Inhibitors in hemophilia

Flora Peyvandi Angelo Bianchi Bonomi Hemophilia and Thrombosis Center,

Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico and

University of Milan, Italy

ISTH Advanced Course in Hemostasis and ThrombosisMoscow 17 – 19 September 2014

• Inhibitor is the most serious complication associated with the use of factor concentrates

• Inhibitor neutralizes infused factor, rendering patients resistant to conventional replacement treatment

• Most inhibitors are transient, i.e. disappear within 6 months from their occurence, or resolve with immune tolerance therapy

• 20-30% of hemophilia A and 3% of hemophilia B patients show persistent clinically significant inhibitors which result to severe morbidity

Treatment complication

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• Alloantibodies, frequently IgG4 that specifically neutralize the procoagulant activity of FVIII or FIX

• Cause serious complication of replacement therapy in patients with hemophilia

• Become a long-standing problem that seriously affects health and quality of life

Inhibitors

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The inhibitors interfere with important interaction of FVIII at various stages of its

functional pathway

Antibodies directed against C2 domain affect the binding of FVIII to phospholipid and von Willebrand factor (vWF)

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Antibodies directed against C2 domain interfere with cleavage of FVIII by thrombin and FXa.

Anti-A2 e -A3 inhibitors disrupt the interaction FVIIIa with FIXa destabilizing FVIIIa within the

Xase complex.

The formation of antibodies against exogenous FVIII is a T-cell depent event involving antigen-presenting cells (APC), T- and B-lymphocytes

FVIII antibodies

Exogenous FVIII

The development of inhibitory antibodies

(Astermark J hemophilia 2006;12, Suppl.3:52-60)Flora Peyvandi

The development of inhibitory antibodies

1. The infused factor binds to the surface of the APC

2. internalized by endocytosis and proteolytically cleaved in the endocytic processing pathway

3. linear peptides of 13–18 amino acids bind to the major histocompatibility complex (MHC) class II molecules

4. Transferred to the cell surface for interaction with T-cell receptor (TCR-CD3) on CD4+

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The development of inhibitory antibodies

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5. TH-cells released cytokines

6. IL-4, IL-5, IL-6 and IL-10 promote B-cells activation and mediate the humoral response

7. Cytokines secreted by TH2 cells also mediate the characteristic immunoglobulin (Ig) class-switching to IgG4

Factors influencing inhibitor development

Patient-related

FVIII gene mutation

Ethnic origin

Family history of inhibitor

MHC class

Polymorphisms of immune-response genes (IL10-TNFalfa, regulatory molecules)

Treatment-related

Number of FVIII exposure days

Age at the time of first treatment

Type of FVIII concentrates

Intensity of treatment

Current infection/inflammatory state

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Risk of inhibitor development according to specific F8 genotype

• meta-analysis of 5383 severe HA patients from 30 selected studies

• large deletions and nonsense mutations showed an higher risk than intron 22 inversions (pooled OR 3.6, [95% CI], 2.3-5.7 and OR 1.4, 95% CI, 1.1-1.8, respectively)

• intron 1 inversions and splice-site mutations were equal (pooled OR 0.9; 95% CI, 0.6-1.5 and OR 1.0; 95% CI, 0.6-1.5)

• small deletions/insertions and missense mutations showed a lower risk (pooled OR 0.5; 95% CI, 0.4-0.6 and OR 0.3; 95% CI, 0.2-0.4, respectively)

(Gouw SC et al, Blood 2012; 119:2922-2934)

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Inhibitor related studies:Genetic of the immune system

Additional genetic risk factors that have been suggested to influence the inhibitor development are polymorphic genes in the immune response

SAMPLES IMMUNE SYSTEMS RELATED GENES

POLIMORPHISMS GENOTYPED

POLYMORPHISMS SIGNIFICATIVELY ASSOCIATED TO INHIBITOR

DEVELOPEMENT REFERENCES

176 severe HA patients HLA class II HLA alleles DQA1*0102 allele Hay et al. Thromb Haemost 1997

164 HA patients in 78 unrelated families (77 inhibitor positive)

IL1beta RFLP -Astermark et al.

Blood 2006IL4 1 SNP -

IL10 STR Allele 134 bp CA repeats

164 HA patients in 78 unrelated families (77 inhibitor positive)

HLA class I/II HLA alleles - Astermark et al. Blood 2006TNFa 4 SNPs -308 A/G

124 severe HA patients in 60 unrelated families (63 inhibitor patients) CTLA4 2 SNPs -318 C/T Astermark et al.

J Thromb Haemost 2007

915 severe HA patients (282 inhibitor positive) 21 candidate genes 372 SNPs IL1, IL2, IL12 Lozier et al.

hemophilia 2011

833 subjects from 3 independent cohorts (457 inhibitor positive) 1 081 genes 13 331 SNPs

13 SNPs located in: MAPK9, DOCK2, CD44, IQGAP2, CSF1R

PDGFRB, PCGF2, HSP90B1, F13A1, IGSF2, ALOX5AP, MAP2K4, PTPRN2

Astermark et al. Blood 2013

362 severe HA patients(99 inhibitor positive) HMOX1 STR, 2 SNPs Allele >30 GT repeats Repessè et al.

Haematologica 2013

85 severe HA patients (36 inhibitor positive) FCGR 5 SNPs FCGR2A (131HH allele) Eckhardt et al.

J Thromb Haemost 2014

• 833 subjects from 3 independent cohorts: - Hemophilia Growth and Development Study (HGDS)- Malmo International Brother Study (MIBS)- Hemophilia Inhibitor Genetics Study (HIGS)

• Illumina iSelect platform to genotype 13 331 SNPs from 1 081 genes, primarily immune response and immune modifier genes

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Astermark study Results

• 53 SNPs significantly associated with inhibitor development

- 13 with p<0.001 in post meta analysis- 8 significant predictors in discordant brother pairs

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- 13 SNPs passing the meta P<.001

- 8 SNPs significant in discordant pairs

Ethnicity and inhibitor development

* Study subjects received either cryoprecipitate or intermediate purity FVIII concentrates

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Black patients with hemophilia A are twice as likely as white patients to produce inhibitors against factor VIII proteins given as replacement therapy.

Recombinate Ô Kogenate Ô US Retrospective Study*

Total patients (≤2%) 72 64 89

African American

9 8 10

with inhibitors 5 (55,5%) 4 (50%) 5 (50%)

Caucasian and others 63 56 79

with inhibitors 17 (27,4%) 14 (25%) 20 (25%)

(Scharrer et al, Haemophilia 1999; 5:145-154)

(Viel KR et al, N Englan J Med 2009;360:1618-27)

Age at first exposure

First replacement therapy at an early age may increase the risk of inhibitor formation

• the incidence of inhibitors at 3 years was significantly higher in those initiating therapy before 6 months of age compared with patients starting with treatment between 6 and 12 months or those treated at age >12 months (41% vs. 29% and 12% respectively, P=0.03)

• children first treated at age <11 months demonstrated a trend towards an increased risk of inhibitor formation, this data was not confirmed after adjusting for genetic factors

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(Lorenzo et al. Br J Haematol 2001;113: 600-603) (Santagostino et al. Br J Haematol 2005)

‘Age at first exposure’ CANAL cohort study

(Gouw SC et al, Blood 2007;109:4648-4654)

1. the incidence of inhibitors appeared to be associated with age at first treatment, decreasing from 41% for those treated within the first month of age to 18% in those treated after 18 months

2. after adjustment for treatment intensity, this association largely disappeared

Intensity of treatment

Intermediate frequency: 10 to 50 daysHigh frequency: <10 days

• the association of a higher frequency of FVIII treatment and inhibitor risk differed among studies

• the association that was present disappeared after adjustment for dose of FVIII

• the frequency of FVIII treatment was not independently associated with the risk of inhibitor development

(Gouw SC & Fijnvandraat K, Semin Thromb Hemost 2013;39:740-751)Flora Peyvandi

Clinical data

The most controversal risk factor for the development of inhibitors in hemophilia patients depends on the type of the therapeutic molecule used, plasma-derived concentrates or recombinant rFVIII

- Plasma-derived products may vary in purity and VWF content

- Recombinant products produced in mammalian tissue culture are of high purity and do not contain VWF

Type of FVIII concentrates

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Immunogenic potential of different source/type FVIII

• The amount of von Willebrand factor (VWF)

• FVIII physical state

• FVIII structural change

• Affinity of FVIII for phospholipids

• posttranslational modifications(e.g. carboxylation, glycation, sulphation) crucial for correct functioning of the protein and are specific to the cell line

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• Under physiologic conditions, VWF binds to different epitopes in the A3 and C2 domain of the FVIII molecule and has a protective effect on these FVIII epitopes against degradation by proteinases

• In addition, an immunomodulatory effect of VWF has been described by masking B- and T-cell epitopes

• VWF is able to block antigen presentation of FVIII by dendritic cells in a concentration-dependent manner

VWF and FVIII immunogenicity

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(Behrmann et al. Thromb Haemost 2002;88:221-229) (Suzuki et al. Thromb Haemost 1996;76:749-754) (Delignant et al. Haemophilia 2012;18:248-254)

Cumulative incidence of FVIII inhibitors

• Incidence rates of inhibitor development in patients treated with pdFVIII or rFVIII products have been reported in numerous studies

(Mannucci PM hemophilia 2014; 20, Suppl.6:2-16)

(Mannucci PM hemophilia 2014; 20, Suppl.6:2-16)

Cumulative incidence of FVIII inhibitors

• In previously untreated patients (PUPs) treated with pdFVIII products, the crude incidence of inhibitor development was 13.8%

• in PUPs treated with recombinant products, the crude incidence of inhibitors was twofold higher (28.5%)

• the data suggest that plasma-derived products are less immunogenic than recombinant products but, due to study heterogeneity, the results cannot be considered conclusive

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• Calvez et al. has re-examined the data from four different retrospective studies comparing pdFVIII and rFVIII

• The data clearly indicates that there is an trend indicating that recombinant products are more immunogenic

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recombinant better | recombinant worse

Relative risk or odds ratio

AdjustedUnadjusted

*

** p< 0.05

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• Multicenter (13 European and 1 Canadian center) retrospective cohort study

• Included 316 previously untreated patients (PUPs) with severe HA born between 1990 and 2000 who received pdFVIII or rFVIII infusions up to 50 exposure days (EDs) o until inhibitor development

• Describe the inhibitor risk according to different factor VIII product types

The CANAL study: results

• Eighty-two patients (26%) developed clinically relevant inhibitors

• High-titer inhibitors developed in 66 patients (21%)

• Patients developed inhibitors after a median of 14 exposure days (interquartile range [IQR], 8-19 days) and at a median age of 15 months (IQR, 10-22 months)

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1. the risk of inhibitor development was not clearly lower in plasma-derived compared with recombinant factor VIII products (relative risk [RR], 0.8; 95% confidence interval [CI], 0.5-1.3).

2. the inhibitor risk was similar in plasma-derived products containing considerable quantities of VWF (RR, 1.0; CI, 0.6-1.6), and it was 70% decreased in plasma-derived products containing small quantities of VWF (RR, 0.3; CI, 0.1-1.1).

The CANAL study: results

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• Multicenter (29 hemophilia centers in Europe, Israel and Canada) cohort study

• Included 574 PUPs, median age 4.6 (3.5-6.5), with severe HA born between 2000 and 2010 who received pdFVIII or rFVIII infusions up to 75 EDs or until inhibitor development

• Assess whether the types of factor VIII product were associated with inhibitor development

The RODIN study: results

• inhibitory antibodies developed in 177 patients (cumulative incidence, 32.4%; 95% confidence interval [CI], 28.5 to 36.3)

• 116 patients had high-titer inhibitors (cumulative incidence, 22.4%; 95% CI, 18.8 to 26.0)

• Inhibitory antibodies developed after a median of 15 exposure days (interquartile range, 10 to 20) at a median age of 15.5 months (interquartile range, 10.7 to 19.6)

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1. Absence of an evident difference in inhibitor incidences between plasma-derived and recombinant FVIII products (adjusted hazard ratio as compared with recombinant products, 0.96; 95% confidence interval [CI], 0.62 to 1.49)

2. Second-generation full-length products were associated with an increased risk of inhibitor development as compared with third-generation products (adjusted hazard ratio, 1.60; 95% CI, 1.08 to 2.37)

3. the content of von Willebrand factor in the products was not associated with the risk of inhibitor development. Adjusted Relative Risk of inhibitor development,

according to the type of FVIII product.

The RODIN study: results

• data from 24 studies comparing pdFVIII and rFVIII

• 1167 patients treated with pdFVIII and 927 with rFVIII, median age 9.6 months

• pooled incidence rate was 14.3% for pdFVIII and 27.4% for rFVIII

• after multi-way ANOVA, significant differences in study design, study period, testing frequency while type of

concentrate lost statistical significance*Flora Peyvandi

*

Seminars in Thrombosis & Hemostasis, Sept 2013

• data from 28 prospective studies evaluating the incidence of inhibitors in 1421 PUPs

• rates of inhibitors were 23% (0.15-0.33) for pd-FVIII and 29% (0.26-0.32) for rFVIII products

• no statistically significant differences were observed in the inhibitor incidence between pdFVIII and rFVIII concentrates

Inhibitor rate incidence

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The outcomes of numerous studies and systematic reviews have been contradictory.

The studies have been limited by the enrollment of small, heterogeneous study populations and the use of several factor VIII products, and comparisons among studies have been difficult because of different study designs.

THEREFORE…..

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The SIPPET study:(Survey of Inhibitors in Plasma-Product

Exposed Toddlers)

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• Multicentre, international (Europe, America, Africa, Asia), open-label, controlled, randomised trial

• Approximately 300 patients will be enrolled

Study objective

To compare the immunogenicity of the class of plasma-derived

VWF-FVIII concentrates with that of the class of recombinant

FVIII, by determining the frequency of inhibitor development in

PUPs exposed to study products for at least 50 EDs or in the first 3

years from enrollment, whichever comes first.

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• Each patient will be randomly assigned to a treatment with

a single product (pdFVIII or rFVIII)

• Prophylaxis or on-demand regimens will be chosen by the

clinicians according to their guidelines and preferences

Treatment

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Patients recruitment withgeographic distribution

19 pts

38 pts

20 pts

23 pts

83 pts

96 pts

279 patients recruited

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• Inhibitor is a severe complication of FVIII replacement therapy

• the onset of inhibitor is a complex interaction of environmental and genetic factors

• numerous studies have carefully explored the likelihood of developing inhibitors related to FVIII product type

• contradictory data have been reported by numerous studies and systematic reviews

• solid information on the inhibitor risk associated with the use of FVIII product type are expected to be generated from the randomized controlled SIPPET study

Consideration

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