CD274 and head and neck squamous cell carcinoma: So much so that PD-1/PD-L1 axis has broadly demonstrated its value as a therapeutic target and its blockade, as a valuable tool to significantly improve patient outcome in a large number of malignancies including melanoma, non-small cell lung cancer (NSCLC), renal cell carcinoma (RCC), Hodgkin’s lymphoma, bladder cancer, head and neck squamous cell carcinoma (HNSCC), Merkel-cell carcinoma, microsatellite instable-high (MSI-H) or mismatch repair-deficient (dMMR) solid tumors [1].