Although predictive biomarkers have been proposed, such as tumor mutational burden (TMB) and immunohistochemistry for programmed death-ligand 1 (PD-L1), these biomarkers have shown poor-to-modest predictive value, and no single biomarker has been able to predict response with high accuracy: TMB and PDL1 individually achieved area under the receiver operating curve (AUROC) values of 0.61 and 0.62, respectively in R/M HNSCC patients [7,8,9]. Here, CD274 is linked to head and neck squamous cell carcinoma.