ICIs enhance the anti-cancer immune response by inhibiting the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) or by inhibiting the programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) pathways that have a physiological role in preventing autoimmunity [1, 2]. The gene discussed is CTLA4; the disease is cancer.