CD274 and head and neck squamous cell carcinoma: Nivolumab and pembrolizumab, two monoclonal antibodies targeting the interaction between the molecule PD-L1 (Programmed cell Death 1-Ligand 1, encoded by the gene CD274) and its receptor PD1, are approved for the treatment of recurrent/metastatic (R/M) HNSCC [3,4].