The interaction between programmed cell death protein 1 (PD-1) on the T cell surface and programmed death-ligand 1 (PD-L1) on the tumor cell surface was reported to play a vital role in regulating T cell exhaustion via T cell proliferation inhibition and induction of tumor-specific T cell apoptosis resulting in cancer escape from immune surveillance6–8. This evidence concerns the gene PDCD1 and cancer.