [40], proteinuria significantly decreased in both groups, but it is worth noting that the children given CsA had a higher mean growth rate (8.2 vs 2.7 cm/year). No change in the mean creatinine clearance levels was observed.

In another controlled study, 23 adults with lupus nephritis were randomly allocated to CsA or Cyc plus PDN for a maximum of 24 months [31]. There were no

Tab

le 4

. E

ffic

acy

of

CsA

in

pati

ents

wit

h re

frac

tory

SL

E:

sum

mar

y o

f dat

e fr

om c

lini

cal

tria

ls

00

N

Ref

eren

ce

No.

C

sA t

reat

men

t C

sA d

osag

e C

oncu

rren

t D

isea

se a

ctiv

ity

Ste

roid

use

o

fpts

du

rati

on

(mg/

kg p

er d

ay)

trea

tmen

t re

sult

s

Bam

baue

r et

al.

[7]

10

Mea

n 2

y 2

-3

PD

N a

nd/o

r A

ZA

+ T

PE

8/

10 p

ts i

mpr

oved

; 2

deat

hs

~ 50

-90%

in 8

11 0

pts

, w

Id i

n 4

pts

~ in

7/9

pts

Ben

gtss

on e

t al

. [9

] 9

6 m

o-8

y

"Low

-dos

e"

PD

N

SL

ED

AI

~ in

5/9

~

in 7

/9 p

ts

Che

n [2

2]

13

3 m

o 4

PD

N 1

0-30

mg/

day

SL

ED

AI

~; d

isea

se c

ontr

ol

in 1

1Il3

Fav

re e

t al

. [3

4]

36

Mea

n 54

mo

<=5

Ste

roid

s, M

TX

or

CY

C

Act

ivit

y sc

ore

~ 45

%

as r

equi

red

(fro

m m

ean

10 t

o 5.

5) a

t I

y

Fav

re e

t al

. [3

5]

42

Mea

n 5.

3±1.

7 y

3-5

Ste

roid

s, s

tero

ids

for

1-3

y S

LE

und

er c

ontr

ol

~ 50

% in

all

pts

foll

owed

by

AZ

A o

r st

eroi

ds

(SL

ED

AI

<7,

ser

um c

reat

inin

e +

3-4

pul

ses

of

CY

C,

MT

X

<15

0 fl

mol

ll, p

rote

inur

ia

or S

OL

as

requ

ired

<0

.5 g

/24

h) i

n al

l pt

s af

ter

I y

Feu

tren

et

al.

[37]

l3

M

ean

12 m

o 5

-10

in 1

st 5

pts

, PD

N

8113

pts

had

~ di

seas

e ac

itiv

ity

~ 68

',7c

5 fo

r su

bseq

uent

pts

; (f

rom

mea

n 0.

77 t

o 0

mea

n 2.

4 at

end

0.

25 m

g/kg

per

day

) ~

0

of

trea

tmen

t (3

~.

Luk

ac e

t al

. [5

2]

10

1-3

y 3.

5 "E

ffec

ti ve

sup

pres

sion

" <:I

o

f lu

pus

neph

riti

s (8

/1 0

pts

),

0 ar

thri

tis

(4/4

),

~

butt

erfl

y er

ythe

ma

(5/6

),

;;

n m

yoca

rdit

is (

3/3)

, ~ co

C

NS

inv

olve

men

t (3

/3),

>-

sple

nom

egal

y (3

/3)

and

0=

~ Iy

mph

oade

nopa

thy

(2/2

) 00

'

Man

ger

et a

l. [5

31

16

Mea

n 3

0m

o

2.5-

5 P

DN

tap

ered

to

EC

LA

M s

core

~ 33

%

~

(1

<=

12

mg/

day

duri

ng 1

st 6

mo

(fro

m m

ean

12,2

to 8

.2)

"'0

Mie

sche

r 16

>

20

>28

mo

5 F

LU

M

arke

d im

prov

emen

t 0 :=;

and

Mie

sche

r [5

6]

in 8

116

pts

(s' ~

Tab

le 4

. (c

onti

nued

)

Ref

eren

ce

No.

o

fpts

Mie

sche

r et

al.

r57J

73

Tok

uda

et a

l. [8

11

10

Cac

cavo

et

al.

r 17 J

30

Oam

mac

co

10 v

s 8

et a

l. [2

4. 2

5]

(PO

N

alon

e)

CsA

tre

atm

ent

dura

tion

Mea

n 7.

1±7.

9 y

20 w

k

2y

I Y

(f

ollo

w-u

p 2

y)

CsA

dos

age

(mg/

kg p

er d

ay)

5 fo

r 6

days

/wk

1-5

3.8-

-2.6

4.2-

-> 3

.1

Con

curr

ent

trea

tmen

t

FLU

(19

pts

), F

LU

+

MT

X 1

5 m

g/w

k fo

r 4/

6 w

k (2

4),

FLU

+ M

TX

+

CY

C 5

00 m

g/q6

wk

(30)

PON

mea

n 10

.5±

3.2

mg/

day

PON

PO

N 0

.5 m

g/kg

per

day

Dis

ease

act

ivit

y re

sult

s

SL

EO

AI

t 74

%

(fro

m m

ean

10.1

to

2.7)

SL

EO

AI

t 64

%

(fro

m m

ean

10.6

to 3

.8)

SL

AM

17±

5 to

5±

3

SL

EO

AI

21 ±

9 an

d 5±

2.5

vs 2

0± 7

and

9±6

Ste

roid

use

t 76

%

(fro

m m

ean

192.

8 to

45.

8 m

g/w

k)

t St

eroi

d us

e 22

1±94

mg/

wk

to 3

5.6±

25 m

g/w

k

12-m

o cu

m.

dose

17

9±40

.1 v

s 23

1. 8

±97.

1 m

g/kg

CsA

, C

yclo

spor

in A

; A

ZA

, az

athi

opri

ne;

CL

Q,

chlo

roqu

ine;

ey

C,

cycl

opho

spha

mid

e; E

CL

AM

, E

urop

ean

Con

sens

us L

upus

Act

ivit

y M

easu

rem

ent;

FL

U,

f1uo

cort

olon

e;

MT

X,

met

hotr

exat

e; P

ON

, pr

edni

solo

ne/p

redn

ison

e; S

LA

M,

SLE

act

ivit

y m

easu

re;

SL

EO

AI,

SL

E d

isea

se a

ctiv

ity

inde

x; S

OL

, so

lum

edro

l; T

PE

, th

erap

euti

c pl

asm

a ex

ch

ange

; w

id,

wit

hdra

wn;

t, d

ecre

ase;

y,

year

; m

o, m

onth

s; p

ts, p

atie

nts;

wk,

wee

ks;

cum

., cu

mul

ativ

e; q

6wk,

eve

ry 6

wee

ks

ii' a 3 ro ;:;. o .....

V1

r tTl "' :;

l 0- <= "0

~ :;l

(I)

"0 ~ 00

,.,

»

Tab

le 5

. Eff

icac

y o

f C

sA in

pat

ient

s w

ith

lupu

s ne

phri

tis

asso

ciat

ed w

ith S

LE

: su

mm

ary

of d

ata

from

cli

nica

l tr

ials

Ref

eren

ce

No.

of

pts

Tre

atm

ent

CsA

dos

age

Con

curr

ent

Pro

tein

uria

du

rati

on

(mg/

kg p

er d

ay)

trea

tmen

t

Bal

lett

a et

al.

[4]

5 vs

S

I Y

I.S

bid

Pu

lse

PD

N 2

-3 m

g/kg

x3

days

t

89%

(P

DN

alo

ne)

or I

mg/

kg p

er d

ay

(fro

m 2

.7 t

o PO

x2

mo;

the

n ta

pere

d to

0.

3 g/

24 h

; 10

mg/

day

q2d

P<O

.OS)

vs

t 19

%

(fro

m 2

.6 t

o 2.

1 g/

24 h

)

Dos

tal

et a

l. [3

0]

9:6

rfr,

3 i

nit

7-21

mo

5 PD

N 1

6 m

g/da

y t9

2%

(f

rom

6.4

to

0.5

g/24

h)

Dos

tal

et a

l. [3

1]

12 v

s II

(C

yc)

2y

<S

bid

PD

N 5

-10

mg/

day

<O

.S g

124

h si

nce

9 rn

o in

all

pts

Fav

re e

t al

. [3

5]

26 r

fr

2 y

5 bi

d F

LU

tape

red

to d

isea

se a

ctiv

ity

<I

g/24

h

at 9

mo

in a

ll pt

s;

",90

% a

t 2

y (P

<O.O

OO

S)

Pon

s et

al.

[681

6

rfr

Iy

5 ta

pere

d to

2.5

PD

N 5

-10

mg/

day

t 98

%

(fro

m 5

.3

to 0

.13

g124

h)

at I

y

Tes

ar e

t al

. [8

0]

10:2

rfr

, I

y 5

PD

N 2

0 m

g/da

y ta

pere

d ov

er

t 89

%

4 rs

p, 4

ini

t 3

rno

to 1

0 m

g q2

d (f

rom

8.8

1 to

1.0

4 g/

24 h

, ti

meN

S,

P<O

.OO

l)

Oth

er

com

men

ts

..... s

erum

cre

atin

ine

and

crea

tini

ne

clea

ranc

e

Pro

mpt

rem

issi

on;

all

pts

had

stab

le

rena

l fu

ncti

on a

fter

7-2

1 m

o; r

epea

ted

rena

l bi

opsi

es i

n 5

pts

indi

cate

d su

ppre

ssio

n of

rena

l di

seas

e af

ter

I y

Hig

her

risk

of

SA

Es

on e

yc

..... s

erur

n cr

eati

nine

. D

isea

se a

ctiv

ity

t 60

% a

t I

y (1

2.3

to 4

.9);

22/

26 p

ts

had

inac

tive

dis

ease

(sc

ore

<7)

at I

y;

sign

ific

ant

t in

dis

ease

act

ivit

y ("

,50%

; P

<0.

005)

and

ste

roid

use

(",

50%

; P<

O.O

OI)

at

2 y

Pro

mpt

and

per

sist

ent

rem

issi

on

in 8

/9 p

ts w

ith

neph

roti

c sy

ndro

me

(6 c

ompl

ete,

2 p

aI1i

a\).

Dis

ease

act

ivity

t

from

cla

ss I

V to

cla

ss I

II i

n 3

pts,

ex

trar

enal

act

ivit

y su

ppre

ssed

in 2

pts

, 2

rela

pses

(co

ntro

lled

)

00

"'" 0 3::

0 a F·

0 t)

!!. '" n ~

po

:J;> c;:: " ::J. (J

Q

~

(1

"0

0 a o· 5;

Tab

le 5

. (co

ntin

ued)

Ref

eren

ce

No

.ofp

ts

Tre

atm

ent

dura

tion

Rad

hakr

ishn

an

10:6

rfr

. 2

ae,

6-43

mo

et a

l. [6

9]

2 in

it

Aus

tin

et a

l. [3

] 5

vs 8

I

Y

(PO

N a

lone

) vs

6 (

i.v.

Cyc

)

Fu

et a

1. [4

1J

20:2

0 (C

yc+

PO

N)

I y

chil

dren

CsA

dos

age

Con

curr

ent

(mg/

kg p

er d

ay)

trea

tmen

t

2-5

P

ON

10

mg/

day

to 1

20 m

g q2

d in

8 p

ts

<5 b

id

PO

N

<5 b

id

PO

N 5

-10

mg/

day

Pro

tein

uria

t 66

%

(fro

m 6

.5

to 2

.2 g

/24

h,

P<

0.00

2)

PR 4

/5 o

n C

sA

CR

2/5

on

CsA

<0.5

g/2

4 h

in a

ll pt

s

Oth

er

com

men

ts

-seru

m c

reat

inin

e, 3

rel

apse

s (p

rote

inur

ia)

Rel

apse

in

4/4

afte

r C

sA a

brup

t di

scon

tinu

atio

n

-se

rum

cre

atin

ine.

hig

her

incr

ease

in

the

mea

n gr

owth

rat

e on

CsA

(8

.2 v

s 2.

7 cm

/y)

ae,

pts

expe

rien

ced

unac

cept

able

adv

erse

eve

nts

with

pre

viou

s tr

eatm

ent;

bid

, tw

ice

dail

y; C

R,

com

plet

e re

mis

sion

; C

YC

, cy

clop

hosp

ham

ide;

FL

U,

fluo

cort

olon

e; i

n it,

in

itia

l tr

eatm

ent;

i.v

., in

trav

enou

s; N

S,

not

stat

ed;

PR,

part

ial

rem

issi

on;

PO,

oral

ly;

PO

N,

pred

niso

ne/p

redn

isol

one;

pts

, pa

tien

ts;

q2d,

eve

ry 2

day

s; r

sp, r

espo

nded

to p

re

viou

s tr

eatm

ent;

rfr

, re

frac

tory

to

prev

ious

tre

atm

ent;

-, n

o si

gnif

ican

t cha

nge;

Lde

crea

sed

.., iti a a (D ;:; o ....,

CIl l'

t'I'l

po

::l

0- C

'0 1i: ::l ,g ::l' ~: 00

U

1


substantial differences in outcome between the two groups but there was a higher risk of serious adverse effects with Cyc. No signs of CsA nephrotoxicity were found.

On the basis of these results, CsA may find an indication as a steroid-sparing agent in the long-term treatment of patients with severe SLE and lupus nephritis. However, because of its potential nephrotoxicity, it should be used with caution. Patients with renal insufficiency, severe hypertension or marked tubulointerstitial lesions at kidney biopsy are at greater risk of renal toxicity and should not be treated with CsA. The initial doses should not exceed 4 mglkg per day with the new microemulsion [61]. Whenever serum creatinine increases by 30%, the CsA dose should be reduced, and the drug should be stopped if the increases are 50% or more and only resumed when serum creatinine returns to baseline values. Respect for these guidelines minimises the risk of renal toxicity [34, 38, 66].

A multicenter study involving nephrologists, immunologists and rheumatologists is now under way in Italy to explore the role of CsA in the maintenance therapy of SLE nephritis.

Conclusions

Although the etiology of SLE remains unknown, much has been learned about its pathogenetic mechanisms, clinical patterns and prognosis, as well as about the role of various therapies in modifying its course. The most widely used immunosuppressive drugs (particularly corticosteroids, Cyc and Aza) are often criticised as being non-specific, but they may be effective in SLE and lupus nephritis precisely because broad rather than highly selective effects are required to control the aberrant immune system. However, they are not equally effective and are associated with substantial toxicities [6, 42, 50].

The therapeutic prospects include the optimisation of the currently used immunosuppressive combinations of steroids, Cyc, Aza, CsA and MTX, as well as the introduction of new forms and combinations of chemotherapeutic agents such as MMF and adenosine analogues. The attempts to achieve immunological reconstitution using near-ablative chemotherapy (with or without bone marrow or stem cell rescue), monoclonal antibodies and other inhibitors of T cell costimulatory pathways (i.e. anti-CD154 and/or CTLa4-Ig) are the subject of phase II trials. Gene therapy has already been used in some animal models of SLE [6].

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Combination therapy in autoimmune disease: vasculitis

D. Carruthers, P. Bacon

Department of Rheumatology, Division of Immunity and Infection, University of Birmingham, Edgbaston, Birmingham, UK

Introduction

Current therapy of systemic necrotising vasculitis (SNV) has transformed the prognosis of this rare group of diseases from conditions with high acute mortality to chronic diseases with a high morbidity. Recurrent episodes of disease activity, leading to the accumulation of organ damage, adds to the risk of both morbidity and mortality. Thus, the important point in management is to recognise the presence of disease activity early, enabling introduction of effective therapy to limit organ damage. To achieve this goal, carefully structured multi phase treatment regimens are needed where therapy is tailored to the phase of the disease in the individual patient. Effective remission induction should be followed by milder long-term maintenance therapy, preventing relapse. Clinical studies provide evidence that this approach is best achieved by the use of a combination of therapies where the individual drugs change with time depending on the patient's disease state. Improved understanding of the immunopathological processes involved in SNV will allow us to maximise current therapies and develop more specific treatments in the future.

Aims of therapy

The general principle of therapy is to rapidly and effectively suppress disease activity so that disease-related damage is limited. The important issue at presentation is often to recognise that some sort of vasculitis is present and, if critical organ involvement exists, the institution of appropriate therapy should not be delayed while the specific diagnosis is being considered. This can be done at a later date. Delay in treatment may result in irreversible organ damage which occurs early and contributes to the mortality, morbidity and poor quality of life of some patients with SNV [15]. In other cases more clinical information may be necessary before a diagnosis of vasculitis is reached and chemotherapy is commenced.

Correspondence 10: David M. Carruthers, Department of Rheumatology, Division of Immunity and Infection, University of Birmingham, Edgbaston, Birmingham, B 15 2TT, UK, e-mail: [email protected]

92 D. Carruthers, P. Bacon

The need to suppress disease activity must be balanced against the risks of serious drug-induced toxicity [80]. For this reason a short course of effective remission induction therapy, switching to milder maintenance drugs, is preferable [47, 52]. An even more structured regime may be to adopt a three-phase approach to treatment where a brief, aggressive remission induction is followed by a short consolidation period before switching to longer-term maintenance therapy. The complex immunopathological processes involved in different phases of the disease would support the concept of combination therapy where the individual drugs change with time, thus providing maximum effect on effector cell populations. Thorough assessment of disease activity is, however, critical before decisions on treatment are made.

Disease assessment

Several clinical indices have been developed and validated to assist in the process of assessment in vasculitis. Disease activity [53], damage [14] and extent of organ involvement [12, 67] can be assessed and, in conjunction with laboratory tests, can be used to direct therapy. They have been shown to have predictive value for severe disease, where patients are at higher risk of mortality and may therefore need a more aggressive approach to therapy. In addition, when used routinely, these tools will aid the clinician unfamiliar with these rare diseases in diagnosis and recognition of disease activity.

Clinical tools for disease activity and damage

The Birmingham Vasculitis Activity Score (BVAS) is a clinical scoring system, developed by consensus and validated in routine practice, to help in the recognition of disease activity [53]. The BVAS provides a weighted numerical score, dependent on the specific organ involved and the severity of that involvement. An other useful tool, developed specifically for Wegener's granulomatosis (WG) is the Disease Extent Index [67], but its utility in other vasculitides is less clear. Clinical features secondary to active disease must be differentiated from items of irreversible damage that occur after episodes of disease activity, or are a consequence of therapy and do not require further immunosuppression. A cumulative score, where items of damage must be present for a period of 3 months and can be attributable to the disease, drugs or other undefined cause - the vasculitis damage index (VDI) - has been developed [14]. These clinical tools, in conjunction with laboratory investigations [64], can aid in differentiation disease activity, where immunosuppressive therapy may be required, from irreversible organ damage, where more therapy may be potentially harmful.

1.2.2. Prognostic relevance of assessment

These clinical scoring systems are important as they can provide prognostic information. A high initial BVAS (>20), reflecting either critical organ involvement or multisystem disease, predicts higher mortality [53]. A high VDI score, indicating multiple organ involvement, identifies a subgroup of patients with more severe or fatal dis-

Combination therapy in vasculitis 93

ease [15]. Other clinical scoring systems can help with the choice of therapy by indicating patients with a less favorable prognosis. The five factor score (FFS) developed by Guillevan et al. [27] can identify a subgroup of patients with polyarteritis nodosa (PAN) or Churg-Strauss syndome (CSS) who have a worse prognosis. Patients with two or more risk factors (proteinuria> 1 g, creatinine> 140 Jlmmolll, cardiomyopathy, gastrointestinal or CNS involvement) and treated with a combination of corticosteroids (CS) and cyclophosphamide (CP) had a 46% I-year mortality, in contrast to 89% survival in those with a score of O. The FFS can thus be used to direct therapy in patients with CSS; a FFS of 0 may be treated by CS alone, and these patients do not require a combination of steroid and CP as initial therapy.

Prognosis of SNV

Prior to the introduction of CP therapy, the 5-year survival of patients with what was then classified as PAN was less than 15% [20, 69]. The mean survival of untreated WG was 5 months with a I-year mortality of 85% [82]. When CS were introduced in the 1950s the 5-year survival improved to 48%, with a worse prognosis seen in patients with renal disease [20]. A considerable improvement in 5-year survival to 80% was seen after the introduction of combined CP and CS [17]. Despite the limitations of these early uncontrolled studies, continuous daily CP and CS became the treatment of choice for patients with severe SNV, but there are still several important therapeutic areas which could be improved.

Unresolved issues in SNV therapy

There is still an appreciable 5-year mortality of at least 25% in most large studies of SNV [55, 70]. This death rate is due to both the effects of the disease and the complications of its therapy. Morbidity from grumbling disease activity and organ damage from previous episodes of disease activity contribute to a poor quality of life in many patients. In addition, relapse is frequent in some disease groups, with rates as high as 50% in WG [22]. Drug toxicity, with an increased risk of infection and a long-term risk of infertility and malignancy, is also appreciable [46, 80]. A staged approach to therapy where disease activity is treated aggressively to induce remission and is maintained long-term by less toxic agents, should address these issues.

Rationale for combination therapy in SNV

The clinical features of the vasculitides are varied, with most classification criteria based on the size and type of blood vessel involved (Table 1) [40]. In classical PAN, small and medium-sized arteries and rarely veins are affected. The inflammatory lesions asymmetrically involve the vessel wall with disruption of the internal elastic lamina with or without fibrinoid necrosis. In contrast, microscopic polyangiitis (MPA) involves capillaries and arterioles (especially in the kidney producing a glomerulonephritis). The involvement of different sized vessels suggests that the precise immunopathogenetic mechanisms probably differ for each specific disease and also for the phase of disease, particularly in WG.

94

Table 1. Classification of systemic vasculitis

Vessel size

Large vessel

Medium vessel

Small vessel

Diagnosis

Giant cell arteritis Takayasu arteritis

Polyarteritis nodosa Kawasaki disease

Wegener's granulomatosisa

Microscopic polyangiitisa Churg-Strauss syndromea

D. Carruthers, P. Bacon

Cutaneous leucocytoclastic vasculitis Essential cryoglobulinaemic vasculitis Henoch-Schonlein purpura

aAnti-neutrophil cytoplasmic antibody-associated vasculitis

Pathogenesis

Vessel damage in SNV is characterised by inflammation and necrosis of the blood vessel wall. This results in vessel occlusion and local tissue ischaemia. Several immunological mechanisms may contribute to the vessel injury, including anti-endothelial antibody and anti-neutrophil cytoplasmic antibody (ANCA) production, vessel damage secondary to cell-mediated immune responses and granuloma formation [79]. Immune complex formation is particularly involved in secondary vasculitis [3]. Often there is more than one process involved and the predominant mechanism may change with the phase of disease. This is certainly true for WG, where early disease may be localised to the upper and lower airways and a granulomatous inflammatory reaction is found. It is only in the systemic form of disease, often occurring later, that a necrotising vasculitis is seen.

Endothelial cells (EC) are critically involved in the immunopathogenesis of vasculitis [44]. There is a regional variation in the expression of EC in the body, a fact which may influence the characteristics and distribution of the inflammatory response and, therefore, the clinical picture [57]. EC secrete and respond to cytokines and inflammatory mediators, allowing the egress of myeloid and lymphoid cells from the blood vessels into the vessel wall. Adhesion molecule expression on EC is critical in this response allowing the rolling, adherence and migration of marginated leucocytes. Increased levels of VCAM-I, ICAM-I and LFA-3 are seen in the serum of patients with SNV [77] and levels of VCAM-I have been associated with changes in disease activity in WG [28]. This adhesion molecule up-regulation provides one mechanism for leucocyte recruitment into inflammatory sites, but exactly how the process is initiated or perpetuated in vasculitis is unknown.

Initiation of disease may involve EC activation by anti-endothelial antibodies. Subsequent activation of complement and neutrophil attraction via chemotactic factors leads to a necrotising vasculitis with vessel thrombosis, occlusion, haemorrhage and secondary ischaemia of local tissues [5]. The role of ANCA in disease pathogenesis is supported by the clinical association between changing ANCA titres and disease activity in many cases of WG and MPA [21]. In addition to the clinical observations there are experimental data supporting ANCA involvement in the pathogenesis of SNV [36]. Activation of neutrophils and ECs primed by previous exposure to


TNF-a may occur via IgG ANCA, promoting the adherence of neutrophils to the endothelium and enhancing the release of lytic enzymes and reactive oxygen species [79]. These products induce inflammation in the vessel wall at the sites of neutrophil adhesion. Infiltration and degranulation of activated neutrophils contribute to damage of the vessel wall. In addition, activated neutrophils and the targets of ANCA [proteinase 3 (PR3) and myeloperoxidase (MPa)] are found in the glomeruli of vasculitic but not normal kidneys, perhaps promoting renal damage [6]. In fact, the degree of neutrophil infiltration has been correlated with the severity of the renal lesion [6].

However, it is unclear whether EC can secrete PR3 and MPa antigens, but their presence on the cell surface enhances neutrophil binding and activation [45, 56]. The ANCA antigens on EC may be from degranulated neutrophils, possibly having a direct role in increasing the expression of adhesion and chemoattractant molecules from these cells. EC apoptosis or cytolysis may occur secondary to these products of acti vated neutrophils, leading to damage to the vessel wall [4]. The degree of neutrophil activation may be influenced by the FcyR allotype engaged [59], the IgG subclass of ANCA [60J or the epitope that is bound on PR3 [85].

There is also evidence of a role for T cell-mediated immune mechanisms in SNY. Activated CD4+ T cells, in close proximity to macrophages, are found in the inflammatory infiltrate in PAN [47]. T cell reactivity against the vessel wall or antigenic components of PR3 or MPa released from activated neutrophils may exist in ANCA-related vasculitis [42]. In addition, a Th I phenotype of cytokine release is seen in T cells from patients with WG, perhaps promoting a cell-mediated response in this disease [5 I]. In temporal arteritis there is evidence of an antigen-driven response, with T cells recognising antigen on antigen-presenting cells, leading to the production of inflammatory mediators and vessel wall destruction [83]. Subsequent intimal proliferation and thrombus leads to vessel occlusion. There thus exists a complex interaction between the endothelium, T and B cells, circulating ANCA, platelets, activated neutrophils and cytokines in SNY.

Therapeutic success currently requires a broad-based anti-inf1ammatory response that will inf1uence many of the cell populations involved in the disease process. Current therapies to suppress the inf1ammatory response have mostly non-specific effects and evidence from clinical studies generally supports their use in combinations of two or more drugs. Table 2 shows the main drugs used to treat SNY. However, as our understanding of these complex diseases progresses, newer therapies will be more specifically targeted at the major pathogenic cell type or inf1ammatory process.

Effects of individual therapies

As there is no current cure for SNV, the general anti-inf1ammatory and immunosuppressant responses to therapy are important. CS have broad anti-inf1ammatory effects, reducing the release of pro-inf1ammatory cytokines and eicosanoids from many cell types, including macrophages. Expression of activation and adhesion molecules is reduced and increased vascular permeability is inhibited, limiting cell migration. Lymphocyte populations are redistributed to the lymph nodes and IL-2 production is inhibited. The number of circulating eosinophils is also rapidly reduced after high-dose CS. The other main drug used to treat SNV is the alkylating agent, CPo It has wide-ranging effects on the immune system, producing dose-dependent effects


Table 2. Stages and combinations of therapy for patients with systemic necrotising vasculitis

Stage of therapy

Remission induction

Adjuvant/enhanced therapy

Maintenance therapy

Relapse therapy

Rescue therapy

IVIg, Intravenous immunoglobulin

Main treatment options

Cyclophosphamide (continuous oral or intermittent pulse) + corticosteroids

Pulse methylprednisolone Plasma exchange IVIg

Methotrexate Azathioprine Trimethoprim/sulphamethoxazole Cyclosporin A

Short course of cyclophosphamide Methotrexate Azathioprine Cyclosporin A

Monoclonal antibody therapy Immune ablation with stem cell rescue

on neutrophils and lymphocyte populations. Neutropenia occurs 7-10 days after an intravenous pulse of CP, with full recovery occurring by 14-21 days [46]. This transient neutropenia may be beneficial in SNV where there is significant neutrophil infiltration of the vessel wall during flares of disease activity. Rapid elimination of these cells may thus enhance the rate of remission induction. A fall in Band T cell numbers occurs with both pulse and continuous oral therapy; however, memory T cells appear less sensitive than naive cells to standard doses of CP [46]. If SNV are antigen-driven diseases then, for prolonged remission, it will be important to effectively suppress the memory T cell population. The use of CS and CP are both limited by their toxicity. In the short term, there is an increased risk of infection after highdose steroid and if neutropenia is induced after CPo Longer-term risks of osteoporosis, cardiovascular disease and bladder cancer after high cumulative doses of CP need to be reduced [80].

Other immunosuppressive therapies have been mainly found useful for grumbling disease activity or remission maintenance, including azathioprine (Aza), methotrexate (Mtx) and cyclosporin A (CyA). These agents have less long-term risk of toxicity and allow a reduction in the dose of daily steroid. Mtx is an anti-metabolite that inhibits the enzymes dihydrofolate reductase and thymidylate synthetase, antagonising the metabolism of folic acid. Importantly for the therapy of SNV, neutrophil chemotaxis is reduced as is adhesion of this cell population to EC. In addition, the production of the pro-inflammatory cytokines IL-l and IL-6 is decreased [72]. Aza interferes with adenine and guanine nucleotides with predominant effects on circulating Band T cells. There is a fall in lymphocyte number and in production of antibodies and IL-2. CyA has a more specific mechanism of action with inhibition of T cells by binding to cytosolic isomerases, inhibiting the activity of ca1cineurin by Ca2+-calmodulin [48]. The fact that this agent is less effective than CP in the induction phase


supports the role of a broad group of inflammatory cells, rather than T cells alone, in the initiation of disease flares.

The broad anti-inflammatory and immunosuppressive effects of CS and CP can also be combined with various adjuvant therapies where severe disease is present or where there is persistent disease activity despite optimum standard therapy. Intravenous immunoglobulin (IVIg) and plasma exchange have varied effects on the immune system, but more specific treatment approaches with specific monoclonal antibodies or anti-thymocyte globulin have been tried, as has the use of immunoablation followed by stem cell rescue.

Remission induction in SNV

Cyclophosphamide and prednisolone

Combined oral prednisolone and daily oral CP is the preferred choice of therapy for remission induction in SNV in many centres, although there is a paucity of controlled data. The use of this combination of drugs was reported in the series of 158 WG patients from the National Institutes of Health (NIH) [33]. Two more recent studies have further illustrated the efficacy of CP and CS in remission induction in ANCA-associated vasculitis [47, 52]. These studies highlight the importance of a staged approach to treatment where therapy is aimed at the current state of disease activity and, once remission is induced, milder maintenance therapy is commenced. This is in contrast to early regimens where daily oral CP was continued for many months after remission was induced. The result of such prolonged therapy, with a high cumulative dose of CP, was an increased risk of toxicity, supporting current concepts of a move to shorter courses of treatment.

CP, started at a dose of 2 mg/kg per day in conjunction with prednisolone (\ mg/kg per day reducing to 10 mg/day by 3 months) is used at the onset of treatment. The median time to remission induction in two recent studies was 3 months, although some patients still required longer treatment for remission to be established (6-12 months therapy) [47,52]. In the original NIH study, remission induction took longer with 50% of patients requiring more than 12 months CP therapy [33]. This difference in the time to achieve remission may represent patient selection. The European collaborative study recruited patients with new disease only, and incorporates patients with MPA as well as WG [52], while the study by Langford et al. [47] was a prospective study with both relapse and new patients. In contrast, the earlier NIH study was a retrospective review of all WG patients referred to this tertiary centre [331. However, the overall message from these studies is clear - once remission is induced, long-term CP does not need to be maintained in the presence of alternative, effective, maintenance therapy.

An alternative, and possibly safer route of administration of CP, is intermittent pulse therapy. This has been used in an attempt to achieve a faster remission on the basis that more drug can be given in a shorter period of time. Intravenous CP pulses in combination with methylprednisolone have been compared in controlled and open studies for the therapy of SNY. The response to pulse treatment has been variable in these studies, not least because of the interval between pulses, an important but frequently ignored issue. Monthly pulses of CP (\ g/m2 per pulse) in an uncontrolled study of 14 patients with relapsing WG induced remission in only 50% of patients,


all of whom relapsed after 1-2 years [34]. A similar poor rate of remission induction (42%) was seen in a study of 43 WG patients also treated with monthly pulse CP [66]. However, a third study showed that monthly pulses (0.75 g/m2 per pulse) were as effective at inducing and maintaining remission as daily oral CP (2 mg/kg per day) [30]. In patients with good prognosis PAN or CSS, monthly pulses of CP (0.6 g/m2) were found to be as effective as daily oral CP in inducing remission, but were possibly associated with less toxicity.

A more recent study comparing 3 weekly pulses of CP (0.7 g/m2 per pulse) to continuous oral CP (2 mg/kg per day) in patients with WG found similar remission induction rates at 6 months (88.9% vs 78.3% respectively) [25]. Although relapse rates were higher after pulse therapy (59% vs 13% for daily oral CP), 5-year survival was equal in the two groups (66.7% vs 56.5%, respectively). Infectious complications were more frequent with daily oral CP (69.6% vs 40.7% for pulse CP) and contributed more often to death in this group (60% vs 33.3%). The high mortality in both groups highlights the continuing need for new and better approaches to therapy for patients with SNY.

Some units have used smaller dose CP pulses (500 mg) at weekly intervals with complete or partial remission achieved in 74% of patients with SNV [54]. Our standard regimen for remission induction in SNV involves pulse methylprednisolone (10 mg/kg) and CP (15 mg/kg) initially every 2 weeks with a dose interval that increases with time [I]. This 2-weekly pulse regime was compared with daily oral CP in a study of 54 patients with SNV where both groups received the same total dose of CP (12 months pulse therapy or 3-6 months of daily oral CP followed by Aza) [I]. Clinical response was similar in the two groups (mortality, treatment failure, relapse and dialysis requirements) but toxicity was less in the pulse group (less marrow suppression and infection). The better response rate to pulse therapy in this study when compared to earlier studies using pulse CP may reflect the shorter interval between pulses during the induction phase, thus maintaining a greater degree of immunosuppression. In line with the evidence from recent trials, we now switch our pulse CP to milder maintenance therapy once remission is induced, aiming for this change after only six pulses. In addition, daily oral prednisolone has a role to play in-between pulses where intense or persistent inflammation exists.

In summary, short courses of oral CP (3 months) are sufficient to induce clinical remission in most cases, but the definition of remission is often not very precise. Pulse CP (15 mg/kg) at 2-weekly intervals may be associated with less toxicity but possibly a higher relapse rate. The European vasculitis group is currently conducting a trial directly comparing pulse and daily oral CPo

Alternative agents for remission induction in SNV

The use of Aza as initial treatment has been superceded by CP with its broad immunosuppressive effects. Chlorambucil, another alkylating agent, may be as effective as CP, but toxicity limits its longer term use. Mtx (weekly dose 20-25 mg) and prednisolone (I mg/kg per day initially) have been used in an open study of 42 patients without immediately life-threatening manifestations of WG (27 with relapsing disease, 15 with new disease) [75]. Of these patients, 71 % had remission induced in a median time of 4.2 months. Further relapse was a feature in 36% of patients after a median time of 29 months while either on Mtx alone or after Mtx had been discon-


tinued. This study suggests that Mtx is useful, but not as effective as CP. The results of a comparative study of Mtx versus CP for remission induction in non-renal WG are currently awaited from the European collaborative vasculitis group.

Adjuvant therapy

Adjuvant therapies are added on top of standard therapy in circumstances where disease control poses specific problems. They are often used at presentation of a flare in situations where severe disease is identified and there is a risk of critical organ failure.

Plasma exchange

Soluble mediators of inflammation, such as immune complexes, are removed from the circulation by plasma exchange (PE) and the ability of the reticuloendothelial system to clear remaining immune complexes is enhanced [49]. When used in combination with CP and prednisolone in patients with rapidly progressive renal deterioration, there is evidence of better renal recovery [32]. The benefit is greatest in patients with ANCA-associated vasculitides with a creatinine of >500 Jlmmolll at presentation, who are dialysis dependent or have lung haemorrhage [63]. Others have found that PE confers no additional benefit in the initial management of patients with MPA or CSS presenting with renal involvement [24]. There may, however, be a role for PE in non-Hepatitis B (Hep B)-associated PAN where relapse has occurred despite CP and CS therapy, but it has no role in initial therapy of PAN. When PE is added to therapy, there is a higher risk of infection which contributes to mortality.

Pulse methylprednisolone

Where rapidly progressive renal failure or pulmonary haemorrhage exists, empirical therapy on 3 consecutive days with 1000 mg infusions of methylprednisolone is sometimes used. The use of pulse methylprednisolone should not delay the commencement of CP therapy in this group of patients with severe disease.

Intravenous immunoglobulin

This adjuvant therapy has shown mixed results in studies of patients with ANCA-associated vasculitis. When given for uncontrolled disease in a group of 12 patients a high rate of response was seen, resulting in a reduced need for additional immunosuppressive therapy at 12 months follow-up [38]. Others have found a lower response rate to IVIg, with skin, ear, nose and throat, and joint disease improving more than renal, pulmonary and eye disease [68]. It has a wide spectrum of possible mechanisms of action, which include blocking of Fc receptors on phagocytic cells, direct inhibition of NK and T cells and the presence of anti-idiotypic activity against ANCA and other potential pathogenic antibodies [41]. Side effects after IVIg are uncommon but deterioration in renal function, aseptic meningitis and hyperviscosity have been reported.


Maintenance therapy

Once remission is induced with CP, then a switch to milder maintenance therapy can be made. This is often with Aza, Mtx or CyA in combination with a reducing dose of oral prednisolone. The duration for which any therapy is continued will be influenced by the natural history of the disease. Classical PAN is associated with a low rate of relapse though morbidity from the initial episode may be great. In contrast, the ANCA-associated vasculitides have a higher relapse rate, particularly for WG where up to 50% of patients may undergo a flare in disease activity, with the median time to relapse 42 months [22]. For these reasons we limit the duration of maintenance therapy in patients with PAN to 12 months, but continue it in MPA/wG for at least 5 years.

Azathioprine and methotrexate

Aza has been the mainstay of maintenance therapy and has been shown to be as effective as CP in maintaining remission [52]. Alternatives include Mtx and CyA. Mtx has additional benefit in patients with grumbling or relapsing disease, particularly when the upper or lower airways are involved. In this situation, remission can be induced in two thirds of patients who had previous therapy with Aza or CP [35]. Mtx with or without low-dose oral prednisolone may, therefore, be a reasonable option to maintain remission or to induce remission where there is grumbling disease activity or relapse without major organ involvement (e.g. renal disease or pulmonary haemorrhage).

Cyclosporin A

When CyA has been used to control disease in active WG, a high dose has been necessary (5 mg/kg per day) with an increased risk of renal toxicity. When used to maintain remission at low doses (1-2 mg/kg) , relapse still occurred [2]. Another report has demonstrated success in remission maintenance when slightly higher doses were used (mean 2.9 mg/kg per day) in seven patients with ANCA-associated vasculitis who were followed for 24 months [29]. Certainly where there has been severe renal involvement this agent should be avoided, but CyA may have a role where myelosuppression has been a problem after other therapies. We have used CyA in combination with Mtx and low-dose steroid to provide broader immunosuppression where frequent relapse has been a problem in WG.

Trimethoprirnlsulphamethoxazole

The role of anti-microbial therapy has been studied in WG as persistent infection with Staphylococcus aureus is seen in the paranasal sinuses of some patients with WG [16]. The subgroup of WG patients with nasal carriage of S. aureus (found in 63% of 57 patients) were identified as being at increased risk of relapse (relative risk of relapse 7.16) [78]. In a controlled 2-year prospective trial, trimethoprirnlsulphamethoxazole (T/S) (160/800 mg twice daily) maintained remission better than pla-


cebo in WG patients (7/41 relapsed with TIS, 16/40 relapsed with placebo) [76]. Another study has shown that TIS combination is not as effective at maintaining remission in generalised WG [lIJ. However, it was found to be successful when used to induce and maintain remission in greater than half of patients with limited disease [65]. Comparison of TIS with Mtx showed that it was not as effective at maintaining remission as this immunosuppressant [11]. Due to a combined inhibition of folic acid metabolism, there is an increased risk of toxicity in patients on Mtx and TIS and this combination should, therefore, be avoided.

It is entirely possible that the effect of TIS relates to actions other than its anti-microbial role (e.g. an effect on white cell function). In view of the problems of S. aureus carriage in WG patients, it is our practice to screen all these patients for nasal colonisation and if present we try and eradicate it with cyclical topical bactroban ointment used in combination with systemic immunosuppressive therapy where necessary. Controlled trials of the efficacy of local nasal antibiotics in preventing late relapse are in progress.

Relapse therapy

Despite the above therapeutic regimens to maintain remission, relapse still occurs. However, there is generally less organ damage than occurs after the initial flare of disease activity, possibly reflecting earlier detection by patients and family doctors [IS]. As recurrent relapse can be a problem in some patients, we aim to limit the duration of CP therapy given for a major relapse to six pulses. In this way the total dose of CP given over the individual's life time will be limited, reducing the risks of serious CP side effects. In patients with grumbling disease activity or non-life-threatening relapse, we consider the use of prednisolone with Mtx, Aza or CyA, perhaps in combinations.

Experimental approaches to induction/relapse therapy

In those patients unresponsive to standard therapy or where recurrent relapse occurs, a more experimental approach to therapy may be taken.

Monoclonal antibody therapy

In view of the role of T cells in the pathogenesis of SNV, monoclonal antibodies (mAb) directed against this cell population have undergone trials. Depleting (Campath-I H) and non-depleting (anti-CD4) mAb have been used in some patients with ANCA-associated vasculitis that has been resistant to other therapies [39]. A rapid improvement in disease activity was seen with a fall in ANCA titre in one small study [SO]. Inhibition of the pro-inflammatory cytokine TNF-a is currently being explored in SNV as it plays a crucial role in endothelial and T cell activation, promoting the inflammatory cascade [18]. Infusions of anti-TNF mAb could be used either as an induction agent, allowing shorter courses of CP, or as an addon agent in patients with grumbling disease activity that is non-responsive to standard therapy.


High-dose cyclophosphamide

We have tried to generate a more structured approach to therapy where a short induction course (three pulses) of high-dose CP is given to induce a remission as early as possible, with the aim of reducing early disease-related organ damage [8]. This is then followed by three further consolidation CP pulses at standard dose before switching to milder long-term maintenance therapy such as Mtx or Aza. Our experience of these regimes suggests that remission can be induced more rapidly by this approach but this has to be carefully balanced against the risks of significant neutropenia after a higher dose of therapy. However, in view of the role of neutrophils in inflammatory lesions in SNV, a mild degree of transient neutropenia (nadir of I x I 09/1) may be beneficial for early remission induction. Doses of CP that avoid severe neutropenia but are slightly higher than those used in standard regimes under development may maintain the enhanced rate of remission induction that we have seen in our small series of patients, while limiting the risk of short- and long-term toxicity.

Immunoablation with stem cell rescue

There is increasing experience of the use of very high-dose immunosuppression followed by autologous stem cell rescue for autoimmune disease, including vasculitis [7, 74]. In patients with uncontrolled SNV despite standard therapy, one approach may be to consider intensified immunosuppression using high-dose CP (50 mg/kg per day for 3 days) in combination with other anti-T cell therapy, such as anti-thymocyte globulin. The aim of this approach, by removing autoreactive T cells, is to modulate the immune response to putative disease inducing autoantigens. Bone marrow recovery is often severely delayed after such intense immunosuppression and therefore previously harvested, lymphocyte-purged CD34+ autologous stem cells are reinfused into the patient to diminish the duration of severe neutropenia and lymphopenia. We have used this approach successfully for two patients with WG, one of whom is still in remission and is off all therapy at 2 years follow-up. The other patient has relapsed 2 years post transplant.

Other newer agents

Newer immunosuppressants tend to have a more specific mechanism of action than CP and have shown promise in some small studies [23]. Mycophenolate mofetil inhibits de novo purine synthesis by inhibition of inosine monophosphate dehydrogenase. DNA synthesis and cell proliferation are reduced and it has been used in Takayasu's arteritis and a few cases of WG [10, 62]. Leflunamide inhibits pyrimidine synthesis by inhibition of dihydroorotate dehydrogenase and tyrosine kinases. It leads to arrest of stimulated cells at the G I phase and may be useful in maintenance therapy [58]. Deoxyspergualin, originally developed for the treatment of solid organ transplant rejection, has a powerful immunosuppressive activity and has a beneficial effect in animal models of lupus nephritis [37]. These newer agents offer future therapeutic options for patients with SNY.


Disease-specific therapy

The combinations of drugs necessary for control of other forms of vasculitis can differ. The duration and specific treatment also varies, often reflecting the size of vessel involved.

Large vessel arteritis

Giant cell arteritis

There is increasing evidence that giant cell arteritis (GCA) is antigen driven with T cell reactivity against antigenic determinants in the vessel wall. Monotherapy with high-dose steroids (60 mg) has been the treatment of choice for this disease, with the aim of reducing pain and preventing visual loss. There are strong arguments in favour of using a combination of drugs in GCA. Too rapid a reduction in the dose of steroid may result in relapse, requiring an increase in dose of steroid and prolonged use of steroids to longer than 5 years is seen in up to 42% of patients [31]. This prolonged use of high-dose steroid therapy significantly increases the risk of side effects, particularly osteoporosis for which preventative therapy with bisphosphonates is now often started at onset. Several small-scale studies have examined the role of immunosuppressive agents as steroid-sparing agents late in disease, particularly Mtx and Aza lS4]. However, the role of these drugs at disease onset is less clear. They may allow a more rapid reduction in the initial steroid dose, thereby prompting an early remission and a reduction in total steroid dosage, limiting late side effects. Combination therapy of CS and CyA may have a theoretically beneficial effect if this disease is T cell driven [S31. In one small-scale study CyA used late in disease had no additional benefit above the use of steroid alone [711. However, the role of Cy A used as an induction agent with CS is unknown.

Takayasu arteritis

Steroids have long been the mainstay of therapy for patients with Takayasu arteritis, with reports of therapeutic success ranging from 20% to 100% 1191. However, the time to remission induction can be very long (22 months) and the assessment of activity in this disease is difficult. A rise in erythrocyte sedimentation rate (ESR) is taken by many to be the main indication for additional therapy. However, histological studies from operative samples demonstrate that 33% of patients thought clinically to have inactive disease had histological evidence of ongoing activity, while up to a half with a raised ESR in fact had inactive disease [43]. New imaging techniques with magnetic resonance imaging may allow better assessment of disease activity, identifying active int1ammation in the vessel wall [9]. Additional immunosuppressive therapy, in combination with steroids, may theoretically provide a more rapid and complete remission. In an open study, IS patients with steroid-resistant disease were treated by the addition of Mtx. Remission was induced in SI % of the 16 patients who completed the study (mean Mtx dose: IS.1 mg/week), but relapse still occurred (in 44% of patients as the steroid was withdrawn) and 3 patients had progressive disease. Some groups have used CP in steroid-resistant disease and we consider

104 D. Carruthers. P. Bacon

a short course of six pulses of CP (15 mg/kg) followed by maintenance Mtx. Controlled trials are necessary to define which approach is most likely to limit both disease and steroid-related complications.

It is important that other features of the disease are not overlooked, for example hypertension, which may need to be treated with ~-blockers and ACE inhibitors, or transient ischaemic episodes, which may need aspirin or formal anticoagulation.

Medium vessel arteritis

PAN associated with Hep B infection

When PAN is associated with Hep B infection, the approach to therapy differs to that used for PAN where Hep B is absent. In the former situation a combined approach of immunosuppression and anti-viral therapy is often necessary. Suppression of viral replication is important and this has been successfully achieved using vidarabine or interferon-a 2b in combination with PE. This approach achieves a 10-year survival of 83% [26]. At disease onset, steroids may be needed for acute disease suppression but their continued use encourages viral persistence. In the absence of Hep B, PAN generally requires combination therapy with steroids and CP, but is dictated by the FFS [27].

Kawasaki disease

The introduction of IVIg as therapy for Kawasaki disease has improved prognosis considerably [61]. Diagnosis is often delayed while infection as a cause of symptoms is excluded; during this period general support, hydration and antibiotics are important. When the diagnosis is suspected coronary aneurysms should be looked for by 2D echocardiography and IVlg should be commenced (2 gmlkg over 12-18 h or 400 mg/kg per day for 5 days) [61]. Regression of aneurysms can occur, either spontaneously or more frequently after IVIg therapy. Additional treatment with aspirin is useful to reduce fever and also for its anti-platelet effect, but warfarin should be considered if aneurysms are present. PE and prostacyclin have been suggested as possible additional therapies in the presence of large coronary artery aneurysms [81]. Steroids may be useful in those patients who do not respond to IVIg but are not generally advocated as routine use and may actually worsen prognosis if used alone [13], More recent data suggest that steroids should be added after IVlg [73]. Long-term follow-up is advisable due to the future potential risk of atherosclerosis.

Conclusion

Therapy is becoming more effective as it is increasingly tailored to both the degree of activity, or disease extent, and the specific syndrome. As acute mortality has decreased, the need to look beyond the immediate flare has supported the use of staged regimes using combinations of drugs which can diminish toxicity. However, the residual mortality, morbidity and high relapse rate suggest there is a continuing need to improve these regimes.


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Combination therapies for systemic sclerosis

C.P. Denton, C.M. Black

Center for Rheumatology, Royal Free Campus, University College London, Rowland Hill Street, Hampstead, UK

Introduction

Systemic sclerosis (SSc) is a multisystem autoimmune rheumatic disease which forms part of the scleroderma spectrum of disorders. These diverse conditions are listed in Table 1. There are common features to these disorders and some clinical overlap between them but they can be separated into three main categories, those with skin sclerosis but no vascular or internal organ involvement such as morphea, conditions with vascular manifestations only, including primary Raynaud's phenomenon, and the different subsets of systemic sclerosis, which form the main focus of this article. The frequency of the disorders has proven difficult to ascertain but North American studies suggest a prevalence of Raynaud's phenomenon of around 10% of the adult female population (6% overall), and an annual prevalence of SSc of 15 cases per 100,000. Data from the UK has previously estimated a much lower prevalence but a comprehensive local study has led to estimates being revised to levels similar to the North American figures [28].

Diagnosis

The scleroderma spectrum includes SSc, which takes a variety of forms and is subclassified based upon the extent of skin sclerosis and the presence of features of other autoimmune rheumatic disorders such as systemic lupus erythematosus (SLE), polymyositis or inflammatory polyarthritis. Thus, in diffuse cutaneous (dc) SSc skin sclerosis extends proximal to the elbows, often involving the chest and abdominal wall. Limited cutaneous (Ic) SSc, in contrast, shows these changes only in the extremities, distal to the elbow and in most cases restricted to the hands with sclerodactyly being the most typical feature. Involvement of the neck and facial skin can occur in both limited and diffuse subsets. The much rarer subset of sine scleroderma manifests vascular and visceral manifestations of SSc but without skin involvement [44].

Correspondence to: Carol M. Black, Center for Rheumatology, Royal Free Campus, University College London, Rowland Hill Street, Hampstead, NW3 2PF, UK, e-mail: [email protected]

lID c.P. Denton, C.M. Black

The clinical features of other diseases distinguish overlap syndromes, as discussed above. Another major subset of the scleroderma spectrum comprises the localised skin syndromes (localised scleroderma) which have no visceral involvement and generally lack vasospastic symptoms. Again, there is variation in the extent of the clinical problem, from single patches to extensive generalised morphea. The latter has widespread skin involvement and may resemble dcSSc. Distinguishing features are the absence of Raynaud's phenomenon and relative sparing of the skin of the extremities. Linear scleroderma is the commonest form of the disease in childhood. It is often asymmetrical and involvement of underlying structures may compromise growth. A variant form affecting the scalp and underlying mesenchymally derived structures is descriptively termed "en coup de sabre". Raynaud's phenomenon is often grouped with other disorders within the scleroderma spectrum despite the absence of skin changes. Raynaud's patients are most often troubled only by their vaso-

Table 1. Scleroderma spectrum of disorders

Localised

Systemic

Raynaud's phenomenon

Morphea:

Linear scleroderma ell coup de sabre

IeSSc

dcSSc

Overlap syndromes

SSc sire scleroderma

Autoimmune Raynaud's phenomenon

Primary Raynaud's phenomenon

localised One or more skin lesion, often on truncal areas

generalised Widespread skin lesions, can be reminiscent of dcSSc, but Raynaud's or visceral manifestations unusual

The most common form occurring in childhood. Skin changes follow a dermatomal distribution and lead to important secondary growth defects. Midline or parasaggittal variant of linear scleroderma which manifests in childhood and may be associated with facial hemiatrophy (Parry-Romberg syndrome)

Skin sclerosis distal to the wrists (or ankles), over the face and neck. Often longstanding Raynaud's phenomenon.

Truncal and acral skin involvement. Presence of tendon friction rubs. Onset of skin changes (puffy or hidebound) within I year of onset of Raynaud's phenomenon

Features of SSc together with those of at least one other autoimmune rheumatic disease e.g SLE, RA or polymyositis

Vascular or fibrotic visceral features without skin sclerosis (less than I % cases)

Raynaud's phenomenon associated with antinuclear antibodies (or other SSe-associated autoimmune serology), usually also abnormal nailfold capillaroscopy. Some patients later develop SSc

Vasospastic symptoms with normal nailfold capillaroscopy and negative autoimmune serology and no other underlying medical/mechanical cause

SSe, systemic sclerosis; dc, diffuse cutaneous; Ie, limited cutaneous; SLE, systemic lupus erythematosus; RA, rheumatoid arthritis

Combination therapies for systemic sclerosis III

spastic tendency, however in some cases there are features of an underlying connective tissue disorder although these may be subtle and remain undifferentiated, failing to fulfil the classification criteria for any other major conditions. Secondary Raynaud's is generally more severe and more difficult to treat than primary. An important subgroup is isolated Raynaud's who have evidence of a subtle microvasculopathy on nailfold capillaroscopy or who demonstrate an anti-nuclear antibody in their serum. This group is at substantially increased risk of developing a defined or undifferentiated connective tissue disease and is sometimes labelled pre-scleroderma.

Clinical manifestations

As well as Raynaud's phenomenon and skin sclerosis, a number of other important clinical problems characterise SSc. Gastrointestinal involvement is very common. Typically, it is manifest by oesophageal dysmotility and gastro-oesphageal reflux. Other features include anorectal incontinence, colonic involvement and midgut disease with clinically significant small intestinal bacterial overgrowth. Cardiorespiratory complications are probably the greatest cause of SSc-related death. Interstitial lung fibrosis has long been recognised but is now being reclassified to reflect differences in histopathology and outcome. Pulmonary vascular disease is the other common manifestation. It can occur secondary to pulmonary fibrosis but it is the isolated form of this complication that appears to have a much worse prognosis. Typically occurring in the 1cSSc subset, it is associated with progressive dyspnoea and a disproportionate reduction in transfer factor of pulmonary function testing, with preserved lung volumes. It can occasionally complicate dcSSc, especially in the context of antifibrillarin autoantibodies. Cardiac fibrosis occurs in both subsets and causes conduction defects, arrhythmias and impaired ventricular function. Pericardial effusions are quite common but not usually haemodynamically significant. Renal involvement can be indolent but it is the abrupt onset of accelerated hypertension with acute renal failure (renal scleroderma crisis) which is the most feared complication. Even with

Table 2. Scleroderma-associated hallmark autoantibodies with clinical associations

Antigen Antinuclear antibody Frequency Organ staining pattern in patients (%) involvement

Topoisomerase I Scl-70 Speckled (diffuse fine) 20-25 overall Lung fibrosis 40 (diffuse) 10-15 (limited)

centromere ACA Centromere (kinetochore) 25-30 Pulmonary hypertension, 70 (limited) severe gut disease

RNA I and III Speckled/nucleolar (punctate) 20 Renal, Skin

Fibrillarin U3RNP Nucleolar (clumpy) 5 Pulmonary hypertension. Muscle

UlRNP Speckled nuclear 10 Overlap features, Muscle

Th(To) Nucleolar (homogeneous) 5 Pulmonary hypertension. Small bowel

PM-Scl Nucleolar (homogeneous) 3-5 Mixed Muscle

112

Table 3. Pathological processes underlying systemic sclerosis

Vascular

Raynaud's phenomenon Microvascular obliteration in viscera (kidney, gut, lung) Endothelial cell activation in lesional skin Increased circulating markers of vascular perturbation Circulating anti-endothelial cell autoantibodies

Immunological

Hallmark autoantibodies Circulating anti-endothelial cell autoantibodies Increased levels of serum markers of immune cell activation Soluble immune cell derived cytokines in serum

C.P. Denton, C.M. Black

Immune cell infiltrates in lesional tissues - skin, lung, bronchoalveolar lavage (BAL) fluid Altered circulating and BAL lymphocyte profiles

Fibroblast activation

Increased extracellular matrix synthesis by lesional skin or lung fibroblasts Activation of fibroblasts by serum and immune cell derived soluble factors Elevated levels of procollagen peptides (I and III)

effective treatment, this has a high morbidity and mortality, although it is also the first of the major therapeutic triumphs in that mortality fell from 100% to 50% following introduction of angiotensin converting enzyme (ACE) inhibitors.

Although SSc classification is generally based upon the extent of skin sclerosis as outlined above, it is now appreciated that autoantibody reactivities are valuable in refining this classification. Some of the recognised clinical associations of the hallmark SSe-associated autoantibodies are summarised in Table 2. Almost all (95%) patients with SSc have some form of antinuclear reactivity and it is likely that new hallmark antigens may be identified. Their relevance to pathogenesis remains uncertain but it is intriguing that they appear to be generally mutually exclusive and that genetic associations with antibody reactivity are often stronger than those with the disease itself.

Combination therapeutics for SSc

The multifaceted nature of the underlying disease process in SSc (scleroderma) makes combination approaches to disease modifying therapy particularly appropriate. Perturbation of three different components underlies development of SSc: the immune system, the vasculature, and interstitial connective tissue. Although it is possible that these events occur sequentially, so that targeting for example the immune system at a very early stage might prevent other disease events, in practice by the time a diagnosis of SSc is confirmed a range of different pathologies are likely to be present, although to different degrees. Modem approaches to disease-modifying therapy therefore depend upon a combination of agents, which act upon these different aspects of the disease. The cellular and molecular pathologies underlying SSc are summarised in Table 3.

The concept of combination therapy is not new in SSc. In fact almost all therapeutic strategies are likely to be a combination of treatments directed against different aspects of the underlying disease process or against various organ-based compli-

Combination therapies for systemic sclerosis 113

Systemic sclerosis - confirm diagnosis

Disease-modifying therapy

Immunosuppressive (ATG,MFM)

Organ-based treatments

gastro-oesophageal reflux (lansoprazole)

midgut disease (antibiotics)

myositis (prednisolone, methotrexate)

subset and stage within subset

(nifedipine, losartan)

Risk stratification based on stage, subset, autoantibody profile

Screening for organ-based complications

fibrosing alveolitis (cyclophosphamide, prednisolone)

Antifibrotic

pulmonary hypertension (warfarin, Hoprost)

renal insufficiency (quinaprH)

Fig. 1. Combination therapy for systemic sclerosis - integrating disease modifying and organ-based strategies. Once the diagnosis of systemic sclerosis is secure the disease subset and stage should be determined. Early diffuse cutaneous SSc is likely to require a combination of vascular, immunomodulatory and antifibrotic treatments. Late stage diffuse SSc or limited SSc may require only vascular therapy. Risk stratification and appropriate screening allows early intervention for organ-based complications. The majority of cases of SSc will require treatment for gastro-oesophageal disease. Specific agents listed in parentheses are intended for illustrative purposes - see text for details. ATG=antithymocyte globulin, MFM=mycophenolate mofetil

cations. Combination therapies for SSc must be viewed in the context that no agent has yet been shown to be superior to placebo as a disease-modifying agent. However, our current approach to therapy is very much in the model of combination chemotherapy, with different parts of the underlying pathogenic processes being targeted by different therapeutic agents. This is summarised in Fig. I, which illustrates that most physicians now adopt an organ-based treatment approach which complements efforts to screen patients and identify visceral complications at the earliest opportunity. Thus treatments for individual patients with dcSSc and lcSSc may be similar if the visceral complications are the same, whereas treatments of patients within the same subset may be rather different.

This review first delineates the therapeutic options for disease-modifying and organ-based therapies and later discusses current strategies for managing important complications including renal, cardiorespiratory and gastrointestinal manifestations. Both established agents and potential novel therapeutic approaches are discussed.

114 C.P. Denton. C.M. Black

Disease-modifying therapies: targeting the underlying pathology

Few of the agents currently used as disease-modifying treatments for sclerodermaspectrum disorders have undergone rigorous placebo-controlled evaluation, and the results for those which have done are disappointing. No agent has been shown to be of unequivocal benefit, and, even if such data were available, therapeutic gain must be carefully balanced against toxicity and considered in the context of the natural history of the condition. It may not be justifiable to use treatments with potentially serious side effects in some scleroderma subsets such as lcSSc, or even in stable latestage diffuse disease. It is likely that organ-based treatment strategies directed towards complications such as renal disease, pulmonary hypertension or fibrosing alveolitis will have more immediate effect on mortality than the development of generalised disease-modifying strategies.

Immunomodulatory therapies

Cyclophosphamide

Cyclophosphamide is an immunosuppressive drug used in the management of a number of autoimmune rheumatic diseases, especially primary vasculitides and complications of SLE such as glomerulonephritis. It is also used as treatment for SSc-associated lung fibrosis and a number of retrospective series have suggested efficacy and delineated factors associated with responsiveness [52]. There have also been a number of prospective studies, including a small series of five patients treated with intravenous cyclophosphamide [61]. As in other indications, toxicity of cyclophosphamide must be carefully balanced against efficacy. Premature ovarian failure. opportunistic infections and the possibility of late secondary malignancies are important considerations in planning the route, dose and duration of cyclophosphamide administration.

Methotraxate

Methotrexate has been a profoundly effective drug for the treatment of rheumatoid arthritis. There has been reluctance to use it in SSc - partly from concern that it theoretically might be deleterious in a disease having both fibrosis and alveoli tis as features, since it can induce hepatic fibrosis. A recent study from the Netherlands [60] included 29 patients and was placebo-controlled, for 24 weeks, followed by a 24-week open-label continuation in those patients who had apparently responded. This trial suggested benefit for skin score and lung function tests. Unfortunately, a substantially larger study from North America has recently been reported and was negative [45]. In addition to SSc, methotrexate is also used in localised scleroderma and generalised morphea, for which open studies have suggested benefit [48].

Mycophenolate mo/eti!

In addition to a proven efficacy as treatment for allograft rejection, this broad-spectrum immunosuppressive agent has recently been used as treatment for a number of autoim-


mune diseases including lupus nephritis [31]. A pilot study of mycophenolate mofetil as treatment for SSc has been reported and the apparent safety and tolerability of the agent makes it a logical choice as a maintenance immunmodulatory drug for scleroderma [57]. Its precise role needs to be defined by formal controlled clinical trials.

Corticosteroids

Although steroid therapy is sometimes effective in controlling the constitutional symptoms of SSc or for musculoskeletal inflammatory manifestations, the use of doses above 10 mg prednisolone (or equivalent) daily should be avoided. Case-control studies suggest that higher doses are associated with an increased frequency of scleroderma renal crisis [54]. In the context of overlap syndromes with myositis higher doses are occasionally necessary, but their use should be accompanied by vigilant screening for signs of worsening renal function.

Anti-thymocyte globulin

The rationale for using anti-thymocyte globulin (ATG) as a treatment for SSc is based upon its efficacy as an immunosuppressive agent. There were several encouraging case reports [11] and these have been extended by one larger case series and by a randomised placebo-controlled trial in the United Kingdom. The case series of 10 patients with early (less than 3 year duration) dcSSc, confirmed feasibility and tolerability but end-point changes were disappointing [58]. Currently several centres are using ATG as an induction treatment for diffuse SSc according to standardised protocols. The short-term (opportunistic infection, hypersensitivity reactions including serum-sickness) and longer term adverse effects must be balanced against any therapeutic benefit.

Cyclosporin A

Cyclosporin A (CyA) has attractive properties for treating SSc, especially for those cases of aggressive dcSSc in which there is marked immunological activation. However, there remain major concerns about nephrotoxicity. One series suggested that the rate of renal SSc crisis may be twice that expected for patients with aggressive diffuse SSc treated using cyclosporin [38], another report implicates cyclosporin withdrawal in the precipitation of renal crisis [18]. An open-label study of 48 weeks of administration suggested efficacy, although there was significant toxicity, especially at doses above 3--4 mg/kg per day [10]. Earlier open studies also suggested benefit, both for skin and visceral manifestations [14], and for serum markers of collagen biosynthesis [23]. A recent trial using the related agent FK506 has been reported but despite its theoretically safer renal side-effect profile, there was still substantial toxicity [69]. Nevertheless, the use of both cyclosporin and FK506 continues in some centres and so further definitive studies may be warranted [47].

Immunoablation with autologous peripheral stem cell rescue

One of the most aggressive approaches to therapy for SSc is the use of immunoablation followed by reconstitution using autologous peripheral stem cell rescue. Pilot programmes to evaluate this treatment are underway in Europe and in the USA [42].

116 c.P. Denton. C.M. Black

The rationale for this therapy is similar to that in other autoimmune diseases. Thus, if SSc is being driven by an autoimmune process then ablation of self-reactive lymphocyte clones may block pathogenesis. If the immune system is reconstituted in the presence of the neoantigens responsible for autoimmunity then tolerance will be reestablished. However, even if such tolerisation does not occur the intensive immunosuppression during this treatment may be directly beneficial. Preliminary results have been presented in abstract form [13] and further reports are eagerly awaited (Editor's note: this topic is fully reviewed elsewhere in this volume by Moore and Brooks).

Photopheresis jor dcSSe

Another immunosuppressive strategy is extracorporeal photopheresis following sensitisation of host leukocytes by methylpsoralen. This is of proven value for some cutaneous conditions, notably T cell lymphoma. The presence of an infiltrate of active immune cells in early SSc, especially the diffuse cutaneous subset, provides rationale for using this mode of treatment, although recent controlled trials have been less than persuasive [22].

Oral tolerisation to type J collagen

In a disease whose pathological hallmark is increased extracellular matrix deposition, it is somewhat surprising that oral type I collagen administration is being proposed. The rationale is based upon the observation that oral tolerance to type I collagen can be induced and the hypothesis that autoimmune reaction to native collagen in SSc may contribute to pathogenesis [32]. Oral collagen administration is apparently safe and also applicable to established disease which is otherwise difficult to treat.

Tumour necrosis jactor-a blockade

For SSc, as in other autoimmune rheumatic diseases, there has been interest in the possible benefit of blocking tumour necrosis factor-a (TNF-a) using either neutralising antibodies or soluble receptors, as a novel treatment for SSc. Since TNF-a antagonises a number of profibrotic cytokines, including transforming growth factor-~ I, it is uncertain whether its blockade would be beneficial. A pilot study treating ten patients with early dcSSc suggests that treatment with soluble TNF receptor (etanercept) is well tolerated, although conclusions about efficacy would be premature [40].

Antifibrotic therapies

D-Penicillamine

Probably the most widely used agent for treating SSc has been D-penicillamine. There have been a large number of studies examining its effect. Unfortunately most of these studies were retrospective and poorly controlled [20J. A rigorously designed


and carefully executed double-blind controlled clinical trial has recently been completed and reported, comparing two doses of this drug. Rather disappointingly, this study showed no difference between high (750-1,000 mg daily) and low (125 mg alternate day) dose regimens, certainly providing no justification for using high doses [30]. Penicillamine may still have a place in localised disease, childhood scleroderma or generalised morphea and in overlap syndromes when it may also benefit other aspects of the disease, such as arthritis, but this is unproven.

Interferons

Interferons (a, f3 or y) exert pleiotropic effects on fibroblasts in vitro including down-regulating extracellular matrix gene expression. This led to the hope that the interferons might have anti-fibrotic activity in vivo. There were a number of encouraging pilot studies and these prompted more extensive evaluation of interferons-y and -a. Following an encouraging open study [12], a placebo-controlled trial of interferon-a for early dcSSc was undertaken [56]. Unfortunately, no benefit was demonstrable for the main study end-points, skin sclerosis or pulmonary function. Two studies of interferon-y have recently been reported, although neither was placebocontrolled. These suggest modest benefit [5], but open studies require cautious interpretation. Overall, it is disappointing that interferons have not fulfilled their early promise; whether they will ultimately have any place in scleroderma treatment remains uncertain. It is possible that new delivery systems could reduce toxicity, e.g. liposomally encapsulated interferon-a, or that other types of interferon such as interferon-[3 will prove to be effective.

Halofuginone

This plant alkaloid has shown promise as an anti-fibrotic agent [25] and been used in small-scale studies in experimental animals with benefit to pathologies including surgical adhesions and post-angioplasty stenosis or liver cirrhosis [33, 43]. It appears to selectively down-regulate expression of extracellular matrix genes, although its molecular mechanism is poorly defined. It is currently undergoing preliminary assessment in SSc.

Recombinant human relaxin

Another promising agent is recombinant human relaxin. This hormone, normally present in significant amounts only in pregnant woman, appears to have benefit in SSc. In vitro studies suggest that relaxin reduces synthesis of type I collagen by scleroderma fibroblasts [59] and a dose-escalating placebo-controlled trial has shown benefit based on self-reported health assessment questionnaires and skin score [48, 49]. One attraction was that benefit was observed in established SSc, a disease group generally very difficult to treat. Unfortunately, preliminary data from a much larger study do not confirm the benefit reported in the earlier trial.

118 C.P. Denton, C.M. Black

Vascular therapies for SSc

Two of the most important organ-based complications of SSc are primarily vascular pathologies; acute hypertensive renal failure and pulmonary hypertension. In addition, Raynaud's phenomenon, which is almost universally present in SSc, is a major cause of disease morbidity. Treatment of these vascular components of the pathology of SSc is, therefore, of central importance. It is also possible that treatment of these manifestations might also influence other aspects of the disease.

Oral vasodilator therapies

The most frequent vascular manifestation of scleroderma is episodic peripheral vasospasm (Raynaud's phenomenon), present in 95% of cases. Although many studies have confirmed efficacy of oral vasodilators in primary Raynaud's phenomenon [67], treatment of scleroderma-associated vasospasm is much more difficult. One problem is that side effects are often dose-limiting, and patients with secondary Raynaud's phenomenon may require higher doses than those with the primary form. Responses to individual vasodilators are idiosyncratic, and substantial placebo responses and lack of objective assessment tools confound therapeutic trials. The most widely used vasodilator agents in treating Raynaud's phenomenon are probably the calcium channel blocking drugs. Different agents may demonstrate different efficacy or tolerability and it is generally sensible to try several agents before deciding on maintenance treatment. Other classes of oral vasodilator have also been used. Ketanserin appears to be effective, although its superiority to other agents has not been confirmed.

Some vasoactive treatments may have additional disease modifying potential, such as those which influence the renin-angiotensin pathway. Thus, ACE inhibitors, which have been dramatically effective in the management of scleroderma renal crisis may also have beneficial effects on other aspects of the disease [36]. Several prospective studies are currently underway to examine this. By analogy, there is preliminary evidence that the selective angiotensin receptor antagonist losartan may not only improve the severity of Raynaud's symptoms but also beneficially modulate the levels of procollagen peptides and circulating isoforms of cell surface adhesion molecules [19].

Prostacyclin analogues

Intermittent infusions of prostacyclin or its analogues have been shown to be effective [66] but remain inconvenient and costly. In addition to benefiting peripheral vasospasm, one report suggested that iloprost had beneficial effects on renal blood flow, estimated non-invasively [46]. Orally active formulations of prostacyclin or its analogues are an attractive proposition but unfortunately two large studies recently published from Europe and North America have failed to conclusively demonstrate efficacy. In the European study, which followed encouraging results from an earlier investigation of oral iloprost for primary Raynaud's phenomenon, there was some benefit [4], although a parallel North American study was negative. Recent studies using other oral prostacyclin analogues, including beraprost, have suggested that there may be additional benefit from a disease-modifying effect in Raynaud's phenomenon occurring secondary to SSc [62].


Antioxidant agents

There is considerable evidence implicating reactive oxygen species in the pathogenesis of SSc. Indirect support comes from studies showing reduced levels of micronutrient antioxidants in SSc patients and increased susceptibility of serum lipoproteins to oxidation [7]. Further evidence is provided by increased levels of oxidative metabolites of prostaglandins in SSc. It has been suggested that oxidative fragmentation of hallmark antigens to reveal cryptic epitopes may provide a mechanistic link between the vascular and immunological features of SSc [9]. With this background several studies of antioxidant agents have been undertaken. One study has suggested that the potent synthetic antioxidant agent probucol was beneficial in primary and scleroderma-associated Raynaud's phenomenon [16]. Taken together these observations provide a rational basis for exploring antioxidant therapies in SSc.

Difficulties of performing therapeutic trials in scleroderma

Difficulties in conducting clinical trials in scleroderma are well recognised. These include clinical heterogeneity, absence of any treatment of proven efficacy to use as an active-control arm and a reluctance of patients with a life-threatening disorder to participate in placebo-controlled studies. To try and improve trials, guidelines for evaluating disease-modifying treatments in SSc have been published by the American College of Rheumatology [64].

Monitoring treatment effect

Assessment of disease activity or severity in scleroderma patients is difficult. Rapidly increasing skin sclerosis score or the presence of tendon-friction rubs have been shown to be associated with progression of visceral involvement [21] but these are only present in a minority of cases. To provide a more generally applicable assessment tool, modified health assessment questionnaires (HAQ) tailored specifically for SSc patients have been developed in the USA [55] and Europe [51]. This will undoubtedly be of considerable use, particularly since constitutional symptoms and functional impairment are amongst the most troublesome consequences of SSc. For organ-based complications such as pulmonary fibrosis, pulmonary hypertension or renal involvement, objective assessment is easier. There are many investigations which can detect or monitor these manifestations, but it is generally important to consider data from several different techniques and to examine changes over time. To provide a more global index of scleroderma severity, a scoring system has recently been reported and is currently being validated [41].

Regular follow-up and appropriate assessment is the cornerstone of monitoring scleroderma. Serological markers of disease activity have long been sought and those which may be useful include soluble adhesion molecules such as sICAM-l which have been shown to correlate with tissue expression. Other markers of disease activity have also been evaluated, including collagen propeptides [27], products of collagen type I breakdown [29] and serological variables which may reflect immunological activity (e.g. sIL-2 receptor, neopterin) or vascular activation and damage (sE-selectin, thrombomodulin, vonWillebrand factor) [15].


Although the current climate of evidence-based medicine has encouraged critical appraisal of current treatment approaches for SSc, one drawback is that agents may be inadequately evaluated. It is possible that effective therapies risk being discarded due to under-powered studies giving false-negative results. To avoid this, trials will almost certainly have to be multicentre and perhaps even multi-national [1]. Currently, consortia of clinicians around the world are vigorously improving the infrastructure for multi centre clinical trials, under the auspices of the Scleroderma Clinical Trials Consortium (SCTC) in the USA and the European Scleroderma Club.

One approach to facilitating recruitment into clinical trials and also to providing demographic and clinical data about SSc is through centralised SSc clinical databases (or registries). The Michigan scleroderma registry is now well established [39] and others are being set up in North America and Europe. Such initiatives should increase the number of cases available for studies and also help to standardise treatments.

Subset and stage-specific approaches to treatment

Clinical heterogeneity is a hallmark of the scleroderma spectrum, which includes pre-scleroderma (Raynaud's phenomenon plus SSc-associated auto-antibodies) at one end and rapidly progressive dcSSc at the other. Between these extremes lie those with 1cSSc or with less rapidly progressive and extensive diffuse disease. Another group comprises patients with overlap syndromes who demonstrate features of other autoimmune rheumatic disorders such as SLE, rheumatoid arthritis, polymyositis or Sjogren's syndrome. This group often present particular management difficulties since there may be differential activity amongst the various disease components. Clearly not all patients require the same level of investigation or therapeutic intervention.

Current management requires an accurate diagnosis at the earliest opportunity, notwithstanding the fact that in some cases this may depend upon a period of observation over time. Once the diagnosis is established, it is essential that patients with scleroderma are correctly staged and subsetted. This, together with information obtained by clinical investigation, allows risk-stratification to facilitate stage and subset-appropriate investigation, follow-up and treatment.

Serological and genetic markers help to predict particular complications. Thus, patients carrying the HLA-DR52a genotype or with anti-topoisomerase-1 autoantibodies are at increased risk of developing interstitial lung fibrosis, irrespective of their clinical subset [6]. In contrast, anti-RNA polymerase I or III antibodies are associated with renal involvement [8], whereas for limited cutaneous scleroderma, anti-centromere antibodies are associated with isolated pulmonary hypertension and with severe gut involvement [37].

Organ-based therapy for SSe

Combinations of organ-based therapies are effective

The importance of combination therapy in rheumatic disease is well illustrated by the treatment of established organ-based complications of SSc. Thus, although it is prob-


ably important to target the various underlying pathologies in the disease, treatment of the often life-threatening complications of SSc depends upon appropriate use of agents which have been developed for these systems and are often in widespread medical use. Thus, ACE inhibitors have transformed renal crisis outcome, and proton pump inhibitors have been enormously effective in treating SSc-associated gastrooesophageal reflux. Parenteral prostacyclin analogues have been remarkably effective in treating end-stage primary pulmonary hypertension and have already been shown to be effective in SSc-associated disease. Thus, organ-based therapeutics are leading the revolution in SSc treatment, and by definition are likely to be used in combination. It is likely that ultimate therapies for SSc will involve appropriate disease modifying treatments, directed towards underlying vascular, immunological and fibrotic processes, and specific treatment of complications as they develop. Diseasemodifying treatments will be stage and subset orientated. Organ-based therapies will depend upon risk stratification and screening proactively to identify patients at particular risk, so that treatment can be started at the earliest appropriate time. Typical combinations of treatment which patients with limited or diffuse cutaneous scleoderma are likely to need are shown in the algorithm in Fig. 1.

Progress in managing organ-based complications has been made by drawing analogy with other medical disorders such as peptic ulcer disease, idiopathic pulmonary fibrosis and systemic or pulmonary hypertension. As with many other chronic diseases, a multi-disciplinary approach to therapy is useful to address the patient's physical, emotional and social requirements as well as their medical problems. Physiotherapy, exercises to maintain finger function, and skin care are all important. Patient education is an integral component of successful management and careful explanation of the disease and its complications is often necessary. Specialist nurse-educators, telephone help-lines and patient support organizations all have a valuable place in management.

Skin disease

Skin sclerosis is present in almost all forms of SSc, exceptions being some patients with very early disease and those with the rare subset designated SSc sine scleroderma in whom vascular and visceral manifestations occur in the absence of skin involvement [54]. However, treatment of the disease is rarely dictated by its cutaneous manifestations. Visceral involvement is far more important in terms of morbidity and mortality and also even those patients with severe skin sclerosis often demonstrate stabilization and even softening of the skin with time, especially by 5 years after diagnosis. Systemic anti-histamine therapy can provide some relief for intractable itching, which is a feature of early dcSSc.

In addition to sclerosis, other cutaneous manifestations include calcinotic nodules, especially in lcSSc. No medical therapy has been shown to be effective, but local surgery can be helpful. Another complication is skin ulceration, which can arise through a number of mechanisms: ischaemia from Raynaud's, trophic ulcers associated with contractural deformities or underlying calcinosis and perhaps also large vessel vasculopathy. Secondary infection should be vigorously treated, poor tissue perfusion may require increased doses or extended courses of antibiotics. Optimising the circulation using oral or parenteral vasodilators is also important especially when ulceration is associated with severe peripheral vasospasm. Moisturising creams,


emulsifying ointments and molten wax application help by maintaining skin flexibility and reducing susceptibility to trauma.

Another frequent manifestation of scleroderma is the development of cutaneous dilated loops of small blood vessels (telangiectasiae). It should be noted that telangiectasiae, although occurring especially in 1cSSc - sometimes termed CREST syndrome -, are frequently also present in patients with late stage dcSSc. Indeed they may become more florid in the plateau phase of dcSSc even when the skin sclerosis diminishes. These are distressing for patients and may also cause problems if they are at sites prone to trauma. Haemorrhage from mucosal telangiectasiae is also becoming increasingly recognised as a clinical problem and may require local therapy if it is a recurrent problem. Cosmetic camouflage techniques can be very effective for masking facial telangiectasiae and appropriate advice should be offered to all patients who might benefit. Recently the pulsed-dye laser has also been used with some success [11].

Lung fibrosis

With advances in the treatment of renal scleroderma, lung fibrosis is now a prominent cause of disease-related mortality. The lung pathology of SSc is associated with alveolitis in its early stages, later progressing to fibrosis. There are differences between skin and lung disease in terms of natural history and probably also in terms of pathogenesis. Consequently it may be that different treatment strategies are required. Current treatment is based on that used for idiopathic fibrosing alveolitis, although it is likely that there are some important pathogenic differences between these two conditions. One illustration of this difference is that survival for scleroderma-associated fibrosing alveolitis is better than for idiopathic fibrosis, even when corrected for extent of disease [63].

For treatments of organ-based scleroderma to be effective they must be given to the right patients and at the appropriate time. A combined assessment strategy incorporating high resolution CT scanning (HRCT), bronchoalveolar lavage, pulmonary function tests and 99mTc diethylene triamine pentacetate (DTPA) scintigraphy has been shown to reliably detect lung involvement [26] and to follow responses to treatment. Current management of scleroderma-associated interstitial lung disease is based upon standardised assessment methods and repeated evaluation, so that therapy is targeted to those most likely to benefit. Generally patients receive cyclophosphamide when there is evidence of active alveolitis, usually determined by groundglass appearance on CT scan or by the presence of neutrophils in bronchoalveolar lavage fluid. It is our practice to combine cyclophosphamide (monthly intravenous infusions of 500-750 mg for 6 months) with prednisolone, typically 20 mg on alternate days. Repeated investigations every 3-6 months are used to follow progress. Treatment is generally continued for at least 12 months and perimenopausal female patients should receive anti-osteoporosis prophylaxis. Controlled trials comparing cyclophosphamide treatment with placebo are underway, and a recently reported open study was encouraging [65].

Management of renal scleroderma crisis

The most important renal complication is scleroderma renal crisis (SRC), typically occurring in the diffuse disease subset within the first 3 years of diagnosis and as-


sociated with clinical worsening of skin sclerosis. It has recently been reported that corticosteroid use (greater than 10 mg prednisolone/day or equivalent) may predispose to the development of SRC [54]. Patients at risk should be warned to check their blood pressure regularly. At onset this is often elevated markedly with retinopathy and other signs of end-organ damage including blood and protein in the urine. Although the widespread early use of ACE inhibitors, along with other improvements in managing acute renal failure, has undoubtedly improved survival rate [62], prognosis of established SRC is still poor, with over 30% of patients progressing to renal replacement therapy. It is nevertheless a significant mark of progress that renal crisis is no longer the most frequent cause of scleroderma-associated death.

Powerful parenteral anti-hypertensives (e.g intravenous nitroprusside or labetolol) should be avoided in managing SRC since they may exacerbate renal pathology by over-dilatation of a vasoconstricted vascular bed, leading to relative hypovolaemia and renal hypoperfusion. Similarly, diuretic therapy should also be avoided. Central venous pressure monitoring and an indwelling arterial cannula for systemic arterial pressure measurement should be considered, especially if sclerodermatous involvement of the upper limb causes difficulties using a sphygmomanometer. It is crucial to avoid administration of potentially nephrotoxic agents such as non-steroidal anti-inflammatory drugs and or X-ray contrast dyes. Hypertension should be treated using ACE inhibitors; it has been suggested that quinapril may be preferable to other agents, although historically most patients have received either captopril or enalapril, together with calcium channel blockers. Sublingual nifedipine or hydralazine subcutaneously can be used if the patient is vomiting. Intravenous prostacyclin, which may directly benefit the microvascular lesion, is often administered from diagnosis. Regular blood film examination for evidence of red cell fragmentation (including schistocytosis) may provide useful additional information regarding ongoing microangiopathy. Renal function should be monitored until the condition either stabilises or requires renal replacement therapy. Short-term haemodialysis should be given if necessary, and peritoneal dialysis often works well if long-term renal replacement therapy is needed. Considerable recovery in renal function often occurs after an acute crisis, sometimes allowing dialysis to be discontinued, and improvement can continue for up to 2 years. Therefore, decisions regarding renal transplantation should not be made before this time.

Management of pulmonary hypertension

One of the most lethal complications of SSc is pulmonary hypertension (PHT). This can occur in the context of established interstitial lung fibrosis (secondary PHT) or without evidence of significant interstitial fibrosis, termed isolated PHT. The latter is associated with the limited cutaneous subset of SSc. Overall prevalence of PHT is difficult to assess, with frequencies of between 5% and 30% being reported. Recent studies have confirmed benefit from continuous prostacyclin infusions administered to patients with primary PHT [3], and at least some of this benefit can be extrapolated into PHT associated with scleroderma, especially isolated PHT [2]. However, even if shown to be effective it is unlikely that continuous ambulatory iloprost infusion will become widely available. The high cost of long-term therapy and the likelihood that escalating doses of prostacyclin will be required to maintain benefit are


substantial obstacles. Alternative strategies have been explored including the use of intermittent bolus prostacyclin along the lines currently employed to treat severe Raynaud's phenomenon. There are reports that this approach may be useful in PHT in the context of SSc or other connective tissue disorders [64].

Currently it is our practice to screen all patients with scleroderma for evidence of PHT using a yearly Doppler-echocardiographic examination, together with pulmonary function tests (looking for a reduction in carbon monoxide diffusing capacity in the presence of normal spirometry). Doppler-Echo has been shown to correlate reasonably well with measurements obtained at right-heart catheterisation [17]. Borderline results prompt early repeat testing at 6 months. Cardiac catheterisation is used to confirm the diagnosis, assess severity and determine responsiveness to vasodilator therapy. Those patients who respond are placed on calcium channel blockers and treated with intravenous iloprost. Initially this is intermittent but progressive or severe established cases (peak PAP >60 mmHg) are considered for long-term ambulatory iloprost. Oral anti-coagulation, low-dose spironolactone and digitalisation are also used, as is long-term low flow-rate oxygen therapy. Unfortunately, even with these measures, overall prognosis for established SSc-associated PHT remains dismal.

Cardiac disease

It is likely that cardiac involvement from scleroderma, although important and lifethreatening, is under diagnosed. This partly reflects the intrinsic difficulties of detection of manifestations such as paroxysmal arrhythmia or cardiac fibrosis. By analogy with advances which have occurred in the other important complications, it is likely that cardiac scleroderma management will be facilitated when clinicians are better able to identify the stage, subset and perhaps ethnic groups which are particularly susceptible. Accurate risk stratification will then allow screening resources to be applied in a more focused way. Treatment of cardiac manifestations is currently based on the management of similar clinical events occurring outside the context of SSc. Thus, anti-arrhythmic agents are used for haemodynamically significant dysrhythmias and pacemaker insertion considered when there is evidence of significant conduction abnormalities [35]. Recent studies suggest that conduction defects are the most frequent electrophysiological disturbances in SSc, and these may be associated with re-entrant tachyarrhythmias. Some cases of re-entrant monomorphic ventricular tachycardia in SSc patients responding to local ablative therapy have been reported.

Predictors of poor cardiac outcome remain to be established. One study has suggested that prolonged QTc (corrected QT interval on ECG) may be significant [50]. At present management is individualised according to haemodynamic significance of myocardial dysfunction or pericardial disease and, for conduction or rhythm abnormalities, the perceived likelihood of a life-threatening event. Patients with cardiac complications should be managed in close consultation with a cardiologist familiar with the disease and an important clinical research goal is to define better the prevalence and natural history of cardiac scleroderma.

Gastrointestinal complications of scleroderma

Involvement of the gastrointestinal tract is extremely frequent in scleroderma. Abnormalities have been demonstrated throughout its length, although oesophageal involvement is the most frequently involved site, occurring in up to 80% patients. Simple mea-


sures such as elevating the foot of the bed may be a useful adjunct to more sophisticated treatments. Clinical benefit is obtained from acid-suppressive therapies and protonpump inhibitors are dramatically effective so that use of these as first line treatment is often justified. High doses may be needed to control severe oesophagitis. Additional benefit can be obtained from adding cisapride to treat oesophageal spasm or dysmotility.

Anal involvement is also common, but underdiagnosed, incontinence being the most common complaint. It is important to inquire specifically about anorectal dysfunction so that patients can be offered clear advice to help them cope with this distressing manifestation.

Small intestinal bacterial overgrowth has been shown to occur frequently in SSc and also be associated with more symptoms than in non-SSc cases. This probably reflects changes in small bowel structure and motility, although an influence from other therapies has also been suggested, notably acid-suppressive treatments [24]. Broad-spectrum antibiotics are helpful in treating bacterial overgrowth and can be dramatically effective in some cases.

Sometimes intermittent single agent courses are effective but refractory cases may require rotational antibiotics. When this is to be contemplated, it is useful to confirm the diagnosis using a hydrogen breath test prior to starting therapy. Antral venous ectasia has a characteristic appearance at endoscopy, hence the synonym 'watermelon stomach'. It manifests as iron deficiency anaemia due to recurrent or chronic haemorrhage, or as more substantial episodic haematemesis or melaena. It is an important diagnosis because it is potentially life-threatening and also because it is amenable to treatment using laser photocoagulation [34]. Such intervention is warranted because chronic haemorrhage from telangiectatic lesions is now recognised as a significant cause of iron deficiency in SSc.

Musculoskeletal complications

Most patients with SSc describe some musculoskeletal features. Arthralgia and stiffness are the most frequent; frank arthritis is uncommon and points towards an overlap syndrome. Other musculoskeletal manifestations include carpal tunnel syndrome, tendinitis (with friction rubs - most often in dcSSc), and the consequences of contractures, especially affecting the hands but also more proximal joints in dcSSc. Regular exercise programmes may reduce the development of soft-tissue contractures and input from physiotherapists and occupational therapists can be invaluable. Corticosteroids are generally avoided because of their long-term toxicity and the association of steroid therapy with renal crisis. Non-steroidal anti-inflammatory agents may be detrimental to renal function and blood pressure control and can aggravate oesophagitis, although this is likely to be less of an issue for patients who are on maintenance proton-pump inhibitors. The superiority of selective COX-2 inhibitors over other non-steroidal anti-inflammatory agents in terms of efficacy or side effects remains unproven in SSe, as in other rheumatic diseases.

Conclusion

Although SSc is an uncommon disease, it is important because it has the highest mortality of any of the rheumatic diseases, and also because it is a paradigm for other


more common medical conditions in which immunologically triggered fibrosis occurs, such as liver cirrhosis and idiopathic pulmonary fibrosis.

The life-threatening nature of the worst forms of SSc and the lack of treatments of proven efficacy merit careful consideration of the best approaches to treatment. Combination therapy has already established itself by virtue of the need to treat organ-based complications of SSc, and is beginning to transform the long-term outlook in this disease. Although combination approaches also represent the most likely strategies to be effective for disease-modifying treatment, the timing, duration and precise agents needed to achieve this are still being defined. Evaluation of treatments is confounded by the heterogeneity of the disease, its relative rarity and the difficulties associated with objective longitudinal assessment, as outlined above.

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Therapy of Sjogren's syndrome

N.M. Moutsopoulos', H.M. Moutsopoulos2

1 Oral Infection and Immunity Branch, National Institute of Dental Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA 2 National University of Athens, School of Medicine, Department of Pathophysiology, Athens, Greece

Introduction

Sjogren's syndrome (SS) is a common chronic autoimmune disorder affecting primarily females in the fourth and fifth decade of their life. The autoimmune hallmarks of the disease are attested by the focal lymphoid cell infiltration (Fig. 1) of the exocrine glands and various autoantibodies [28]. The clinical spectrum of the syndrome extends from an organ-specific autoimmune disorder to a systemic process. In addition, features of SS are frequently encountered (5-20%) in patients with almost all autoimmune rheumatic disorders. Patients with SS are also known to have an increased risk for developing B cell lymphoproliferative disorders. The correct diagnosis requires evaluation by various specialists [35]. Differential diagnosis includes adverse effects of drugs, chronic viral infection, e.g., hepatitis C virus (HCV) and HIV, sarcoidosis, lipoproteinemias, amyloidosis, lymphomas and age-related glandular degeneration [12].

The etiology of the syndrome is unknown and therapy remains empirical and symptomatic. Alleviation of symptoms and assurance for comfort and quality of life, as well as close monitoring to allow early diagnosis of systemic manifestations, or development of B cell lymphoma, are the main goals of therapy for these patients. It is important to educate patients that the disorder requires follow-up by physicians, dentists and ophthalmologists aware and eager to treat this syndrome.

Extensive research to develop new therapeutic modalities is in progress; these will treat the disease and prevent progression from a local autoimmune disorder to malignant lymphoproliferation.

Treatment of glandular manifestations

Dryness of the eyes and mouth, due to diminished secretion of saliva and tears, is the rule. However, virtually all moistening exocrine glands may be affected, and in its entire form dryness may be variably present in almost all mucosal surfaces, includ-

Niki M. Moutsopoulos, Oral Infection and Immunity Branch, National Institute of Dental Craniofacial Research, National Institutes of Health, BL. 30, Room 327, 30 Convent Dr., Bethesda, MD 20892, USA

132 N.M. Moutsopoulos, H.M. Moutsopoulos

Fig, l, Labial minor salivary gland biopsy specimen from a 42-year-old female patient primary SS. The classical focal lymphocytic infiltrates are shown (55, Sjogren's syndrome). x I 0

Table l, Sjogren's syndrome: signs and symptoms

Glandular signs and symptoms

Dry eyes Dry mouth Parotid swelling Dry cough (Small airway disease) Dyspareunia

Incidence (%)

95 92 53 38 37

ing the nose, the pharynx, the tracheobronchial tree, the skin and the gastrointestinal (GI) tract (Table 1).

Ophthalmological manifestations - keratoconjunctivitis sicca

The diminished tear secretion with ensuing dryness of the eyes leads to chronic irritation and damage of the corneal orland bulbar conjunctival epithelium (keratoconjunctivitis sicca, KCS). Clinical characteristics of KCS, are "foreign body sensation" in the eye, accumulation of thick ropy secretions along the inner canthi , photosensitivity or blurred vision.

Three tests are helpful to assess KCS: Schirmer's I test, which measures tear production (Fig. 2); The breakup time, which measures tear quality; and Rose Bengal staining of the cornea, which may reveal superficial erosions of the corneal or bulbar epithelium, filamentary keratitis, or ulcers of the cornea [33].

The therapeutic modalities applied for dry eyes are: local and systemic stimulators of tear secretion, protective bicarbonate buffered solutions, replacement therapy; and supportive operative procedures.

Therapy of Sjogren's syndrome 133

Fig. 2. A young female patient with primary SS. Note the reduced ability for tear production as it is shown with the small length of the Whiteman filter paper wetness

Stimulators of tear secretion

Local stimulation. A cyclic adenosine monophosphate (AMP) stimulator, 3-isobutylI-methyl-xanthine, administered as eye drops, has been found to decrease tear film osmolarity and Rose Bengal staining [6]. A bromhexine derivative such as N-cyclohexyl-N-methyl-2-phenylethylamine HCI, increases tear and protein secretion in rabbit eyes [17, 36]. Cyclosporin A, 2% in olive solution, in the form of eye drops, has been shown to be relatively effective in a placebo-controlled clinical trial. Cyclosporin A is a hydrophobic peptide, and penetrates very easily the intact hydrophobic corneal epithelium to accumulate on the stroma. Major side effects are a mild discomfort due to local irritation, which can be decreased by concomitant use of artificial tears [7].

Systemic stimulation. Oral administration of 5 mg pilocarpine hydrochloride four times daily, has been shown, in placebo-controlled studies, to provide significant relief of dry eyes [34].

Bicarbonate-buffered electrolyte solutions

These contain electrolytes, which mimic the electrolyte composition of human lacrimal gland fluids , enriched in a bicarbonate buffer. Bicarbonate interacts with mucin secreted by the conjunctival goblet cells to form a mucin-bicarbonate gel which protects the ocular surface in a mode of action well known in the physiology of gastric mucosa [17]. An open pilot study has shown encouraging results. A non-preserved bicarbonate-buffered solution containing NaCI, KCI, CaCI2, MgMI2, NaC03 and ZnCl2 is commercially available (BION Tears, Alcon Laboratories, Forth Worth, Tex).

134 N.M. Moutsopou!os, H.M. Moutsopou!os

Replacement therapy (artificial lubricants)

These products mimic the physical properties (pH, osmolarity) and not the chemical or the biological properties of the tears. They consist of a polymer, electrolytes, buffers and EDT A and some contain preservatives [l7, 35]. Lubricating agents, which contain preservatives, are often toxic to the ocular surface and cause local burning, in which case they should be replaced by a different preparation. A reasonable strategy for the alleviation of dry eye symptoms is the following. If the patient has tears, she or he may use sustained-release carbomethylpropy1cellulose capsules placed in each eye twice daily. If the patient does not have tears, the capsules act as irritants and the use of lubricants in the form of eye drops is preferred. If vision is blurred, a preparation with lower viscosity should be used [35].

Three preparations have been tested in randomized, controlled clinical trials: (a) a solution of 1 % carboxymethy1cellulose containing CaC12, KCl, NaCl and sodium lactate (Celluvisc, Allergen pharmaceuticals, Irvine, Calif.) [7,17], (b) a preparation containing propyethyleneglycol 400, dextran and polycorbophil in an NaCl solution containing EDTA (Aquasite TM, Civa vision, Duluth, Ga.) [17, 30], and (c) topical sodium hyaluronate and topical fibronectin preparations, which are at least as good as other commercially available lubricants [18, 19]. If the patient has found an appropriate eye lubricant and applies it more frequently than once an hour, a combination of a lubricating ointment during the night with eye drops during the day should be tried [5, 35].

Supportive operative procedures

If the patient has severely dry eyes, punctual cauterization is the procedure of choice. If the patient has mildly dry eyes, cauterization may result in tearing, which would require reopening of the canaliculus puncta. Therefore, it is important to apply the above procedure, first on a temporary basis to determine whether the patients receive some symptomatic relief. Finally, in the case of severe dryness, lateral tarsorrhaphy is indicated to decrease the ocular surface. In cases of corneal perforation a corneal transplant is necessary [5, 35].

Oral manifestations

Oral manifestations are due to decreased saliva secretion. The absence of the moisturizing role of saliva is responsible for patients experiencing difficulty in eating dry foods without sufficient water, adherence of food to buccal surfaces, dysphagia, the need for frequent ingestion of liquids and carrying water bottles, and loss of taste and smell. Additionally, as a result of the reduced salivary flow rate (xerostomia) changes in microbial ecology as well as reduced buffer capacity of saliva occur, and lead to susceptibility to plaque formation, hypoca1cification-dental caries and oral infections (primarily candidiasis) [1, 35]. Due to the lack of saliva, the tongue may lose its papillae, develop deep fissures and have a beefy red appearance (Fig. 3). The lips become chapped, and angular cheilitis often develops. A dry, parched erythematous mucosa may be present. Treatment related to oral manifestations aims at minimizing xerostomia by using saliva substitutes, stimulating


Fig. 3. Patient with SS. Note the atrophy of papillae in the dorsum of the tongue which appears smooth and with deep fissures

saliva secretion and preventing consequences of xerostomia (dental caries and infections) .

Saliva substitutes

The best saliva substitute is water; therefore, the best preventive measure against dryness is sipping fluids throughout the day. In an effort to provide longer relief and increased moistening and lubrication, saliva substitutes with thickening agents have been developed. Saliva substitutes contain sorbitol as lubricant, electrolytes, calcium, phosphorus and a preservative [4]. Nevertheless, they alleviate xerostomia for limited time periods. They should be prescribed in cases of severe dryness with no residual salivary function . Drugs with antidepressant, anticholinergic, antihistamine, and antidiuretic properties should be used with caution in SS patients [5, 35].

Stimulation of salivary secretion

Salivary secretion can be increased by non-specific mechanical and gustatory stimulants such as administration of citric acid and chewing gum. In dry mouth patients these stimulants are discouraged because of their effect on the dentition (demineralization) unless the gum is sugar free.

Pilocarpine hydrochloride stimulates salivary secretion both in normal subjects and in patients suffering from impaired salivary function. Pilocarpine is a cholinergic parasympathomimetic agonist that binds to muscarinic-M3 receptors and can cause pharmacological smooth muscle contraction. Salivary flow rate increases within 15 min after oral pilocarpine administration and peak flow rate is maintained for at least 4 h. Oral administration of 5 mg pilocarpine four times daily in SS patients increases salivary secretion [34]. Although some studies have shown evidence of increased


salivary secretion rate as measured by sial orne try, symptoms improved, perhaps because of increased secretion from minor salivary glands or better conditioning of oral mucosa. The observed side effects such as sweating, chills and nausea are mild but common.

New generation muscarinic agonists, such as cevimeline "evoxac", have been shown to improve symptoms of dry mouth and are now commercially available in the United States (SnowBrand Pharmaceutics, FDA News). The recommended dose is 30 mg three times a day and the drug should be used with caution in patients with cardiovascular disease.

Dental caries

The predominant dental problem in SS patients is caries. Root and incisal caries are common [1]. It has been shown that in patients with SS 62% of the patients are completely or partially edentulous compared to 21 % in the control patient group [321. To prevent dental caries the patient should avoid dietary sugar, perform excellent oral hygiene and maintain frequent dental visits that will reinforce hygiene practices and will achieve early diagnosis of caries (dental visits every 4 months are advised). The use of fluoride is essential in the prevention of caries. Fluoride enhances mineralization of the hydroxyapatite structure of the enamel and renders it less susceptible to decay. Common fluoride containing dentifrices, preferably with mild taste should be utilized. Upon progressive hyposalivation, fluoride gels containing 0.4-1.25% fluoride and neutral pH should be used at least once a week, up to two times daily. Combination of a fluoride and agents containing chlorhexidine has proven to be effective in irradiated patients, although chlorhexidine may be an irritant for the oral mucosa [4,20,21].

Candidiasis

Candidiasis occurs in 30% of SS patients. The risk of development of oral candidiasis is higher in patients wearing removable dentures because Candida species can lodge in the denture acrylate. Therefore, dentures should be cleaned with chlorhexidine solution 0.2% overnight or a chlorhexidine gel 1 % two times daily in case of clinical manifestations of oral candida. Denture wearing during the night is discouraged [321. Oral candidiasis can be treated with topical nystatin 200,000 unit pastilles four to five times daily, or 10 mg clotrimazole oral lozenges five times daily. Since the above preparations contain sugar, they are not indicated for maintenance therapy in cases of recurrent candidiasis. In such cases, 100,000 unit nystatin vaginal tablets, which can be slowly dissolved over 20 min two to three times daily for weeks, or even months, are recommended [4 J.

Parotid gland enlargement (Fig. 4)

Parotid and/or other major salivary gland enlargement occurs very frequently in patients with primary SS (pSS), whereas lacrimal gland enlargement is very uncommon. It is a result of cellular infiltration and/or ductal obstruction and can be asymp-


Fig, 4, Patient with SS and bilateral parotid gland enlargement

tomatic and self-limited, However, if the salivary gland enlargement is more permanent and associated with pain and erythema, a superinfection of the gland or the development of lymphoma should be suspected [15, 28], If a superinfection is suspected, appropriate antibiotic therapy should be administered, Local radiation and/or cytotoxic drugs are not recommended because these modalities increase the risk of lymphoma,

Other glandular manifestations

Involvement of the other exocrine glands, such as those of the upper airways, gastrointestinal tract, and skin occurs less frequently in SS (Table 1), Dryness of the upper respiratory tract mucosa attributed to lymphocytic inflammation and an alteration in secretion as a result of gland damage can cause dry, crusted secretions in the nose, epitaxis, hoarseness, and bronchial hyper-responsi veness [10],

Among gastrointestinal manifestations of SS, chronic atrophic gastritis is the most common finding, Gastric discomfort and anemia due to loss of gastric mucosal function associated with the loss of intrinsic factor may be the most common complications [28, 31, 35], Sub-clinical lymphocytic invasion of the pancreas is not uncommon, This is evident by hyperamylasemia, Furthermore, when pancreatic function testing was carried out in primary or secondary SS patients, exocrine pancreatic impairment was frequently found [31], This abnormality tended to be more severe in patients with longer disease duration and was related to the degree of salivary flow reduction,

Treatment of dryness of the airways

A home humidifier to moisten the air and/or bromhexine at a dose of 48 mg/day may be effective measures for dry airways in SS, Supportive measures are also of impor-

138 N.M. Moutsopoulos. H.M. Moutsopoulos

tance: immunization with pneumonococcal polysaccharide vaccine to prevent pneumonococcal pneumonia, antibiotic treatment of sinusitis, and removal of dry, crusted secretions to leave the sinuses clear [35].

Treatment of atrophic gastritis

Atrophic gastritis and esophagitis are usually mild and require no therapy. Anemia in pSS should be evaluated with serum vitamin B 12 levels and treated appropriately. In severe cases of epigastric discomfort and/or pain, anti-acids are of some value [5, 36].

Systemic therapeutic intervention for exocrine gland involvement

Corticosteroids are mainly employed for severe extraglandular manifestations. In general, due to marginal or no clinical benefit and the potential for side etlects, the administration of immunosuppressive agents is not advocated for the everyday treatment of SS [11]. Previous trials with oral cyclosporin A (5 mg/kg body weight per day) or methotrexate (3 mg/kg body weight per week), have not shown significant alterations in lacrimal and parotid flows, despite the improvement of subjective symptoms. These drugs are also moderately toxic at these doses. Administration of methotrexate may also reduce the frequency of parotid gland enlargement, dry cough and purpura, whereas a trial with azathioprine (l mg/kg body weight per day) has demonstrated no therapeutic benefit and an increased frequency of side etlects [12].

On the other hand oral administration of natural human interferon-a (IFN-a) 150 IU three times daily in SS patients improved stimulated whole saliva output and decreased complaints of xerostomia as compared to placebo after 12 weeks of treatment. Oral administration of IFN-a did not produce any of the significant side effects seen in high dose parenteral IFN treatment. Additional clinical trials, however, are required to confirm the safety and effectiveness of low-dose IFN-a therapy for SS [25].

Combination therapies have not been applied to the treatment of SS.

Treatment of (extraglandular) manifestations

In most patients, systemic manifestations are mild and subclinical. Constitutional symptoms, such as easy fatigue and low-grade fever are more frequent in patients with clinically significant extraglandular manifestations. Certain features, such as musculoskeletal manifestations or Raynaud's phenomenon may be present for years prior to the diagnosis of the syndrome [27]. Others may become apparent later on, as part of the disease course. Thorough clinical assessment may also uncover the presence of SS in a patient with a seemingly-unrelated disorder, e.g., interstitial nephritis with nephrocalcinosis. The development of certain extraglandular manifestations most possibly reflects a more aggressive immune activation process, whereby the lymphocytic infiltration process spreads to diverse epithelial sites and/or immune complex-mediated pathology takes place (for example, in the development of interstitial nephritis or membranoproliferative glomerulonephritis, respectively) [12] (Table 2).

Therapy of Sjogren's syndrome

Table 2. Sjogren's syndrome: manifestations

Systemic manifestations

Easy fatigue Fever Arthralgia Arthritis Raynaud's phenomenon Lymphadenopathy Splenomegaly Purpura

(nonpalpable) (palpable)

Pulmonary involvement (interstitial) Serositis (pleuritis, pericarditis) Nephritis

(interstitial) (glomerulonephritis)

Primary biliary cirrhosis Myositis Peripheral neuropathy Lymphoproliferative disorders

Musculoskeletal manifestations

Incidence (%)

36 17 75 23 48 32

7

3 8 6 2

9 2 4 I 2 4

139

pSS patients frequently manifest arthralgias, myalgias and morning stiffness, and features of fibromyalgia are quite common, occurring in approximately 30% of patients (our unpublished observations). Transient episodes of arthritis of variable severity and duration are experienced by the majority of patients during the course of the disease, and this may precede sicca manifestations. In some cases it may result in Jaccoud's arthropathy. Chronic symmetric polyarthritis that is sometimes indistinguishable from rheumatoid arthritis (RA) may also be encountered. In contrast to RA, hand radiography usually reveals mild joint space narrowing without erosions. Despite myalgias and easy fatigue, muscle enzymes are usually normal or only mildly elevated, but severe myositis is unusual. Cases of SS patients with inclusion body myositis have been also described.

Non-steroidal anti-inflammatory drugs or hydroxychloroquine (200 mg daily) are frequently used for the treatment of arthralgias, myalgias and constitutional symptoms. Treatment with hydroxychloroquine has been reported to improve features of immunological hyper-reactivity in pSS patients, but double-blind controlled studies are lacking. For persistent arthritis, methotrexate may be used, as recommended for RA [12].

Raynaud's phenomenon

Raynaud's phenomenon occurs in one third of SS patients and usually precedes sicca manifestations by many years. pSS patients with Raynaud's phenomenon have a greater tendency to develop extraglandular manifestations despite similar autoanti-

140 N.M. Moutsopou1os, H.M. Moutsopoulos

body profiles. Avoidance of physical and emotional stress, together with nifedipine 5-10 mg three times daily are indicated to decrease the severity and frequency of Raynaud's phenomenon [35].

Pulmonary manifestations

Pulmonary manifestations are due to lymphocytic infiltration of the lung parenchyma and manifest radiologically as interstitial lung disease, pulmonary infiltrates especially in perialveolar areas [22], and rarely as nodular or cavitary lesions which may represent lymphoma. When pulmonary involvement is symptomatic, it manifests as exertional dyspnea, recently developed cough and bibasilar crackles on auscultation [3 J. If solid or cavitary lung nodules or hilar adenopathy are present, open biopsy is necessary to establish the diagnosis. Diffuse interstitial lung disease is usually mild and requires no therapy. In case the interstitial lesion is progressive, it must be treated with prednisone. The initial dose should be 1 mg/kg per day for 1 month, followed by progressive tapering of dosage according to the improvement in the pulmonary function and diffusion capacity parameters 128, 35].

Hepatic manifestations

Hepatic involvement is rare, affecting 5% of patients. It manifests either as mild primary biliary cirrhosis (PBC) with antimitochondrial antibodies (AMA) [24] and elevated liver enzymes or as autoimmune chronic hepatitis.

In addition, hepatitis related to HCY has been described in a limited number of patients [8]. Patients with SS and PBe can be treated with ursodeoxycholic acid, and SS patients with hepatitis C with IFN-a and ribavirin.

Renal involvement

Two types of renal involvement occur in pSS patients: glomerulonephritis and interstitial nephritis. Glomerulonephritis is considered a consequence of systemic vasculitis and manifests with proteinuria, active urine sediment and hypertension [14]. Interstitial nephritis is considered a consequence of lymphocytic infiltration of the renal interstitial space. It manifests with renal tubular dysfunction with or without acidosis and Fanconi's syndrome. Untreated renal tubular acidosis usually leads to renal calculi and nephrocalcinosis (Fig. 5).

Glomerulonephritis is treated with prednisone at a dose of 0.5-1.0 mg/kg per day. With the dose being reduced according to the clinical situation. If the disease is refractory to prednisone, pulse intravenous cyclophosphamide should be given at monthly intervals at the same dose as for lupus nephritis [2]. In case of interstitial nephritis, the major problem is hypokalemic, hyperchloremic acidosis, which can be corrected with oral potassium and sodium bicarbonate. The administration of sodium bicarbonate should begin with 1 g three times daily, but up to 12 g daily may be required. If the patient has gastrointestinal discomfort, a sodium citrate solution may be given instead [5, 28, 35].


Fig. 5. Percutaneous kidney biopsy in a patient with primary SS who presented with hyposthenouria, hypokalemic, hyperchloremic renal tubular acidosis and compromised renal function. Note the intense interstitiallymphocytic infiltrates. x40

Vasculitis

Two forms of vasculitis can occur in pSS [15, 28]: (a) vasculitis limited to the skin (20% of pSS patients), which manifests as palpable purpura (leukoclastic vasculitis), and (b) systemic necrotizing vasculitis involving small and medium-sized arteries . The latter occurs in a minority of pSS patients, and usually affects the skin, peripheral nerves, gastrointestinal tract, and kidneys. It is often associated with fever, cryoglobulinemia, and high titers of rheumatoid factor. It manifests clinically as ulcerative skin lesions, digital gangrene, mononeuritis multiplex, mesenteric arteritis, myositis, and glomerulonephritis . Systemic necrotizing vasculitis is treated with a combination of prednisolone, cyclophosphamide and plasmapheresis [35].

Obstetric and gynecological problems

Fertility, parity and sexual activity of women with pSS does not differ from that of healthy individuals. Dyspareunia, however, is observed in 40% of premenopausal women with pSS as compared to 3% in healthy controls. The histological picture of patient's vaginal tissue reveals perivascular infiltration. Knowing that vaginal lubrication is related mainly to transudate from vaginal walls, small vessel vasculitis has been considered responsible for vaginal dryness [26]. Vaginal dryness can cause painful intercourse. Vaginal lubricants such as K- Y jelly or recently available vaginal inserts can be helpful. Patients should avoid cortisone creams. In postmenopausal women estrogen preparations are recommended.

Treatment of lymphoma in SS

Lymphomas develop 44 times more frequently in SS than in the general popUlation and are of B cell origin [9, 28, 29, 37]. Chronic enlargement of the parotid glands,

142 N.M. Moutsopoulos. H.M. Moutsopoulos

Fig. 6. Chest X-ray of patient with primary SS. Note a mass on the right hilum. Biopsy revealed malignant lymphoma

with the glandular tissue becoming firmer and tender, the recent development of lymph nodes or hepatosplenomegaly, cough, dyspnea on exertion, mediastinal or hilar lymph nodes, and nodular lung lesions may herald lymphoma development. There is some agreement that bilateral small reticulonodular opacities are more compatible with lymphocytic pneumonitis, whereas larger, unilaterally localized nodules are more compatible with lymphoma [3, 28, 35] (Fig. 6).

Treatment of lymphoma is based on histological grading. Patients with lymphomas affecting exocrine glands should be completely evaluated for the extent of the disease. If the disease is localized and low grade, a close follow-up by an oncologist is necessary. If the lymphomas are high grade and clinically aggressive, the patient should receive combination chemotherapy [23] .

Future therapeutic directions

The aim of research in the field of SS has been to understand the trigger mechanisms of this disease and the pathogenic mechanisms that lead to tissue destruction to be able to target them in future therapeutic approaches. There have been two major approaches for the development of future treatment. The first approach has been to target pro-inflammatory events that are known or thought to lead to the hyperactive immune response observed in SS . The second approach has been to try and induce anergy or tolerance of the autoreactive Band/or T cells present in the disease that have been held responsible for pathoiogicallesions in SS.

The idea of targeting CD4 T cells, as a population responsible for the immune response in SS, with monoclonal antibodies was abandoned early; poor results of antiCD4 therapy in RA were achieved [13] . Targeting pro-inflammatory cytokines, present in pathological lesions of SS, has been a more appealing approach. The use of "etanercept", which contains soluble TNF-a receptors and could inhibit TNF-a activity, has been shown to be beneficial in RA and is now in a phase I clinical trial for SS (S. Pillemer, personal communication). The use of thalidomide, which is consid-


ered to have an immunomodulatory role and has been reported to inhibit TNF-a, is in a phase I clinical trial for pSS (S. Pillemer, personal communication). In addition, administration of anti-inflammatory cytokines such as transforming growth factor beta or interleukin-l0 remains an interesting possibility [13].

T and B cell epitope mapping for the autoantigens [16], which are the main targets of the autoimmune response in SS, as well as the discovery of a new exocrine tissue-related antigen, may offer novel immunogens that could be used to induce tolerance [36]. Furthermore, within an immunogen there are sequences which are tolerogenic instead of immunogenic; a paradigm for this is the myelin basic protein. The problem with the oral tolerance model is that it is used with the prerequisite that the gastrointestinal epithelium is occupied by a large number of immunoregulatory lymphocytes [36]. In SS, a disease mainly affecting human epithelia, it seems that such endogenous mechanisms of human epithelial tissues are missing. However, suitable constructs of SS-specific autoantigens should be used for oral tolerance studies in the future.

Conclusions

SS is a common disorder with significant morbidity that may involve multiple glandular and extraglandular sites with variable severity. A small but significant number of patients (5%) may eventually develop malignant lymphoma. In addition, some aspects of the syndrome are frequently encountered in patients with other autoimmune disorders. This multi-faceted presentation of the disorder demands refined measures for diagnosis and management.

The management of SS patients requires the co-operation of multiple medical disciplines and aims at alleviating symptoms and recognizing and treating complications. Despite significant progress in the understanding of the pathogenesis of SS, treatment of the syndrome remains empirical and symptomatic.

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5. Fox RI (1992) Treatment of the patient with Sjogren's syndrome. Rheum Dis Clin North Am 18: 699 6. Gilbard JP, Rossi SR, Heyda KG, Dartt DA (1991) Stimulation of tear secretion and treatment of dry

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Spondylarthropathies: options for combination therapy

A.M. van Thbergen I, R.B.M. Landewe 1,2, Sjef van der Linden 1

1 Department of Internal Medicine, Division of Rheumatology, University Hospital Maastricht, Maastricht, The Netherlands 2 Atrium Medical Center, Heerlen, The Netherlands

Introduction

The spondylarthropathies (SpA) are a family of rheumatic diseases classified together because of common features, including the absence of rheumatoid factor, the presence of mono- or oligoarthritis predominantly of the lower limbs, and inflammatory back pain (spondylitis, sacroiliitis). They are strongly associated with the class I HLA-antigen B27. Organ-specific manifestations such as acute anterior uveitis, inflammatory bowel disease, psoriasis, enthesitis (inflammation of the tendon-bone junction), carditis, conjunctivitis, and genital inflammation are characteristic features for this group of diseases. Patients may have more than one symptom at the same time or at different moments during life. A positive family history is an important hallmark of SpA, and reflects its genetic background.

Two sets of criteria for classifying the SpA have been proposed by Amor et al. [2] and the European Spondylarthropathy Study Group (ESSG) [231, respectively. The ESSG criteria were developed to encompass not only the major disorders belonging to the group of SpA (for which specific classification criteria already existed), but also to include the so-called undifferentiated SpA, syndromes that share certain features of major SpA disorders, but that did not fulfil the available classification criteria for these disorders [23].

The family of SpA includes ankylosing spondylitis (AS), psoriatic arthritis (PsA), reactive arthritis, arthritis associated with inflammatory bowel disease (Crohn's disease and ulcerative colitis), one subform of juvenile chronic arthritis, as well as undifferentiated SpA. For some disorders - SAPHO (synovitis, acne, pustulosis, hyperostosis and osteomyelitis) syndrome, Beh~et's disease, and Whipple's disease - the association with the family of SpA is still somewhat controversial.

Currently, no curative treatment is available for SpA. Treatment is aimed at alleviation of symptoms of inflammation [with non-steroidal anti-inflammatory drugs (NSAIDs)], maintaining mobility (with physical therapy), and long-term suppression of disease activity [with so-called disease modifying anti-rheumatic drugs

Correspondence to: Rohert B.M. Landewe, Department of Internal Medicine, Division of Rheumatology, University Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands

148 A.M. van Tubergen. R.B.M. Landewe, Sjef van der Linden

(DMARDs)]. Only very recently, the armamentarium of drugs available for disease suppression has been expanded with "biologicals", products of modem biotechnology that specifically inhibit mediators of inflammation.

Here we review drug treatment for SpA. Unfortunately, only a limited number of studies explicitly report combinations of treatment. Unlike diseases such as rheumatoid arthritis (RA), in which combination therapy refers to combinations of DMARDs, in SpA it is difficult to state what combination therapy means, since many combinations can be made. For instance, patients with SpA who use secondline drugs will usually continue their NSAIDs, and patients with AS are recommended to do special physical exercises in addition to drug treatment. Although usually not identified as such in the literature, the treatment of SpA is often a combination of several strategies.

A second limitation we encountered in preparing our review was the absence of clear response criteria for clinical trials in SpA in general, and in subgroups of SpA. Comparison of results is therefore difficult. It is only very recently that core sets for clinical record keeping, physical therapy, symptom-modifying anti-rheumatic drugs and disease-controlling anti-rheumatic therapy in AS have been selected to facilitate comparison across studies [72 J.

We focus here on the treatment of SpA in general. However, much clinical research has been performed in more homogeneous patient groups, comprising patients with for instance only AS or PsA. Although SpA are classified together for their common features, subgroups may respond differently to similar treatments. We therefore also discuss the main therapeutic options for (combination) therapy in AS and PsA. We have made our choice on the basis of the prevalence of the underlying disorders and the availability of (controlled) clinical trials.

General treatment of the SpA

NSAIDs

In the treatment of SpA the NSAIDs playa central role. NSAIDs have a rapid effect on inflammatory manifestations. In particular, patients with involvement of the axial skeleton respond well to NSAID treatment. Amor et al. [2] even included the presence of such a response as one of the criteria for SpA.

A major disadvantage of the NSAIDs are the commonly occurring gastrointestinal adverse events. The prevalence of gastric and duodenal ulceration in patients with RA and osteoarthritis regularly using NSAIDs for less than 1 year was reported to be 14%, which increased to 26% in patients taking NSAIDs for more than 1 year up to 15 years [14]. It is unknown whether the prevalence of NSAID-gastropathy is similar in SpA. Singh and Rosen Ramey [64] described differences among NSAIDs with respect to toxicity. They found ibuprofen and aspirin to be the least toxic NSAID, whereas fenoprofen, indomethacin and ketoprofen were the most toxic. However, the new generation NSAIDs [cyclo-oxygenase (COX)-2-selective drugs] that are presumed to have less gastrointestinal toxicity were not yet included in this study.

NSAIDs inhibit COX, of which two isoforms exist. COX-l is the constitutive form and has physiological functions; COX-2 is induced in inflammation [39]. The anti-inflammatory effects of NSAIDs are attributed to inhibition of COX-2, whereas

Spondylarthropathies: options for combination therapy 149

inhibition of COX-l may result in adverse events. The expression of COX-2, but not the expression of COX-I, is increased not only in synovial tissue of patients with inflammatory arthritis, but also, and preferably, in synovial tissue of AS patients [63]. These findings may have implications for the use of COX-2-selective NSAIDs in patients with AS, who might benefit more from these drugs compared to patients with other rheumatic disorders. These new COX-2-selective drugs have been recently introduced. A reduction in the number of gastrointestinal side effects compared to established non-selective NSAIDs was found in osteoarthritis patients, the level now being similar or equivalent to placebo [391. As expected, COX-2-selective NSAIDs were not more effective than standard NSAIDs in these patients. We are now awaiting the results of COX-2-selective studies in SpA.

Local steroids

In case of a contraindication for the use of NSAIDs or an inadequate disease control with these drugs, several other treatment options are available. In acute peripheral joint inflammation local steroid injections may reduce inflammatory symptoms in SpA. Three studies reported the efficacy of corticosteroid injections in the sacroiliac joint, two of which were double-blind randomised controlled studies [9, 44, 47]. In all studies a significant reduction of pain up to 80% was observed. The use of NSAIDs decreased in 50% of the patients, and some even discontinued. Braun et al. [9] observed a clear improvement of MRI assessed sacroiliitis and inflammatory back pain in 25 of 30 patients treated, subjectively lasting for a mean of 8.9 months (0.2-15 months).

DMARDs

Second-line drugs or DMARDs may be considered for patients inadequately responding to NSAIDs, or with persistent peripheral joint involvement. Most experience with DMARDs in SpA is with sulfasalazine (SSZ). SSZ is a slow-acting drug, the effects of which become apparent after several weeks or months of intake. The dosage is gradually increased, and SSZ is often supplied in combination with an appropriate NSAID.

The efficacy and tolerability of SSZ in the entire group of SpA was investigated by Dougados et al. [24]. In a randomised double-blind placebo-controlled trial, SpA patients refractory to treatment with NSAIDs received SSZ or placebo. Patients suffered from AS (n= 134), PsA (11= 136) or reactive arthritis (11=81). The withdrawal rates due to side effects were 5% in the placebo group, and 16% in the SSZ group. After 6 months, in the intention-to-treat analysis, a statistically significant difference was found with respect to the patient's overall assessment of disease activity (60% of the patients in the SSZ group and 44% of the placebo patients improved by at least I point on a 5-point scale). There was a strong tendency in favour of SSZ with respect to improvement in pain and physician's overall assessment. In the completer analysis, a significant difference for these three outcome variables was found in favour of the SSZ group. Subgroup analysis showed that most impressive improvements were seen in patients with PsA, especially in those with polyarticular involvement.

150 A.M. van Tubergen, R.B.M. Landewe, Sjef van der Linden

Clegg et al. [15] performed a re-analysis of three previously conducted randomised double-blind controlled trials of SSZ versus placebo in 264 AS, 221 PsA, and 134 reactive arthritis patients. They focussed on the efficacy of SSZ in peripheral versus axial manifestations of SpA, and found that in particular patients with peripheral joint involvement benefited from SSZ treatment.

There is still controversy as to which is the active moiety of SSZ: the sulfonamide sulfapyridine (SP) or the 5-aminosalicylic acid (5-ASA) moiety. Taggart et al. [69] showed in a comparative randomised study of SSZ versus SP or 5-ASA that SP appeared to be the active moiety. Patients receiving SP had significantly better outcome compared to those treated with 5-ASA. However, the results of the SSZ group showed a trend towards more improvement compared to SP alone. More recently, two open studies in patients with active SpA showed positive results for a group of patients treated with 5-ASA, suggesting that 5-ASA might be the active moiety [20, 70].

In conclusion, there seems to be some place for SSZ as DMARD in patients with SpA, preferably in those with polyarticular peripheral arthritis.

Combination DMARD therapy

A comparison of different combination strategies in SpA has been reported by C;algtineri et al. [11]. They studied in 138 SpA patients whether a combination of two or three DMARDs given concurrently was superior to one DMARD. Patients with active SpA and peripheral joint involvement were divided into three groups: group 1 (n=48) SSZ 1-2 g/day; group 2 (n=45) SSZ 1-2 g/day in combination with methotrexate (MTX) 7.5-15 mg/week; group 3 (n=45) SSZ 1-2 g/day in combination with MTX 7.5-15 mg/week and hydroxychloroquine 200 mg/day. After 2 years significant improvements compared to baseline were found with all three regimens, but the improvements were greater with combination therapies. Group 3 showed most improvement. Statistically significantly more improvement was found in group 3 versus 1 or 2 with respect to erythrocyte sedimentation rate (ESR), morning stiffness, total joint count, spinal mobility, patients' and physician's global assessments and analgesics consumption.

This preliminary study emphasises that combination DMARD treatment may certainly be a valuable option in patients with SpA. More studies and studies including subgroups of SpA patients, performed on the basis of proper response criteria to increase statistical power, are needed to establish the role of DMARD-combination therapy in SpA.

Biologicals

Although a number of patients experience adequate disease control with an NSAID, with or without corticosteroid injections or DMARD therapy, a group of patients remains refractory to these treatments. The latest developments in the treatment of SpA comprise the administration of the tumour necrosis factor-alpha (TNF-a) inhibiting drugs, including thalidomide, as well as the soluble TNF-a receptors (etanercept), and chimerised monoclonal antibodies against human TNF-a (infliximab). TNF-a is a pro-inflammatory cytokine mainly produced by macrophages and mono-


cytes, and plays a major role in inflammation and immune responses in general [4]. In patients with AS, high levels of TNF-a mRNA were found in the sacroiliac joints, implying that TNF-a may be important in inflammatory sacroiliac joint disease [8]. Based on these findings inhibition of TNF-a may be an interesting therapeutic option. So far, only a limited number of studies with anti-TNF-a therapy in SpA in general have been published, but remarkable improvements of symptoms were observed [25, 71].

El Hassani et al. [25] assessed the efficacy of thalidomide, a drug that inhibits production of TNF-a, in 11 SpA patients (AS n=7, PsA n=l, undifferentiated SpA n=3) refractory to standard treatment. Patients received thalidomide 100-300 mg/day for 6 months. Three patients discontinued because of side effects. Clinical parameters improved in 5 patients, and remained stable in 3; biological parameters of inflammation improved in 6 patients.

Van den Bosch et al [71] assessed the efficacy of infliximab in an open pilot study of 21 patients with active SpA (AS n=lO, PsA n=9, undifferentiated SpA n=2) refractory to established treatments. The patients received three infusions of 5 mg/kg infliximab at weeks 0, 2 and 6. A rapid and statistically significant improvement in sUbjective and objective variables was observed from day 3 onwards, and persisted for another 12 weeks. After 12 weeks both patients' and physician's global assessment improved with 82%, and pain with 86%. The mean ESR decreased from 44 mm/h to 4 mmlh; mean CRP decreased from 4.6 mgllOO ml to 0.6 mg/lOO ml. Morning stiffness reduced from 90 min to 5 min on average. In patients with peripheral joint involvement, the number of tender and swollen joints significantly decreased; patients with axial involvement showed significant improvements in functioning and disease activity. Furthermore, and interestingly, a decrease in psoriatic skin involvement was observed in patients with PsA. Only minor side effects were reported, which did not cause withdrawal from the study.

Ankylosing spondylitis

AS is a key disorder of the family of SpA, because of its rather high prevalence (0.1 %), and because AS potentially includes all symptoms of SpA. In AS, it is predominantly the axial skeleton which is affected. Sacroiliitis is the hallmark of the disease. AS may cause serious functional impairment as the disease progresses. Treatment in AS is aimed at reducing inflammatory symptoms and preventing or at least minimising deformity and disability. The standard therapy in active AS remains drug therapy with NSAIDs, which reduce inflammatory symptoms. In patients not adequately responding to NSAIDs, DMARDs may be added to the treatment.

Ward and Kuzis [75] surveyed 226 AS patients, participating in a longitudinal outcome study, and 123 American rheumatologists about their judgements of the effectiveness of different treatments for AS [75]. Of these patients 83% reported using NSAIDs, 27% analgesics, 17% second-line medication, and 10% no medication. Twenty-five percent used indomethacin, 4% phenylbutazone, 12% SSZ, 5% MTX, and 12% received physical exercise therapy. This is in contrast to the opinion of the rheumatologists: 81 % rated indomethacin and 90% phenylbutazone 'very' or 'extremely effective' in treating active AS. Indomethacin was recommended by 82% of rheumatologists for patients with active AS; 64% recommended SSZ, and 20% MTX for patients refractory to NSAIDs.


Physical therapy

Physical exercises are important in the treatment of AS to maintain and improve mobility, fitness and strength, and to prevent deformity [361- Exercises may be done at home or at a physiotherapy practice, or in group settings supervised by a physiotherapist. Hidding et al. [36] showed in a randomised controlled study that patients attending weekly group physical therapy had more improvement in global health, thoracolumbar mobility and fitness than patients continuing unsupervised therapy at home.

Spa therapy is also frequently performed by AS patients. Recently, the efficacy of a 3-weeks course of spa therapy in combination with exercises and followed by weekly group physical therapy was compared to weekly group physical therapy alone in a randomised controlled trial [73]. Significantly more improvement in the primary outcome measures, i.e. functioning, patients' global well-being and inflammatory symptoms, were observed in the spa-exercise groups compared to the physical therapy group. Beneficial effects lasted for at least 40 weeks.

SulJasalazine

SSZ has been used since the mid 1980s in the treatment of AS. In 1990, a meta-analysis of five randomised controlled studies of SSZ versus placebo in AS patients showed that SSZ was a well-tolerated and effective drug [29]. The pooled estimate of improvement in favour of SSZ was 28% in duration of morning stiffness, 31 % in severity of morning stiffness, 27% in severity of pain, 7% in general well-being, 9% in ESR, and 12% in IgA, all over placebo. Adverse events were more frequently observed in the SSZ group than in the placebo group (odds ratio l.57), but this difference was not statistically significant. However, studies published after this metaanalysis showed less convincing evidence for the efficacy of SSZ in AS, especially in patients with axial involvement and longstanding disease duration [17,41].

Kirwan et al. [41 J studied 89 patients with established AS, most of them with symptoms confined to the axial skeleton, allocated to either SSZ or placebo treatment (it was unclear whether the allocation was random). After 3 years, the results for the SSZ group were not better than those for the placebo group, although a trend favouring SSZ was seen with respect to spinal mobility, stiffness, and sleep quality. The only statistically significant difference included a lower number of episodes of peripheral joint symptoms in the SSZ group (0.298 episodes/year) compared to the placebo group (0.392 episodes/year). Although the results in this study may have suffered from insufficient statistical power, the lack of significant differences emphasises that the effects of SSZ in AS are certainly not dramatic.

Clegg et al. [17J also compared SSZ with placebo in patients with longstanding AS (n=264). Response rates (based on non-validated criteria such as patients' and physician's assessment, duration of morning stiffness, and severity of back pain) were 38% for the SSZ group and 36% for the placebo group. Only the ESR had decreased significantly more in the SSZ group compared to controls. However, the subgroup of patients with peripheral joint involvement showed significantly better response rates (56%) compared to placebo (30%).

Therefore, SSZ may have some value in the treatment of AS patients, but should probably be prescribed preferentially to those with short disease duration and peripheral joint involvement.


Methotrexate

Patients failing both on NSAIDs and SSZ may benefit from MTX [5, 19]. In an open study Creemers et al. [19] treated II AS patients (3-26 years disease duration and refractory to NSAIDs and SSZ) with MTX 7.5-15 mg/week. Nine patients were evaluable after 24 weeks and improvements of more than 15% were observed for pain in 6 of 9 patients, general well-being in 6 of 9, morning stiffness in 5 of 9, functioning in 5 of 9, spinal mobility (Schober index) in 6 of 9, and peripheral joint involvement in 5 of 6, although individual patients responded differently. Side effects were mild and reversible.

Biasi et al. [5] treated 17 patients with short disease duration (4.8 years) with MTX 7.5-10 mg/kg in an open study. After 3 years, 16 patients were evaluable. Night pain had completely disappeared, general well-being improved with 94%, Schober index improved from 2 cm to 5 cm (59%), finger-floor distance decreased from 33 cm to 7 cm (78%), and both ESR and CRP significantly decreased. The number of swollen joints declined from 5 to 2, the number of tender joints from 8 to 3. Fifteen patients showed a significant clinical amelioration. Nine patients had discontinued NSAIDs.

In contrast to these positive results, Ostendorf et al. [52] did not observe significant clinical and laboratory improvements in 10 AS patients refractory to NSAIDs and SSZ (disease duration II years) after I year of treatment with MTX 7.5-15 mg/week. In the same study, however, two other groups of 10 patients each, with RA and PsA, respectively, responded significantly to treatment with MTX.

To our knowledge, no controlled studies have been published, so that the real value of MTX therapy in AS cannot be established, yet.

Other therapeutic options

Only a few studies have tested the efficacy of systemic corticosteroids in AS [51, 55]. Mintz et al. LSI] studied the effects of pulse therapy with I g methylprednisolone one, two, three or four times on consecutive days in 5 patients with severe AS. The duration of improvements in spinal mobility, morning stiffness and pain after one or two pulses was short, but after three or four pulses improvements lasted for I year on average. A comparative study of I g versus 375 mg methylprednisolone did not show statistically significant differences between the two groups, although there was a trend towards more and longer lasting improvements in the high-dose group [55]. Unfortunately, no other controlled studies have been conducted.

It has been suggested that bisphosphonates may suppress the generation of proinflammatory cytokines and they have, therefore, been studied by Maksymowych et al. [46] in 16 AS patients (disease duration 3-32 years). Eight patients received intravenous pamidronate, 30 mg each month for 3 months, followed by an additional 3 months of 60 mg per month (group I), and 8 patients received 60 mg monthly for 3 months only (group 2). After 6 months, improvements of 37% in disease activity, 21 % in functioning and 36% in metrology index were found for group I; and of 31 %, 18%, and 31 %, respectively, for group 2. However, no randomised controlled trials have yet been published.

D-Penicillamine in the treatment of AS has been investigated in a single small randomised controlled trial [68]. After 6 months, none of the patients felt improved


and no significant changes were observed. Although the study was small, the results do not support a role for penicillamine in treatment of AS.

Biologicals

Anti-TNF-a therapy in AS is now under investigation. Breban et al. [10] reported impressive clinical and laboratory improvements in two patients refractory to NSAIDs and DMARDs after treatment with thalidomide. Recently, Brandt et al. [7] conducted an open trial on the efficacy of treatment with three infusions of infliximab in II AS patients. One patient had withdrawn after the first infusion, because of a generalised rash. At weeks 2 and 4 improvements of more than 50% in disease activity, functioning and pain were observed in 9 of 10 patients. The positive effects persisted until 12 weeks in 8 of 10 patients. Quality of life significantly improved in 6 of the 9 dimensions of the Short Form-36 at 4 weeks. The use of NSAIDs decreased with 50%, and 5 patients completely stopped taking NSAIDs. Randomised controlled studies are now in progress.

Psoriatic arthritis

PsA is an inflammatory arthritis associated with psoriasis. More than I % of the population suffers from psoriatic skin lesions. Arthritis may complicate psoriasis in approximately 10% of the patients, although the skin lesions may be absent. This figure makes PsA one of the more common disorders of the SpA group. PsA is a heterogenic disease and as such has an unpredictable disease course. Different treatment strategies may be necessary. Predictive factors for disease severity include significant inflammation at the first visit and carriership for HLA B27, B39 and/or DQw3, "protective" factors are a low ESR at presentation and carriership for HLA DR7 [32, 33].

The majority of PsA patients can be managed with NSAIDs alone, if necessary combined with local corticosteroid injections. In patients not adequately responding to NSAIDs, and in severe progressively destructive PsA, second-line drugs can be added. MTX, cyclosporin A (CsA) and SSZ are currently the most frequently used DMARDs in PsA. A systematic review on drug therapy in PsA concluded that only the efficacy of SSZ and parental high-dose MTX had been sufficiently proven [40]. Azathioprine, etretinate, oral low-dose MTX and perhaps colchicine were suggested to be effective, but further clinical trials are necessary to establish efficacy. No studies on combination therapy were reviewed.

Chang [13] conducted a survey among 109 American rheumatologists to determine their perceptions on the effectiveness of DMARDs and treatment choices for peripheral PsA; 59% of the rheumatologists responded. MTX was ranked as the most effective drug by 92% of the rheumatologists. To their opinion, the next most effective drugs were SSZ (28%), gold (23%), steroids (21%) and CsA (15%). In 'mild' PsA, SSZ was the drug of first choice in 55%, and MTX second choice (37%). In 'moderate' and 'severe' PsA, MTX was the drug of first choice in 77% and 92%, respectively. Thirty-six percent used combinations of MTX with another DMARD (not specified).


SulJasalazine

Several randomised controlled trials have studied the efficacy of SSZ in PsA [16, 18, 28, 30, 34]. Three small studies, with less than 40 patients in each, and in which the patient groups were not well defined, all suggested beneficial effects of SSZ [28, 30, 34]. More recently, two large multicenter trials confirmed earlier observations [16, 18].

Combe et al. [18] compared the efficacy of SSZ 2.0 g/day (n=53) versus placebo (n=64), in PsA patients (disease duration of arthritis 8 years) [18]. Pain significantly decreased in the SSZ group with 41 %, compared to 24% in the placebo group. Morning stiffness, joint pain/tenderness index and ESR showed a trend favouring SSZ.

Clegg et al. [16] also compared the efficacy of SSZ 2.0 g/day (n=109) with placebo (n=112) in PsA patients resistant to NSAIDs (disease duration 12 years). After 36 weeks, a treatment response (based on non-validated criteria such as improvements in patients' and physician's global assessment, joint pain/tenderness, and joint swelling) of 58% was found in the SSZ group versus 45% in the placebo group (P=0.05). Only the difference in patients' global assessment of the treatment response reached statistical significance, and a trend favouring SSZ over placebo with respect to physician's global assessment was found. The difference between SSZ and placebo reached a maximum at 36 weeks, suggesting that the full effects of SSZ may take some time to become apparent. In all studies SSZ was well tolerated. Side effects were often reported, and led to withdrawal in 13-30% for the SSZ group, and 5-23% for the placebo group. Gastrointestinal side effects were most often reported.

Methotrexate

Although MTX is currently considered as the preferred second-line drug treatment in PsA, no large randomised double-blind placebo controlled studies could be found in the English literature. Two small randomised controlled trials on the efficacy of respectively high-dose MTX (n=21), and low-dose MTX (n=37) in PsA have been published [6, 76]. Both studies showed significant improvements in skin involvement. Black et al. [6] observed significant improvement in joint involvement and ESR. In the study by Wilkens et al. [76] only the between-group difference with respect to physician's assessment of disease severity reached statistical significance. There was, however, a trend favouring MTX with respect to morning stiffness and patients' assessment of disease severity. Both studies might have suffered from insufficient statistical power. It seems likely that a well-powered clinical trial may confirm the efficacy of MTX in PsA.

Several open studies and one case-controlled study of MTX in PsA patients with both peripheral and axial joint involvement were performed after the above-mentioned randomised controlled trials [1, 27, 56, 78]. The numbers of patients studied ranged from 28 to 54 (disease duration approximately 10 years). The patients received MTX 7.5-15 mg/week and were followed for 12 months up to 2.8 years. Withdrawals due to side effects were found in up to 21 % of the patients. Different outcome measures were used, but all showed a significant reduction in the number of swollen and tender joints. Improvements in the Ritchie index (joint tenderness count) of up to 83%, a reduction in pain of up to 66%, and significant decreases in ESR and CRP were observed. Skin involvement improved in all studies. Nail involvement


dramatically improved in the study by Espinoza et aL [27], but did not change in the study by Pigatto et aL [56],

Abu Shakra et al. [1] described the results of a case-control study on clinical and radiological outcome of 38 PsA patients treated with MTX for 24 months, compared to 38 matched controls who had never taken MTX in the past, Clinical response was defined as 'improvement' if there was a reduction in the number of actively inflamed joints of >40%, and 'poor' if there was a reduction of <20% or any increase in joint count, After 24 months similar treatment responses were found between the MTX group and matched controls, of which half were identified as being 'improved'. The radiographs showed an increase in damage score of 63% in the MTX group, and 47% in the matched controls (not significant).

Taking into account that most rheumatologists world-wide prefer MTX as a drug of first choice in patients with severe and less severe PsA, the evidence to endorse such a policy is extremely sparse, It is to be recommended that in PsA - before exploring the potential of MTX as a component in DMARD combination therapy -first of all the place of MTX as monotherapy should be established by sufficiently large, well-performed randomised controlled trials,

Cyclosporin A

CsA is also frequently prescribed as a DMARD in PsA, but mainly uncontrolled studies have been conducted [35, 45, 57, 59, 60, 67, 74], In these open studies the results of 6-55 PsA patients treated with CsA \.5-7 mg/kg per day for 2 months to 2 years were described. Side effects that led to discontinuation were found in up to 15% of the patients. Significant improvements of 46-57% in number of painful joints, 49-72% in the Ritchie index, 30-81 % in number of swollen joints, 35-61 % in pain, and 37-95% in morning stiffness were found, Also clinically relevant reductions in skin involvement were observed.

Salvarani et aL [61] performed a multicenter randomised open trial comparing a group with CsA 3 mg/kg per day, a group with SSZ 2 g/day, and a group with symptomatic treatment only (NSAIDs, analgesics and/or prednisone <5 mg/day), in 99 patients with active PsA. The primary end-point was the 6-month change in pain, The CsA group showed significantly more improvement in pain and skin involvement compared to both the SSZ group and the symptomatic treatment group. No significant clinical differences between SSZ and symptomatic therapy were found, ESR significantly decreased in the SSZ group versus symptomatic therapy; CRP significantly decreased in the CsA group, Using the American College of Rheumatology (ACR) criteria for defining improvement in patients with RA the number of patients meeting an ACR70 response (almost similar to clinical remission) was significantly higher in the CsA group compared to SSZ (P=0.05). These results seem promising, but one should keep in mind that the ACR criteria have been developed for patients with active RA who are enroled in clinical trials, so that a 70% response in PsA is not comparable with such a response in RA,

Spadaro et aL [65] compared in a randomised controlled trial the efficacy of CsA 3-5 mg/kg per day (n=17) with MTX 7.5-\5 mg/week (n=18) in PsA patients with active peripheral joint involvement, After 1 year, significant improvements in all clinical parameters were observed in both groups. No significant differences between the two treatment groups were found, but more patients from the CsA group had


withdrawn because of side effects. This again, probably, is a study that suffered from insufficient statistical power, which does not allow a clear distinction between the two drugs with respect to efficacy.

Discontinuation of treatment is frequently observed in patients on esA. Using a life-table analysis Spadaro et al. [66] compared the efficacy and toxicity of several DMARDs prescribed in PsA. The study showed that PsA patients had a significantly lower probability for continuing esA over time compared to MTX. The most common cause for discontinuation of esA was hypertension (29%). MTX showed a significantly lower rate of withdrawal for inefficacy, compared to gold and esA. Since patients taking esA compared to MTX are less likely to continue long-term treatment, esA seems not to be the drug of first choice in PsA.

Combination therapy

In two small and uncontrolled studies combination therapy with MTX and esA was investigated [26,48]. Mazzanti et al. [48] reported the results of 8 PsA patients with both peripheral and axial involvement refractory to several DMARDs including MTX and esA when given separately [48]. They were treated with a combination of MTX 10-15 mg/week and esA 3-5 mg/kg per day. After 6 months the Ritchie index had decreased with 60%, pain with 55% and ESR declined from 75 mm/h to 35 mm/h.

Espinoza et al. [26] investigated combination therapy with MTX and esA in 10 PsA patients (mean duration of arthritis 10 years) who failed MTX monotherapy with doses up to 50 mg/week. They were switched to a combination of MTX (doses up to 20 mg/week) and esA (2-3 mg/kg per day). After an average of 15 months follow up, clear improvements in skin involvement, Ritchie index, well-being and a decrease in ESR from 55 mmlh to 18 mmlh were observed. However, radiographic deterioration occurred in 7 out of 10 patients, with development of new erosions.

The above-mentioned studies suggest that combination therapy with MTX and esA may be of value in patients with severe treatment-refractory PsA, but sufficient evidence can only be elicited from properly conducted randomised controlled trials, which are currently lacking.

Other treatment options

The administration of colchicine, frequently used as an anti-inflammatory agent in gout, has also been investigated in PsA patients in two randomised controlled crossover trials in 25 and 15 patients, respectively [49, 62]. Patients received either colchicine or placebo and switched to the other treatment after 2 months. Seideman et al. [62] found significant improvements in Ritchie index, joint pain, joint size and overall assessment in patients taking colchicine, but no changes in psoriatic skin lesions and laboratory values. McKendry et al. [49] failed to find significant changes in any of the outcome measures. No large studies on colchicine treatment in PsA have been published to date.

The efficacy of etretinate, a vitamin A derivate that has been shown to reduce psoriatic skin involvement, was also investigated for PsA [37,42]. In a double-blind randomised trial by Hopkins et al. [37] patients received either etretinate (n=20) or


ibuprofen (n=20). Due to lack of efficacy, all but one patient from the ibuprofen group had discontinued at 24 weeks. No statistically significant between-group differences were found in the clinical parameters at any time point. ESR and CRP both decreased significantly in the etretinate group compared to the ibuprofen group. In addition, less skin involvement was observed in the etretinate group. In a pilot study Klinkhoff et al. [42] treated 40 patients with etretinate 50 mg/day. Patients were followed up for 8-24 weeks. Significant improvements were observed for number of tender joints 50%, swollen joints 61 %, morning stiffness 56%, pain 44%, patients' global well-being 43% and ESR reduced from 39 mm/h to 23 mm/h.

The efficacy of gold salts in PsA patients has been studied in two double-blind controlled multicenter trials [12, 53]. No significant clinical changes were found after treatment with oral gold. However, treatment with intramuscular gold showed significant changes in pain score and Ritchie index [531. In a comparative study on the efficacy of intramuscular gold in patients with PsA (n=14) and RA (n=42) Dorwart et al. [21] showed a total of improvement (defined as >50% reduction in inflamed joints and disease activity) and remission in 71 % of the PsA patients, and in 60% of the RA patients, suggesting that injections of gold may be effective in PsA.

Several other drugs have been studied in the treatment of PsA. All of these studies were only performed once and comprised a small sample size. Vitamin D produced significant improvements in tender joint count, global well-being and ESR in a pilot study [381. Azathioprine produced improvements in skin involvement, joint count and morning stiffness compared to placebo [43]. D-Penicillamine [58] and fumaric acid [54] did not show significantly better results compared to placebo. However, within-group analyses showed (significant) improvements in pain, stiffness, Ritchie index, patients' global well-being and ESR. Anti-malarials have been assessed in a case-control study [31]. A trend towards more improvement in the number of inflamed joints in the active treatment group was seen, but failed to reach statistical significance. In addition, more exacerbations of psoriasis were observed in the anti-malarial group [31].

Biologicals

To date, only a few studies have published results with anti-TNF-a in PsA [3, 50, 77]. In an open study Antoni et al. [3] treated 10 PsA patients with infliximab 5 mg/kg on weeks 0, 2, and 6. Eight patients continued MTX, I patient SSZ. At 10 weeks, all patients had improved according to the ACR50 criteria, and 7 of 10 fulfilled the ACR70 criteria. The number of swollen joints had decreased with 93% and tender joints with 90%. Physician's global assessment improved with 90% and functioning with 80%. CRP and ESR also dramatically improved. Yazici et al. [771 treated 10 patients with active arthritis, and refractory to a mean of three DMARDs, with etanercept 25 mg twice weekly administered subcutaneously. At 3 months, 5 of 10 patients had a complete remission of arthritis, and joint count had decreased with 82%. At 12 months, 8 patients were still taking etanercept and maintained a good response; 1 patient discontinued due to side effects; 1 patient discontinued due to increased disease activity. Mease et al. [50] conducted a randomised controlled trial of etanercept versus placebo in 60 PsA patients (disease duration 9 years). Forty-seven percent of the patients continued MTX. After 12 weeks, re-


sponse to treatment (based on non-validated criteria adapted from Clegg et al. [16] and including improvements in patients and physicians global assessment, joint tenderness, and joint swelling) was observed in 87% of the etanercept group, and in 23% of the placebo group; the ACR20 criteria were met by 73% of the etanercept group and 13% of the placebo group. Skin involvement only improved in the etanercept group.

Concluding remarks

In contrast with the trends in RA, surprisingly little information on DMARD combination therapy is available with respect to patients with SpA. Reasons for this may be that the place of DMARD monotherapy in SpA has not yet been properly defined, that the prevalence of SpA is somewhat lower than that of RA, that up to now treatment response criteria were not defined for diseases of the SpA group, and that the long term course of diseases of the SpA group is considered generally better than that ofRA.

DMARDs are frequently prescribed in addition to NSAIDs, and also physical therapy plays an important role in the overall management of patients with SpA, but the combinations of these treatments were only sparsely described in the methodology sections of the reports studied.

SSZ is the most thoroughly studied DMARD for monotherapy in SpA. A number of randomised clinical trials on the efficacy of SSZ in patients with SpA in general, AS, and PsA are available [15-18, 20, 22, 28-30, 34, 41,69,70]. The general opinion is that SSZ is effective in suppressing inflammation, but only in peripheral joints rather than in axial joints.

Referring to the small number of studies available, it looks as if the popularity of MTX as a DMARD in PsA has been extrapolated to the entire SpA group. It is questionable whether this policy, which is not evidence based, is correct. It is recommended that the positive results of MTX elicited from small open studies be confirmed in randomised controlled trials.

Only three studies were identified which reported the effects of treatment with more than one DMARD [11, 26, 48]. Two of these studies were small and not blinded (a drawback that has influenced the results of many trials in SpA) [26, 48]. <;algiineri et al. [11] used a larger number of patients, but it could not be deduced whether the patients were randomly allocated to the treatment arms. However, all studies showed promising results, and larger randomised controlled studies are certainly justified.

Anti-TNF-a therapy might be a breakthrough in the treatment of SpA. Dramatic improvements in SpA patients refractory to several established treatments have been reported in a number of open studies [3, 7, 10,25,50,71,77], and one of the few randomised controlled trials presently available for PsA showed impressive efficacy of etanercept [50]. Anti-TNF-a might be effective in suppressing symptoms of inflammation of both axial and peripheral joints and have positive effects on skin manifestations. The results of well-performed randomised controlled trials are needed to define the role of anti-TNF-a in the treatment of SpA. In particular, combinations of DMARDs with anti-TNF-a therapy should be studied in patients with severe refractory SpA, in which anti-TNF-a therapy may induce, and conventional DMARDs (presumably MTX) may maintain clinical remission.


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Combination therapy in rheumatoid arthritis

S. Bingham, P. Emery

Rheumatology and Rehabilitation, Research Unit, University of Leeds, Leeds, UK

Introduction

The definition of combination therapy is difficult, as the prescribing of several drugs concurrently is standard practice in rheumatoid arthritis (RA). In addition to diseasemodifying anti-rheumatic drugs (DMARDs), non-steroidal anti-inflammatory drugs (NSAIDs) and systemic and local corticosteroids are almost invariably given. However, the standard definition of combination therapy is of two DMARDs being given simultaneously, and it is this definition that will be used here. Whilst 10 years ago combination therapy was a rarity, now it is used by the majority of rheumatologists [32]. In light of increasing evidence that persistent disease activity is associated with a worse outcome in terms of end organ destruction and disability [54], the rationale for combination therapy is multiple. First, more intensive therapy has shown to be more effective in patients with RA not in remission on monotherapy. Second, more therapy has not been shown to be more toxic. Thus, increasing the doses of combination therapy has become standard, although there is a great debate about whether this should be used as a blanket approach in early disease. A step-up approach (adding in successive therapies following inadequate response) is used in most cases of RA, but there is some evidence that combination therapy in early disease can have a beneficial effect without increased toxicity [5]. Finally, recent advances in assessment of disease activity using imaging techniques (magnetic resonance imaging and highresolution ultrasonography) allow detection of subclinical synovitis and will increase expectations from new therapies and combinations.

Clinical experience of combination therapy

Early studies of combination therapy in RA

Studies of combination therapy in RA were first published in the 1950s. Early combinations included D-penicillamine (D-Pen) and hydroxychloroquine (HCQ) or chloroquine,

Correspondence to: Paul Emery, Rheumatology and Rehabilitation, Research Unit, University of Leeds. 36 Clarendon Road, Leeds LS2 9NZ, UK

166 S. Bingham, P. Emery

gold and HCQ, sulphasalazine (SSZ) and D-Pen and cyclophosphamide (Cy), azathioprine (AZA) and HCQ. The majority of the open studies showed an improved outcome with significant reductions in disease activity indicators, but benefit was not so clear in randomised studies. Increased toxicity was seen in combination groups, and it was felt at that time that combination therapy did not offer any real advantage over monotherapy.

Open studies (Table 1)

The first study published was from McCarty and Carerra [35] and involved Cy, AZA and HCQ in patients with progressive refractory RA. Only 3 of 27 cases showed no response. The authors felt that combinations of small doses of drugs already proven efficacious in RA are beneficial in severe cases. In a further report of 31 patients receiving Cy, AZA and HCQ, only I patient failed to respond [13J. Three patients developed significant adverse reactions and 4 patients developed malignancy during therapy, 3 of whom died. Long-term follow-up of 169 patients treated with methotrexate (MTX), AZA and HCQ or chloroquine revealed response in the majority of patients, a high incidence of herpes zoster infection and no increased mortality over the general population [36].

Bitter et al. [4] used a variety of DMARD combinations in 71 RA patients over 18 months and felt that there was a small (but insignificant) advantage with combination therapy. They felt that a combination of gold and D-Pen was the most promising. In a study of the addition of D-Pen to patients with a partial response to SSZ [18] 68% improved, but 29% discontinued D-Pen and 6% discontinued SSZ due to adverse events during the first year. During a study of MTX and D-Pen, no patients withdrew due to toxicity [31].

Table 1. Early open studies of combination therapy in RA

Ref Cases Duration Drugs Outcome (months)

[35] 17 27 Cy/AZA/HCQ 14 responded

[ 13] 31 43 Cy/AZA/HCQ 16 complete remission, I no response

[36] 169 84 MTXI AZA/HCQ or chloroquine 76 complete remission

[4] 71 18 Gold/CHLID-Pen Small insignificant improvement in all groups

[14] 25 6 Gold/D-Pen/SSZ Significant improvement in 7/8 clinical and laboratory parameters

[18] 31 36 SSZID-Pen 21 improved in 4/6 clinical parameters

[50] 16 12 HCQ/Pred/SSZ/MTX Improvement at 3 months. lost at 6 months

[31] 16 5-86 D-PenIMTX 8/12 complete remission

RA, rheumatoid arthritis; Cy, cyclophosphamide; AZA, azathioprine; HCQ, hydroxychloroquine; MTX, methotrexate; CHL, chloroquine; D-Pen, D-penicillamine; SSZ. sulphasalazine; Pred, prednisolone

Combination therapy in rheumatoid arthritis 167

Early randomised trials (Table 2)

The first randomised double blind trial was published in 1984 [10], comparing DPen and HCQ either alone or in combination. The best response was seen in the group receiving D-Pen alone. Minor toxicity was common in all groups. Gibson et al. [21] studied 72 patients given chloroquine, D-Pen or both over 1 year. All three groups improved, but greater toxicity was seen in the combination group. A prospective randomised controlled trial comparing gold and HCQ with gold and placebo, showed an advantage for combination therapy that was statistically significant only for C-reactive protein [51]. A greater number of patients withdrew from the combination group due to toxicity. A meta-analysis of early combination studies published by Felson et al. [19 J concluded that combination therapy did not offer any advantage over monotherapy and was associated with increased toxicity.

Combination therapy with MTX

The advent of low-dose weekly methotrexate as treatment for RA in the late 1980s signalled the start of a new therapeutic era. MTX has since become the most commonly used DMARD in RA. It has been shown to be efficacious in patients whose disease has been resistant to other therapies [59], and more recently MTX has become regarded by most physicians as first or second line therapy. MTX has been shown to reduce the progression of erosions when used first line [48]. In addition, mortality is reduced in patients who respond to MTX [281. It is well tolerated by patients and therapy is continued significantly longer than other DMARDs [29]. MTX is effective monotherapy but rarely induces remission [59]. Control of disease activity may become less effective over time requiring increased doses [65 J and some patients are unable to tolerate an effective dose. This has led to the use of combination therapy with other drugs added to MTX. This strategy has been shown to be effective in patients with disease not controlled by MTX alone [42,571.

Combination therapy with MTX and SSZ

In a study of early RA patients [5], where MTX, SSZ and prednisolone were commenced together and subsequently discontinued in a step-down approach, combination therapy was found to be more efficacious than SSZ alone. However, the advantage was lost following the discontinuation of steroids at week 28, and patients did not deteriorate following discontinuation of MTX at 40 weeks. In patients with an in-

Table 2. Early randomised studies of combination therapy in RA

Ref Cases Duration Drugs Benefit (months)

[10] S6 24 D-Pen/HCQ Best response in D-Pen alone group [211 72 12 D-Pen/chloroquine All three groups improved lSI] 101 12 Gold/HCQ Greater etlicacy. but greater toxicity

in combination group


sufficient response to SSZ alone, the addition of MTX in combination was found to be superior to switching to MTX monotherapy in an open label controlled study [24]. Forty RA patients with active arthritis despite adequate SSZ therapy were allocated randomly to regimes of either SSZ/MTX or MTX alone. The patients were evaluated openly by a single observer for 24 weeks. Thirty-eight patients completed the trial. The mean decrease in the disease activity score in the group of patients receiving combination therapy was significantly greater than in the MTX group (-2.6 vs -1.3, respectively) without an excess of toxicity. However, this is in contrast to results from a subsequent study where the combination of MTX and SSZ offered no advantage over MTX or SSZ alone [25].

Dougados et al. [16] studied combination therapy in patients with early RA who had not previously been exposed to DMARD therapy. Two hundred and five patients with less than 1 year of disease were enrolled in this randomised controlled doubleblind study. Sixty-eight patients received monotherapy with SSZ, 69 monotherapy with MTX and 68 combination therapy with SSZ/MTX for 52 weeks. A significant (P=0.019) reduction in disease activity score occurred in the SSZ/MTX group compared to the SSZ and MTX groups (-1.26, -1.15 and -0.87 respectively). However, no significant reduction was seen in terms of EULAR or ACR response criteria. Significantly more toxicity occurred in the combination therapy group (mainly nausea), but the authors felt that this level of toxicity was acceptable.

Combinations involving MTX, SSZ and HCQ

Triple combination therapy with MTX, SSZ and HCQ has been shown to be significantly superior to MTX alone. In the study of O'Dell et al. [41] patients with RA who had failed one or more DMARD were given MTX or SSZ and HCQ or all three drugs in a blinded fashion. Triple therapy was significantly more effective than MTX alone, whereas most toxicity was seen on the MTX alone arm. The efficacy of SSZ and HCQ was similar to MTX alone. The authors also studied patients who withdrew from the MTX alone arm due to inefficacy, and were subsequently given MTX, SSZ and HCQ in an observational manner [42]. Significant improvements in laboratory and clinical parameters were seen following the commencement of triple therapy (Table 3), suggesting that patients with a sub-optimal response to MTX are likely to respond to the addition of SSZ and HCQ. Six patients (of 60) who were followed long-term (275 patient-years) had to withdraw due to toxicity; one with cervical can-

Table 3. Reduction of clinical parameters of disease activity on addition of SSZ and HCQ to MTX in patients with a suboptimal response to MTX monotherapy [421 (Reproduced with permission)

Variable Initial Follow-up P

ESR (mm/h) 30.3 19 0.06 Morning stiffness (min) 104 28 0.03 Swollen joint score 29.7 11.7 0.001 Tender joint score 30.1 10.4 0.001 Patient global status 4.1 2.6 0.03 Physician global 5.1 3.1 0.009

ESR, Erythrocyte sedimentation rate


cer, one with nausea, one with weight gain during the blinded part of the study, one with possible ocular toxicity, one with gastrointestinal upset and one with liver enzyme elevation during the extended observational part of the study. More recently, the same group have published results of a 2-year study comparing MTX/SSZIHCQ with MTXlHCQ or MTX/SSZ [44]. Triple therapy with MTX/SSZ/HCQ was found to be well tolerated and superior in efficacy to therapy with MTXlHCQ or MTX/SSZ; 77% of patients achieved ACR20 in the triple therapy group compared to 52% and 47% in the MTX/HCQ and MTX/SSZ groups, respectively.

In a study of patients with early RA, with disease remission as the primary outcome measure, 97 patients were given combination therapy with MTXlSSZ/HCQI prednisolone and 98 monotherapy with SSZ with or without prednisolone [40]. In 51 patients on monotherapy, MTX was later substituted. Eighty-seven patients in the combination group and 91 in the single therapy group completed the trial. After 1 year, remission was achieved in 24 patients with combination therapy and 11 with single drug therapy (P=O.OI1). At 2 years, the remission frequencies were 36 in the combination group and 18 in the monotherapy group (P=0.003). Seventy-five percent of patients receiving combination therapy achieved ACR50 response after 1 year, compared to 60% receiving monotherapy (P=0.028). The frequencies of adverse events were similar in the two groups.

In a recent study, the effects of therapy with MTX or SSZ or HCQ, or MTXlSSZ or MTX/HCQ, or all three drugs were compared [11]. At the end of the trial there were significant improvements in the clinical and laboratory parameters in all three groups. However, improvements were greater and much more significant in the patients who were given combination therapies. The combination of MTX and SSZ and HCQ was more effective than monotherapy or the two drug combinations.

These studies suggest the superior efficacy of triple therapy with MTX/SSZIHCQ when compared to combination therapy with two drugs or monotherapy. In addition, the study of O'Dell et al. [42] showed that for patients with active disease on MTX monotherapy, the addition of SSZ and HCQ to therapy is likely to be of benefit.

MTX and cyclosporin

Cyclosporin (CsA) is efficacious as monotherapy in RA [56] and two studies have shown the benefits of combination therapy with MTX and CsA. The first is a randomised double-blind, placebo-controlled study of the addition of CsA or placebo to MTX in patients who have had an incomplete response to MTX [57]. In the second, an extension study, all patients received MTX and CsA in an open fashion [52]. In the blinded study, significant improvements in all outcome parameters [except erythrocyte sedimentation rate (ESR)] were seen in the CsAIMTX arm. In the open extension, significant improvement was seen in patients switching from MTXlplacebo to MTX/CsA. Of 75 patients, 9 in the MTXlCsA group withdrew during the blinded study due to toxicity (the majority complaining of gastrointestinal upset). During the extension phase, an increase in serum creatinine of more than 30% was seen more frequently than during the initial blinded phase where patients were exposed to CsA for the first time. As MTX is renally excreted, long-term effects of MTXlCsA combination need careful monitoring especially if the patient is also taking NSAIDs. In a more recent study, the long-term efficacy and tolerability of the combination of CsA, intravenous pulsed MTX and fIuocortolone was evaluated in 140 patients treated for


96 months [45). The combination was well tolerated, significant improvements in clinical and laboratory measurements were observed, and little radiological progression occurred during the study. Renal toxicity (>50% increase in plasma creatinine over baseline) occurred in 8.5% of patients.

In the treatment of early RA, aggressive therapy with CsA, MTX and intra-articular steroids have been shown to be more effective than monotherapy with SSZ [46).

MTX and leflunomide

Leflunomide is a relatively new DMARD that has been shown to be as effective as MTX as monotherapy in RA [55). In a 52-week open label study in which leflunomide was added to therapy in patients with insufficient response to MTX, results suggested an advantage without increased toxicity of the combination therapy [61]. Of 30 patients, 23 completed the study. Three patients withdrew due to toxicity (raised liver enzymes) and 2 due to inefficacy. No significant myelosuppression, leukopenia or change in renal function was seen. Increased hepatic enzymes occurred in 19 patients. After 9 months 57% of the patients achieved an ACR20 response; at 1 year 37% achieved an ACR50 response. Two patients achieved ACR remission. In a controlled study of the addition of leflunomide or placebo to patients with active disease on MTX monotherapy, significantly more patients achieved an ACR20 response at 24 weeks in the combination group compared to the mono therapy group (46.2% vs 19.5%, P=O.OOOl) [30). A higher incidence of toxicity (diarrhoea, nausea, dizziness and raised liver enzymes) was seen in the combination group, although the authors felt that combination therapy was well tolerated and offered an advantage in patients failing therapy with MTX alone.

MTX and intramuscular gold

Combination therapy with MTX and intramuscular (1M) gold compared to MTX alone has been evaluated in a long-term open observational study [47). No difference between the two groups was seen with respect to side effects, and the therapy discontinuation rate was actually lower in the combination group. Although this was an open non-randomised study, the authors felt that efficacy was greater in the combination group. On further analysis of the data, they also found that patients continuing treatment (MTX alone or combination) and responding to it, had a dramatically reduced standard mortality rate compared with patients not responding to treatment or discontinuing it. A further study of 1M gold and MTX showed no benefit [6].

MTXandAZA

Combination therapy with MTX and AZA compared to MTX or AZA alone was studied in a 48-week randomised trial [62,63]. More patients on combination therapy discontinued due to toxicity without any evidence of increased efficacy.


Other combination therapy

Combination therapy in 20 patients with 1M gold and CsA was assessed in an uncontrolled, non-randomised add-on study [3]. Improvements in clinical markers of disease activity were seen, 3 patients withdrew from the study because of rising plasma creatinine, and 1 withdrew due to lack of effect. Disease flared in most patients at 6 months when CsA was withdrawn, suggesting therapeutic benefit. A double-blind trial studied the effect of adding CSA (1.25 mg/kg per day or 2.5 mg/kg per day) or placebo to patients with a sub-optimal response to 16 weeks of therapy with chloroquine [58]. This did not show the benefit of combination therapy expected following in vitro work utilising the synergistic mechanisms of action of these two drugs.

The combination of HCQ and 1M gold has been studied in a double-blind randomised controlled trial over 1 year [51]. Fifty-two patients received HCQ and 1M gold and 49 patients received 1M gold and placebo. A non-significant advantage of combination therapy was found, but half the combination group withdrew due to adverse events (mainly rash). A study of combination therapy with SSZ and leflunomide is currently underway (RELIEF study).

Combinations with biologics

Recently, a new generation of disease-modifying agents has been developed that utilise our increased understanding of disease pathogenesis. The cytokine tumour necrosis factor-alpha (TNF-a) is known to be a crucial element in the inflammatory cascade. TNF-a directly or indirectly induces vasodilatation and cell migration and activation. In addition, TNF-a increases the production of the enzyme, cyclo-oxygenase-2 (COX-2), which promotes synthesis of further pro-inflammatory factors. Increased release of TNF-a has a central role in the continuation of the pathological process in RA. Two TNF-a antagonists are currently licensed for RA and several more are under development. Infliximab (Centocor, Schering-Plough) is a humanmouse chimeric antibody that is given by intravenous infusion (3 mg/kg, 8 weekly maintenance dose). Etanercept (Immunex, Wyeth) consists of a soluble TNF receptor (p75) joined to the heavy chain or Fc portion of an antibody molecule and both parts are humanised to reduce immunogenicity. Etanercept is given by subcutaneous injection (25 mg twice a week). D2E7 (Knoll) is currently undergoing phase III trials and is likely to be licensed for RA in the near future. This is a fully humanised chimeric antibody given by subcutaneous injection. Studies with TNF-a antagonists have shown increased efficacy compared to conventional DMARDs and a favourable short-term toxicity profile. As long-term follow-up data become available, initial concerns regarding long-term increased incidence of malignancy have not been confirmed.

Infliximab and MTX

Early studies with infliximab confirmed its potential as an effective therapy in RA [17]. However, efficacy diminished with repeated infusions of infliximab and was felt to be due to antibody immunogenicity. A subsequent double-blind trial of three doses of infliximab (1, 3 or 10 mg/kg) or placebo and MTX or placebo revealed syn-

172

Table 4. ACR response scores in patients receiving infliximab and MTX

Dosing regime

Placebo and MTX Infliximab 3 mg/kg 8 weekly and MTX Infliximab 3 mg/kg 4 weekly and MTX Infliximab 10 mg/kg 8 weekly and MTX Infliximab 10 mg/kg 4 weekly and MTX

ACR, American College of Rheumatology

At 30 weeks

ACR20 p

20% 50% <0.001 53% <0.001 52'1c <0.001 58'1r <0.001

s. Bingham. P. Emery

ACRSO P

5% 27% <0.001 29% <0.001 31% <0.001 26% <0.001

ergy with increased efficacy in the low intliximab dose group and prolonged response time in all treatment groups [33]. The levels of human anti-chimeric A2 antibodies (HAC A) produced in each patient group in this study have been published more recently [1]. The HACA response was clearly dose related, with 53%,21 % and 7% of the patients in the cohorts receiving 1, 3 or 10 mg/kg of intliximab monotherapy, respectively. Concomitant MTX therapy reduced the rate of HACA formation to 15%, 7% and 0%, respectively. The HACA response and the clinical response were reflected in the pharmacokinetic data from this trail. In the 1 mg/kg infliximab group without MTX, plasma levels of infliximab dropped below the detection limit of 0.1 /lg/ml after the second and subsequent infusions. By contrast, plasma levels in patients receiving concomitant MTX remained around 10 /lg/ml. After the fifth infusion at 14 weeks, the decline in plasma levels was slower in the combination groups. However, whether the appearance of HACA interferes with the function of intliximab by neutralising antibody activity has not yet been established beyond doubt.

A subsequent larger study compared different doses of infliximab (3 mg/kg or 10 mg/kg or placebo at 4- or 8-week intervals) in patients with an inadequate response to MTX [34]. MTX was continued in all patients at the previous dose (median 15 mg/week for >6 months, range 10-53 mg/week). There was significant improvement in all treatment groups compared with placebo (Table 4). The degree of improvement (50-58%) is particularly noteworthy in view of the inclusion of patients resistant to at least three DMARDs (including MTX) and aggressive disease. Intliximab was well tolerated; withdrawals for adverse events or serious infections did not exceed those in the placebo group. Information regarding development of HACA is not yet available.

Etanercept and MTX

Etanercept has been shown to be efficacious as monotherapy in the treatment of RA [37] (Table 5). A subsequent study evaluated the efficacy of etanercept (25 mg twice a week) and MTX versus MTX and placebo in patients with persistent disease activity despite MTX 15-25 mg/week for more than 6 months [60]. The etanercept/MTX group had significantly better outcomes than the placebo/MTX group (Table 6). The etanercept/MTX group was superior in response parameters regardless of the dose of MTX, the duration of MTX therapy, or each group's use of corticosteroids or NSAIDs. The only significant difference in adverse events between the eta-


Table 5. Efficacy of etanercept monotherapy in RA

Dose

Placebo 10 mg twice a week 25 mg twice a week

At 26 weeks

ACR20

11% 51% 59%

p

<0.001 <0.001

ACR50

5% 24% 40%

Table 6. Efficacy of etanercept and MTX in patients with active disease on MTX monotherapy

Treatment

Placebo and MTX Etanercept and MTX

At 24 weeks

ACR20

27% 71%

p

<0.001

ACR50

3% 39%

p

<0.001 <0.001

p

<0.001

173

nerceptIMTX and the placebo/MTX group (42% vs 7%) was in the frequency of infection site reactions (ISRs). These were mild, and were characterised by erythema, pain and swelling. No patients withdrew because of ISRs. Potential antibodies to etanercept were detected in only one patient during the study.

Combined TNF-a and interleukin-l blockade

Evidence is emerging that TNF-a and interleukin (IL)-l are both pivotal cytokines driving inflammation in RA [2]. Evidence for the efficacy of anti-TNF-a has already been discussed. Blockade of IL-l with a receptor antagonist (IL-I ra) has not yet shown a clear improvement in clinical parameters, but has been shown to reduce radiographic progression [9]. Animal studies have suggested that TNF-a and IL-I act synergistically and therefore anti-TNF therapy alone is not sufficient to control inflammation. Combination therapy with anti-IL-I was found to be more potent in animal studies. This is despite other evidence that TNF-a is the major stimulant of IL-I production in synovium [7]. Evidence points to IL-la being the dominant cytokine in early RA and IL-lj3 being more important in late RA. lt is likely that RA represents a heterogeneous disease with variable cytokine profiles between patients and time points, and that a double-hit approach inhibiting TNF-a and IL-lj3 in humans is likely to be beneficial. This combination is of proven benefit in an animal model of arthritis [64] and has been studied in humans with RA, although the results have not yet been published.

Other combinations of biological therapy

The rationale for combination biological therapy is the ability to specifically block various stages in various pathways of inflammation known to be important in RA.

174 S. Bingham. P. Emery

Agents that block cytokine action. T cell activation and T cell function are available. Other agents under development target synoviocytes and/or matrix-degrading enzymes. Theoretically, the use of two or more agents should result in a syngeneic response.

Combination therapy with humanised anti-CD4 antibody and a TNF-a antagonist (p55 TNF receptor-human-lgG 1 fusion protein) has been studied in nine patients [38, 39]. Short-term therapy in six patients did reveal a synergistic effect. Longer-term therapy in three patients for 3 months induced reduction in disease activity that was maintained for over 1 year.

Role of corticosteroids in combination therapy

The role of corticosteroids in combination therapy has not been well defined. Steroids can rapidly reduce the level of inflammation, but are associated with significant toxicity when a high cumulative dose is given. The use of oral prednisolone in early disease has been shown to reduce the rate of erosion [27]. In the COBRA study, combination therapy with prednisolone, SSZ and MTX was significantly superior to SSZ alone, but this effect was lost on the withdrawal of prednisolone at 28 weeks [5]. Short-term steroids can be useful when waiting for DMARDs to start working and certainly in our unit 1M depots of steroids are often given to patients with active disease on the commencement of a new disease-modifying agent. Anecdotal evidence suggests that a new disease modifying agent is more likely to be successful if the inflammatory load is already reduced by systemic steroids. A more targeted application of steroids with intra-articular injections has been shown to be superior to DMARDs alone in two studies in early disease. Intra-articular therapy reduced erosion rate when given to patients with early disease also receiving MTX [12]. Aggressive therapy with CsAlMTX and intra-articular steroids was shown to be more effective than SSZ alone during the first 6 months of therapy, although this advantage was lost at 12 months [46].

Pharmacological rationale for combination therapy

Since the mechanism of action of most DMARDs is not precisely known, there is little logical rationale for the combinations of therapies used at present. As more becomes known about the way DMARDs work in relation to disease pathogenesis (Table 7), reasonable arguments could be made for the use of certain combinations of therapies in RA. In addition to the mechanism of action, pharmacodynamic properties of drugs are important when considering possible therapeutic combinations. From Table 7, one could expect a synergistic effect between leflunomide and MTX as they have complementary mechanisms of action. The active metabolite of leflunomide inhibits hydroorotate dehydrogenase, which leads to inhibition of the cell cycle in activated cells via a p53-dependent mechanism. The therapeutic effects of MTX are not believed to be due to inhibition of lymphocyte proliferation. MTX inhibits purine biosynthesis and cytokine production, and increases the production of the pro-inflammatory molecule adenosine. The advantage of combining these two drugs was confirmed in the recently published study of the effect of adding leflunomide to existing MTX in patients with persistent disease [61]. A significant num-


Table 7. Mechanism of action of disease modifying agents

Drug

AZA

CsA

Gold

HCQ

IL-l antagonists

Lef

Min

Possible mechanisms of action

Interferes with adenine and guanine ribonucleotides via suppression of inosinic acid synthesis

Interferes with gene transcription for cytokines

Inhibits transcription factor AP-I binding. Formation of aurocyanide in polymorphonuclear cell phagocytosis

Alkalinizes Iysosomes and interferes with protease function and release. Inhibition of IL-l release and RNA and DNA synthesis

Monoclonal antibody receptor antagonist

Active metabolite inhibits hydroorotate dehydrogenase inhibiting cell cycle of activated cells

Multiple effects including reduced IFN-y induced production of nitric oxide synthase in macrophages

Effect

Decreased T cell number (CD8) and function, reduced 8 cell function, decreased IL-2

Decreased IL-2 and hence cellular immune amplification. Decreased 8 cell response to T cell-dependent antigens. Decreased IFN-y and NK function

Effects on polymorphonuclear cell, monocyte and macrophage phagocytosis. Decreased HLA class II expression on monocytes. Inhibition of synovial cell proliferation. Reduced IL-I induced lymphocyte proliferation

Effects on lysosome function and antigen processing in lymphocytes, macrophages, fibroblasts and polymorphs. Decreased IL-I

Inhibits IL-I effects

Decreased lymphocyte immune functions. Inhibition of antigen processing

Inhibits metalloproteinases. Decreased polymorphonuclear cell function. Inhibition of lymphocyte proliferation and inhibition of IFN-y production

MTX Inhibits 5-aminoimidazole-carboxamide- Reduced leukocyte trafficking, inhibition

D-Pen

SSZ

TNF-a antagonists

ribonucleotide-transformlase increasing of T cell and macrophage function. adenosine levels. Inhibits dihydrofolate reductase Decreased IL-I and IL-2 production leading to lack of purine nucleotides

Exchange reactions in or on cell surface receptor sulphydryl groups. Inhibits binding of transcription factor AP-I

Scavenges pro-inflammatory reactive oxygen species. Lowers prostenoid levels (e.g. leukotriene 8 4)

Monoclonal antibodies or soluble receptors

Modulates activities of T cells, NK cells, monocytes and macrophages

Reduced numbers of activated lymphocytes

Inhibits TNF-a effects

CsA, Cyclosporin A; IL, interleukin; TNF, tumour necrosis factor; Min, minocycline; IFN, interferon; NK, natural killer

ber of patients improved on combination therapy. The added benefit of triple therapy with MTX/SSZ/HCQ may have been predicted as the combination of all three drugs has effects on lymphocyte, monocyte, macrophage and polymorph function. This benefit was proven in the study of O'Dell et al. [42] of combination therapy in patients with active disease on MTX monotherapy. However, could it be predicted by this rationale that the combination of AZA and MTX was likely to be ineffective as


shown previously [62, 63]7 Both drugs have similar toxicity profiles and during the study the combination group suffered an increased incidence of side effects which, perhaps could have been predicted (see below).

In general too little is known about the precise mechanism of action of DMARDs to be able to make firm predictions of the likely outcome of combination therapy. Good double-blind randomised studies are the best way to prove effectiveness of combination therapy in RA.

Combination therapy may be of benefit in those patients who have the multipledrug resistance gene and express its product p-glycoprotein 170 (pgp-170). This is a transmembrane transporter, which actively excretes drugs from tumour cells and has been studied in RA [26]. CsA and HCQ are competitive inhibitors of pgp-170 and, therefore, the addition of one of these drugs in combination therapy would be expected to result in increased efficacy. However, the clinical effects of this theory are not yet proven.

Predicting toxicity of combination therapy

From the mechanisms of action of various DMARDs given in Table 7 and the method of metabolism and side effects given in Table 8, it should be possible to predict toxicity that may occur when drugs are used in combination. The combination of gold and D-Pen, for example, is unlikely to be used due to both drugs having caused proteinuria in a significant number of patients. The combination of leflunomide and MTX has been proven to be of benefit as expected from their complementary mechanisms of action [30], but in effect this combination of drugs would also be expected to result in increased toxicity. Both drugs can cause increased hepatic enzymes and marrow suppression. In the open study of 30 patients over 52 weeks, 3 patients withdrew due to toxicity (raised liver enzymes). No significant myelosuppression or leukopenia was seen. An increase in hepatic enzymes occurred in 19 patients, but was not severe enough to require discontinuation of therapy. Combination therapy with leflunomide and SSZ is currently under investigation in a large randomised doubleblind study.

The combination of CsA and MTX was initially predicted to be toxic due to CsAinduced renal impairment in a significant number of patients which impedes the renal excretion of MTX. However, two studies have shown the clinical benefits of this combination [52, 57] with the only significantly more frequent adverse event in the combination group being a >30% rise in serum creatinine. The combination of MTX and CsA may be useful in selected patients who are monitored carefully.

When to use combination therapy

In general, DMARDs are now commenced earlier in disease to prevent joint damage. The degree of inflammation and the time spent with unsatisfactory disease control (area under the curve) is related to the extent of damage. Furthermore, there is an accelerated phase of damage early in disease [15, 23]. Previously, a pyramidal approach to therapy was used, in which patients were initially commenced on NSAIDs and analgesia, while DMARDs, which were considered to be more toxic, were withheld until later in the disease process when joint damage had occurred. This had the


Table 8. Metabolism and side effects of disease-modifying agents

Drug

AZA

CsA

Gold (1M)

HCQ

IL-I antagonists

Lef

Min

MTX

D-Pen

SSZ

TNF-a antagonists

Metabolism

Cleaved to 6-mercaptopurine (6-MP) which is metabolised to thioinosinic and thioguanylic acid through the action of hypoxanthine phosphorridosyltransferase. Two distinct populations of AZA metabolisers: fast and slow, leading to a fourfold variation in the rate of clearance. The enzyme which metabolises 6-MP (thiopurine methyltransferase) exhibits genetic polymorphism with a small subset of the population producing low levels leading to increased toxicity (usually bone marrow suppression)

Metabolised in the liver and then renally excreted

Mainly excreted unchanged in the urine

Metabolised in the liver and then renally excreted

Glomerular filtration and proximal tubular cell metabolism

The active metabolite is further metabolised and then renally excreted

Some hepatic metabolism, excreted in urine and faeces

MTX and its metabolites mainly eliminated via the kidney

Cleared largely through oxidation to form disulphides with plasma albumin, L-cysteine, homocysteine and itself. Patients with impaired sulphoxidation status have increased risk of toxicity

Sulphapyridine and 5-aminosalicylic acid liberated from sulphasalazine in the colon. Sulphapyridine is metabolised by N4-acetylation, ring hydroxylation and subsequent gluconuration

Infliximab: as intact IgG 1

1M, Intramuscular; GI, gastrointestinal

Major side effects

Hypersensitivity reactions, marrow suppression, hair loss, increased infection risk, nausea

177

Increased serum creatinine and urea, renal impairment, hypertrichosis, tremor, hypertension, hepatic impairment, GI upset

Hypersensitivity reaction, proteinuria, blood disorders

GI upset, headache, rash, retinopathy

Rash, hypersensitivity, increased infection risk

Hypertension, leukopenia, hepatic impairment, GI upset, headache, hair loss, rash

Rash, dizziness, lupus-like syndrome

Marrow suppression, hepatic impairment, pneumonitis, GI upset

Nausea, rash, marrow suppression, proteinuria, haematuria, haemolytic anaemia, lupus-like syndrome, myasthenia gravis-like syndrome

Rash, GI upset, marrow suppression

Rash, hypersensitivity, increased infection risk

unfortunate effect of treating patients with early RA - those patients with the greatest potential for clinical response - with the least effective agents during the most prolonged and most damaging period of inflammation of the entire disease course. Current management plans for patients with early RA aim to assess patients as early as possible to establish the risk of persistence and severity to target more effective ther-

178

Table 9. Predictors of persistent and severe disease in early RA - the PISA score

Factor evaluated by PISA

HAQ score: 4-11 >12

ESRlCRP elevation Rheumatoid factor positive Presence of 3AHVR (disease epitopes) Female sex Score .. 3 - treat immediately with aggressive therapy

Points

2

S. Bingham. P. Emery

Persistent=disease duration >6 weeks; Inflammatory=signs of inflammation of joints (warmth and swelling); Symmetrical=involvement of metacarpophalangeal joints and/or metatarsophalangeal joints±proximal interphalangeal joints on both sides HAQ, Health Assessment Questionnaire, ESR, erythrocyte sedimentation rate; CRp, C reactive protein; 3AHVR, major histocompatibility complex type II (DR4) hypervariable region

apies to those poor prognosis patients. In our unit, we have used the persistent inflammatory symmetrical arthritis (PISA) score (Table 9). This approach excludes those patients who fulfil the ACR 1987 criteria for diagnosis but who have a better prognosis.

Improved imaging techniques (MRI and ultrasonography) facilitate the detection of erosive disease much earlier than conventional radiography. Assessment of patients with early disease allows patients with a poor prognosis to be targeted as early as possible with aggressive therapy including combination therapy.

The merits of combination therapy in early RA have been indicated in several studies. In the COBRA study discussed earlier, patients with early disease were given MTX, SSZ and prednisolone, which were later withdrawn in a step-down manner and compared to SSZ alone [5]. Combination therapy was found to be more efficacious than SSZ alone in reducing disease activity. In addition, a significant delay in bone damage was observed in the combined therapy group. Aggressive therapy with CsA, MTX and intra-articular corticosteroids was effective in reducing disease activity in early disease [46]. Combination therapy with MTX/SSZIHCQ/prednisolone was found to induce a higher rate of remission in patients with early RA than treatment with SSZ alone [16]. It is logical to presume that if combination therapy is more efficacious than monotherapy with respect to reducing disease activity, then combination therapy is likely to be more effective at inducing disease remission.

How to use combination therapy

Several different strategies for the use of combination therapy in RA have been proposed. The step-up approach involves adding in a new drug to an existing drug that fails to reduce disease activity to an acceptable level. In the step-down approach, several drugs (usually including corticosteroids) are commenced simultaneously and the most toxic drugs are withdrawn as disease activity reduces. A modification of the step-down approach, called the step-down bridge approach, involves the administration of a fast-acting corticosteroid with MTX, withdrawing steroids when inflammation has reduced and replacing them with another DMARD [49]. The saw-tooth strategy advocated by Fries [20] involves substituting or adding a DMARD if the pa-


tient's level of disability deteriorates to a predetermined level. In this way DMARDs are employed soon after diagnosis and are continued throughout the course of the disease with the aim of maintaining the patient's level of disability close to normal levels. The parallel or blanket approach involves commencing two DMARDs at the same time as early as possible in disease. In all these approaches the level of acceptable disease activity needs to be defined. It is well recognised that any disease activity represented by persistent synovitis or elevated acute phase response is associated with increased joint damage and destruction and ultimately long-term disability. In addition, with improved methods of patient assessment using imaging modalities, the ability to detect subclinical synovitis is increased. This in turn moves the goal posts with regards to the desired response to therapy.

In reality, a combination of approaches is used. Often monotherapy is used following diagnosis and further DMARDs are added in if disease remains active. If the desired response to the first combination is not achieved, either all drugs are stopped or a new drug is commenced or some of the combination drugs are stopped (e.g. leaving MTX) and new drugs are added on top. If the patient does not respond to the second drug or combination of drugs, the process is repeated; stopping some or all of the drugs, starting new monotherapy or adding in new DMARDs to existing therapy. In this era of evidence based medicine, a consistent logical approach is needed. Two facts are certain: early intervention with disease-modifying agents reduces disease progression and disability, and combination of drugs is effective in most patients who continue to have active disease on monotherapy. What has changed in recent years is the level of int1ammation that is deemed unacceptable; modern imaging modalities such as MRI or ultrasonography allow the detection of sub-clinical synovitis. Minimal synovitis is the ideal and hence the required response to therapy has increased.

Who needs combination?

Combination therapy needs to be targeted at patients with a worse prognosis to minimise the cost/benefit ratio. Several strategies have been used to predict patients with more aggressive disease. Patients with severe arthritis with multiple joint involvement, rheumatoid factor positive, high C-reactive protein, and nodules have been shown to have a worse outcome [81. A high baseline level of disability evaluated by the Health Assessment Questionnaire is associated with a greater increase in the level of disability [53]. The association between RA and specific class II major histocompatibility complex alleles is well established [22]. Sub-types of HLA-DR4 associated with RA show conservation of the "shared epitope", an amino acid sequence in the third hypervariable region of the ~ chain. The presence of the shared epitope is associated with a poorer prognosis in RA. In addition, the presence of the shared epitope can be used to predict response to therapy. In the study of O'Dell et al. [43] patients with the shared epitope were less likely to respond to MTX monotherapy than those without it, but there was no difference in the response to triple therapy with MTX/SSZ/HCQ. Therefore, although one might expect that all patients would benefit from triple therapy, patients without the shared epitope responded equally well to MTX alone and to triple therapy. Further studies are necessary, but these results suggest that the early evaluation of HLA status can aid management decisions with respect to commencing combination therapy.

180

Table 10. Summary of combination therapy in RA - the story so far

Combination Benefit

MTX/SSZ/HCQ Yes MTX/SSZ Yes MTX/HCQ Yes MTX/CsA Yes

MTXlIMgold Possible MTX/AZA No MTXlLef * Lef/SSZ * CsAIIM gold Possible 1M goldlHCQ Possible MTX and infliximab Essential MTX and etanercept Yes

*Studies in progress

Conclusion

S. Bingham, P. Emery

Possible toxicity/interaction

Renal impairment Hepatic, bone marrow

Hepatic, bone marrow

Rashes

Increasing evidence is emerging of the advantages of combination therapy in RA. However, not all combinations of disease-modifying agents are effective or tolerated by the patient (Table lO). Improved understanding of the mechanism of action of disease-modifying agents and the role of multiple-drug resistance genes may allow the logical development of effective combinations. Combination therapy can be used in a variety of ways, including step-up or step-down approaches. As joint damage occurs early in disease it is logical to commence therapy as soon as the diagnosis is confirmed. Combination therapy can be used in early disease if those patients with persistent aggressive disease can be identified. The use of intensive therapy may increase the rate of remission if used in appropriate patients early enough. Targeting aggressive therapy to patients with poor prognosis disease minimises the costlbenefit ratio, and strategies for predicting poor prognosis are now becoming available. New biological therapies with well-defined mechanisms of action are also just becoming available and combining these to produce a multi-hit approach is likely to be beneficial in the future.

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roquine treatment of rheumatoid arthritis - a comparative study. Br J Rheumatol 26:279 22. Gough A, Faint J, Salmon M, Hassell A, Wordsworth P, Pilling D, Birley A, Emery P (1994) Genetic

typing of patients with early rheumatoid arthritis at presentation can be used to predict outcome. Arthritis Rheum 37: 1166

23. Gough A, Lilley J, Eyre S, Holder RL, Emery P (1994) Generalised bone loss in patients with early rheumatoid arthritis. Lancet 344:23

24. Haagsma CJ, Riel PLCM van, Rooij DJ de, Vree TB, Russel FJ, Hof MA van't, Putte LB van de (1994) Combination of methotrexate and sulphasalazine vs methotrexate alone: a randomised open clinical trial in rheumatoid arthritis patients resistant to sulphasalazine therapy. Br J Rheumatol 33: 1049

25. Haagsma CJ, Riel PLCM van, De Jong AJL, Van De Putte LBA (1997) Combination of sulphasalazine and methotrexate versus the single components in early rheumatoid arthritis: a randomised controlled double-blind 52 week clinical trial. Br J Rheumatol 36: 1082

26. Jorgensen C, Sun R, Rossi JF, Costes J, Richard D, Bologna C, Sany J (1995) Expression of multiple drug resistance gene in human rheumatoid synovium. Rheumatol Int 15:83


27. Kirwan lR and the Arthritis and Rheumatism Council Low-Dose Glucocorticoid Study Group (1995) The effects of glucocorticoids on joint destruction in rheumatoid arthritis. N Eng J Med 333: 142

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31. Lee S, Soloman G (1990) Combination D-Penicillamine and methotrexate therapy: proposal for early and aggressive therapy for rheumatoid arthritis. Dis Orthop Inst 50: 160

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33. Maini RN, Breedveld FC, Kalden JR, Smolen JS, Davis D, Macfarlane JD, Antoni C, Leeb B, Elliott MJ, Woody IN, Schaible TF, Feldman M (1998) Therapeutic efficacy of multiple intravenous infusions of anti-tumour necrosis factor a monoclonal antibody combined with low-dose weekly methotrexate in rheumatoid arthritis. Arthritis Rheum 41: 1552

34. Maini R, St Clair EW, Breedveld F, Furst D, Kalden J, Weisman M, Smolen J, Emery P, Harriman G, Feldmann M, Lipsky P (1999) Infliximab (chimeric anti-tumour necrosis factor a antibody) versus placebo in rheumatoid arthritis patients receiving concomitant methotrexate: a randomised phase III trial. Lancet 354: 1932

35. McCarty Dl, Carrera GF (1982) Intractable rheumatoid arthritis. Treatment with combined cyclophosphamide, azathioprine, and hydroxychloroquine. JAMA 248: 1718

36. McCarty DJ, Harman IG, Grassanovich lL, Qian C, Klein JP (1995) Combination drug therapy of seropositive rheumatoid arthritis. 1 Rheumatol 22: 1636

37. Moreland LW, Schiff MH, Baumgartner SW, Tindall EA, Fleischmann RM, Bulpitt Kl, Weaver AI, Keystone EC, Furst DE, Mease Pl, Ruderman EM, Horwitz DA, Arkfield DG, Garrison L, Burge Dl, Bolsch CM, Lange ML, McDonnell ND, Weinblatt ME (1999) Etanercept therapy in rheumatoid arthritis. A randomized, controlled trial. Ann Intern Med 130:478

38. Morgan AW, Hale G, Rebello P, Richards S, Waldman H, Emery P, Isaacs 1 (1997) Combination therapy with a TNF antagonist and CD4 monoclonal antibody in rheumatoid arthritis: A pilot study. Arthritis Rheum 40: S81

39. Morgan AW, Hale G, Waldman H, Emery P, Isaacs ID (1998) Prolonged combination immunotherapy ofRA using CD4 and TNFa blockade - A pilot study. Arthritis Rheum 41:S138

40. Mottonen T, Hannonen P, Leirisalo-Repo M, Nissila M, Kautianen H, Korpela M, Laasonen L, lulkunen H, Luukkainen R, Vuori K, Paimela L. Blafield H, Hakala M, llya K, Yli-Kerttula U, Poulakka K, Javinen P, Hakola M, Piirainen H, Ahonen J, Palvimaki IIppo, Forsberg S, Koota K, Friman C, for the FIN-RACo Trial Group (1999) Comparison of combination therapy with single drug therapy in early rheumatoid arthritis: a randomised trial. FlN-RACo trial group. Lancet 353: 1568

41. O'Dell lR, Haire CE, Erikson N, Drymalski W, Palmer W, Eckhoff Pl, Garwood V, Maloley P, Klassen LW, Wees S, Klein H, Moore GF (1996) Treatment of rheumatoid arthritis with methotrexate, sulfasalazine and hydroxychloroquine, or a combination of these medications. N Engl J Med 334:1287

42. O'Dell JR, Haire C, Erickson N, Drymalski W, Palmer W, Maloley P, Klassen LW, Wees S, Moore GF (1996) Efficacy of triple DMARD therapy in patients with RA with suboptimal response to methotrexate. 1 Rheumatol 23 [SuppI44]:72

43. O'Dell lR, Nepom BS, Haire C, Gersuk VH, Gaur L, Moore GF, Drymalski W, Palmer W, Eckhoff Pl, Klassen LW, Wees S, Thiele G, Nepom GT (1998) HLA-DRB I typing in rheumatoid arthritis: predicting response to specific treatments. Ann Rheum Dis 57:209

44. O'Dell 1, Leff R, Paulsen G, Haire C, Mallek 1, Eckhoff Pl, Fernandez A, Blakely K, Wees S, Hadley S, Felt 1, Palmer W, Waytz P, Churchill M, Klassen L, Moore G (1999) Methotrexate (M) - hydroxychloroquine (H) - sulfasalazine (S) versus M-H or M-S for rheumatoid arthritis (RA): results of a double-blind study. Arthritis Rheum 42 [Suppl]:S 117

45. Pascalis L, Aresu G, Pia G (1999) Long-term efficacy and toxicity of cyclosporin A + fluocortolone + methotrexate in the treatment of rheumatoid arthritis. Clin Exp Rheum 17:679

46. Proudman SM, Conaghan P, Richardson C, Griffiths B, Green MJ, McGonagle D, Wakefield R, Reece R, Miles S, Adebajo A, Gough A, Helliwell P, Martin M, Huston G, Pease C, Veale D, Isaacs 1, van


der Heijde DMFM, Emery P (2000) Treatment of poor prognosis early rheumatoid arthritis. A randomised study of treatment with methotrexate, cyclosporin A and intraarticular corticosteroids compared with sulfasalazine alone. Arthritis Rheum 43: 1809

47. Rau R, Schleusser B, Herborn G, Karger T (1998) Long-term combination therapy of refractory and destructive rheumatoid arthritis with methotrexate (MTX) and intramuscular gold or other disease modifying antirheumatic drugs compared to MTX monotherapy. J Rheumatol 25: 1485

48. Rich E, Morland LW, Alarcon GS (1999) Paucity of radiographic progression in rheumatoid arthritis treated with methotrexate as the first disease modifying antirheumatic drug. J Rheumatol 26:259

49. Schiff M (1997) Emerging treatments for rheumatoid arthritis. Am Med 102: II S 50. Schwarzer AC, Arnold MH, Kelly D, Jones M, Beller E, McNaught PJ (1990) The cycling of combi

nation anti-rheumatic drug therapy in rheumatoid arthritis. Br J Rheumatol 29:445 51. Scott DL, Dawes PT, Tunn E, Fowler PD, Shadforth MF, Fisher J, Clarke S, Collins M, Jones P,

Popert AJ, Bacon P (1989) Combination therapy with gold and hydroxychloroquine in rheumatoid arthritis: A prospective, randomized, placebo-controlled study. Br J Rheumatol 28: 128

52. Stein CM, Pincus T, Yocum D, Tugwell P. Wells G. Gluck 0, Kraag G, Torley H, Tesser J, McKendry R, Brooks RH (1997) Combination treatment of severe rheumatoid arthritis with cyclosporine and methotrexate for forty-eight weeks: an open-label extension study. The Methotrexate-Cyclosporine Combination Study Group. Arthritis Rheum 40: 1843

53. Scott DL (2000) Prognostic factors in early rheumatoid arthritis. Rheumatology (Oxford) 39 [Suppl IJ:24

54. Stenger AA, Van Leewen MA, Houtman PM, Bruyn GA, Speerstra F, Barendsen BC, Velthuysen E, van Rijswijk MH (1998) Early effective suppression of int1ammation in rheumatoid arthritis reduces radiographic progression. Br J Rheumatol 37: 1157

55. Strand V, Cohen S, Schiff M. Weaver A, Fleischmann R, Cannon G, Fox R, Moreland L, Olsen N. Furst D, Caldwell J, Kaine J, Sharp J, Hurley F, Loew-Friedrich I (1999) Treatment of active rheumatoid arthritis with let1unomide compared with placebo and methotrexate. Let1unomide Rheumatoid Arthritis Investigators group. Arch Int Med 159:2542

56. Tugwell P, Bombardier C, Gent M, Bennett KJ, Bensen WG, Carette S, Chalmers A, Esdaile JM, Klinkhoff AV, Kraag GR, Ludwin D, Roberts R (1990) Low-dose cyclosporin versus placebo in patients with rheumatoid arthritis. Lancet 335: I 051

57. Tugwell P, Pincus T, Yocum D, Stein M, Gluck 0, Kraag G, McKendry R, Tesser J, Baker P, Wells G (1995) Combination therapy with cyclosporine and methotrexate in severe rheumatoid arthritis. N Engl J Med 333: 137

58. Van den Borne BE, Landewe RB, Goei The HS, Reitveld JH, Zwinderman AH, Bruyn GA, Breedveld FC, Dijkmans BA (1998) Combination therapy in recent onset rheumatoid arthritis: a randomised double blind trial of the addition of low dose cyc1osporine to patients treated with low dose chloroquine. J Rheumatol25: 1493

59. Weinblatt ME, Coblyn JS, Fox DA, Fraser PA, Holdsworth DE, Glass DN, Trentham DE (1985) Efficacy of low-dose methotrexate in rheumatoid arthritis. N Engl J Med: 312:818

60. Weinblatt ME, Kremer JM, Bankhurst AD, Bullpitt KJ, Fleischmann RM, Fox RI, Jackson CG, Lange M, Burge DJ (1999) A trial of etanercept, a recombinant tumor necrosis factor receptor: Fc fusion protein, in patients with rheumatoid arthritis receiving methotrexate. N Eng J Med 340:253

61. Weinblatt ME. Kremer JM, Coblyn JS, Maier AL, Helfgott SM, Morrell M, Byrne VM, Kaymakcian MV, Strand V (1999) Pharmacokinetics, safety and efficacy of the combination of methotrexate and let1unomide in patients with active rheumatoid arthritis. Arthritis Rheum 42: 1322

62. Wilkens RF, Stablein D (1996) Combination treatment of rheumatoid arthritis using azathioprine and methotrexate: A 48-week controlled clinical trial. J Rheumatol 23 [SuppI44J:64

63. Wilkens RF, Urowitz MB, Stablein DM, McKendry RJ Jr, Berger RG, Box JH, Fiechtner 11, Fudman EJ, Hudson NP, Marks CR, Brooks R, Rooney TW, Rubin BR, Schmid FR, Segal AM, Thomas JW, Goldstein AG, Yunus MB, Wortman RL, Sherrer YRS (1992) Comparison of azathioprine, methotrexate and the combination of both in the treatnnent of RA: a controlled trial. Arthritis Rheum 35:849

64. Williams RO, Feldman M, Maini RN (1994) Evaluation of anti-IL-I Rand anti-TNF therapy in murine collagen arthritis and comparison with combined anti-TNF/antiCD4 therapy. Arthritis Rheum 37:S279

65. Wolfe F, Hawley DJ, Cathey MA (1990) Termination of slow-acting anti-rheumatic therapy in rheumatoid arthritis: 14-year prospective evaluation of 1017 consecutive starts. J Rheumatol 17:994

Part III Futurology

What will treatment of autoimmune diseases entail in 2010?

T.W.J. Huizinga, F.e. Breedveld

Department of rheumatology, Leiden University Medical Center, The Netherlands

Introduction

"Everyone overestimates the changes that will occur in 1 year but underestimates the changes that will occur in a decade" is one of the favourite quotations of Bill Gates. If this quotation is true, we probably underestimate the changes in the treatment of the autoimmune diseases rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) that will occur in the next decade. In particular, in RA we have witnessed great changes between 1990 and 2000 with the dramatic step of abandoning the pyramid strategy in the treatment of this disease and the unforeseen availability to almost all rheumatologists of TNF blocking drugs. Thus, the afore-mentioned quotation may also be valid for the field of the autoimmune diseases.

In our predictions for treatment of autoimmune diseases in 2010, three conditional assumptions are made [12]. Economic growth will probably follow the same Jines as during the last couple of decades; therefore, the amount of money to be spent on treatment of autoimmune diseases like RA and SLE will be about 30% higher than today [4]. The population pyramid will be different, with relatively more old people and a shortage of young people to take care of the older generation. This will lead to a stronger demand of patients to stay self sufficient for as long as possible [2]. The time needed for a drug to go from the preclinical laboratories to availability for patients will still be at least 4-5 years, thus most of the commonly used drugs in 2010 must be on the shelves today.

In this article we will present some of the highlights of fields where developments are already emerging:

- Genetics - New treatments - Tissue engineering - Co-morbidity

Correspondence to: Tom W.J. Huizinga, Department of rheumatology, Leiden University Medical Center, Postbox 2300 RC, Leiden, The Netherlands

188 T.W.J. Huizinga, Fe. Breedveld

Genetics

Rheumatoid arthritis

Based upon the higher prevalence of RA in older people, the expectation is that the total percentage of the population suffering from RA will be slightly larger than today. Thus a large population of patients will demand treatments that are effective in maintaining functional status. However, long-term cohort studies [4, 12] demonstrate that, depending on the prognostic characteristics, the joint destruction differs, which indicates different needs for treatment for different patient categories. With the current knowledge of genetic risk factors, less than 10% of the variation in joint destruction between the RA patients can be explained (unpublished data from our group). Based upon completion of the human genome project in 2001, we expect that the genetic risk factors that predict joint destruction in RA will be well known. Moreover, we expect that genetic risk factors could explain a significant proportion of the individual variations in joint destruction and will, therefore, be commonly used to guide treatment decisions in patients with RA in 20 I O. Furthermore, the easy testing of genetic variation will also lead to the individualisation of treatment strategies, which will individualise the benefit/side-effect ratio of the drugs used.

Knowledge of the genetic risk factors, and complete and detailed knowledge of the patterns of genes expressed in RA, will also implicate a much better understanding of the pathogenesis of RA. This implies that treatment strategies could be designed based on these new insights. From the perspective of treatment of patients, this knowledge will allow the development of drugs that specifically down-regulate genes that are over-expressed in the synovial tissue.

Systemic lupus erythematosus

Given the current focus on detecting the genes that determine susceptibility to SLE, it is to be expected that the genetic variants that determine susceptibility to SLE will be identified during the coming decade. Although this does not imply that the genes involved in progression of disease will be known in 2010, the identification of the genetic variants associated with susceptibility to SLE may lead to the identification of relevant pathways in the pathogenesis of SLE, and may thus reveal new drug targets. It is difficult to predict if this progression in scientific knowledge will affect clinical medicine. For example, our current knowledge on the high prevalence of SLE in patients with complement deficiencies [2], the subsequent research that demonstrated the involvement of complement products in the removal of apoptotic cells [3] and the demonstration that this pathway is involved in autoantibody production in SLE patients [13J, illustrates how rapidly the study of genetic heterogeneity could lead to new insights in pathogenesis. However, it remains to be seen if and how quickly this knowledge will lead to the introduction of new treatment strategies.

New treatments


During the period 1990-2000, unequivocal evidence has emerged that reduction of disease activity leads to preservation of joint integrity and subsequently joint func-

What will treatment of autoimmune diseases entail in 2010 189

tion rS]. During the coming decade, the results of trials in which different treatment strategies are evaluated will become available and implementation into daily practice is expected to be achieved in 201 O. Based upon the current data, we expect that reduction of disease activity to a level [10] compatible with remission will be the standard goal in 2010. Given the economic limitations that will still be present in the first part of the next decade, the vast majority of RA patients will be treated with relatively cheap disease-modifying anti-rheumatic drugs like methotrexate. Nevertheless, the TNF-blocking agents are the most effective drugs of the current armamentarium with respect to inhibition of disease activity and prevention of destruction. Furthermore, technical innovations in the biotechnology industry will reduce production costs of biological agents [6, 8J. Thus, it is to be envisioned that TNF-blocking agents will be more commonly used in 20 I O.

Apart from strategies to neutralise TNF with biological agents, new strategies to inhibit TNF production are already being explored. These strategies consist of small molecules that can be administered orally, in contrast to the need for parenteral administration of the currently used TNF-blocking agents. These new drugs inhibit TNF processing in the cell (TNF-converting enzyme inhibitors), which prevents the production of bioactive TNF, or inhibits the pathways that lead to TNF production. Although these new drugs have theoretical advantages, such as oral administration and low production costs, it is not yet clear if the period from 2000 to 2010 will be long enough to overcome all the problems associated with a new drug strategy. In summary, we expect that inhibition of TNF will be one of the cornerstones of RA treatment in 20 I 0 but also that different strategies will be available to achieve this goal.

Apart from therapies which target TNF, there are various other strategies for redirecting the disturbed balance. In the coming decade, different strategies aimed at the inhibition of the cytokines involved in the dysregulated cytokine cascade will be evaluated. In our view, no prediction can be made as to which strategy will have the highest chance of being commonly exploited in 201 O.


In the last four decades (1960-2000), impressive progress has been made in the treatment of life-threatening complications of SLE by the introduction of (high-dose) prednisone, azathioprine and cyclophosphamide. We expect that in the coming decade a more detailed knowledge of the immunomodulatory effects of high myeJoablative doses of cyclophosphamide versus currently used lower dosage regimens will lead to a different use of cyclophosphamide compared to today. The expected widespread use of hematopoietic growth factors, as well as improvement in supportive care, may lead to a considerable reduction in morbidity associated with the cytopenic period of immunoablative dosages. A daunting perspective is that high immunoablative dosages may be used in patients suffering from severe life-threatening lupus, to reset "the immunostat", as opposed to the dosing regimens of cyclophosphamide currently used for less threatening organ involvement. Apart from treatment of lifethreatening SLE, new drugs claimed to have similar efficacity to cyclophosphamide but less toxicity may enter clinical practice for the treatment of non-life-threatening organ involvement. Obvious candidates are leflunomide, micofenolfenolate and methotrexate. Apart from the drugs currently used for other indications, very specific drugs are being designed that inhibit T cell/B cell interaction to specifically inhibit

190 T.w.J. Huizinga, F.e. Breedve1d

production of pathogenic antibodies. Given the already detailed and still expanding knowledge of the molecules involved in T cell-B cell interaction with respect to regulation of (auto)antibody production, it is to be expected that one of these molecules will be a target for drugs affecting auto-antibody production.

Tissue engineering


Many RA patients in 20 I 0 will already have joint damage. Apart from prevention of progression of joint damage in a considerable proportion of the patients, strategies aimed at rebuilding the joint should be explored. Mesenchymal stem cells can differentiate in vitro to cartilage cells, thereby providing the possibility to heal cartilage defects [7, Ill. The current identification of the pathways leading to differentiation of a mesenchymal stem cell to a cartilage cell [ll indicates that treatment strategies will be explored that will allow differentiation in vivo of mesenchymal stem cells in the joint, thereby healing cartilage defect. The application of mesenchymal stem cells injected intra-articularly into a joint, and the possibility of regulating the outgrowth of these cells to new cartilage cells, is a treatment strategy which will most likely be pioneered in the coming decade. The predicted possibility to "rebuild a joint" will affect clinical decision-making with regard to replacement of a joint by a prosthesis, or earlier treatment focussed on rebuilding defective cartilage in the joint. Because the life expectancy of RA patients has increased during the period 1970-2000, and the lifespan of the general population will be greater in 2010 than now, the number of patients who will need joint replacement/joint rebuilding will increase. This will create an interesting dilemma: a large popUlation asking for either joint replacements or alternative treatments such as rebuilding the joint by tissue engineering in vivo.


SLE is a relatively rare multiorgan disease with an unpredictable course. Although the promises of tissue engineering for the respective tissues involved in SLE, such as the kidney, may eventually also benefit SLE patients, therapeutic strategies based on tissue engineering are most likely tested first in patients with disease limited to one organ. One exception may be avascular bone necrosis, a disorder that could theoretically be corrected by mesenchymal stem cells that differentiate to osteoblasts. The young age of SLE patients and the lack of other treatment options for this disorder will make SLE patients particularly appropriate for inclusion in studies using mesenchymal stem cells to treat bone defects caused by avascular necrosis.

Co-morbidity


The expected increase in lifespan of the population will shift attention even more towards preventive strategies in 2010 than is the case today. The current availability of

What will treatment of autoimmune diseases entail in 20 I 0 191

COX-2-specific non-steroid anti-inflammatory drugs (NSAIDs) at a cost similar to that of conventional NSAIDs is expected to change the prescription pattern of NSAIDs in the coming decade towards COX-2-specific NSAIDs. This will lead to reduction of gastrointestinal morbidity in patients with RA. The expected emphasis on reduction of disease activity will partly prevent osteoporosis. Moreover, more detailed knowledge on the influence of lifestyle factors on disease activity will allow the rheumatologist to offer evidence-based counseling with regard to the amount of exercise necessary to maintain fitness and to prevent osteoporosis.


The excessive mortality in SLE patients is caused mainly by an increased prevalence of cardiovascular disease [9]. General measures to prevent cardiovascular morbidity in SLE, such as cessation of smoking, blood-pressure control, attention to lipid homeostasis, etc., is currently a major issue in lupus clinics, but none of these measures has been shown to be particularly effective with regard to reducing the excessive cardiovascular mortality in SLE patients.

The cause of this increased prevalence of cardiovascular disease is unknown but is expected to be identified by 2010, and this will then open new avenues for prevention of cardiovascular disease.

In conclusion, the daily work of those involved in the treatment of autoimmune diseases will change dramatically with respect to the pharmacological armamentarium, prognostic factors, possibility to tailor treatments, and the attention paid to comorbid conditions. It will be even more challenging in 2010 than today to be involved in the treatment of these patients with the therapeutic possibilities that will have a dramatic impact on their lives. Given this prediction, it will be a privilege to be involved in the treatment of autoimmune diseases in 2010.

References

I. Atkinson BL, Fantle KS, Benedict 11, Huffer WE, Gutierrez-Hartman A (1997) Combination of osteoinductive bone proteins differentiates mesenchymal C3H/IOTl12 cells specifically to the cartilage lineage. J Cell Biochem 65:325

2. Atkinson JP, Schifferli JA( 1999) Complement system and systemic lupus erythematosus. Lupus 7:540

3. Botto M, Dellagnola C, Bygrave AE, Thompson EM, Cook HT, Petry F, Loos M, Pandolfi PP, Walport MJ (1998) Homozygous Clq deficiency causes glomerulonephritis associated with multiple apoptotic bodies. Nat Genet 19:56

4. Drossaersbakker KW, Debuck M, Vanzeben D, Zwinderman AH, Breedveld FC, Hazes JW (2000) Long-term course and outcome of functional capacity in rheumatoid arthritis - The effect of disease activity and radiologic damage over time. Arthritis Rheum 43: 178

5. Graudal N, Tarp U, Jurik AG, Galloe AM, GaITed P, Milman N, Graudal HK (2000) Inflammatory patterns in rheumatoid arthritis estimated by the number of swollen and tender joints, the erythrocyte sedimentation rate, and hemoglobin: long-term course and association to radiographic progression. J Rheumatol27:47

6. Hiatt A, Ma JK (1992) MAb engineering in plants. FEBS Lett 307:71 7. Hunziker EB (1999) Articular cartilage repair, are the intrinsic biological constraints undermining this

process insuperably? Osteoarthritis Cartilage 7: 15 8. Ma JK, Lehner T, Stabila P, Fox CI, Hiatt A (1994) Assembly of mAb with IgG and IgA heavy do

mains in transgenic tobacco plants. Eur J Immunol 24: 131

192 T.W.J. Huizinga. EC. Breedveld

9. Petri M, Lakatta C, Magder L, Goldman D (1994) Effect of prednisone and hydroxychloroquine on coronary artery disease risk factors in systemic lupus erythematosus - A longitudinal data analysis. Am J Med 96:254

10. Pincus T, Stein CM (1999) ACR20: clinical or statistical significance? Arthritis Rheum 42: 1572 II. Pittenger MF, Mackay AM, Beck SC, Jaiswal RK, Douglas R, Mosca JA, Moorman MA, Simonetti

DW, Graig S, Marshak DR (1999) Multilineage potential of mesenchymal stem cells. Science 284: 143 12. Vanzeben D, Hazes JMW, Zwinderman AH, Vandenbroucke JP, Breedveld FC (1993) Factors predict

ing outcome of rheumatoid arthritis - results of a followup study. J Rheumatol 20:2179 13. Walport MJ, Davies KA, Botto M (1998) Clq and systemic lupus erythematosus. Immunobiology

199:265

Stem cell transplantation for autoimmune diseases

J. Moore', P. Brooks2

1 Clinical Research Fellow, Haematology Department, St. Vincents Hospital, NSW, Australia 2 Faculty of Health Sciences, University of Queensland, Brisbane, Australia

Introduction

Autoimmune diseases such as rheumatoid arthritis (RA) [50], systemic lupus erythematosus (SLE) [1], systemic sclerosis (SSc) [8] and multiple sclerosis (MS) [54] cause significant morbidity and mortality. These diseases not only place a major burden on the patients and their carers but result in increased economic and social costs to the community as a whole. As a result, there has been a trend in recent years to more aggressive early therapy for diseases like RA [70] and SLE [47]. This reappraisal of therapy for autoimmune diseases has led to an attempt to prevent irreversible end organ damage. As part of this reappraisal, an appreciation of the role of the immuno-haemopoietic system in the pathogenesis of these crippling diseases is now more evident. All these diseases have mature haemopoietic cells involved in the lesions of the target organ, suggesting they are integral to the autoimmune process. Haemopoietic stem cell transplantation (HSCT) can therefore be seen as a way of replacing or immunomodulating these cells in the affected tissues and thus ameliorating or even curing the disease. Evidence is now accumulating to suggest that HSCT is a viable and encouraging treatment option for autoimmune disease based on animal models of diseases, case reports of transplantation for coexistent malignancy and now phase llII trials of HSCT in various disease states. This review aims to give an overview of the current status and future directions of this exciting area of therapy for autoimmune diseases.

Clinical haemopoietic stem cell transplantation

E. Donnall Thomas and coworkers in the United States along with other groups, pioneered HSCT in the late 1960s utilising the basic premise that high-dose chemotherapy (conditioning) would ablate the residual diseased host haemopoiesis and infusion of a donor marrow (allogeneic HSCT) would allow engraftment of a new immunohaemo-

Correspondence to: John Moore, Clinical Research Fellow, Haematology Department, St. Vincents Hospital, NSW, Australia, e-mail: [email protected]

194 J. Moore, P. Brooks

poietic system from the pluripotent stem cell. One of the first diseases to be cured by this approach was aplastic anaemia - the prototype haematological autoimmune discease [64]. A large proportion of these patients have now survived for over 20 years and 90% of them have returned to work [15] - an important 'gold standard' by which allogeneic HSCT in non-haematological autoimmune diseases will be measured. Since the mid 1980s the use of the patient's own bone marrow (autologous HSCT) or more recently the use of peripheral blood stem cells has become a standard procedure [25] for a variety of diseases including lymphoma, myeloma, leukaemia and breast cancer. However, a different hypothesis has underpinned the use of autologous stem cells in transplantation. In these diseases, the use of high-dose chemotherapy has been a way of maximising 'tumour-kill' with the reinfused stem cells overcoming potential myelotoxicity.

Choice of stem cell graft

HSCT requires collection of stem cells, followed by conditioning or chemotherapy before reinfusion of these cells (the graft). A pancytopenic period follows where the patient is supported until engraftment. HSCT can be autologous (the patient's own bone marrow), syngeneic (an identical twin transplant), allogeneic related (a sibling or relative) or allogeneic unrelated. Each type of transplant has its own indications, advantages and disadvantages (see Table 1). In general terms, the use of autologous HSCT has been associated with a low transplant-related mortality and morbidity, but with relapse of diseases partly because of residual disease in the patient and/or the graft [5]. On the other hand, allogeneic HSCT does not carry the risk of disease contamination in the graft and, therefore, has a low relapse rate. However, this is offset by graft-versus-host disease (GVHD) which, along with opportunistic infections, contributes to a higher transplant-related mortality [3]. The choice of the appropriate graft for the disease poses an ongoing dilemma for patients and clinicians - at present, however, only autologous HSCT has been employed in autoimmune diseases according to the EBMT/EULAR consensus guidelines [73]. This consensus document decided on autologous HSCT because of the lower transplant-related mortality and evidence of efficacy from both animal and human models (see below). A brief, general overview of the transplant procedure is as follows.

Stem cell collection

The source of stem cells can be blood or marrow. Marrow harvesting requires a general anaesthetic and marrow is aspirated by needle punctures into TME posterior superior iliac crests - 5-10 ml is aspirated each time with an aim of collecting 3x 108

nucleated cells/kg of recipient weight. Peripheral blood stem cells (PBSC) can be collected via peripheral cannulae on a cell separator machine as an outpatient and have now become the stem cell source of choice. Only a small number of stem cells (measured by the CD34 antigen) circulate in the normal steady state but when a donor/patient is given granulocyte colony-stimulating factor (G-CSF) the number increases significantly so that they can be collected by leucopheresis. The combination of G-CSF and cytotoxic chemotherapy further enhances the numbers of CD34 stem cells in the peripheral blood and can be employed in the setting of autologous transplantation [68]. The major advantage of PBSC is that engraftment is more rapid, thus

Stem cell transplantation for autoimmune diseases 195

Table 1. Disease indications, advantages and disadvantages of autologous, syngeneic and allogeneic HSCT

Type of Indications transplant

Autologous AML, non-Hodgkin's lymphoma, Hodgkin's disease, multiple myeloma, breast cancer, autoimmune disease

Syngeneic Most diseases

Allogeneic AML, ALL, CML, aplastic anaemia, MDS, thalassemia, sickle cell disease, inherited immunodeficiency

Advantages

Guaranteed source of stem cells Low morbidity and mortality (0-5%) All ages <65-70 years No GVHD

Guaranteed source of stem cells Low morbidity and mortality (0-10%) No GVHD

Normal stem cells High chance of cure

Disadvantages

Risk of relapse MDS/secondary leukaemia Infertility

Opportunistic infection Risk of relapse Infertility

High morbidity and mortality (15-30%) Younger patients «55 years) GVHD/opportunistic infections Only 30% chance of sibling donor Infertility

AML, Acute myeloid leukaemia; ALL, acute lymphoid leukaemia; CML, chronic myeloid leukaemia; GVHD, graft-versus-host disease; HSCT, haemopoietic stem cell transplantation; MDS, myelodysplastic syndrome

reducing morbidity and mortality from infection and bleeding [2]. A secondary advantage is that most donors prefer the option of avoiding a general anaesthetic and remaining an outpatient. The minimum number of stem cells required for adequate engraftment is considered to be 2x 106 CD34 cells/kg recipient weight, but higher doses (e.g. >3x106 CD34 cells/kg) may further reduce morbidity and mortality. In the autologous setting, stem cells are cryopreserved in a rate control freezer until transplantation. In allogeneic transplants the donor usually has stem cells collected while their relative is undergoing conditioning and are given back fresh on the same day as collection. The consensus guidelines of EULARlEBMT for HSCT in autoimmune diseases has suggested that stem cells be used where possible and that physicians aim for a minimum dose of >2x106 CD34 cells/kg [73].

Conditioning

The choice of chemotherapy for patients prior to reinfusion of the stem cells is individualised to the disease process being treated. Acute and chronic leukaemias usually have a cyclophosphamide-based regimen such as 16 mg/kg Bulsulphan and 120 mg/kg cyclophosphamide or total body irradiation (TBI) with the same dose of cyclophosphamide. Aplastic anaemia patients receive anti-thymocyte globulin (ATG) and 200 mg/kg cyclophosphamide predominantly for immunosuppresion so that rejection


of the new marrow is minimized [63]. Autologous transplants for lymphoma are usually conditioned with the BEAM (BCNU, etoposide, cytosine arabanoside and melphalan) regimen and myeloma patients receive high-dose melphalan. The choice of BEAM allows penetration of the blood-brain barrier by cytotoxics such as cytosine arabanoside, which is the reason it has been chosen for MS in phase I trials [20]. Some cytotoxic agents such as cyclophosphamide have also been used as immunosuppressants for many years in diseases such as SLE [47] and aplastic anaemia, where it can alone induce remissions without stem cell support [7], suggesting that it can temporarily kill the autoreactive clone. The maximum tolerated dose is 200 mg/kg because of the potential for haemorrhagic cardiomyopathy, but the fact that stem cell support is not necessarily required [6] suggests that it is not myeloablative at that dose raising the question as to whether it is also permanently ablative to autoreactive clones.

Because many conditioning regimens are immunosuppressive, some haematologists have recently questioned the actual mechanism of action of conditioning, particularly in the allogeneic setting - is it immunosuppression allowing the allogeneic graft to "take" or is it killing of residual disease in the marrow? This has recently led to the concept of mini-allografting [11]. The basic premise behind mini-allografts is that attaining a complete donor chimera is the main objective of allogeneic HSCT. Previously, it was thought that the use of high-dose chemotherapy in the form of conditioning was a requirement to ablate residual disease in the recipient - this is now considered less imperative as it has become clear that the allogeneic donor immune system can eradicate disease by the "graft-versus-tumour effect". In mini-allografting the conditioning is kept to a minimum but is highly immunosuppressive to allow adequate engraftment of donor haematopoietic tissue - a similar rationale to transplantation in aplastic anaemia. The main advantage of this radical new way of performing HSCT is that patients engraft rapidly, with less toxicity because of the reduced conditioning; however, GVHD still remains a major problem. Thus, mini-allografting has many potential advantages for autoimmune disease and it may not be unreasonable to commence small pilot studies using this technique in severely affected patients.

Supportive care

In the 2-3 weeks following conditioning, patients become neutropenic and thrombocytopenic as a result of the chemotherapy (and/or radiotherapy). During this period, supportive care with transfusions and intravenous antibiotics is standard care. Some patients experience mucositis and diarrhoea due to temporary damage of mucosal surfaces but in general this is manageable with analgesics and intravenous fluids. Peripheral blood stem cell transplant recipients tend to engraft (defined as a neutrophil count >0.5xI09fl and platelet count >20xI09/1) around day 9-15 post transplant, whereas marrow transplant recipients engraft 4-7 days later [68]. Reduced transplant related mortality in the autologous setting (from 10% to <5%) over the past decade has been partly attributed to this enhanced engraftment ability of peripheral blood stem cells [2].

Complications

Autologous and allogeneic transplant recipients both suffer from short-term complications such as mucositis, diarrhoea and neutropenic sepsis. Following engraftment both


groups are at potential risk of opportunistic infections (e.g. Pneumocystis carinii pneumonia and herpes zoster infection) predominantly on the basis of a low CD4 count «300/j.l1 for up to 1 year post transplant). This lymphopenia is more marked in the allogeneic setting for a number of reasons including post-transplant immunosuppression, GVHD and increased apoptosis in the T cell compartment [52]. A problem unique to allogeneic transplantation is GVHD which is mediated by mature donor T cells present in the donor inoculum which recognise histocompatibility antigen disparities present in the recipient and absent in the donor. This is usually prevented by cyclosporin and methotrexate, which are continued for 6-12 months post transplant (in contrast to solid organ transplantation) until immune tolerance occurs. Autologous transplant patients suffer from the ongoing risk of recurrence of disease - attempts to reduce this risk by "purging" the graft of malignant cells have yet to yield any significant survival benefit.

Long-term complications common to both forms of transplantation are infertility, cataracts and secondary malignancy [65]. One of the commonest types of secondary malignancy is myelodysplasia/acute myeloid leukaemia, suggesting that an intrinsic stem cell disorder exists in some patients that is exacerbated by cytotoxics. Nevertheless, recipients of HSCT who survive the first 3 years after their transplant have a high performance status and are likely to return to full time work and schooling [66] - goals that would be highly desirable in therapy of any disease including autoimmune diseases.

Efficacy of haemopoietic stem cell transplantation

The cure rate of marrow transplantation depends on the underlying disease and the status of the disease and the patient at the time of the transplant (see Table 2). In gen-

Table 2. Efficacy of HSCT for various diseases"

Disease

AML

ALL

CML

Aplastic anaemia

Myeloma

Non-Hodgkin's lymphoma (intermediate or high grade)

Thalassemia

Sickle cell disease

Autologous HSCT

CRt: 55o/c, CR2: 35o/c

Not routinely performed



55% «18 months duration) 43% (> 18 months duration)

67% CRI 55% CR2 46% never in remission



Allogeneic HSCT

CR 1: 60%, CR2: 40o/c

CRI: 52%, CR2: 42%

Chronic phase: 67% «I year from diagnosis) 57o/c (> I year from diagnosis)

74% «20 years old) 65% (>20 years old)

39%

39% CRI 25% never in remission

92% [36]

91% [81]

Most results are courtesy of the IBMTR newsletter, volume 7, issue I, 2000 except where stated. Allogeneic HSCT refers to sibling transplants only. Transplantation is reversed for relapsed diseases in many cases (e.g. NHL, AML) CR, Complete remission a Percentages represent survival at 3 years post HSCT


eral, most forms of acute and chronic leukaemia are now potentially curable by haemopoietic transplantation. Relapsed lymphoma is still curable by autologous transplantation [49] and in patients with myeloma, autologous HSCT increases survival compared to conventional therapy [4]. Non-malignant diseases amenable to HSCT are thalassemia [36], sickle cell diseases [81], inherited immunodeficiencies and aplastic anaemia [63]. For a full list of disease indications and outcomes the reader is referred to the International Bone Marrow Transplant Registry website (www.ibmtr.org.).

Animal experiments suggesting a role for HSCT in autoimmune diseases

Animal models of autoimmune diseases can be of two types: hereditary (spontaneous) or induced. Spontaneous models of lupus-like diseases (e.g. MRLllpr or NZB mice) have a basic genetic defect causing the phenotype and are characterised by autoantibody production, nephritis and in some cases vascular disease (NZW.BXSB) [26]. The induced models [e.g. adjuvant arthritis and experimental allergic encephalitis (EAE)] are elicited by immunization in a genetically susceptible strain and may better reflect the genetic and environmental components of human disease [75].

Spontaneous models

Ikehara et al. [26] have shown that both organ-specific (e.g. non-obese diabetic mice) and systemic autoimmune diseases (NZWxBXSB) in spontaneous mouse models originate from bone marrow stem cells [26]. By transplanting stem cells from the diseased animals they were able to demonstrate the disease phenotype in the recipient. This clearly has wide ranging consequences in the human setting, suggesting that the stem cell may be a key to unraveling the mysteries of autoimmune disease. The study by Ikehara et al. [261 raises the intriguing concept that to cure autoimmune disease one has to purge the stem cell by replacing it with a new non-diseased stem cell (i.e. an allogeneic transplant) or alternatively, modification of the autologous stem cell (e.g. gene therapy).

As one might expect, autologous transplantation was not successful in these spontaneous animal models but surprisingly allogeneic HSCT was also unsuccessful in eradicating disease in MRLllpr mice [27]. Successful allogeneic HSCT was, however, achieved in the MRLllpr mouse by transplanting stromal cells in conjunction with the marrow [281. Thus, clear animal evidence exists for the concept of autoimmune disease as a stem cell disease - it can be transferred and it can be cured with allogeneic HSCT in these models.

Induced animal models

On the other hand, induced autoimmune disease animal models are effectively treated by both allogeneic and surprisingly by autologous HSCT. Van Bekkum et al. [76] showed that regression of adjuvant-induced arthritis could be accomplished with


12

10

E 8

E

~ 0 u 6 (J)

U +"' ~

--E <{ 4

2

o 4 6 8 10 12 14

Time after immunization (weeks)

Fig. 1. Reproduction of Fig. 2 from [33] (with permission)

both allogeneic and syngeneic HSCT using TBI-based conditioning. Subsequently, this group showed that autologous HSCT was as effective as syngeneic transplant [33J even after re-immunization post transplant (see Fig. 1). In the EAE model, allogeneic HSCT is curative and autologous HSCT is also effective but less so than in aplastic anaemia. Following an autograft in EAE, with the maximally tolerated dose of TBI, the relapse rate is 33% [77] (72% after re-immunization).

These results indicate attractive models for the human setting - the use of autologous transplantation is more desirable to both clinicians and patients due to lower morbidity and mortality. However, the use of radiation in the conditioning is associated with increased risk of secondary malignancy in the malignant HSCT setting [62] and more importantly in RA [51], suggesting that it would be unwise to use it in human trials at this dose.

Overall, caution needs to be exercised in extrapolating results from animal models of autoimmune disease to the human setting. The complexity of human disease and the numerous environmental variables that combine to contribute to the pathogenesis of disease makes it hard to be certain that what is observed in these animal models is applicable to human HSCT. However, there is a consistent trend in all the animal models with respect to HSCT - the procedure does indeed cure or ameliorate the disease process. In addition, the transfer of disease by stem cell transplantation demonstrates that the stem cell is implicated in disease pathophysiology. For these reasons alone, as in most areas of medicine, this would warrant phase IIII trials in humans and this is indeed the current status of HSCT in autoimmune disease.


HSCT in autoimmune disease: human experience

Initial experience of HSCT for autoimmune disease was in the context of HSCT for haematological malignancy in patients with a co-existent autoimmune disease. Profound remissions were seen in the allogeneic setting [60] and major disease remissions in the autologous setting [61] as discussed below. This led to early case series in four major diseases (RA, SLE, SSc and MS) demonstrating similar benefits which are outlined below. A consensus meeting chaired jointly by the EBMT and EULAR published guidelines [74], and randomised trials of HSCT in these diseases are in the early planning stages in our institute. By June, 2000, there were 281 HSCT procedures registered with the EBMTIEULAR database - RA, MS, SLE and SSc compose almost 70% of these indications for HSCT (personal communication, A. Tyndall).

Coexistent malignancy case reports

The Fred Hutchinson Cancer Research Center in Seattle, USA is one of the largest and most experienced bone marrow transplant units in the world. In a retrospective analysis of patients who had an allogeneic HSCT for a coexistent malignancy, Nelson et al. [45] assessed 13 patients with a variety of autoimmune diseases (including 1 RA, 1 SLE, 1 DLE, 1 Crohns disease, 3 IDDM, 4 Grave's disease, 1 dermatitis herpetiformis, and 1 vasculitis). With a median of 14 years follow up, all patients were alive with no recurrence of their diseases. Three case reports of RA patients with gold-induced aplastic anaemia have been reported to be in complete remission of their arthritis up to 13 years after allogeneic bone marrow transplants from HLAmatched siblings [60]. One patient had a recurrence of disease at 2 years, and recommenced disease-modifying anti-rheumatic drugs (DMARD) for 2 years, after which the disease ran an attenuated course. Complete donor chimerism was never established in this patient, in contrast to a case report by McKendry et al. [41] which showed complete donor chimerism but the disease also recurred after 2 years; it is noteworthy that this case did not develop GVHD, suggesting that like HSCT for malignancy, GVHD is necessary for eradication of diseases in the host. Likewise, in five cases of allogeneic HSCT for malignancy in patients with Crohn's disease [35], the only patient in whom the disease was not cured also did not have GVHD. Some authors have suggested a "graft-versus-autoimmune" effect as a possible mechanism of cure in these cases which is supported by a possible correlation between cure, relapse and GVHD [59]. These cases and the animal data suggest that allogeneic HSCT would be curative due to a combination of factors such as more intense immunosuppression pre and post transplantation, the lack of autoreactive cells (such as lymphocytes) in the donor graft and possibly the "graft-versus-autoimmune" effect.

Coexistent autologous HSCT case reports have also shown substantial remissions, but cures on long-term follow up appear less likely. Case reports of SLE [61], Crohn's disease [32, 57], RA [13, 29] and other diseases [18] have been reported in the last 5 years, confirming the initial benefit of the intense immunosuppression associated with HSCT, although recurrence of disease is usually the case. Some have argued that this is due to lack of T cell depletion of the graft [18] but this would be a premature assumption until adequate randomised trials between CD34 selection and unmanipulated grafts have been performed (see below).


Following these encouraging case reports, it did not seem unreasonable to embark on phase IIII trials of autologous HSCT in severe autoimmune disease. This was in keeping with the consensus guidelines published in 1997 [73] where it was generally agreed that allogeneic HSCT in its present form is not applicable because of high morbidity and mortality. Outlined below are updates on the current reported case series of autologous HSCT for RA, SLE, SSc and MS. Readers should bear in mind that it is expected there is a publication bias towards positive outcomes in the literature at this early stage of the procodure.

Autologous case reports


Joske et al. [30] reported the first autologous PBSCT performed solely for RA in Australia. A wheelchair-bound patient who had received all previously available therapies for RA underwent stem cell collection with 4 g/m2 cyclophosphamide and G-CSF. He then received 200 mg/kg cyclophosphamide as conditioning followed by infusion of an unmanipulated PBSC graft. Transplant-related morbidity was minimal and the patient attained an American College of Rheumatology (ACR) 70 remission for 25 months. Reintroduction of only 10 mg methotrexate (which had previously been unsuccessful) has maintained his disease under substantial control for a further 12 months at last follow up (personal communication, D. Joske).

Snowden et al. [58], at St. Vincents Hospital in Sydney, performed a dose-escalation study in two cohorts of four RA patients each; one receiving 100 mg/kg and the other 200 mg/kg cyclophosphamide. The analysis of the safety of the procedure was the primary objective of this study but by comparing two dose schedules of cyclophosphamide it was possible to gain preliminary data upon which to base the current randomised trial. All patients had stem cells collected with G-CSF alone and received unmanipulated PBSC. Cohort 1 (100 mg/kg cyclophosphamide) attained moderate responses in all parameters but the disease recurred in all four at 2-3 months. The second cohort has now been followed extensively for over 2 years. The degree of response in this group of patients has been longer and more substantial. Three of the four patients attained ACR70 status and one attained ACR50 (see Fig. 2 for swollen joint counts). However, there has not been complete eradication of disease, with all patients now having returned to some form of DMARD but still with an overall reduced dose of prednisone, reflecting a significant reduction in disease activity in all patients compared to pre-PBSCT. Two patients (2.2 and 2.3) had successful reintroduction of DMARD at 4 and 6 months, respectively - both patients had been previously unresponsive to these agents and now are in ACR50. The remaining two patients (2.1 and 2.4) had disease recurrence just prior to 2 years - one has come under rapid disease control within 1 month using leflunamide (ACR70). The second patient has recommenced prednisone (at a smaller dose than pre PBSCT) and is still experiencing some joint discomfort despite DMARD. Three of the four patients have expressed willingness to undergo the procedure again if required. Of interest, one of these patients was a 26-year old who became pregnant 10 months after the HSCT and delivered a healthy male. There have been no long-term sequelae from the stem cell rescue and as a disease modulator one could argue it has been a success for these severe resistant RA patients.

202

45 40 35

.... 30 = = o 25 u ~

20 rJ1 15

10 5

2.2: 1 x dose GOLD

2 . .3: MTX7.5

J. Moore, P. Brooks

-+-2.1 ....... 2.2 ....... 2.3

2.1: MTXlCya ...... 2.4

2.2: MTX

o +-----~------~----~------~--~~----~ PreTx 3Mth 6Mth 12 Mth 18 Mth 2 Yrs

Fig. 2. Swollen joint counts in four rheumatoid arthritis patients receiving 200 mg/kg cyclophosphamide

Burt et al. [10] has treated four severe RA patients with 200 mg/kg cyclophosphamide, 90 mg/kg ATG and in one patient 400 cGy TBI. All patients received a T celldepleted PBSC graft. Two patients attained ACR70 status at 9 and 20 months follow up. One patient attained ACR70 at 3 months until recurrence of disease at 6 months, while another patient failed to attain a response (defined as response <ACR20) - it is of interest to note that these two patients had the largest T cell depletion of their stem cell graft. Durez et al. [17] reported a 22-year-old patient with refractory RA who was treated with 16 mg/kg busulphan, 120 mg/kg cyclophosphamide followed by a highly purified PBSC graft; this patient was in complete remission at 11 months follow up despite complete reconstitution of the T cell repertoire to pretransplant levels. Further phase IIII trials are being conducted in Leiden, Leeds and Omaha. Thus far there has been only one reported death associated with HSCT in an RA patient.

These important cases thus far illustrate that, although autologous PBSCT is not curative, it has resulted in a form of immunomodulation of the disease process that can be long lasting in previously resistant patients. The mechanism of this immunomodulation is unclear but at up to 3 years follow up it presumably represents some form of "lymphohaemopoietic re-setting" rather than simple immunosuppression due to the conditioning itself. At this stage there appears to be no difference in remissions between T cell-depleted and unmanipulated HSCT but a current randomised trial being conducted in Australia, with 31 patients now transplanted, will help to answer this question.

In contrast to the autologous setting, one would expect that a syngeneic HSCT could be curative and McColl et al. [40] reported the first syngeneic PBSCT for autoimmune disease. A 42-year-old man with severe seronegative RA received cyclophosphamide/ATG conditioning and an un manipulated PBSC graft with minimal transplant-related toxicity. Post-transplant T cell receptor V-beta gene usage of circulating lymphocytes demonstrated evidence of full donor T cells, which corresponded to complete remission of the disease, now at 36 months follow up (personal communication, J. Szer). This case appears to demonstrate the importance of full donor chi-


merism at the T cell level - a situation that may be a necessity for allogeneic PBSCT to be totally successful.


Fourteen cases (11 adults, 2 children) of autologous HSCT in SLE have been reported in the literature or in abstract form. Nearly all reported cases have had severe systemic and renal disease unresponsive to corticosteroids and monthly IV cyclophosphamide. Of the 14 cases, 10 have received 200 mg/kg cyclophosphamide with ATG as conditioning. The first reported case in 1997 was a 46 year-old woman with an 18-year history of SLE who was treated with thiotepa and cyclophosphamide followed by a T cell-depleted graft [38]. A sustained remission of up to 2 years was achieved with the prednisone dose reducing from 40 mg to 5-10 mg. Burt et al. [10] reported on two patients with severe SLE (one suffering from nephritis and the other with alveolar haemorrhage and vasculitis) who received 200 mg/kg cyclophosphamide and 90 mg/kg ATG followed by a CD34-selected PBSC. Both patients have had major responses, with reduction in prednisone doses, normalisation of complement levels and reduced autoantibody titres. A further five cases have been reported in abstract form [69]. Further successful procedures have been reported in Paris [21], Berlin [53] and Palermo [43]. Fassas et al. [19] reported, in abstract form, a case of autoimmune pancytopenia associated with SLE which was only transiently successful following BEAM conditioning and ATG. Although beyond the scope of this review, it is of interest that autoimmune cytopenias have generally yielded disappointing results [55] with one case failing autografting but subsequently responding to an allogeneic HSCT [14].

Vleiger et al. [80] reported the use of HSCT of (cyclophosphamide/ATG/lowdose TBI conditioning followed by CD34-selected autologous HSCT) in two children suffering severe growth retardation associated with prednisone therapy for lupus nephritis. Both children had major responses from their nephritis with reduction or cessation of all medications. The use of HSCT in these cases and juvenile chronic arthritis (lCA) [83] by the group from Utrecht suggests a role for this procedure in children who have uncontrollable inflammatory problems. A "re-setting" of their disease has the added benefit of reducing their side effect profile from corticosteroids [46] so that growth can occur. Caution must still be exercised in taking the immunosuppression and T cell depletion too far, as the risks of opportunistic infection and haemophagocytosis [79] have recently become significant concerns with the death of three children with lCA.

Systemic sclerosis

SSc is the second most common indication for HSCT in the EBMT registry after MS, probably reflecting the lack of therapeutic advances in this disease. The Basel group have reported two patients with SSc who had CD34-selected HSCT after 200 mg/kg cyclophosphamide conditioning [67, 71]. The first patient had cutaneous disease and pulmonary fibrosis, both of which have continued to improve (decreased skin score) or stabilise (stable DLCO) with up to 2 years follow up. The other patient had CREST with pulmonary hypertension and moderate symptomatic and serologi-


cal improvement with a marked improvement of quality of life at 2 years follow up. The Seattle group have commenced a pilot study of HSCT using 120 mg/kg cyclophosphamide, 90 mg/kg ATG and 800 cGy of TBI in severe SSc, for which seven patients have now been transplanted [44J. Pulmonary toxicity has been noted in some patients, so that lung shielding has been introduced, but in those without lung toxicity there has been improvement or stabilisation of disease activity in all patients. The same group have performed an allogeneic HSCT for SSc with severe pulmonary fibrosis, with stable engraftment and full donor chimerism at 6 months [44]. There has been improvement in this patient's clinical status and the long-term outcome of this patient will be watched with interest particularly with respect to the ability of the allogeneic graft to reverse the lung fibrosis.

One child with SSc has been reported [39]. An ll-year-old girl with pulmonary and cutaneous SSc was treated with 200 mg/kg cyclophosphamide and 10 mg/day Campath-1 G for 2 days followed by a CD34-selected HSCT. Now at 2 years follow up she has had a reduced skin score (21 to 10), reversal of alveolitis and dyspnoea with a rapid increase in growth (16 cm) presumably due to cessation of all immunosuppressive medications.

Although procedures for SSc have in general been successful, there have been deaths associated with both mobilisation and the transplant itself [72], usually in patients with advanced disease. This highlights the issue of patient choice in HSCT for autoimmune disease, particularly in SSc where earlier intervention before advanced fibrosis develops may be beneficial. In addition, it reminds us that this procedure is experimental and should now only be conducted in experienced centres in recognised clinical trials.

Multiple sclerosis

Of all HSCT procedures registered with the EBMT registry 25% are for severe MS, usually primary or secondary progressive disease. Although interferon-(3 has been shown to delay the time to progression of disease based on EDSS (Expanded Disablity Status scale) scores [31] there are still numerous patients for whom there are no other therapeutic options. This lack of success and the expense associated with interferon therapy have prompted some groups to investigate the role of high-dose immunosuppression and HSCT in MS. Recently, the EBMT and the European Charcot Foundation have published guidelines on marrow stem cell transplantation based on an analysis of the first 42 cases registered with the EBMT [12]. With a mean follow up of 18 months there has been improvement or stabilisation of 82% of patients, which compares favourably with 60% progression-free survival at 18 months reported with interferon-(3 [31]. The patients in the interferon study had EDSS scores that were generally lower (mean 5.1, range 3-6.5) than the HSCT patients (median 6, range 4.5-8.5), suggesting that patients with more advanced disability have been chosen for HSCT. Of concern were the three treatment-related deaths (3/42) and the high morbidity associated with stem cell collection and transplantation in these patients; this may also reflect the advanced state of disease in this patient group. The results of autografting almost certainly reflect publication bias and a randomised trial would be the only method to determine the superiority of HSCT over interferon in secondary progressive disease. At this early stage of HSCT in autoimmune diseases this would be premature until the optimal form of HSCT is determined. As a result,


Table 3. Summary of guidelines from the EBMT and European Charcot Foundation for HSCT in multiple sclerosis [12]

Patient selection

Stem cell mobilisation

Graft manipulation (T cell depletion)

Conditioning

Endpoints

EDSS 3-6.5, satisfied Poser criteria, MRI abnormalities, failed all conventional therapy, sustained disability in preceeding 6 months

10 flg/kg GCSF + 2 g/m2 cyclophosphamide

Mandatory or in vivo with ATG: CD34 >2xI06/kg CD3 <I x 105/kg

120 mg/kg cyclophosphamidefTBI 120 mg/kg cyclophosphamide/16 mg/kg busulphan BEAM

Confirmed Progression at 3 years: EDSS > I point (if baseline <5) EDSS >0.5 point (if baseline >5) MRI abnormalities HSCT related death

EDSS, Expanded Disability Status scale; BEAM, BCNU, etoposide, cytosine, arabanoside and melphalam; ATG, anti-thymocyte globulin; TBI, total body irradiation

the EBMT and the European Charcot Foundation have established guidelines for HSCT in MS, which are summarised in Table 3. The aim is for centres performing HSCT in MS to register their patients with the EBMT registry in a multicentre, multinational, uncontrolled trial. In particular, patients must have an EDSS between 3 and 6.5 and have had an unsatisfactory response to other therapies. Conditioning will be either cyclophosphamide/TBI, busulphan/cyclophosphamide or BEAM with an option to add ATG if T cell depletion of the graft is not used. The major endpoint will be to have 80% of patients progression-free (based on EDSS or MRI) within 3 years. Following an analysis of this trial with 3 years follow up, it would be possible to establish the role of HSCT in MS and design a controlled prospective phase III trial.

Future directions

To determine the future role of HSCT in severe autoimmune diseases there are some fundamental issues to be resolved. Currently, there are case series being performed as units decide which patients are best suited to this therapy - this decision predominantly being the domain of the treating rheumatologists, immunologists and neurologists. For clinicians, the optimal and safest method of performing the HSCT is their main concern at this point in time. Finally, one needs adequate disease outcomes to determine the success of the procedure. The extensive co-operation and consultation across various specialty fields to answer these questions make this area of autoimmune therapy an exciting and rewarding exercise. The aim of the current phase IIII trials is to determine the optimal transplant procedure that is safe and efficacious so that eventually a randomised trial comparing HSCT against gold standard therapy can be performed. One would expect these phase III trials to be several years away but are likely to occur in SSc and MS earlier than RA and SLE given the therapeutic nihilism associated with the two former diseases. The EBMTIEULAR database will


Table 4. Proposed patient selection, conditioning and outcome measures for RA, SLE and SSc upon which optimal HSCT procedures can be based

RA SLE SSc

Patient selection Age 18-65 Age 15-65 Age 15-65 ACR criteria 4111 ACR criteria Rodnan score> 16 FailedMTX Unresponsive Poor prognostic factors Failed TNF-a antibody to cyclo/prednisone (DLCO <70%, ESR >25,

SLEDAI score> 10 proteinuria or cardiac disease) Early disease «3 years duration)

Conditioning Cyclo 200±ATG Cyclo/ATG Cyclo 200 mg/kg±ATG - maintenance (e.g. MTX) Cyclo 120ITBI/ATG

Outcome measures ACR criteria SLEDAI Skin score (>50% ACR @ 2 Years) CRP, ESR, C3, C4 ESR, proteinuria

Autoantibody titre DLCO Proteinuria Autoantibody titre

RA, Rheumatoid arthritis; SLE, systemic lupus erythematosus; SSc, systemic sclerosis; ACR, American College of Rheumatology; MTX, methotrexate; cyclo, cyclophosphamide

Table 5. Possible design of future phase III trials of HSCT in autoimmune disease

Disease

RA

SLE SSc MS

Possible trial designs

1. HSCT vs MTX±TNF-a antibody 2. HSCT plus maintenance MTX vs MTX + TNF-a antibody HSCT vs monthly cyclophosphamide I gx6 HSCT vs monthly cyclophosphamide 1 gx6 HSCT vs interferon-~

provide invaluable information to assist the design of these trials. The registry also can provide ongoing quality assurance about the morbidity and mortality of HSCT in these diseases, In addition, meta-analyses of the database cases may aid in determining the patients most likely to benefit from HSCT and the optimal conditioning, etc,

We have outlined in Table 4 the questions that need to be answered about HSCT for RA, SLE, SSc and MS to determine the optimal procedure. In Table 5 we list the possible phase III trials that could be conducted in this area in the future. Below we discuss some issues that we believe need more urgent consideration in this field,

The role of T cell depletion of the graft

One question about the HSCT procedure that needs more urgent attention in all four diseases is the role of T cell depletion of the stem cell graft. The EBMT database now has over 280 cases registered, of which the vast majority are CD34 selected (A. Tyndall, personal communication), indicative of the widely held belief that graft manipulation is imperative to remove autoreactive cells (presumed to be T lympho-


cytes) [18]. The rationale behind CD34 selection is that by running a PBSC product through an immunomagnetic column it will be depleted of all cells except the CD34 stem cell [34] - the pure stem cell capable of both self renewal and differentiation. CD34 selection has been used to "purge" the marrow of tumour cells (such as myeloma) or other unwanted cells (such as autoreactive lymphocytes in autoimmune disease) prior to high-dose chemotherapy. It follows then that one will rely on the conditioning to remove residual autoreactive cells left in the host before re-infusing a pure population of stem cells. Unfortunately, it is unlikely that any available conditioning regimen will completely ablate host lymphoid tissue, as has been demonstrated by chimerism studies in allogeneic HSCT with maximally tolerated conditioning [37]. The goal of a CD34-selected PBSCT would be that the "pure" stem cells obtained after CD34 selection will be able to regenerate without causing autoimmune disease. Current CD34 selection devices will only deplete around 3-4 log of T cells: leaving lxlOL lOx104 CD3 cells/kg which are still likely to contain "autoreactive" T cells. Therefore, it is likely that autoreactive T cells will remain both in the host after conditioning and in the graft making the process of regeneration of a new "reeducated" immune system by T cell depletion unlikely. However, the observation by our group and others that patients are easier to treat after unmanipulated autologous HSCT suggests there is immunomodulation by some other unknown mechanism.

The depletion of T cells by CD34 selection in auto-PBSCT for autoimmune disease makes a number of assumptions. The first is that one knows which is the autoreactive cell that you are removing and that a 3-log depletion is enough to eradicate it. For instance, in RA, the pathogenic cell is difficult to define. The T cell is often considered the most likely culprit because of the association of RA with certain HLADR SUbtypes and the abundance of T cells in the synovium of RA sufferers. However, these T cells secrete very low levels of pro-inflammatory cytokines and are relatively inactive, with little evidence of oligoclonality [22]. The number of T cells in the joint has little correlation with subsequent joint damage [42] and anti-T cell therapies such as anti-CD4 monoclonal antibodies have been relatively ineffective [78].

It is generally assumed that CD34 selection is relatively safe, which is generally true; engraftment is usually similar to unmanipulated PBSCT. However, immune recovery of CD4 and in particular CD4+, 45RA+ cells is delayed in recipients of these grafts [16], which has led to concern about infection with opportunistic organisms. There have been recent reports of a death in a CD34-selected patient from EBV-associated lymphoma [48] and an increased incidence of CMV viraemia [24] in recipients of autologous CD34-selected grafts. The experience with lCA patients is that the children who died with haemophagocytosis all had grafts infused with less than 3x 104 T cells/kg, although severe uncontrolled systemic disease may also have been involved [79]. It should also be pointed out that small trials thus far have not shown a superior outcome for CD34 selection in the autologous setting for malignant disease [23].

For all these reasons it is important to be sure of the role of CD34-selection procedures in HSCT in autoimmune diseases. In Australia we are now following up 31 RA patients who were randomised to CD34-selection or unmanipulated PBSCT following 200 mg/kg cyclophosphamide conditioning. Results of this trial will help to determine the role of T cell depletion in HSCT for RA, but this trial should be repeated in all other diseases before embarking on phase III trials against gold standard therapies.

208 1. Moore, P. Brooks

Maintenance

It has been our experience that if RA patients have a recurrence of their disease after HSCT, they rapidly respond to DMARD (see Case report section). Another case to support this concept includes the patient of loske et al. [30] (returned to ACR70 with just 10 mg methotrexate when he was previously unresponsive, personal communication, D. 10ske). These cases illustrate the possibility that the HSCT procedure may immunomodulate the disease but not cure it. However, the pre-emptive recommencement of DMARD post PBSCT may be an important option to prolong remissions in these patients. The exact timing of recommencement of therapy and the agents to be used should be the subject of future studies. A prospective trial may allow the recognition of potential markers of disease recurrence before clinically evident, thus allowing the design of future protocols. In the current Australian randomised trial, we have arranged to see patients every month for 1 year and then 3 monthly. In this way we can assess a number of parameters of the disease including inflammatory markers, cytokine analysis, immune reconstitution and, in some patients, synovial biopsies.

Mini-allografts

A future development that is likely, given the success of allogeneic HSCT in eradicating autoimmune diseases in coexistent malignancy or aplasia, is the use of "miniallografting" (see above). The use of minimal conditioning may be ideal for non-malignant diseases where there is no desire to remove a malignant clone but more a need to create a "new immune system" by means of chimerism. Slavin et al. [56] have pioneered this work in the malignant setting and have recently reported resolution of co-existent psoriasis in a patient with acute myeloid leukaemia following a "mini-allo". Thus, the concept of eradicating autoimmune disease with reduced transplant toxicity compared to conventional allo-HSCT has now been demonstrated. However, mortality from the procedure still remains high and morbidity can be significant from illnesses such as infection and GYHD. If the morbidity and mortality are reduced, and GYHD could be controlled, the use of mini-allografting will become more widespread because of the reduced risk benefit ratio in chronic autoimmune diseases. It should be remembered when assessing these patients that they all have increased standardised mortality ratios compared to the general population. However, one should bear in mind that if these diseases are the result of a novel antigenic stimulus then even allogeneic transplantation may be followed by relapse in some patients.

The importance of clinical trials

Although HSCT for autoimmune disease appears an attractive option for some patients, it is important to ensure that patients are transplanted in a clinical trial setting. The procedure is still experimental and will probably always be reserved for patients with the most severe disease. There are published guidelines [73], which should aid clinicians in their decisions about patient selection and conditioning. Prospective trials will help answer many questions including the role of maintenance and markers


for recurrence of disease. Other issues that will need to be addressed in a trial would be the cost-effectiveness of the procedure, especially in the new era of expensive monoclonal antibodies such as anti-TNF-a antibody [82].

Conclusion

HSCT in autoimmune diseases has now become one of the potential therapeutic options for physicians looking after patients with severe intractable autoimmune diseases. It has now progressed beyond theory based on animal and human case reports, but at this stage it has been appropriately reserved for patients with resistant disease in a clinical trial setting. Ongoing analysis of the safety and efficacy of patients in phase 1111 trials will allow us to determine if there is a wider role for the procedure in diseases such as RA, SLE, SSc and MS. Meta-analyses of the data will enable appropriate selection of patients and the optimal transplant procedure, so that eventually randomised trials against gold standard therapy will become a reality. In the future, with a decreased morbidity and mortality from allogeneic transplantation, cure of these diseases is not an unrealistic option.

Acknowledgements. The authors would like to thank our rheumatology and haematology colleagues at St. Vincents Hospital, Sydney, Royal Perth Hospital, Sir Charles Gardiner Hospital, The Mater Hospital, Brisbane and Royal Melbourne Hospital, who are involved in the current trial. We would also like to thank Jeff Szer, and David Joske for follow up on their patients and the kind assistance of Alan Tyndall on recent updates of the EBMTIEULAR data base. The financial support of Amgen Australia, the NHMRC and the Woodend Foundation is appreciated. We would like to thank our colleagues at St. Vincents Hospital (Sam Milliken, Jim Biggs and David Ma) for their review of the manuscript. Finally, we would like to thank Dirk van Bekkum for allowing us to reproduce a figure from one of his pUblications.

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