Programmed Cell Death 1 (PD-1) is a recombinant human immunoglobulin G (IgG4) type monoclonal antibody Programmed Cell Death 1 (PD-1). By binding PD-1 and blocking the binding of PD-1 to PD-L1 and PD-L2, the immunosuppressive effect is lifted and the function of T-cells is activated. Enhance the immune surveillance and killing ability of T-cells to tumor, and generate tumor immune response. This evidence concerns the gene PDCD1LG2 and neoplasm.