Studies in lung-cancer tissue suggest overexpression as defined as the percentage of viable tumor cells showing partial or complete membrane staining as compared to all viable tumor cells (tumor proportion score or TPS) being greater than 50% as a stronger predictive biomarker [59]; in HNSCC, different cutoff values for PD-L-1 overexpression have been used in clinical trials (Table 2). Here, CD274 is linked to head and neck squamous cell carcinoma.