Le DT, Kim TW, Cutsem EV, et al. - In this phase II open-label study involved 128 centers globally of 124 persons aged ≥ 18 years and who had metastatic microsatellite instability-high/mismatch repair–deficient (MSI-H/dMMR) colorectal cancer (CRC) treated with ≥ 2 former lines of standard therapy, including fluoropyrimidine, oxaliplatin, and irinotecan with or without anti-vascular endothelial growth factor/epidermal growth factor receptor monoclonal antibody (cohort A, n = 61) or ≥ 1 former line of therapy (cohort B, n = 63), experts assessed the antitumor activity of pembrolizumab in formerly treated, MSI-H/dMMR CRC. It was concluded that in individuals with MSI-H/dMMR CRC, pembrolizumab is efficient with a flexible safety profile.