CD274 and head and neck squamous cell carcinoma: In fact, the use of immune checkpoint inhibitors (ICIs) blocking PD1/PD-L1 axis is a recognized therapeutic option for several malignancies including NSCLC, melanoma, head and neck squamous cell carcinoma (HNSCC), renal cell carcinoma, urothelial cancer, Merkel cell carcinoma, gastric cancer, esophageal carcinoma, microsatellite instable (MSI-H) colorectal cancer and HCC [49].