CTLA4 and cancer: Immune checkpoint inhibitors (ICIs) such as PD1 (e.g., nivolumab or pembrolizumab), programmed death-protein-ligand PD-L1 (e.g., durvalumab), or cytotoxic T lymphocyte-associated protein 4 CTLA-4 (e.g., ipilimumab) inhibitors have dramatically improved prognosis of cancers and are widely used.