lumretuzumab + paclitaxel + pertuzumab

This is a combination regimen of three drugs: - **Lumretuzumab** is a humanized monoclonal antibody targeting human epidermal growth factor receptor 3 (HER3/ERBB3), inhibiting its activation and downstream signaling. - **Pertuzumab** is a monoclonal antibody that targets human epidermal growth factor receptor 2 (HER2/ERBB2), preventing dimerization with other HER family receptors and thereby blocking cell proliferation signals. - **Paclitaxel** is a small molecule chemotherapeutic agent that stabilizes microtubules and inhibits their disassembly during cell division. The combination was investigated in metastatic breast cancer patients with HER3-positive and HER2-low tumors. The rationale was to achieve comprehensive blockade of the HER family signaling pathways by simultaneously inhibiting HER3 (lumretuzumab) and HER2 (pertuzumab) while using paclitaxel for cytotoxic chemotherapy. Clinical studies found high rates of diarrhea as dose-limiting toxicity; despite some clinical activity (objective response rates up to 55% in first-line settings), the therapeutic window was too narrow for further development[1][2].