Download Screening of Champions Predictive TumorGraft Platform Guides the

Screening of Champions Predictive TumorGraft Platform Guides the Clinical Development
of the Selective Dual BRAF-EGFR Inhibitor CEP-32496
Bruce Ruggeri2, Elizabeth Bruckheimer1, Brandy Wilkinson1, Bruce Dorsey2, Steve Trusko2, Jay Friedman1
Champions Oncology, Inc.1, Teva Pharmaceuticals Inc. (Oncology Discovery Research, Discovery& Product Development, Global R&D) 2
A)
Abstract
B)
C)
Mutations in the BRAF gene have been identified in approximately 7% of cancers, including 60-70% of melanomas and 4–16%
colorectal cancers. CEP-32496 (Teva Pharmaceuticals) is an orally active dual inhibitor of wild type and V600E-mutant BRAF kinase
and EGFR, as well as other oncogenic protein kinases, including BCR/ABL and RET. Champions Oncology has developed a predictive
platform that utilizes the implantation of patient derived xenografts (PDX) in immune-deficient mice that preserves the biological
properties of the original human tumor and provides an accelerated and focused translational path into clinical trials. A screening
study using a panel of Champions TumorGraft® models of human colorectal cancer and melanoma possessing either the BRAF
mutant or BRAF wild type genotype was conducted to compare the therapeutic activity of CEP-32496 versus a clinically approved
BRAF inhibitor, vemurafenib, as well as two standard of care agents (irinotecan or temozolomide). This screening study
demonstrated an overall comparable or superior response (p<0.05) of CEP-32496 compared to vemurafenib in 13 out of 15
tumorgraft models of melanoma. Notably, CEP-32496 displayed robust therapeutic activity (p<0.05) over vemurafenib in 7
tumorgraft models of BRAF-mutated colorectal cancer. Given these initial results in colorectal cancer, we further explored the antitumor activity of CEP-32496 and several standard of care agents for colorectal cancer (irinotecan, oxaliplatin, 5-FU, and cetuximab)
given as monotherapy or in combination in two tumorgraft models of BRAF-mutated colorectal cancer. In both colorectal tumorgraft
models, the combinations of sub-optimal oral doses of CEP-32496 and optimal doses of each standard of care agent achieved
significantly improved anti-tumor activity (p<0.05) relative to standard of care agents and in many cases vehicle-treated animals.
The combination treatment regimens were generally well tolerated exhibiting no body weight loss or mortality. Based on this
dataset, CEP-32496 is currently in clinical trials in cancer patients.
D)
E)
Methods
In Vivo Studies
Female immunocompromised nu/nu (Harlan) mice between 4-6 weeks of age were implanted unilaterally on the right flank
with 5x5 mm tumor fragments. When tumors reached approximately 150-250 mm3, animals were matched by tumor volume
into treatment and control groups, and dosing initiated. Animal care and efficacy studies were performed under Champions
Oncology’s approved Animal Care and Use protocol (CHA-003-2013). Treatment groups were given one of the following
regimens for the screening study involving Champions TumorGrafts® models of melanoma and colorectal cancer (CRC): CEP32496 (Teva Pharmaceuticals; 35 mg/kg, p.o., bid), vemurafenib (Teva Pharmaceuticals; 35 mg/kg, p.o., bid), irinotecan (Teva
Pharmaceuticals; 100 mg/kg, i.v., q7dx3), or temozolomide (Merck; 100 mg/kg, p.o., qdx5). TumorGraft models of colorectal
cancer and melanoma were administered irinotecan and temozolomide, respectively. Combination studies involving
Champions TumorGraft® models of colorectal cancer, CTG-0064 and CTG-0360, were given one of following as a single agent
or in combination: CEP-32496 (Teva Pharmaceuticals; 17.5 or 35 mg/kg, p.o., bid), irinotecan (Selleckchem; 100 mg/kg, i.v.,
q7dx3), oxaliplatin (LC labs; 6 mg/kg, i.v., q4dx3), 5-FU (Sigma; 15 mg/kg, i.v., qdx5), and cetuximab (Selleckchem; 10 mg/kg,
i.p., 2qwx4). Tumor dimensions were measured twice weekly by digital caliper and tumor volume was calculated using the
formula: TV= width2 x length x 0.52. Treatment response at study completion for the screening study was calculated as T/C
(%) = (Tf-Ti/Cf-Ci) x100.
Data Analysis
Statistical differences in tumor volume were determined using a two-tailed One-Way Analysis of Variance (ANOVA) followed
by the Dunnett’s multiple comparisons test comparing treated groups with control and appropriate comparisons amongst
treated groups.
Figure 4A-E: Effect of CEP-32496, irinotecan, oxaliplatin, 5-FU, and cetuximab as single agents or in combination on
tumor growth in a Champions TumorGraftTM model of BRaf mutated colorectal cancer (CTG-0064).
Figure 1: Bar graph demonstrating varying treatment responses in a panel of Champions’ TumorGraftTM models of melanoma and
colorectal cancer that were administered CEP-32496 (35 mg/kg, p.o., bid), vemurafenib (35 mg/kg, p.o., bid), or relevant standard
of care agent (irinotecan [100 mg/kg, i.p., q7dx3]; temozolomide [100 mg/kg, p.o., qdx5]).
Results
Model Name
Tumor Type Mutational Status (B-raf)
Age
Gender
Ethnicity
CTG-0064
Colorectal
G469E
47
M
Caucasian
CTG-0074
Colorectal
V600E
70
M
Unknown
CTG-0678
Colorectal
D594G
64
M
Caucasian
CTG-0000
Colorectal
V600E
Unknown
Unknown
Unknown
CTG-0068
Colorectal
WT
55
M
Caucasian
CTG-0089
Colorectal
WT
63
M
Asian
CTG-0360
Colorectal
V600E
78
F
Caucasian
CTG-0883
Melanoma
V600E
66
M
Caucasian
CTG-0882
Melanoma
V600R
64
F
Caucasian
CTG-0884
Melanoma
V600R
75
F
Caucasian
CTG-0202
Melanoma
V600E
40
M
Unknown
CTG-0203
Melanoma
WT
56
M
Unknown
CTG-0204
Melanoma
WT
76
M
Caucasian
CTG-0435
Melanoma
CTG-0500
•
Conclusions
Superior anti-tumor efficacy of CEP-32496 versus vemurafenib against 15 of 24 primary melanoma and CRC
tumorgrafts, comparable efficacy in 7 of 24 tumorgraft models, and inferior activity in 2/24 melanoma models.
•
CEP-32496 demonstrates significant in vivo anti-tumor efficacy against tumorgrafts harboring a variety of BRaf
activating mutations, not simply V600E/K.
•
Clear superiority of CEP-32496 demonstrated in 7/7 Braf mutated colon carcinoma tumorgrafts relative to both
vemurafenib and dabrafenib.
•
Combinations of sub-optimal oral doses of CEP-32496 and optimal doses of each standard of care agent for colorectal
cancer achieved significantly improved anti-tumor activity (p<0.05) relative to standard of care agents and were well
tolerated.
•
PDX models are valuable tools for drug development and biomarker discovery, and provided an accelerated and
focused path for CEP-32496 into clinical trials in BRaf mutated colorectal cancer.
Future directions
•
Characterize the molecular effects of CEP-32496 on various signaling pathways known to play a role in resistance
in BRaf mutated melanoma and CRC and ascertain potential combination strategies that could be used in the
clinic.
References
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V600M
53
M
Caucasian
Melanoma
V600E
39
M
Caucasian
CTG-0210
Melanoma
V600E
63
Male
Unknown
CTG-0205
Melanoma
V600E, K601E
46
Male
Hispanic
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CTG-0206
Melanoma
Female
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V600E
40
V600E
98
CTG-0207
Melanoma
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CTG-0208
Melanoma
V600E
65
Male
Caucasian
CTG-0209
Melanoma
L584F
79
Female
Unknown
CTG-0608
Melanoma
V600K
Unknown
Table 1: Characteristics of Champions TumorGraft models of Colorectal Cancer and Melanoma.
Unknown
Unknown
Figure 2: Bar graph demonstrating varying treatment responses in a panel of Champions’ TumorGraftTM models of melanoma that
were administered CEP-32496 (35 mg/kg, p.o., bid) or vemurafenib (35 mg/kg, p.o., bid). Models were segregated based upon
mutational status of BRAF (mutant versus wild type).
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NCT01877811. Available from: https://clinicaltrials.gov/ct2/show/NCT01877811?term=cep-32496&rank=1. Sponsored by: Teva Pharmaceutical Industries.