CD274 and neoplasm: PD-1 binding to PD-L1 is responsible for blocking the proliferation and survival of cytotoxic CD8+T. The purpose of ICIs is not to kill tumor cells directly, but to enhance immune response and endogenous antitumor activity by anti-CTLA-4 to increase co-stimulation or blocking PD-1/PD-L1 to inhibit the induced death of effector T cells [18].