In the last decade a great variety of immunotherapeutic approaches emerged that transformed modern cancer treatment, including antibodies targeting immune inhibitory checkpoints (e.g., PD-1 and CTLA-4), monoclonal antibodies (mAbs) directed against tumor-associated antigens (TAA), anti-cancer vaccines, and chimeric antigen receptor T cells (CAR T cells). The gene discussed is CTLA4; the disease is cancer.