Pembrolizumab Plus Binimetinib With or Without Chemotherapy for MSS/pMMR Metastatic Colorectal Cancer: Outcomes From KEYNOTE-651 Cohorts A, C, and E.

BACKGROUND

Cohorts A, C, and E of the phase Ib KEYNOTE-651 study evaluated pembrolizumab + binimetinib ± chemotherapy in microsatellite stable/mismatch repair-proficient metastatic colorectal cancer.

PATIENTS AND METHODS

Patients received pembrolizumab 200 mg every 3 weeks plus binimetinib 30 mg twice daily alone (cohort A; previously treated with any chemotherapy) or with 5-fluorouracil, leucovorin, oxaliplatin (cohort C; previously untreated) or 5-fluorouracil, leucovorin, irinotecan (cohort E; previously treated with 1 line of therapy including fluoropyrimidine + oxaliplatin-based regimen) every 2 weeks. Binimetinib dose-escalation to 45 mg twice daily was planned in all cohorts using a modified toxicity probability interval design (target dose-limiting toxicity [DLT], 30%). The primary endpoint was safety; investigator-assessed objective response rate was secondary.

RESULTS

In cohort A, 1/6 patients (17%) had DLTs with binimetinib 30 mg; none occurred in 14 patients with 45 mg. In cohort C, 3/9 patients (33%) had DLTs with binimetinib 30 mg; dose was not escalated to 45 mg. In cohort E, 1/5 patients (20%) had DLTs with binimetinib 30 mg; 5/10 patients (50%) had DLTs with 45 mg. Enrollment was stopped in cohort E binimetinib 45 mg and deescalated to 30 mg; 2/4 additional patients (50%) had DLTs with binimetinib 30 mg (total 3/9 [33%] had DLTs with binimetinib 30 mg). Objective response rate was 0% in cohort A, 9% in cohort C, and 15% in cohort E.

CONCLUSION

Per DLT criteria, binimetinib + pembrolizumab (cohort A) was tolerable, binimetinib + pembrolizumab + 5-fluorouracil, leucovorin, oxaliplatin (cohort C) did not qualify for binimetinib dose escalation to 45 mg, and binimetinib + pembrolizumab + 5-fluorouracil, leucovorin, irinotecan (cohort E) required binimetinib dose reduction from 45 to 30 mg. No new safety findings were observed across cohorts. There was no apparent additive efficacy when binimetinib + pembrolizumab was added to chemotherapy. Data did not support continued enrollment in cohorts C and E.

Informations de copyright

Copyright © 2024. Published by Elsevier Inc.

Déclaration de conflit d'intérêts

Disclosure E. X. Chen reports advisory/consultancy roles from AstraZeneca, Eisai, and GSK; research funding to their institution from AstraZeneca, Merck & Co., Inc., Rahway, NJ, USA, BMS, Novartis, Roche, Zymeworks, and 1Globe. 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. M. Tehfe reports advisory/consultancy roles with Merck & Co., Inc., Rahway, NJ, USA, BMS, Taiho, and Pfizer; and speaker bureau for BMS and Taiho. J. S. Kortmansky reports research funding to their institution from Merck & Co., Inc., Rahway, NJ, USA and Genentech. M. B. Sawyer reports honoraria from Ipsen, BMS, Mylan, Amgen, AstraZeneca, Eisai, Sandoz, Celgene, Servier, Novartis, Leo, Taiho, and Shire; advisory/consultancy roles with AstraZeneca, Leo, and Immuneering; expert testimony for AstraZeneca; research funding to their institution from AstraZeneca and BMS; and travel/accommodation expenses from Ipsen. 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 & Co., Inc., Rahway, NJ, USA, Novartis, Rafael, and Stemline; and travel/accommodation from G1 Therapeutics. C. H. Lieu reports research funding to their institution from 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 from QED Therapeutics, Helsinn, Lynx Group, and Caris. C. Li, P. Leconte, and D. Adelberg report employment with Merck & Co., Inc., Rahway, NJ, USA; P. Leconte and D. Adelberg report stock ownership at Merck & Co., Inc., Rahway, NJ, USA. R. Kim reports honoraria from Taiho; advisory/consultancy roles with Bayer Servier, Ipsen and Roche; and speaker bureau for Eisai, Pfizer, and Incyte. B. Polite, L. Wong, and J. Chaves report no conflicts of interest.