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: Neu5Acα2-3Galβ1-3GalNAcα-O-Ser/Thr. STF results from an early sialylation of the TF antigen due to overexpression of the enzyme α2,3sialylT and/or disruption of further glycan elongation processes. STF is negligibly expressed in healthy tissues but overexpressed in human carcinomas . As such, STF is implicated in tumour cell organotropic metastasis. Targeting immune responses to truncated variants of O-glycan chains expressed by tumour cells represents a promising approach for the development of antigen-specific therapeutic vaccines against cancers, and accumulated evidence has rendered STF a prime target for cancer immunotherapy.
