BSI-721

BSI-721 is a novel antibody-drug conjugate (ADC) targeting Cadherin 17 (CDH17), a cell adhesion protein that is highly restricted to tight junctions in normal gastrointestinal (GI) tissues but frequently overexpressed and accessible in GI malignancies. Developed by Biosion, BSI-721 consists of a fully humanized anti-CDH17 monoclonal antibody conjugated to the microtubule inhibitor monomethyl auristatin E (MMAE) via a protease-cleavable valine-citrulline linker. The ADC is designed with a drug-to-antibody ratio (DAR) of 4. Preclinical studies presented at AACR 2025 demonstrated that BSI-721 exhibits potent cytotoxicity against CDH17-expressing cell lines and significant anti-tumor activity in gastric and pancreatic cancer models. The drug is currently undergoing IND-enabling studies for the treatment of various gastrointestinal cancers, including colorectal, gastric, pancreatic, and esophageal cancers.