PDCD1 and neoplasm: PD-1 (nivolumab or pembrolizumab) and PD-L1 (durvalumab, atezolizumab, or avelumab) inhibitors block the PD-1/PD-L1 inhibitory interaction, thus allowing cytotoxic T-lymphocytes to exert - their anti-tumor effect, particularly in tumors with a high neoantigen burden and an already established T-cell-mediated immune response.