TF and cancer: Furthermore, the prevalence of truncated saccharide antigens such as the Tn antigen [11], the Thomsen–Friedenreich (TF) antigen, and their sialylated congeners [8–10, 12] leads to an insufficient shielding of the peptide backbone, which becomes accessible to the immune system and can be used as an additional immunogenic determinant for carbohydrate-based cancer vaccines [13].