AT-03 (Axcynsis Therapeutics)

AT-03 is a first-in-class Claudin-6 (CLDN6)-targeted antibody-drug conjugate (ADC) being developed by Axcynsis Therapeutics (Taichengsi). The molecule is engineered using the proprietary AxcynDOT platform, which is designed to optimize the drug-to-antibody ratio (DAR) and stability of the conjugate. AT-03 selectively binds to CLDN6, a fetal cell surface antigen that is aberrantly re-expressed in various cancers—including ovarian, lung, and endometrial tumors—while remaining absent in healthy adult tissues. Upon binding and internalization, the ADC delivers a potent cytotoxic payload to induce tumor cell apoptosis. It is currently in Phase 1 clinical development for the treatment of advanced solid tumors.