GB251

GB251 is a biosimilar candidate of trastuzumab emtansine (Kadcyla), an antibody-drug conjugate (ADC) targeting the human epidermal growth factor receptor 2 (HER2). Developed by Genor Biopharma, GB251 consists of the monoclonal antibody trastuzumab covalently linked to the cytotoxic agent emtansine (DM1), a microtubule inhibitory maytansinoid, via a stable non-cleavable thioether linker (MCC). The drug is designed to deliver the cytotoxic payload directly to HER2-overexpressing cancer cells, primarily for the treatment of HER2-positive metastatic breast cancer. Upon binding to the HER2 receptor, the ADC is internalized via receptor-mediated endocytosis and undergoes lysosomal degradation, releasing active DM1 metabolites. These metabolites bind to tubulin, inhibiting microtubule polymerization and leading to cell cycle arrest in the G2/M phase and subsequent apoptosis. GB251 is currently being evaluated in Phase 3 clinical trials in China to compare its efficacy and safety with the reference product, Kadcyla.

Other names

trastuzumab emtansine biosimilar