Immune checkpoint inhibitors such as anti-Programmed Cell Death Protein (PD1), anti-Programmed Death-Ligand 1 (PD-L1), and anti-Cytotoxic T-Lymphocyte Protein 4 (CTLA-4) have recently been approved for cancer treatment use due to their potent antitumor effects. The gene discussed is CTLA4; the disease is cancer.