CD274 and Epstein-Barr virus infection: Epstein–Barr virus (EBV) infection plays an important role in the occurrence and development of NPC [4], and the common feature of EBV-positive NPCs is the dense lymphocyte infiltration in the tumor stroma and programmed death ligand-1 (PD-L1) overexpression in tumor cells, making it a potential target for immunotherapy, especially immune checkpoint inhibitors (ICIs), such as programmed death-1/programmed death ligand-1 (PD-1/PD-L1) blockade [5–7].