CD274 and head and neck cancer: The following keywords were used: Head and Neck Cancer, Head and Neck Squamous Cell Cancer, HNSCC, Metastatic Head and Neck Cancer, Recurrent Head and Neck Cancer, Unresectable Head and Neck Cancer, Pembrolizumab, Programmed Death Receptor-1 Blocking Antibody, PDL1 Blocking Antibody, Programmed Death Receptor-1 Inhibitor, Immune Check Point Inhibitor.