KRT17 and head and neck squamous cell carcinoma: While CK17 has been recognized as a negative predictive biomarker of resistance to gemcitabine in pancreatic carcinoma [19] and a positive predictive biomarker of response to ICB in colorectal carcinoma [42], our group is the first to have explored the role of CK17 as a biomarker of response to ICB in HNSCC [4].