CD274 and head and neck squamous cell carcinoma: This communication contains therapeutic guidelines, i.e., inclusion/exclusion clinical criteria, immunological, immunohistochemical (IHC) and clinical parameters for patient selection, immunotherapy sequence, monitoring of the response to immunotherapy, management of adverse events and analysis of specific prognostic biomarkers that have been evaluated in HNSCC; these include the programmed death ligand 1 (PD-L1) expression, tumour mutational burden (TMB), and immune gene signatures within both the tumour and the surrounding tissue [42,587].