CTLA4 and renal cell carcinoma: As a part of cancer immunotherapies, immune checkpoint blockade (ICB) has come to the foreground in recent years, including cytotoxic T lymphocyte-associated protein 4 (CTLA-4) inhibitor, programmed death protein 1 (PD-1) inhibitor, and programmed cell death 1 ligand 1 (PD-L1) inhibitor, which are widely applied to the treatment of renal cell carcinoma, lung cancer, and gastric cancer, etc. [7].