BAY 2701439

BAY 2701439 is an investigational antibody-drug conjugate (ADC) developed by Bayer, designed to target cells expressing Human Epidermal Growth Factor Receptor 2 (HER2). The molecule consists of a humanized anti-HER2 monoclonal antibody conjugated to a potent kinesin spindle protein (KSP) inhibitor payload via a protease-cleavable linker. Unlike many established HER2-targeted ADCs that utilize microtubule inhibitors or topoisomerase I inhibitors, BAY 2701439 employs a KSP inhibitor which induces mitotic arrest by preventing the formation of a bipolar spindle, leading to apoptosis. This distinct mechanism of action is intended to provide a therapeutic alternative for patients with advanced HER2-expressing breast, gastric, gastroesophageal, and other solid tumors, particularly those who have developed resistance to existing HER2-targeted therapies. It is currently undergoing Phase 1 clinical evaluation to determine safety, pharmacokinetics, and maximum tolerated dose.