Over the last decade, with the development of monoclonal antibodies that target the regulatory immune “checkpoint” receptors CTLA-4, PD-1, and PD-L1, immune therapy has now become standard therapy for diverse malignancies including melanoma, lung cancer, and renal cell carcinoma with the list of responsive tumors rapidly expanding (2–11). Here, CTLA4 is linked to renal cell carcinoma.