By Fineline Cube 
Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (HKG: 6990) announced on October 17, 2025, that its Human Epidermal Growth Factor Receptor 2 (HER2)-targeting Antibody-Drug Conjugate (ADC), trastuzumab botidotin (A166), has received marketing approval from China’s National Medical Products Administration (NMPA). The drug is indicated for adult patients with unresectable or metastatic HER2-positive breast cancer who have previously received one or more anti-HER2 therapies.
Mechanism of Action
Trastuzumab botidotin, an innovative HER2 ADC developed by Kelun-Biotech, employs a stable enzyme-cleavable linker to attach a novel MMAF derivative, Duo-5, a highly cytotoxic microtubule inhibitor, to a HER2 monoclonal antibody, with a Drug-to-Antibody Ratio (DAR) of 2. The ADC specifically binds to HER2 on tumor cells, is internalized, and releases Duo-5, inducing G2/M phase cell cycle arrest and apoptosis in tumor cells.-Fineline Info & Tech