Tn antigen (Thomsen-nouveau antigen) (Tn)

The Tn antigen (GalNAcα1-O-Ser/Thr) is a truncated, tumor-associated carbohydrate antigen (TACA) that arises from the incomplete biosynthesis of mucin-type O-glycans. In normal cells, the Tn antigen is a transient intermediate that is rapidly extended by T-synthase (C1GALT1) into more complex structures; however, in many epithelial cancers, mutations or epigenetic silencing of the molecular chaperone COSMC or dysregulation of glycosyltransferases lead to its stable expression on the cell surface. This aberrant glycosylation promotes tumor progression by enhancing cell migration, invasion, and epithelial-mesenchymal transition (EMT), while also contributing to immune evasion through interactions with lectins like MGL on myeloid cells. Because the Tn antigen is highly expressed in over 70% of human carcinomas (including breast, colorectal, and pancreatic cancers) but is virtually absent in healthy adult tissues, it is a prime target for precision immunotherapies. Current therapeutic strategies include cancer vaccines (e.g., Mag-Tn3), monoclonal antibodies (e.g., Gatipotuzumab), and chimeric antigen receptor (CAR) T cells designed to recognize Tn-glycopeptide epitopes, particularly those on the MUC1 protein backbone. These therapies aim to induce potent anti-tumor immune responses while minimizing off-target toxicity due to the antigen's high tumor specificity.

Other names

CD175GalNAc-alpha-Ser/ThrThomsen-nouveau antigenGalNAc-O-Ser/ThrTruncated O-glycanTn-glycopeptide

Immune activation, antibody-dependent cellular cytotoxicity (ADCC), and targeted cell lysis via CAR-T cells.