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Clinical Trial
. 2024 Jun;23(2):118-127.e6.
doi: 10.1016/j.clcc.2024.03.001. Epub 2024 Apr 1.

Pembrolizumab Plus mFOLFOX7 or FOLFIRI for Microsatellite Stable/Mismatch Repair-Proficient Metastatic Colorectal Cancer: KEYNOTE-651 Cohorts B and D

Richard Kim  1 , Mustapha Tehfe  2 , Petr Kavan  3 , Jorge Chaves  4 , Jeremy S Kortmansky  5 , Eric X Chen  6 , Christopher H Lieu  7 , Lucas Wong  8 , Marwan Fakih  9 , Kristen Spencer  10 , Qing Zhao  11 , Raluca Predoiu  11 , Chenxiang Li  11 , Pierre Leconte  12 , David Adelberg  13 , E Gabriela Chiorean  14
Affiliations
Clinical Trial

Pembrolizumab Plus mFOLFOX7 or FOLFIRI for Microsatellite Stable/Mismatch Repair-Proficient Metastatic Colorectal Cancer: KEYNOTE-651 Cohorts B and D

Richard Kim et al. Clin Colorectal Cancer. 2024 Jun.

Abstract

Background: The phase 1b KEYNOTE-651 study evaluated pembrolizumab plus chemotherapy in microsatellite stable or mismatch repair-proficient metastatic colorectal cancer.

Patients and methods: Patients with microsatellite stable or mismatch repair-proficient metastatic colorectal cancer received pembrolizumab 200 mg every 3 weeks plus 5-fluorouracil, leucovorin, oxaliplatin (previously untreated; cohort B) or 5-fluorouracil, leucovorin, irinotecan (previously treated with fluoropyrimidine plus oxaliplatin; cohort D) every 2 weeks. Primary end point was safety; investigator-assessed objective response rate per RECIST v1.1 was secondary and biomarker analysis was exploratory.

Results: Thirty-one patients were enrolled in cohort B and 32 in cohort D; median follow-up was 30.2 and 33.5 months, respectively. One dose-limiting toxicity (grade 3 small intestine obstruction) occurred in cohort D. In cohort B, grade 3 or 4 treatment-related adverse events (AEs) occurred in 18 patients (58%), most commonly neutropenia and decreased neutrophil count (n = 5 each). In cohort D, grade 3 or 4 treatment-related AEs occurred in 17 patients (53%), most commonly neutropenia (n = 7). No grade 5 treatment-related AEs occurred. Objective response rate was 61% in cohort B (KRAS wildtype: 71%; KRAS mutant: 53%) and 25% in cohort D (KRAS wildtype: 47%; KRAS mutant: 6%). In both cohorts, PD-L1 combined positive score and T-cell-inflamed gene expression profiles were higher and HER2 expression was lower in responders than nonresponders. No association between tumor mutational burden and response was observed.

Conclusion: Pembrolizumab plus 5-fluorouracil, leucovorin, oxaliplatin/5-fluorouracil, leucovorin, irinotecan demonstrated an acceptable AE profile. Efficacy data appeared comparable with current standard of care (including by KRAS mutation status). Biomarker analyses were hypothesis-generating, warranting further exploration.

Gov identifier: ClinicalTrials.gov; NCT03374254.

Keywords: CRC; Chemotherapy; Microsatellite stable; Mismatch repair-proficient; Pembrolizumab.

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Conflict of interest statement

Disclosure R. Kim reports honoraria from Taiho; advisory/consultancy roles with Bayer Servier, Ipsen, and Roche; and speakers bureau for Eisai, Pfizer, and Incyte. M. Tehfe reports advisory/consultancy roles with Merck & Co., Inc., Rahway, NJ, USA, BMS, Taiho, and Pfizer; and speakers bureau for BMS and Taiho. P. Kavan reports advisory/consultancy role with Merck; expert testimony for Merck & Co., Inc., Rahway, NJ, USA; and an institutional educational grant to their institution. J. S. Kortmansky reports research funding to their institution from Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA, and Genentech. E. X. Chen reports advisory/consultancy roles from AstraZeneca, Eisai, and GSK and research funding to their institution from AstraZeneca, Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA, BMS, Novartis, Roche, Zymeworks, and 1Globe. C. H. Lieu reports advisory/consultancy roles with Natera; and research funding to their institution from Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA. M. Fakih reports advisory/consultancy roles with AstraZeneca, Bayer, Bristol Myers Squibb, GlaxoSmithKline, Incyte, Mirati, Nouscom, PsiOxus, Roche/Genentech, and Taiho. K. Spencer reports advisory/consultancy roles with QED Therapeutics, Helsinn, Lynx Group, and Caris. Q. Zhao reports stock ownership at Merck & Co., Inc., Rahway, NJ, USA. R. Predoiu, C. Li, P. Leconte, and D. Adelberg report employment with Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA. P. Leconte and D. Adelberg report stock ownership at Merck & Co., Inc., Rahway, NJ, USA. E. G. Chiorean reports advisory/consultancy roles with Astellas, Bayer, Cardiff, Foundation, G1 Therapeutics, Ipsen, Noxxon, Novartis, Merck & Co., Inc., Rahway, NJ, USA, Pfizer, and Stemline; research funding to their institution from Aadi, Biosplice, BioMed Valley, Boehringer Ingelheim, Clovis, Corcept, Erasca, Fibrogen, Lona, Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA, Novartis, Rafael, and Stemline; and travel/accommodations from G1 Therapeutics. J. Chaves and L. Wong report no conflicts of interest.

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