CTLA4 and neoplasm: To this aim, breast cancer immunotherapy consists of vaccines that target immune responses to tumor-associated antigens and also antibodies that block the checkpoint and inhibit immune suppression by targeting the key pathways mediated by cytotoxic T lymphocyte-associated antigen 4 (CTLA4), programmed death 1 (PD-1), and programmed death ligand 1 (PD-L1).