Results from KEYNOTE016 (NCT01876511) first revealed that 28 patients with deficient mismatch repair high microsatellite instability (dMMR-MSI-H) CRC receiving pembrolizumab (anti-PD-1 antibody) had a response rate (RR) of 50% (95% CI 31–69%) and disease control rate (DCR) of 89% (19). This evidence concerns the gene PDCD1 and colorectal carcinoma.