CD274 and head and neck squamous cell carcinoma: Data from studies of pembrolizumab in HNSCC have shown that, compared with tumor proportion score (defined as the percentage of TCs with complete or partial membrane staining at any intensity), a combined positive score (CPS; the number of PD-L1–stained TCs and ICs relative to the total number of all TCs, with ICs including lymphocytes and macrophages) had a superior predictive value (12, 13, 27).