Immunological checkpoints can deactivate immunological responses in the tumor microenvironment (TME), such as PD-1/PD-L1 (programmed cell death protein 1/programmed cell death ligand 1)8, and immune checkpoint inhibitors (ICIs), such as anti-PD1/PD-L1 antibodies are clinically effective in treating various solid malignancies. Here, PDCD1 is linked to neoplasm.