TP53 and head and neck squamous cell carcinoma: This discrepancy is consistent with our previous finding relating frequencies of these tet+ CD8+ T cells in the peripheral circulation of HNSCC patients and p53 mutational sites in their tumors9 and suggests that these CTL in responsive patients could have eliminated tumor cells capable of processing and presenting the targeted epitope resulting in the immunoselection and outgrowth of “epitope-loss” tumors.