CTLA4 and neoplasm: The receptors of anti-program death 1 (PD-1) and anti-cytotoxic T lymphocyte antigen-4 (CTLA-4) are expressed on activated T cells that normally downregulate excessive immune responses, while tumor cells and tumor-infiltrating immune cells express programmed death-ligand 1 (PD-L1) to evade antitumor immunity through the interaction with these molecules [17].