Inspired by the phenomenal success of inhibitors that block CTLA-4 and PD-1 in melanoma, pharmaceutical industries have been marketing three FDA-approved monoclonal antibody drugs, Yervoy (Ipilimumab, against CTLA-4), Keytruda (pembrolizumab, against PD-1), and Opdivo (nivolumab, against PD-1) [22,23,24]. The gene discussed is PDCD1; the disease is melanoma.