CD274 and neoplasm: The interaction between PD-1 on activated T cells and PD-L1 on tumor cells allows tumors to evade T-cell immune surveillance, directly suppressing tumor cell apoptosis (1, 2) PD-1 inhibitors block the binding of PD-1 to PD-L1, which relieves tumor-induced suppression of T lymphocytes, and prevents immune evasion by tumor cells, and achieving antitumor effects (3).