For example, agents targeting programmed cell death protein 1 (PD-1), its ligand PD-L1, or cytotoxic T lymphocyte-associated antigen 4 (CTLA4) receptors have been shown to have antitumor activity in different tumor entities such as melanoma, non-small cell lung cancer, and renal cancer [13]. The gene discussed is PDCD1; the disease is melanoma.