Sialyl-di-Lewis a (s-di-Lea)

Sialyl-di-Lewis a (s-di-Lea) is a tumor-associated carbohydrate antigen (TACA) that is significantly overexpressed on the surface of various epithelial cancers, including pancreatic, colorectal, and gastric malignancies [1, 2]. It consists of a dimeric Lewis a glycan structure terminated with a sialic acid residue, typically found on glycoproteins rather than glycolipids [2, 3]. This specific glycan modification plays a critical role in cancer progression by facilitating cell adhesion to the vascular endothelium via E-selectin and contributing to immune evasion within the tumor microenvironment [1, 6]. Unlike the related Sialyl-Lewis a (CA19-9) antigen, Sialyl-di-Lewis a exhibits a highly restricted distribution in normal tissues, making it a promising target for selective cancer therapies [2, 7]. Therapeutic approaches currently under development include monoclonal antibodies such as FG129 and its chimeric derivative CH129, which can induce tumor cell death through antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) [1, 5]. Additionally, the internalizing nature of the s-di-Lea epitope allows for the development of antibody-drug conjugates (ADCs) that deliver potent cytotoxic payloads directly into cancer cells [1, 9].

Other names

Sialyl-dimeric-Lewis aSialyl-di-LeaFG129 antigenSialyl-Lewis a-a

Drugs targeting Sialyl-di-Lewis a, such as the monoclonal antibody FG129 and its derivatives, work by binding to the glycan epitope on the tumor cell surface. This binding triggers immune-mediated destruction through antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). In the case of antibody-drug conjugates (ADCs) like CH129-vcMMAE, the antibody facilitates the internalization of the complex, allowing for the intracellular release of cytotoxic payloads that induce cell death. Some antibodies may also induce direct cell killing via oncotic necrosis.