Sialyl Lewis A antigen (CA 19-9)

Sialyl Lewis A antigen (CA 19-9) is a tumor-associated carbohydrate epitope—specifically, a sialylated tetrasaccharide (Neu5Acα2-3Galβ1-3[Fucα1-4]GlcNAcβ)—that is normally present in low amounts on the surface of epithelial cells in the pancreas, biliary tract, and other tissues. It is overexpressed in many cancers, particularly pancreatic ductal adenocarcinoma, and functions as a ligand for endothelial E-selectin, facilitating metastatic spread via the bloodstream[1][2][3][4][5]. CA 19-9 is widely used as a serum biomarker in the management of pancreatic and biliary cancers for monitoring disease recurrence and response to treatment, rather than as a primary diagnostic or screening test due to issues with specificity and genetic non-producers[1][2][8]. Therapeutically, CA 19-9 continues to be an important target for development of antibody-based treatments and imaging agents[3][1][5].

Other names

Carbohydrate antigen 19-9CA 19-9Sialyl-Lewis ASialyl Lewis (a)SLe^a^CA19-9 antigen

Antibody-based therapeutics (bind CA19-9 epitopes to selectively target or mark tumor cells for immune clearance) Diagnostic agents (e.g. radiolabeled or fluorescent antibodies for detection/imaging)