Sialyl-di-Lewis^a^ glycan antigen

Sialyl-di-Lewis^a^ glycan antigen is a specific, tetrasaccharide-based carbohydrate motif characterized by two sialylated Lewis^a^ (Le^a^) units, typically found on glycans attached to glycoproteins on the surfaces of certain cells. It is closely related to the cancer-associated carbohydrate antigen sialyl-Lewis^a^ (known clinically as CA19-9) but contains an additional sialic acid residue, differentiating it chemically and functionally. This antigen is rarely found on glycolipids but is overexpressed on the glycoproteins of malignant epithelial cells—especially in the hepato-biliary system, pancreas, and gastrointestinal tract—whereas its "natural" counterpart, featuring an extra sialic acid, is more restricted to non-malignant cells. It serves as a functional ligand for selectins (notably E-selectin), mediating cancer cell adhesion to the endothelium, which likely contributes to metastatic dissemination. Intensely investigated as a tumor-associated carbohydrate antigen, sialyl-di-Lewis^a^ is being pursued as a specific immunotherapy and diagnostic target. Antibodies against it have been developed for use in both research and potential clinical applications in cancer. Because its expression is restricted compared to canonical sialyl-Lewis^a^, it may offer advantages in specificity as a cancer marker and immunotherapy target, but its exact clinical utility is still under investigation.

Other names

Sialyl-di-Lewis^a^di-sialyl-Lewis^a^di-sLe^a^Disialyl Lewis^a^CA19-9-related antigens

Anticancer antibodies: By binding to tumor cell surface-expressed sialyl-di-Lewis^a^, these antibodies may enable immune-mediated killing (e.g., via complement-mediated cytotoxicity or antibody-dependent cellular cytotoxicity). Vaccines: Induction of anti-glycan immune response that targets and eliminates cells expressing the glycan epitope.