Vol. 4, 2053-2063, September 1998 Clinical Cancer Research 2053
Advances in Brief
Prevention of Intestinal Toxic Effects and Intensification of
Irinotecan’s Therapeutic Efficacy against Murine Colon
Cancer Liver Metastases by Oral Administration of the
Lipopeptide JBT 3002’
Hisashi Shinohara, Jerald J. Killion,
Hiroki Kuniyasu, Rakesh Kumar, and
Isaiah J. Fid1er�
Department of Cell Biology, The University of Texas M. D.
Anderson Cancer Center, Houston, Texas 77030
Abstract
The induction ofsevere diarrhea limits the usefuiness ofthe DNA topoisomerase I inhibitor irinotecan (CPT-11) inthe treatment of advanced colon cancer. We investigatedwhether oral administration of the new synthetic bacterial
ilpopeptide, JBT 3002, encapsulated in phospholipid Hpo-
somes could prevent damage to the intestinal epithellum andlainina propria and thus allow for the parenteral adminis-tration of high-dose irinotecan to mice with established syn-
geneic CT-26 colon cancer liver metastases. Treatment ofmice with four daily i.p. injections of 100 mg/kg irinotecanwas effective against liver metastases but also resulted in loss
of body weight and early death. Histopathological examina-
tion of the intestines after this treatment revealed loss ofvilli, epithelial vacuolation, decrease in the number of cellsin the crypts In S-phase, increase in the number of apoptoticcells, and reduction in the number of lymphocytes In the
lamina propria. In contrast, treatment ofmlce with the same
irinotecan regimen after oral administration of JBT 3002
produced highly significant inhibition of liver metastases
without detectable damage to the intestines. Studies thatused irinotecan administered once a week for 3 weeks after
pretreatment with oral JBT 3002 demonstrated significantly
intensified eradication of established CT-26 liver metastases
compared with treatment with once-weekly irinotecan alone.
Received 4/8/98; revised 6/9/98; accepted 6/10/98.The costs of publication of this article were defrayed in part by thepayment of page charges. This article must therefore be hereby markedadvertisement in accordance with 18 U.S.C. Section 1734 solely toindicate this fact.I This work was supported in part by Cancer Center Support Core GrantCA16672 and NIH Grant R35-CA 42107 from the National CancerInstitute, by the Japan Society for the Promotion of Science, and by asponsored research agreement from Jenner Biotherapies, Inc. (SanRamon, CA). I. J. F. received an equity interest in Jenner Biotherapies,Inc. The terms of this agreement have been reviewed and approved bythe M. D. Anderson Cancer Center in accordance with its conflict ofinterest policies.2 To whom requests for reprints should be addressed, at Department ofCell Biology, Box 173, The University ofTexas M. D. Anderson CancerCenter, 1515 Holcombe Boulevard, Houston, TX 77030. Phone: (713)792-8577; Fax: (713) 792-8747.
Histological studies revealed that the liver metastases In
mice treated with oral JBT 3002 and i.p. irinotecan con-
tamed a higher number of macrophages than metastases In
mice treated with either drug alone. In vitro studies revealed
that irinotecan produced direct antiproliferative effects butJBT 3002 did not. Tumor cells exposed to both irinotecanand macrophages activated by JBT 3002 were highly sus-
ceptible to lysis. These data show that oral administration ofJBT 3002 can prevent Irinotecan-induced gastrointestinal
toxic effects and maintain the Integrity of the lamina pro-
pria, thus allowIng for Intensification of Irinotecan therapyagainst liver metastases from colon cancer.
Introduction
Irinotecan (CPT-l 1), a semisynthetic derivative of camp-
tothecin, is a potent chemotherapeutic agent gaining increased
use in drug-refractory colorectal cancer (1-4). Irinotecan exerts
S-phase-specific cytotoxicity through the inhibition of DNA
topoisomerase I (5, 6). One of the major dose-limiting side
effects of irinotecan is severe delayed-onset diarrhea accompa-
nied by dehydration and electrolyte imbalance (1, 4). These
symptoms are often treated with loperamide or diphenoxylate
derivatives (7, 8), but side effects remain common.
Although the exact mechanism of irinotecan-induced diar-
rhea is unknown, a recent study in mice ascribed the toxicity to
structural changes in intestinal architecture resulting from dis-
ordered epithelial cell differentiation and apoptosis rather than a
secretory mechanism (9). Mucosal injury could also be a result
of infection due to chemotherapy-induced depletion or dysfunc-
tion of leukocytes within the lamina propria (10) or lack of
production of growth factors and cytokines by intestinal epithe-
hal cells and cells of the lamina propria (1 1 , 12).
Mucosal integrity and immunity may be preserved by
macrophage-derived cytokines that regulate development and
differentiation of lymphocytes within the lamina propria (13-
17). Previous studies from our laboratory have demonstrated
that the incubation of monocytes-macrophages with synthetic
analogues of bacterial cell walls, such as MTP-PE,3 can induce
production of monocyte-derived cytokines in vitro (18). Sys-
temic administration of MLVs containing MTP-PE prevents
destruction of the intestinal mucosa and monocytopenia induced
3 The abbreviations used are: MTP-PE, muramyl tripeptide phosphati-dylethanolamine; MLV, multilamellar liposome vesicle; IL, interleukin;
BrdUrd, bromodeoxyuridine; TUNEL, terminal deoxynucleotidyl trans-ferase-mediated dUTP-biotin nick end labeling; PEM, peritoneal exu-date macrophage; Scav-R, scavenger receptor; rIFN--y, recombinantinterferon -y.
Research. on April 28, 2021. © 1998 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
2054 Prevention of Mucositis by Oral JBT 3002
by chemotherapy with doxorubicin (19). Moreover, these ira-
munomodulators activate tumoricidal properties in macrophages
(18, 20, 21), which results in the eradication of lymph node,
lung, and liver metastases in murine tumor models (22).
We have recently reported (23, 24) that a new synthetic
lipopeptide (N-acylated derivative of ‘I’-amino-Cl-C3-alkane-
sulfonic acid, JBT 3002) potenfly activates murine macrophages
to become tumoricidal and to release IL-la, IL-6, tumor necro-
sis factor-a, and nitric oxide. In the study reported here, we
evaluated the ability of JBT 3002 to protect mice from the
intestinal toxic effects produced by the administration of irino-
tecan for treatment of liver metastasis from syngeneic colon
carcinoma. We found that the oral administration of JBT 3002
prevents damage to the intestines and enhances the therapeutic
efficacy of irinotecan.
Materials and Methods
Animals. Specific pathogen-free BALB/c mice were
purchased from the Animal Production Area of the National
Cancer Institute (Frederick, MD). Animals were maintained
according to institutional guidelines in facilities approved by the
American Association for Accreditation of Laboratory Animal
Care in accordance with United States Department of Agricul-
ture, Department of Health and Human Services, and NIH
regulations and standards.
Reagents. Eagle’s MEM, Ca2�- and Mg2�-free HBSS,
and fetal bovine serum were purchased from M. A. Bioproducts
(Walkersville, MD). JBT 3002 was obtained from Jenner Bio-
therapies (San Ramon, CA). l-Palmitoyl-2-oleoyl-phosphatidyl-
choline and dioleoyl-phosphatidylserine were purchased from
Avanti Polar Lipids (Birmingham, AL). Irinotecan, produced by
Yakult Honsha Co. (Tokyo, Japan), was used according to the
manufacturer’s instructions. rIFN--y (specific activity, l0� units.’mg) was obtained from PharMingen (San Diego, CA). Allreagents used in tissue culture were free of endotoxin as deter-
mined by the Limulus amebocyte lysate assay (Associates of
Cape Cod, Inc., Falmouth, MA).
Tumor Cell Cultures. CT-26 murine colon carcinoma
cells syngeneic to BALB/c mice (25) were grown as monolayer
cultures in MEM supplemented with 5% fetal bovine serum,
vitamins, sodium pyruvate, L-glutamlne, and nonessential amino
acids. The adherent monolayer cultures were incubated at 37#{176}C
in a humidified atmosphere containing 5% CO2 in air. All
cultures were free of mycoplasma, reovirus type 3, pneumonia
virus of mice, K virus, encephalitis virus, lymphocytic chorio-
meningitis virus, ectromelia virus, and lactate dehydrogenase
virus (assayed by M. A. Bioproducts).
Preparation and Administration of Liposomes.l-Palmitoyl-2-oleoyl-phosphatidylcholine and dioleoyl-
phosphatidylsenne (7:3 molar ratio) with or without the
indicated amounts of JBT 3002 were dissolved in chloroform.
Aliquots were retroevaporated under a stream of nitrogen gas
and incubated overnight in a vacuum chamber at room tern-
perature to remove residual chloroform. MLVs were prepared
by hydration of the lipid film with HBSS, followed by
vigorous shaking for 6 mm using a vortex shaker. Oral
administration of JBT 3002 was performed using a rigid,
curved feeding tube. Each dose consisted of 5 p�mol of MLV
suspended in 0.2 ml HBSS. For in vitro assay, the liposomes
were diluted in medium before use.
Experimental Liver Metastasis. To prepare tumor
cells for inoculation, CT-26 cells in exponential growth phase
were harvested by a brief exposure to a solution of 0.25%
trypsin and 0.1% EDTA. The cell suspension was pipetted to
produce a single-cell suspension, washed, and resuspended in
HBSS. Cell viability was determined by trypan blue exclu-
sion, and only single-cell suspensions of >90% viability
were used. Tumor cells (1 X l0�/0.05 ml HBSS) were
injected into the spleens of BALB/c mice after laparotomy
under methoxyflurane anesthesia. The incision was closed in
one layer with wound clips (25). This protocol resulted in a
100% incidence of liver metastasis. The mice were eutha-
nized when animals in the control group became moribund.
Primary spleen tumor volume was estimated with the follow-
ing formula: tumor volume = L (mm) X W2 (mm2)12, where
L and W represent the length and the width of the tumor mass,
respectively. The livers were harvested and placed in Bouin’s
solution for 24 h before fixation in 10% buffered formalin.
The number of experimental liver metastases was determined
using a dissecting microscope. When the number of metas-
tases exceeded 100, we assigned a value of > 100. The
median number of liver metastases was compared among the
treatment groups using the Mann-Whitney U test.
Immunohistochemical Analysis. Mice were injected
i.v. with 0.2 ml saline containing 250 p.g BrdUrd 1 h before they
were killed (26). The small and large intestines and the caudate
lobe of the liver were resected, and tissue samples were fixed in
10% buffered formalin or snap-frozen in liquid nitrogen. Immu-
nohistochemical staining was performed by the immunoperoxi-
dase technique (27). Paraffin sections were dewaxed in xylene
and then rinsed in graded ethanol hydration in PBS. Antigenretrieval was performed by incubating the sections with Pepsin
Reagent (Biomeda Corp., Foster City, CA) for 20 mm. For
S-phase labeling with BrdUrd, the sections were incubated with
2 N HC1 for 30 mm at 37#{176}Cand then rinsed three times with
PBS. Endogenous peroxidase was inactivated by incubating thesections with 3% hydrogen peroxide in methanol for 10 mm.
Nonspecific reactions were blocked by incubating the sections
in a solution containing 5% normal horse serum and 1% normal
goat serum. The sections were incubated with a 1 : 100 dilution of
a monoclonal mouse antikeratin AE1/AE3 antibody that recog-
nizes pan cytokeratin (Boehringer Mannheim Corp., Indianap-
ohs, IN) or a 1 :50 dilution of a monoclonal mouse anti-BrdUrd
antibody (Becton Dickinson, Mountain View, CA) overnight at
4#{176}C.
Frozen sections for staining with antimouse CD3 (spe-
cific for lymphocytes) or antimouse macrophage Scav-R
were processed as described previously (27). The antibodies
used were a monoclonal rat antimouse CD3 antibody (Sero-
tec, Ltd., Oxford, England) at a dilution of 1:2000 and a
monoclonal rat antimouse Scav-R antibody (Serotec) at a
dilution of 1:70. Antibodies used for developing were goat
antimouse IgG + 1gM antibody (Jackson ImmunoResearch
Labs., Inc., West Grove, PA) at a dilution of 1:200 for
keratin, antimouse IgGl antibody (PharMingen) at a dilution
of 1:100 for BrdUrd, and antirat IgG antibody (Jackson
ImmunoResearch) at a dilution of 1 :200 for CD3 and Scav-R.
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Table 2 Therapy of experimental liver metastases produced by murine CT-26 colon carcinoma with intensive irinotecan therapy in combinationwith oral JBT 3002 given on different schedules
BALB/c mice were injected in the spleen with 1 X l0’� viable CT-26 cells on day 0. Mice were treated with oral feedings of 5 p.mol MLV-HBSSor MLV-JBT 3002 (1 p.g/dose) for 3 consecutive days beginning 3 days after tumor cell inoculation. Seven days later, groups of mice received 4 dailyi.p. injections of 100 mg/kg irinotecan (CFF-ll). All groups were killed on day 18.
Spleen tumor Liver metastasis
Mean tumor Median, n
Treatment I�BWa (%) Incidence volume (mm3) Incidence (range) Liver weight (g)
5 of 5 44 (7-> 100) 2.4 ± 0.8
lof5c #{216}(�1)b 15�02b
5 of5 21 (3->lOO) 2.2 ± 0.80 of 5 0 (all #{216})d 1 .5 ± O.OY’0 of 5 0 (all #{216})d I .4 ± 0.1”1 of 5 0 (fJ2)b I .4 ± 0. 1d
100, where A is the mean body weight of mice at death
Clinical Cancer Research 2055
Table 1 Therapy of experimental liver metastases produced by murine CT-26 colon carcinoma with irinotecan with or without oral JBT 3002
BALB/c mice were injected in the spleen with 1 X l0� viable CT-26 cells on day 0. Mice were treated with oral feedings of 5 iimol MLV-HBSS
or MLV-JBT 3002 (1 p.g/dose) for 3 consecutive days beginning 3 days after tumor cell inoculation. Seven days later, groups of mice received 4 dailyi.p. injections of irinotecan (CPT-ll). Mice were killed on day 18-20.
Spleen tumor Liver metastasis
Mean tumor Median, n
Treatment ABW� (%) Incidence volume (mm3) Incidence (range) Liver weight (g)
MLV-HBSS 6.6 16 of 16 172 ± 71 16 of 16 50 (5->l0O) 2.8 ± 1.0MLV-HBSS + CPT-ll (50 mg/kg) 3.6 13 of 13 125 ± 37” 9of13 lO(0->lOO) 2.0 ± 0�8b
MLV-HBSS + CPT-l 1 (100 mg/kg) -22.1 15 of 15 48 ± 20” 1 of l5C 0 (#{216}5)b 1.5 ± 0.3”MLV-JBT 3002 8.2 15 of 15 194 ± 68 15 of 15 20 (5->lOO) 2.5 ± I .1MLV-JBT 3002 + CPT-1 1 (100 mg/kg) -6.1 13 of 15 20 ± 8” 1 of 15 0 (0-5)” 1 .4 ± 0. 1d
a I�BW, changes in body weight, calculated by the formula i�BW (%) =(A - B)/B X 100, where A is the mean body weight of mice at death
and B is the mean body weight of mice on day 0.b p < 0.05 as compared with MLV-HBSS.C Six mice died during therapy. They were free of liver metastasis.d p < 0.005 as compared with MLV-HBSS.
MLV-HBSS 4.5 5 of 5MLV-HBSS + CPT-1 1 - 18.3 5 of 5MLV-JBT 3002 (3 days) 8.9 5 of 5MLV-JBT 3002 (3 days) + CPT-1 1 -4.0 5 of 5MLV-JBT 3002 (2 days) + CPT-l 1 -2.2 4 of 5MLV-JBT 3002 (1 day) + CPT-l 1 -3.0 5 of 5
147 ± 6244 ± 18b
185 ± 5819 ± 7d.e
18 ± 12”17 ± 5d.e
a L�BW, changes in body weight, calculated by the formula i�.BW (%) = (A - B)/B X
and B is the mean body weight of mice on day 0.b p < 0.05 as compared with MLV-HBSS.C Two mice died during therapy. They were free of liver metastasis.dp < 0�0O5 as compared with MLV-HBSS.
‘P < 0.05 as compared with MLV-HBSS + CPT-ll.
After three rinses with physiological saline, the sections were
incubated with diaminobenzidine substrate (Research Genet-
ics, Huntsville, AL) for 5 mm. The sections were rinsed with
distilled water and counterstained with Mayer’s hematoxylin.
Apoptotic cells in intestinal tissues were detected by
TUNEL assay exactly as previously described (28). BrdUrd-
and TUNEL-positive cells in the intestines and Scav-R-la-
beled cells in the liver were counted under a light microscope
at X200 (i.e., objective X20 and ocular X 10). The results are
presented as the number of positive cells/0.25 mm2 for Br-
dUrd and TUNEL and the number of positive cells/0.Ol mm2
for Scav-R.
Isolation and Activation of Macrophages. PEMs were
collected by peritoneal lavage of BALB/c mice given an i.p.
injection of 1.5 ml of thioglycollate broth 4 days before being
killed (23). The cells were washed with HBSS, and 1 X i0�
cells that were resuspended in 0. 1 ml serum-free MEM were
plated into 96-well microculture plates. One h later, the
nonadherent cells were removed by washing with medium. At
that time, more than 98% of adherent cell populations were
composed of rnacrophages according to morphological and
phagocytic criteria (20). PEMs were then incubated for 20 h
with medium alone or with medium containing rIFN-y (10
units/ml) plus MLV-JBT 3002 (50 nmollwell).In Vitro Cytotoxiclty Assay. Macrophage-mediated tu-
mor cytotoxicity was assessed by a radioactive release assay
as described previously (20, 29). CT-26 cells in their expo-
nential growth phase were incubated for 24 h in medium
containing 0.2 �.Ci/ml [3H]thymidine (>2500 Ci/mmol; ICN
Biomedicals, Costa Mesa, CA). The cells were washed three
times with HBSS to remove unbound radioisotope, harvested
by a brief trypsinization, and resuspended in medium. The
target cells were plated (1 X iO� cells/well) into wells
containing control or test macrophages to obtain an initial
macrophage:target cell ratio of 10: 1. Radiolabeled target
cells were also plated alone as a negative control for spon-
taneous macrophage activation. Three h later, irinotecan at
different concentrations was added to each well. At 72 h after
Research. on April 28, 2021. © 1998 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Control
4
CpT-11 JBT3002/CPT-11
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2056 Prevention of Mucositis by Oral JBT 3002
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Fig. I Histopathological changes in the ileum of BALB/c mice treated with MLV-HBSS (control), MLV-HBSS plus irinotecan (CPT-l1), or
MLV-JBT 3002 plus irinotecan (JBT 3002JCPT-1 1). BALB/c mice were injected in the spleen with 1 X 10” viable CT-26 cells on day 0. Mice weretreated with oral feedings of 5 p.mol MLV-HBSS or 5 �imol MLV-JBT 3002 containing 1 �xg JBT 3002/dose for 3 consecutive days beginning 3 daysafter tumor cell inoculation. Seven days later, groups of mice received 4 daily i.p. injections of CPT-1l (100 mg/kg). Mice were killed on day 18.Tissue sections from the ileum were analyzed for morphology with H&E staining, epithelial organization with antikeratin antibody, S-phase labeling
with anti-BrdUrd antibody, apoptosis (TUNEL), lymphocytes in the lamina propria by staining with anti-mouse CD3 antibody, and for macrophage
infiltration with antimouse macrophage Scav-R antibody. bar, 50 p.m.
plating, the cultures were washed twice with physiological
saline, and adherent viable cells were lysed with 0. 1 ml of 0.1
N KOH. The lysates were harvested with a Harvester 96
(Tomtec, Orange, CT) and counted in a liquid scintillation
counter. Percentage cytotoxicity was calculated with the fol-
lowing formula: cytotoxicity (%) (A - B)/A X 100, where
A is cpm in cultures of target cells alone (no irinotecan), and
B is cpm in other test cultures.
Research. on April 28, 2021. © 1998 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Control CPT-11 JBT3002/CPT-H
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Fig. 2 Histopathological changes in the colon of BALB/c mice treated with MLV-HBSS (control), MLV-HBSS plus irinotecan (CPT-1 1), orMLV-JBT 3002 plus irinotecan (JBT 3002/CPT-ll), as described in Fig. 1. Tissue sections from the colon were analyzed for morphology with H&Estaining, epithelial organization with anti-keratin antibody, S-phase labeling with anti-BrdUrd antibody, apoptosis (TUNEL), lymphocytes withanti-mouse CD3 antibody, and macrophages with anti-mouse macrophage Scav-R antibody. bar, 50 p.m.
Statistical Analysis. The significance of the in vitro data Results
was analyzed by unpaired Student’s t test. The significance of Therapeutic Effects of Irinotecan Administered Alone.
the in vivo data was analyzed by the Mann-Whitney U test and In the first set of experiments, we determined the dose of
Student’s t test. Ps that were <0.05 were regarded as statisti- irinotecan necessary to inhibit experimental liver metastases.
cally significant. BALB/c mice were given intrasplenic injections of 1 X l0�
Clinical Cancer Research 2057
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Research. on April 28, 2021. © 1998 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
2I
I:I
2058 Prevention of Mucositis by Oral JBT 3002
viable CT-26 cells on day 0. Seven days later, mice were treated
with i.p. injections of 50 or 100 mg/kg irinotecan daily for 4
days. These doses of irinotecan were similar to those given in a
previous study (9). Although these doses were higher than the
maximum tolerated dose identified in clinical studies (125-350
mg/m2; Refs. 1-4), they did not produce immediate death in
mice. As shown in Table 1, treatment with irinotecan at a dose
of 50 mg/kg produced only a modest therapeutic effect, whereas
the administration of 100 mg/kg resulted in significant regres-
sion of splenic tumors and complete inhibition of liver metas-
tasis in 14 of 15 treated mice. However, severe diarrhea and
corresponding loss of body weight were evident in all of the
mice treated with 100 mg/kg irmnotecan, and 6 of 15 treated mice
died within 7 days after the last injection (Table 1).
Therapeutic Effects of Irinotecan Administered after
Three Daily Oral Doses of JBT 3002. Next, BALB/c mice
were given intrasplenic injections of 1 X l0� viable CT-26 cells.
Three days later, the mice were given JBT 3002 by mouth.
Because we have found previously (23) that JBT 3002 is sig-
mficantly more potent than MTP-PE for activation of macro-
phages, we used a dose of 1 p.g JBT 3002 contained in 5 p�mol
MLV. After three consecutive daily doses ofJBT 3002, the mice
were given i.p. injections of 100 mg/kg irmnotecan once daily for
4 consecutive days. As shown in Table 1, all of the mice treated
with this combination survived the high dose of irmnotecan, and
this dose significantly suppressed both primary spleen tumorsand liver metastases (P < 0.005). No discernible differences in
the incidence or median number of hepatic metastases were
found between control mice or those receiving only oral JBT
3002.
Effects of Intensive Irinotecan Therapy Administered
after JBT 3002 Given on Different Schedules. In the next
set of experiments, we evaluated the effect of varying the
schedule of JBT 3002 administration. Mice were given i.p.
injections of 1 x iO’� viable CT-26 cells on day 0. Groups of
five mice were given one, two, or three daily doses of 5 pmol
MLV-HBSS or 1 p.g JBT 3002 in 5 p.mol MLV by mouth
starting 3 days after tumor cell inoculation. Seven days after
tumor cell injection, some mice were given four daily i.p.
injections of 100 mg/kg irmnotecan. The mice were euthanized
and necropsied when the control group became moribund (on
day 18 after tumor cell injection). The results of this second set
of experiments are shown in Table 2. The size of the primary
spleen tumors and the incidence and median number of exper-
imental liver metastases were significantly reduced in the mice
treated with irinotecan (P < 0.05). However, mice that were
treated with irinotecan alone again had severe diarrhea associ-
ated with intestinal bleeding. Two of five mice died within 7
days after the last treatment, and three of five mice became
moribund by day 18 of the study. Upon necropsy, we found that
the small intestines of all mice in this group were shortened andhad thickened walls. Notably, oral administration of JBT 3002
before i.p. irinotecan intensified the antitumor effects of irino-
tecan (P < 0.005). Moreover, this combination therapy was not
associated with significant loss in body weight, and none of the
mice in this group died.
Tissues from the small and large intestines of all mice were
harvested and processed for histopathological analysis. H&E
staining revealed severe morphological changes in the ileum
I
I
Fig. 3 Quantitation of S-phase labeling of cells in intestinal crypts (A)
and apoptosis of differentiated epithelial cells (B) in the ileum and colonof BALB/c mice that were treated as described in Fig. 1. S-phase
labeling and apoptosis indices were obtained by counting the number of
BrdUrd-positive (A) and TUNEL-positive (B) cells/high-power fieldunder a light microscope at X 200. Each bar represents the mean ± SD
in five different areas. *, P < 0.05; **, P < 0.005 as compared with
control mice receiving MLV-HBSS.
(Fig. 1) and colon (Fig. 2) of mice injected with 100 mg/kg
irinotecan. Loss of viffi, epitheial vacuolation, and inflamma-
tory cell infiltrates were found in the ileum; and hyperplasia,
regeneration of glandular tubules, and scattered crypt abscesses
were found in the colon. In contrast, in mice treated with JBT
3002 before irmnotecan, the architecture of the ileum remained
ordered (Fig. 1), and the colonic mucosa exhibited only mildgoblet-cell hyperplasia (Fig. 2).
Epitheial cell organization and the presence of proliferat-
ing and apoptotic cells in the intestinal mucosa were determined
by immunohistochemical staining for keratin (30), S-phase la-
beling with anti-BrdUrd antibody (26), and TUNEL (28), re-
spectively (Fig. 1 and 2). This analysis revealed loss of tissue
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Clinical Cancer Research 2059
Table 3 Therapy of experimental liver metastases produced by murine CT-26 colon carcinoma with once weekly irinotecan injections in
combination with oral JBT 3002 given on different schedules
BALB/c mice were injected in the spleen with 1 X 10” viable CT-26 cells on day 0. Groups of mice were treated with oral feedings of 5 p.molMLV-HBSS or MLV-JBT 3002 (1 p.g/dose) once, twice, or thrice weekly for 3 weeks beginning 3 days after tumor cell inoculation. Some micereceived an i.p. injection of 100 mg/kg irinotecan (CPT-ll) once a week (on days 7, 14, and 21). All groups were killed on day 24.
Spleen tumor Liver metastasis
Mean tumor
Treatment I�BWa (%) Incidence volume (mm3) Incidence Median, n (range) Liver weight (g)
MLV-HBSS 6.5 5 of 5 498 ± 249 5 of 5 >100 (74-> 100) 3.5 ± 1.5MLV-HBSS + CPT-l 1 -0.1 5 of 5 131 ± 79” 5 of 5 32 (3�>l00)” 1.8 ± 0.4”MLV-JBT 3002 (3/wk) 9.6 5 of 5 580 ± 153 5 of 5 >100 (26->lOO) 3.4 ± 0.9
MLV-JBT 3002 (3/wk) + CPT-l 1 3.8 4 of 5 67 ± 53C 4 of 5 6 (fJ21)C.d I .6 ± 01c.d
MLV-JBT 3002 (2/wk) + CPT-l 1 3.6 5 of 5 69 ± 66” 5 of 5 3 (515)C.d 1.6 ± 0. 1c.d
MLV-JBT 3002 (l/wk) + CPT-l 1 0.9 5 of 5 73 ± 57” 4 of 5 4 (0-> 100)” 1.8 ± 0.4”
a �BW, changes in body weight, calculated by the formula, �.BW (%) = (A - B)/B X 100, where A is the mean body weight of mice at death
and B is the mean body weight of mice on day 0.b p .< 0.05 as compared with MLV-HBSS.C p .< 0.005 as compared with MLV-HBSS.d p < 0.05 as compared with MLV-HBSS + CPT-1 1.
stability that was associated with a nearly two-thirds reduction
in the number of dividing cells in the crypts and a nearly 8-fold
increase in the number of apoptotic cells along the mucosal
surface (Fig. 3). These toxic effects were greatly diminished
when mice were given one, two, or three oral doses of JBT 3002
before irmnotecan.
We also characterized the presence of leukocytes within
the lamina propria (Fig. 1 and 2). In control mice, the lamina
propria was occupied by both lymphocytes and macrophages as
determined by labeling with CD3 and Scav-R, respectively. In
contrast, in mice that received repeated i.p. injections of 100
mg/kg irinotecan, the structure of the lamina propria was thor-
oughly destroyed, and the population of CD3-positive cells was
markedly decreased, whereas a large infiltrate of Scav-R-posi-
tive cells (macrophages) was observed. In mice that received
oral JET 3002 before irinotecan, the populations of these im-
mune cells were normal (Fig. 1 and 2).
Effects of Once-Weekly Irinotecan Therapy Adminis-
tered after JBT 3002 Given on Different Schedules. Since
the intensive schedule of chemotherapy in the second set of
experiments was too toxic to allow full evaluation of the effi-
cacy of the combination therapy, we conducted a third set of
experiments, in which we administered irinotecan on a pro-
tracted schedule of once a week for 3 weeks, similar to the
schedule used to treat colon cancer in humans (2, 4). In these
experiments, mice were given intrasplenic injections of 1 X iO�
viable CT-26 cells. Three days later, groups of mice (n 5)
were given oral MLV-HBSS (control), or 1 p.g JBT 3002 in 5
p�mol phospholipid daily for 1, 2, or 3 days. On day 7 after
tumor cell injection, some mice were given a single i.p. injection
of 100 mg/kg irinotecan. This treatment schedule was repeated
weekly for 3 weeks. The mice were killed and necropsied when
the control group became moribund (day 24 after tumor cell
injection). As shown in Table 3, once-per-week administration
of irinotecan produced a significant reduction in the size of
spleen tumors (P < 0.05) and the extent of liver metastases (P <
0.005), albeit to a lesser degree than found for the schedule of
four daily injections of irinotecan. The combination of oral
JBT-3002 and i.p. irinotecan produced a further reduction in the
number of liver metastases (-4-fold) as compared with irino-
tecan alone (P < 0.005).
Macrophage Infiltration into Hepatic Metastases. Us-ing immunohistochemical methods, we looked for changes in
rnacrophage infiltration within the CT-26 experimental liver
rnetastases. Our findings are shown in Fig. 4. In control mice,
the majority of the cells that stained with the macrophage
marker Scav-R were found on the periphery of the lesions; only
a few infiltrated the metastases (mean, 11 ± 2 cells/0.Ol mm2).
In contrast, in mice treated with irmnotecan, there was an intense
infiltration of macrophages into the liver tumor nodules. The
number of Scav-R-positive cells was 33 ± 4 cells/0.Ol mm2, a
significant increase compared with the number in control mice
(P < 0.001). In mice given JBT 3002 without innotecan, the
number of Scav-R-positive cells within metastases was not
increased (mean, 14 ± 6 cells/0.Ol mm2). However, mice
treated with JBT 3002 before irmnotecan had a dense inflamma-
tory infiltrate (mean, 67 ± 10 cells/0.Ol mm2) that actually
obscured recognition of viable tumor cells. The immunohisto-
chemical analyses of macrophage infiltration correlated with the
macroscopic findings described in Table 3.
Mechanism of Effect of Combination Therapy with
JBT 3002 and Irinotecan. We next examined a possible
mechanism to explain the effects of the combination therapy
against liver metastases. To rule out direct antiproliferative
effects, we incubated CT-26 cells for 4 days with different
concentrations of MLV-JBT 3002 (0-100 nmol/38-mm2 well; 1
mg JBT 3002/300 p.mol phospholipids) with or without differ-
ent concentrations of irinotecan. Four days later, the number of
viable tumor cells was determined. MLV-JBT 3002 did not alter
the direct antiproliferative effects of irinotecan (IC50, -8 p.g/ml;
data not shown).
We then examined whether the activation of macrophages
by MLV-JBT 3002 (23, 24) could contribute to the lysis of
tumor cells by irinotecan. Results of a representative experiment
are shown in Fig. 5. The peritoneal macrophages incubated with
medium (control) were not cytotoxic against CT-26 cells. The
Research. on April 28, 2021. © 1998 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
H&E Scav.R
S5 , ‘� ,, S
‘.P�
� ‘. � S � : -
‘I � ‘ ‘,t :�‘� ) ‘�#{149}‘3
.S._ � S�#{149}� � �S � � .,l� �S � � � � S � � �
S #{149}‘ #{149}� � r :�
,�. ‘ �, � S�
&4 �
� ,S. � #{149} �
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: #{149}
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.., “-.5--p.
Fig. 4 Macrophage infiltration into
CT-26 hepatic metastases. BALB/c micewere injected intrasplenicly with viable1 X 10’ viable CT-26 cells on day 0. Themice were treated with repeated oralfeedings of 5 p.mol MLV-HBSS or 5p.mol MLV containing I p.g JBT 3002/dose three times/week for 3 weeks begin-fling 3 days after tumor cell inoculation.Some mice received i.p. injections of 100mg/kg CPT-l 1 once a week (on days 7,14, and 21). All mice were killed on day24 and necropsied. Liver sections were
fixed in 10% buffered formalin for H&Estaining or in liquid nitrogen for immu-nohistochemical staining with antimousemacrophage Scav-R antibody. bar, 50
p.m.
.i� ‘ 5.,
2060 Prevention of Mucositis by Oral JBT 3002
. S � � :�.� , � . #{149} ‘�‘.
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p. �
exposure of tumor cells to 7 p.g/ml and 10 p�g/ml of innotecan
resulted in 24.5% and 33.5% cytotoxicity, respectively. The
incubation of C1’-26 target cells with macrophages activated
with MLV-JBT 3002 plus rIFN-y resulted in 50% cytotoxicity
(P < 0.05), which increased to 65% (P < 0.005) in the presence
of 10 p.g/ml irinotecan.
Discussion
The present study demonstrates that oral administration of
JBT 3002, a new synthetic lipopeptide and macrophage activa-
tor (23, 24) overcomes irinotecan-induced damage to intestinal
epithelium and enhances the therapeutic efficacy of innotecan
against liver metastases of CT-26 murine colon carcinoma.
Significant inhibition of liver metastases of murine colon cancer
required repeated daily injections of 100 mg/kg innotecan
(CPT-l 1). Unfortunately, at this dose, all of the mice developed
severe intestinal damage, and many died within 1 week after the
fourth (final) i.p. injection. Treatment with 50 mg/kg of inno-
tecan was less toxic but also less effective. These data suggest
that to have a significant therapeutic effect, irinotecan must be
given at a relatively high dose that is likely to produce damage
to the intestines. Oral administration of JBT 3002 before info-
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Clinical Cancer Research 2061
0
0
00
0 4 7 10 0 4 7 10 0 4 7 10
CPT-11 (p.g/mI)
Fig. 5 Increase of CPT-l 1-induced cytotoxicity against CT-26 cells byincubation with JBT 3002-activated PEM. PEM were incubated with
medium alone or with medium containing rIFN--y (10 units/mI) plusMLV-JBT 3002 (50 nmol/well). Twenty-four h later, the cultures werewashed and [3H]thymidine-labeled CT-26 cells were plated into thewells. Radiolabeled target cells were also plated alone as an additionalcontrol. Three h later, CPT- I 1 was added at the indicated concentra-
tions. Cytotoxicity was determined after 72 h of cocultivation. Thevalues are the mean ± SD of triplicate cultures. *, P < 0.05: **, P <
0.005 compared with cytolysis produced in the absence of CPT-l 1. �,P < 0.0001 as compared with the cytolysis in cultures of target cellscultured with the respective concentrations of CPT- 1 1 . This is onerepresentative experiment of three.
tecan (100 mg/kg) prevented severe side effects and allowed the
use of high-dose ininotecan, which produced superior therapeu-
tic results.
The development of severe diarrhea limits the clinical use
of irinotecan (1, 2, 4). Topoisomerase I inhibitors such as
ininotecan are highly S-phase specific; therefore, diarrhea may
result from the direct toxic effects of innotecan against dividing
epithelial cells in the crypt of the intestines (6, 3 1 ) as well as
from induction of apoptosis in the differentiated epithelium (9).
Immunohistochemical analyses of the intestines showed a 3-fold
decrease of S-phase labeling with BrdUrd and a 10-fold increase
in the number of TUNEL-positive cells in mice given 100
mg/kg ininotecan daily for 4 days. In contrast, in mice that
received repeated oral doses of the synthetic lipopeptide JBT
3002 before treatment with innotecan, there was increased cell
division in the crypts and a lower rate of cell death in the villi;
and these were associated with a normalized epithelial organi-
zation. These findings indicate that JBT 3002 probably prevents
chemotherapy-induced injury to the intestinal mucosa by ele-
vating epithelial stem cell proliferation and reducing the mci-
dence of apoptosis.
The present results confirm the findings that in mice,
ininotecan-induced gastrointestinal toxicity was associated with
structural changes in intestinal architecture resulting from dis-
ordered epithelial cell differentiation and apoptosis (9). Whether
this pathology is also responsible for secretory diarrhea in
humans is unclear.
Recent studies have demonstrated that a variety of growth
factors and cytokines, produced both by the epithelium itself and
by leukocytes within the lamina propria, may regulate the pro-
liferation of intestinal epithelial cells ( 1 1 , 1 2). These include
members of the epithelial growth factor/transforming growth
factor and the fibroblast growth factor families (1 1 ) as well as
keratinocyte growth factor (32) and IL-l, IL-2, IL-4, IL- 15, and
IFN-�y (1 1). For example, IL-15, produced by activated macro-
phages (33), can up-regulate the expression of transforming
growth factor-�3, which in turn can stimulate epithelial cell
migration and thereby promote recovery of epithelial integrity
after wounding (34). JBT 3002 is a potent activator of macro-
phages (23, 24), and its oral administration can activate tissue
macrophages to generate numerous cytokines that affect prolif-
eration and turnover of intestinal epithelial cells (19, 22, 23). We
are currently attempting to identify these specific cytokines.
Mucosal infections due to translocation of aerobic bacteria
may be another mechanism responsible for chemotherapy-
induced diarrhea (10). Studies from several laboratories have
suggested that macrophage-derived cytokines are of particular
importance for the preservation of mucosal immunity through
activation of lymphocytes within the lamina propria. Cytokines
may regulate mucosal immunity; these include: (a) IL-6, a
differentiation factor for B cells that can induce production of
secretory IgA, which protects the mucosal surface area from
pathogens ( 13, 14); (b) IL-15, a regulator of proliferation and
differentiation ofT cells (15) and B cells (16); and (c) IL-18, an
IFN-�y-inducing factor (17). Our results show that changes in
intestinal immune cell populations produced by treatment with
innotecan are characterized by the loss of lymphocytes and a
diffuse infiltration of macrophages in response to mucosal in-
flammation. Combination therapy with JBT 3002 and irinote-
can, however, preserved the cellular composition within the
lamina propna. JBT 3002 has been shown to induce production
of macrophage-denived cytokines including IL-l and IL-6 (24);
and, therefore, systemic administration of JBT 3002 may enable
intestinal macrophages to release cytokines that activate the
lymphocytes within the lamina propria, which would result in
the preservation of mucosal immunity during chemotherapy.
It is well established that systemic treatment of mice with
liposomes that contain immunomodulators activates macro-
phages to a tumoricidal state and can cause eradication of lymph
node, lung, and liver metastases (22). However, the efficacy of
this form of immunotherapy is limited to minimal tumor burden
associated with micrometastases or residual tumor after conven-
tional therapy (35-37). The results presented here demonstrate
the efficacy of combining chemotherapy with biological ther-
apy. Although treatment of mice with irinotecan once a week
did result in a significant reduction of liver metastasis, the
addition of orally administered JBT 3002 led to superior ther-
apeutic results, most likely because of the tumoricidal properties
of inflammatory macrophages. Blood monocytes migrate to
areas of inflammation (38), and the induction of inflammatory
changes by local thoracic irradiation has been shown to produce
significant regression of experimental fibrosarcoma pulmonary
metastases in mice treated with systemic injections of liposomes
containing macrophage activators (2 1 ). Inflammation and ne-
crotic tissues (39) were observed in the mice treated with
ininotecan. Notably, combination therapy with JBT 3002 and
innotecan (but not JBT 3002 alone) led to enhanced infiltration
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2062 Prevention of Mucositis by Oral JBT 3002
of macrophages within the liver metastases, suggesting that
inflammatory changes due to irinotecan treatment are chemo-
tactic to activated macrophages. The enhanced antitumor effects
observed in mice that were given both irinotecan and JBT 3002
may also have been due to the increased sensitivity of target
CT-26 tumor cells to the toxic effects of irinotecan in the
presence of activated macrophages. In vitro treatment of human
ovarian cancer cells with irinotecan plus IL-la (40) has been
shown to produce additive cytotoxicity, and macrophages that
are incubated with �T 3002 release IL-la (24). Whether IL-la
and irinotecan produce additive antitumor effects against CT-26
cells is currently being investigated.
CPT-ll is metabolized to SN-38 in mouse serum (41) and
liver (42) by the enzyme carboxylesterase (42). One distinct
possibility for the enhanced effects of CPT-l 1 in mice that
receive oral JBT-3002 may be the increased carboxylesterase
activity in macrophages. This possibility is presently under
investigation.
In summary, we have demonstrated the ability of orally
administered JBT 3002: (a) to prevent irinotecan-induced dose-
limiting gastrointestinal toxicity; (b) to maintain lymphocyte
and monocyte populations within the lamina propria, a prereq-
uisite for intact mucosal immunity; and (c) to induce potent
tumoricidal properties in tissue macrophages, resulting in an
enhanced therapeutic effect of irmnotecan. The pleiotropic effects
of immunomodulation by oral JBT 3002 against experimental
liver metastases described here, together with our previous
observations that the monocytopenia and intestinal damage
caused by doxorubicin or X-irradiation can be prevented by
immunomodulation with MTP-PE (19), recommend the clinical
use of orally administered JBT 3002 combined with irmnotecan
for the treatment of advanced colon cancer.
Acknowledgments
We thank Stephanie Deming for critical editorial comments and
Lola Ldpez for expert assistance in the preparation of this manuscript.
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1998;4:2053-2063. Clin Cancer Res H Shinohara, J J Killion, H Kuniyasu, et al. 3002.liver metastases by oral administration of the lipopeptide JBTirinotecan's therapeutic efficacy against murine colon cancer Prevention of intestinal toxic effects and intensification of
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