The PD-1/PD-L1 inhibitor operates by blocking the interaction between PD-1 located on T cell membranes and the overexpressed PD-L1 on cancer cell membranes, while CTLA-4 inhibitor works by blocking the binding of B7 on antigen-presenting cells to CTLA-4 in T cells [8, 9]. This evidence concerns the gene PDCD1 and cancer.