CTLA4 and cancer: In recent years, immune checkpoint blockers, such as those inducing cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) blockade, programmed death 1/programmed death ligand 1 (PD-1/PD-L1) blockade, and indoleamine 2,3-dioxygenase (IDO) blockade, have often been used as immunotherapeutic agents combined with chemotherapy to enhance the effectiveness of cancer treatment 122, 123.