CTLA4 and renal cell carcinoma: Nivolumab, a fully human monoclonal IgG4 antibody targeting programed cell death-1 (PD-1), and ipilimumab, a recombinant human IgG1 antibody that binds to cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), have both demonstrated therapeutic efficacy in the treatment of RCC (9, 10).