Sialoglycotope CA6 epitope of Mucin-1 (CA6) (CA6)

The Sialoglycotope CA6 epitope is a tumor-associated carbohydrate antigen (TACA) found on the Mucin-1 (MUC1) glycoprotein (Smith et al., 2005, PMID: 15897589). While the MUC1 protein is widely expressed on normal epithelial surfaces, the specific CA6 glycoform is characterized by a unique sialic acid-dependent glycosylation pattern that is predominantly found in solid tumors such as ovarian, breast, cervical, and non-small cell lung cancers (Boutonnet et al., 2015, PMID: 26431456). In normal tissues, CA6 expression is highly restricted to the ductal epithelium of the breast, lung, and pancreas, making it a promising target for selective cancer therapy (Whiteman et al., 2014, PMID: 24916153). The epitope is specifically recognized by the DS6 monoclonal antibody, which has been utilized in the development of antibody-drug conjugates (ADCs) like SAR566658. These therapies aim to bind the CA6 epitope, undergo internalization, and release cytotoxic payloads such as DM4 to induce apoptosis in malignant cells while minimizing damage to healthy tissues (Ab et al., 2015, PMID: 25824331). Clinical development of CA6-targeted agents has focused on patients with high CA6 expression, as determined by immunohistochemistry. Despite promising preclinical results, challenges such as ocular toxicity and limited efficacy in some patient populations have been observed in clinical trials.

Other names

CA6 antigenDS6 antigenMUC1-CA6Sialylated MUC1 epitopeDS6-antigen

The primary mechanism involves the use of an antibody-drug conjugate (ADC), such as SAR566658, which consists of a humanized DS6 antibody (huDS6) linked to the cytotoxic maytansinoid DM4. Upon binding to the CA6 epitope on the cell surface, the ADC is internalized via receptor-mediated endocytosis. Once inside the lysosome, the linker is cleaved, releasing active DM4, which inhibits tubulin polymerization, leading to cell cycle arrest and apoptosis (Whiteman et al., 2014, PMID: 24916153; Boutonnet et al., 2015, PMID: 26431456).