Cancer immunotherapies that harness host immune system to kill cancer cells have gained considerable ground over the past decade as witnessed by the clinical successes of adoptive transfer of either tumor-infiltrating lymphocytes (TILs) or T cells with chimeric antigen receptors, as well as therapeutic antibodies against either tumor cells (e.g. Rituximab, Trastuzumab, etc) or suppressive immune-checkpoint molecules (e.g. anti-CTLA4, anti-PD-1/PD-L1)1–5. The gene discussed is CTLA4; the disease is cancer.