Sialyl-Tn tumor-associated carbohydrate antigen (sTn) (sTn)

Sialyl-Tn (sTn) is a truncated O-glycan consisting of a sialic acid residue linked α2-6 to N-acetylgalactosamine (GalNAc) attached to serine or threonine residues on proteins [1]. It is a well-characterized tumor-associated carbohydrate antigen (TACA) that is virtually absent in normal adult tissues but highly expressed in various epithelial cancers, including breast, ovarian, gastric, and colorectal carcinomas [2]. The expression of sTn is typically the result of premature sialylation of the Tn antigen by the sialyltransferase ST6GalNAc-I, which prevents further glycan chain elongation [1]. In the tumor microenvironment, sTn plays a critical role in promoting cancer cell invasiveness, metastasis, and immune evasion by interacting with lectin receptors like Siglecs on immune cells [3]. Due to its high tumor specificity, sTn has been a major target for cancer immunotherapy, including the development of glycan-based vaccines like STn-KLH (Theratope) and monoclonal antibodies like CC49 [4, 5]. While early clinical trials for sTn vaccines faced challenges in achieving significant overall survival benefits, ongoing research focuses on more potent formulations, antibody-drug conjugates (ADCs), and CAR-T cell therapies to exploit this biomarker for precision oncology [2, 5].

Other names

Sialyl-TnSTnCD175sNeu5Ac-alpha-2,6-GalNAc-alpha-Ser/ThrTAG-72 epitopeSialyl-Tn antigen

Induction of anti-sTn antibodies through active vaccination; Antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) via monoclonal antibodies; Targeted delivery of cytotoxic payloads; T-cell mediated tumor cell lysis via chimeric antigen receptors (CARs).