CTLA4 and cancer: In response to these findings, extensive efforts have been made to develop immunotherapeutic strategies for cancer, including the development of ICIs, such as anti-programmed death 1 (PD-1), programmed death ligand-1 (PD-L1), and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) antibodies for treating advanced cancer patients [8].