Thus, PD-L1 positivity may be considered as a potential marker for clinical response of HPV (+) HNSCC patients to checkpoint inhibitors, although a recent study of 126 HNSCC patients treated with anti-PD-1/L1 therapy demonstrated that PD-L1 alone could not serve as a robust predictor of clinical response (Hanna et al., 2018). This evidence concerns the gene CD274 and head and neck squamous cell carcinoma.