CD274 and head and neck squamous cell carcinoma: PD-L1/PD-1 blockade is demonstrating good overall efficacies for the treatment of many tumor types, and it is currently used for the treatment of NSCLC [5], melanoma [6,7], head and neck squamous cell carcinoma (HNSCC) [8,9], renal cell carcinoma [10,11], urothelial carcinoma [12], gastric cancer [13], microsatellite instability-high (MSI-H) cancers [14], and mismatch-repair deficiency [15].