CD274 and head and neck squamous cell carcinoma: Of note, a recent RNASeq gene expression profiling in more than 500 treatment-naïve HNSCC tissue samples did not identify differences in PD-L1 expression in HPV-positive and HPV-negative HNSCC, even though IFN-γ (an inducer of PD-L1) was significantly higher in the HPV-positive group (47).