CD274 and head and neck squamous cell carcinoma: Taking the percentage of PD-L1 expression of tumor cells and immune cells into account, the tumor-positivity score (TPS) and immune score (IC) can be determined and a combined positive score (CPS) calculated to describe the PD-L1 status in HNSCC (14) that is linked to differences in response and survival of patients (8, 17, 18).