Tumor-associated O-glycan antigen (TACA)

Truncated O-glycans on a peptide backbone, primarily the Tn (GalNAc-alpha-Ser/Thr), Sialyl-Tn (STn), and Thomsen-Friedenreich (T) antigens, represent a hallmark of aberrant glycosylation in epithelial cancers (Frontiers in Oncology, 2024; NIH, 2022). In healthy cells, O-glycans are typically elongated into complex, branched structures; however, in malignant cells, this process is often disrupted by the loss of key enzymes like T-synthase or its chaperone COSMC (MDPI, 2022; PNAS, 2014). This results in the exposure of immature, truncated glycan structures on the surface of glycoproteins, most notably mucins such as MUC1 (Precision Biologics, 2026; BOC Sciences, 2023). These antigens are highly tumor-specific and are associated with increased invasiveness, metastasis, and poor clinical prognosis (NIH, 2025; NIH, 2022). They facilitate tumor progression by modulating cell signaling pathways and promoting immune evasion through interactions with glycan-binding receptors on immune cells (NIH, 2025; MDPI, 2020). Because of their restricted expression in normal tissues, they are prime targets for various immunotherapies, including monoclonal antibodies, cancer vaccines, and CAR-T cells (BOC Sciences, 2023; ResearchGate, 2026). Therapeutic agents are designed to recognize the specific glycopeptide epitope formed by the truncated glycan and the underlying protein backbone (BOC Sciences, 2023).

Other names

Tn antigenSialyl-Tn antigenSTn antigenThomsen-Friedenreich antigenT antigenCD175CD175sCD176Aberrant O-glycanTruncated O-glycanTn-MUC1STn-MUC1

Antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and T-cell mediated lysis targeting the aberrant glycopeptide epitope; also includes active immunization to induce endogenous anti-tumor antibodies.