PD-L1 or PD-1 blocking therapeutics. TCR on the surface of cytotoxic T cells promotes the activation of cytotoxic T cells by recognizing antigens presented by MHCⅠclass molecules on the surface of tumor cells. (Left) Reactive expression of PD-L1 or PD-1 stimulates interactions with each other, resulting in cytotoxic T cells that attempt to attack tumor tissue being suppressed and left at the edge of the tumor. (Right) PD-1 or PD-L1 binds to antibodies and cannot interact with each other, thus blocking the inhibitory effect on cytotoxic T cells, leading to the proliferation and infiltration of cytotoxic T cells into the tumor to exert cytotoxic effects and kill tumor cells.