Pembrolizumab for previously treated, microsatellite instability–high/mismatch repair–deficient advanced colorectal cancer: final analysis of KEYNOTE-164

•KEYNOTE-164 evaluated pembro in MSI-H/dMMR unresectable/metastatic colorectal cancer (85/85).•Additional responses were observed, and median DOR was still NR (64/85).•Second-course pembro showed some benefit in patients with progressive disease after initial response (78/85).•OS was lengthy for a population with previously treated CRC (73/85).•Pembro continued to be well tolerated, and no new safety signals were observed (78/85).