Cancer immunotherapy refers to a therapeutic method to remove and kill tumor cells by mobilizing the function of the body’s immune system and enhancing the body’s anti-tumor immune response, and the most clinically applied immune checkpoint inhibitors (ICI) of the programmed cell death protein 1 (PD1) and PD1-ligand (PD-L1) antibody class are currently used. Here, PDCD1 is linked to neoplasm.