CD274 and neoplasm: Because the FDA approved the anti-PD-1 (programmed death-1) antibodies nivolumab and pembrolizumab, as well as the anti-PD-L1 antibodies atezolimuab, durvalumab and avelumab, the signaling pathway involving PD-1 and its ligand PD-L1 has become a research hotspot in the field of tumor immunology and oncology (Dong et al., 2002).