CD274 and head and neck squamous cell carcinoma: However, despite advancements in diagnoses and effective treatment modalities, such as intensity-modulated radiotherapy (IMRT), low-invasive transoral surgery, immunotherapy (anti-programmed death-ligand 1 (PD-L1) therapy), and drug targeting (anti-EGFR therapy) [5], overall survival (OS) rates of advanced-stage HNSCC patients have remained poor [8].