CD274 and head and neck squamous cell carcinoma: PD‐L1 is a US Food and Drug Administration‐approved diagnostic biomarker that is related to response to pembrolizumab monotherapy in several cancers, including HNSCC when used as first‐line therapy,3 and is considered to be driven by interferon‐gamma signaling as partly indicative of a T‐cell‐inflamed tumor microenvironment.