CD274 and head and neck squamous cell carcinoma: This is not surprising given the emerging evidence that supports the use of PD-1–targeted therapies to treat both HPV-associated and non–HPV-associated HNSCC.18,29 Although HPV-associated and non–HPV-associated HNSCC differ in several ways, and the mechanisms that lead to PD-L1 expression may differ between the two, PD-L1 has been shown to be overexpressed in both settings.