Tumor-associated carbohydrate antigen Tn (Tn antigen)

Tumor-associated carbohydrate antigen Tn is a simple O-linked glycan structure consisting of an N-acetylgalactosamine (GalNAc) residue α-linked to serine or threonine residues on proteins (GalNAcα1-O–Ser/Thr). It is also known as the Thomsen-nouveau antigen. The presence of this truncated glycan results from aberrant O-glycosylation processes commonly found in malignant transformation. The Tn antigen is overexpressed on the surface of many carcinoma cells—including breast, colon, prostate, and lung cancers—while being largely absent from healthy adult tissues. Its pathological exposure promotes cancer progression by contributing to immunosuppression within the tumor microenvironment through reduced cytotoxic lymphocyte infiltration and increased suppressive myeloid populations. Because it is highly immunogenic when presented as part of a vaccine or conjugate molecule, it has been explored as a target for anticancer vaccines and diagnostic tools. The structural presentation can vary depending on whether it is attached to serine or threonine residues; this affects both its recognition by antibodies and its biological properties. Overall, the Tn antigen serves as an important biomarker for malignancy with ongoing research into therapeutic exploitation via targeted immunotherapies.

Other names

Thomsen-nouveau antigenGalNAc-α1-O-Ser/Thrα-GalNAc-O-Ser/Thr glycanTn (short form)

Experimental approaches include vaccine-induced immune responses against cells expressing the Tn antigen or antibody-mediated targeting for cancer therapy.