PDCD1 and neoplasm: One of the most important breakthroughs was achieved using humanized monoclonal antibodies against programmed cell death-1/programmed cell death-ligand 1 (PD-1/PD-L1) and cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4), such as ipilimumab (anti-CTLA-4), nivolumab, pembrolizumab (anti-PD-1), and avelumab, durvalumab, atezolizumab (anti-PD-L1) (10, 12, 13), which reverse T cell exhaustion and represent a powerful anti-tumor immune response (14).