IL-2 was one of the first FDA-approved immunotherapies for metastatic melanoma and renal cell cancer (94, 117), (fn. 7). Since IL2 expands effector T cells at the cost of Treg proliferation, engineered IL2 is necessary to preferentially target IL2 receptors on effector T cells (107). The gene discussed is IL2; the disease is renal cell adenocarcinoma.