Anti-PD-1 or anti-PD-L1 mAbs block the interaction of PD-1 on T and NK cells with its ligand, PD-L1 and this restores the function of exhausted cytolytic T cells, augments T cell proliferation, and enhances NK cell cytokine production and cytotoxicity responses, leading to enhanced anti-tumor effector responses and tumor regression in multiple murine models (146, 149). This evidence concerns the gene PDCD1 and neoplasm.