CD274 and head and neck squamous cell carcinoma: On the one hand, certain studies demonstrated that STAT1 activation exhibits antitumor properties by enhancing IFN-α and -γ-dependent intracellular responses and downregulating the PD-1/PD-L1 axis in cancers such as non-small-cell lung cancer (NSCLC), colorectal cancer, and head and neck squamous cell carcinoma (HNSCC) [28,29,30,31,32,33].