In Europe, first-line treatment of patients with recurrent and/or metastatic head and neck squamous cell carcinoma (R/M HNSCC) ineligible to curative treatment is guided by programmed death-ligand 1 (PD-L1) tumor expression,7 assessed by the combined positive score (CPS), defined as the number of PD-L1-staining cells (tumor cells, lymphocytes and macrophages) divided by the total number of tumor cells multiplied by 100.8 The gene discussed is CD274; the disease is head and neck squamous cell carcinoma.