In 2011 and 2014, ipilimumab (anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4)) and pembrolizumab (anti-programmed cell death-1 (anti-PD-1)) were FDA-approved respectively, to treat melanoma patients with disseminated tumor, and they produced better patient survival (from 9 months to over 3.5 years), which was mediated through an antitumor immune response [6,20,24,25,26]. Here, PDCD1 is linked to melanoma.