PDCD1 and cancer: Pembrolizumab, a humanized IgG4κ anti-PD-1 monoclonal antibody marketed as Keytruda® by Merck, later received expanded approval for the treatment of various cancers including cervical cancer (15), endometrial carcinoma (65), esophageal cancer (26), gastric cancer (18), urothelial cancer (19), Hodgkin’s lymphoma (16), hepatocellular carcinoma (21), Merkel cell carcinoma (27), squamous cell carcinoma (25), colorectal cancer (20, 66), non-small cell lung cancer (22), diffuse large B-cell lymphoma (17), renal cell carcinoma (24) and small cell lung cancer (15–22, 24–27, 66, 67).