IFNG and head and neck squamous cell carcinoma: Furthermore, the identification of predictive biomarkers in treatment with checkpoint inhibitors is crucial, and predictive biomarkers have been identified in pivotal trials of pembrolizumab and nivolumab in HNSCC with PD-L1 expression in tumor microenvironments, T-cell activity as assessed by GEP and IFN-γ gene expression signature, as well as TMB.