We note that Trop2 overexpression has been reported in some tumors, including HNSCC [37, 41]; however, we and others have reported high-level basal expression of Trop2 in normal epithelia of the tonsil and oral cavity, as well as other stratified squamous epithelia [7, 42]. This evidence concerns the gene TACSTD2 and head and neck squamous cell carcinoma.