Tn antigen cluster (Tn antigen)

The **Tn antigen cluster** refers to a tumor-associated carbohydrate antigen defined as N-acetylgalactosamine (GalNAc) monosaccharides in α-glycosidic linkage to serine or threonine residues within proteins, often found clustered in regions rich in serine/threonine (such as mucins)[1][2][3][5]. Normally absent on cell surfaces, the Tn antigen is exposed in many human carcinomas due to defects in glycosylation—particularly loss of function of T-synthase (C1GALT1) or its chaperone Cosmc—thereby serving as a **neoantigen**[3][7]. Expression of Tn antigen correlates with tumor progression, metastasis, and poor prognosis, and is under intense investigation as a **diagnostic biomarker** and potential **therapeutic target** for monoclonal antibodies and cancer vaccines[1][3][7][8]. The related sialyl-Tn (STn) antigen also shares these roles in oncology. Anti-Tn antibodies have shown activity in preclinical models, but challenges remain due to antibody cross-reactivity and the need for highly specific recognition of clustered Tn antigen on tumors[1][4][8].

Other names

CD175Thomsen-nouveau antigenGalNAc-α-O-Ser/ThrTnO-GalNAc antigen

Antibody-dependent cellular cytotoxicity (ADCC), direct tumor cell recognition by monoclonal antibodies, vaccine antigen for immunotherapy[1][8].