STAT3 and head and neck squamous cell carcinoma: Similar studies suggesting a STAT3-mediated transcriptional regulation of PD-L1 have been performed in nucleophosmin—anaplastic lymphoma kinase (NPM-ALK) positive (+) anaplastic large cell lymphoma (ALCL) [10], in ALK (-) ALCL [11], in KRAS- and EGFR- mutant non-small cell lung cancer [20,21] and in head and neck squamous cell carcinoma [22].