CD274 and head and neck squamous cell carcinoma: In a survey of 74 cases of primary HNSCC, Roper et al. suggested that the expression of PD-L1 was higher on tumor cells and TILs, while individual higher expression of PD - L1 (>5%) on primary tumor cells, primary TILs, and metastatic TILs was associated with longer diseases-free survival (109).