Journal Article

Pembrolizumab versus chemotherapy for microsatellite instability-high or mismatch repair-deficient metastatic colorectal cancer (KEYNOTE-177): final analysis of a randomised, open-label, phase 3 study

Shiu, Kai-Keen, de la Fourchardiere, Christelle, Kim, Tae-Won, Punt, Cornelis, Garcia-Carbonero, Rocio, Gibbs, Peter, Fogelman, David, Jensen, Benny Vittrup, Smith, Denis, Zhong, Wen Yan, Yoshino, Takayuki, Marinello, Patricia, Jensen, Lars Henrik, Elez, Elena, Rivera, Fernando, Diaz, Luis A, Benavides, Manuel, Le, Dung T, Andre, Thierry

2022

Overview

Pembrolizumab has shown improved progression-free survival versus chemotherapy in patients with newly diagnosed microsatellite instability-high or mismatch repair-deficient metastatic colorectal cancer. However, the treatment's effect on overall survival in this cohort of patients was unknown. Here, we present the final overall survival analysis of the KEYNOTE-177 study. This randomised, open-label, phase 3 study was done in 193 academic medical centres and hospitals in 23 countries. We recruited patients aged at least 18 years, with an Eastern Cooperative Oncology Group performance status of 0 or 1, and who had previously untreated microsatellite instability-high or mismatch repair-deficient metastatic colorectal cancer. Patients were randomly assigned (1:1) in blocks of four using an interactive voice response system or integrated web response system to intravenous pembrolizumab 200 mg every 3 weeks or to the investigator's choice of intravenous mFOLFOX6 (oxaliplatin 85 mg/m2 on day 1, leucovorin 400 mg/m2 on day 1, and fluorouracil 400 mg/m2 bolus on day 1 followed by a continuous infusion of 1200 mg/m2 per day for 2 days on days 1–2) or intravenous FOLFIRI (irinotecan 180 mg/m2 on day 1, leucovorin 400 mg/m2 on day 1, and fluorouracil 400 mg/m2 bolus on day 1 followed by a continuous infusion of 1200 mg/m2 per day for 2 days on days 1–2), every 2 weeks with or without intravenous bevacizumab 5 mg/kg every 2 weeks or intravenous weekly cetuximab (first dose 400 mg/m2, then 250 mg/m2 for every subsequent dose). Patients receiving chemotherapy could cross over to pembrolizumab for up to 35 treatment cycles after progression. The co-primary endpoints were overall survival and progression-free survival in the intention-to-treat population. KEYNOTE-177 is registered at ClinicalTrials.gov, NCT02563002, and is no longer enrolling patients. Between Feb 11, 2016, and Feb 19, 2018, 852 patients were screened, of whom 307 (36%) were randomly assigned to pembrolizumab (n=153) or chemotherapy (n=154). 93 (60%) patients crossed over from chemotherapy to anti-PD-1 or anti-PD-L1 therapy (56 patients to on-study pembrolizumab and 37 patients to off-study therapy). At final analysis (median follow-up of 44·5 months [IQR 39·7–49·8]), median overall survival was not reached (NR; 95% CI 49·2–NR) with pembrolizumab vs 36·7 months (27·6–NR) with chemotherapy (hazard ratio [HR] 0·74; 95% CI 0·53–1·03; p=0·036). Superiority of pembrolizumab versus chemotherapy for overall survival was not demonstrated because the prespecified α of 0·025 needed for statistical significance was not achieved. At this updated analysis, median progression-free survival was 16·5 months (95% CI 5·4–38·1) with pembrolizumab versus 8·2 months (6·1–10·2) with chemotherapy (HR 0·59, 95% CI 0·45–0·79). Treatment-related adverse events of grade 3 or worse occurred in 33 (22%) of 153 patients in the pembrolizumab group versus 95 (66%) of 143 patients in the chemotherapy group. Common adverse events of grade 3 or worse that were attributed to pembrolizumab were increased alanine aminotransferase, colitis, diarrhoea, and fatigue in three (2%) patients each, and those attributed to chemotherapy were decreased neutrophil count (in 24 [17%] patients), neutropenia (22 [15%]), diarrhoea (14 [10%]), and fatigue (13 [9%]). Serious adverse events attributed to study treatment occurred in 25 (16%) patients in the pembrolizumab group and in 41 (29%) patients in the chemotherapy group. No deaths attributed to pembrolizumab occurred; one death due to intestinal perforation was attributed to chemotherapy. In this updated analysis, although pembrolizumab continued to show durable antitumour activity and fewer treatment-related adverse events compared with chemotherapy, there was no significant difference in overall survival between the two treatment groups. These findings support pembrolizumab as an efficacious first-line therapy in patients with microsatellite instability-high or mismatch repair-deficient metastatic colorectal cancer. MSD.

• Publisher: Elsevier Ltd,Elsevier Limited
• Subject: 5-Fluorouracil / Adolescent / Adult / Alanine / Alanine transaminase / Antibodies, Monoclonal, Humanized - adverse effects / Antineoplastic Combined Chemotherapy Protocols - adverse effects / Bevacizumab / Cancer / Cancer therapies / Chemotherapy / Colitis / Colorectal cancer / Colorectal Neoplasms - drug therapy / Colorectal Neoplasms - genetics / Creatinine / Diarrhea / Diarrhea - etiology / DNA Mismatch Repair - genetics / Fatigue / Fatigue - etiology / FDA approval / Fluorouracil / Hematology, Oncology, and Palliative Medicine / Humans / Immunotherapy / Intravenous administration / Irinotecan / Leucovorin / Leukocytes (neutrophilic) / Metastases / Metastasis / Microsatellite Instability / Mismatch repair / Monoclonal antibodies / Neutropenia / Oncology / Oxaliplatin / Patients / PD-1 protein / PD-L1 protein / Pembrolizumab / Survival analysis / Targeted cancer therapy / Tumors / Yeast