Inhibitors of immune checkpoint proteins such as cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) and antiprogrammed death-1 (PD-1) or its ligand (PDL-1) were evaluated in several tumor types such as melanoma, head and neck squamous carcinoma, NSCLC, renal cell and urothelial carcinoma, gastric cancer and Hodgkin’s lymphoma with satisfactory results [83]. The gene discussed is PDCD1; the disease is melanoma.