Pembrolizumab for Microsatellite-Instability–High Advanced Colorectal Cancer

Single-agent therapy and combination immune checkpoint inhibitor therapy are now approved for microsatellite-instability (MSI)–high colorectal cancer (CRC), based on their high degree and durability of activity. Pilot studies have also suggested that these agents have significant activity in the initial treatment of patients with metastatic CRC.

Investigators now report the results of the industry-sponsored, international, open-label, randomized, phase 3 KEYNOTE 177 trial, in which 307 patients (median age, 63 years) with MSI-high or DNA mismatch repair protein–deficient metastatic CRC received first-line pembrolizumab or physician's choice of conventional chemotherapy (5-fluorouracil–based therapy with or without bevacizumab or cetuximab). …