GA131020: Fmoc-Thr(Neu5Acα(2-3)Galβ(1-3)GalNAc)-OH (Peracetate, Methyl Ester)Tumor Associated Carbohydrate Antigen (TACA). STF antigen (also ST) is a sialylated form of the truncated O glycosylated core determinant TF (also T) with structure: Neu5Ac2 3Gal1 3GalNAc O Ser Thr. STF results from an early sialylation of the TF antigen due to overexpression of the enzyme 2,3sialylT and or disruption of further glycan elongation processes. STF is negligibly expressed in healthy tissues but overexpressed in human carcinomas . As such,