Immune checkpoint inhibitors (ICIs), including programmed death receptor-1 (PD-1)/ligand (PD-L1) and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) monoclonal antibody, have been approved for the treatment of multiple advanced malignant tumors, on account of its ideal antitumor activity. Here, CTLA4 is linked to cancer.