Sialyl-Lewis A (sLea)

Sialyl-Lewis A (sLea), clinically recognized as Carbohydrate Antigen 19-9 (CA19-9), is a tetrasaccharide ligand that plays a critical role in cell-cell recognition and adhesion (PubMed ID: 11003554). It is primarily known for its high-affinity binding to E-selectin, which facilitates the extravasation of leukocytes and, pathologically, the metastasis of tumor cells (NIH: PMC2945722). While expressed at low levels in healthy ductal tissues such as the gallbladder and pancreas, sLea is significantly overexpressed in various gastrointestinal malignancies, making it a hallmark biomarker for pancreatic ductal adenocarcinoma (PDAC) (PubMed ID: 30146473). Therapeutics like the monoclonal antibody MVT-5873 are being developed to target sLea-expressing tumors, leveraging antibody-dependent cellular cytotoxicity (ADCC) to eliminate malignant cells (ClinicalTrials.gov: NCT02672020). However, its efficacy as a target is limited by the fact that approximately 5-10% of the population are Lewis-negative and cannot synthesize the antigen due to lack of the fucosyltransferase 3 (FUT3) enzyme (PubMed ID: 25031441).

Other names

CA19-9Carbohydrate antigen 19-9Sialyl-Lewis^aSialyl-Lewis a tetrasaccharide

Monoclonal antibodies target the Sialyl-Lewis A epitope to induce antibody-dependent cellular cytotoxicity (ADCC) or deliver radionuclides for imaging and therapy; additionally, targeting prevents E-selectin mediated adhesion and metastasis (PubMed ID: 25827393).