Immune checkpoint receptors, including Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and Programmed cell death 1(PD-1)/Programmed cell death-ligand 1 (PD-L1), are coinhibitory receptors that function in the attenuation of immune cell activation and have recently become a main target in the treatment of cancer (8). This evidence concerns the gene PDCD1 and cancer.