CTLA4 and neoplasm: In recent years, immune checkpoint inhibitors (ICIs) have been shown to be one of the most promising and effective immunotherapies, which reconstitute anti-tumor responses and prevent tumor cells from evading immune surveillance by targeting specific molecules, such as programmed death receptor 1 (PD-1) or its ligand (PD-L1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4)48–50.