Pembrolizumab (Keytruda), a human programmed death receptor-1 (PD-1)–blocking antibody for intravenous infusion, was approved in September 2014 for the treatment of patients with unresectable or metastatic melanoma and disease progression following previous ipilimumab (Yervoy) and, if BRAF V600 mutation–positive, a BRAF inhibitor (Merck, 2014a). This evidence concerns the gene BRAF and metastatic melanoma.