inetetamab + trastuzumab

Inetetamab + trastuzumab is a **combination of two monoclonal antibodies** targeting the HER2 (human epidermal growth factor receptor 2) protein, primarily developed and used in HER2-positive cancers, most notably breast cancer. **Inetetamab** is a trastuzumab analogue with identical Fab (antigen-binding) region but differs from trastuzumab in two Fc domain amino acids (positions 359 and 361), affecting its constant region but not the HER2 binding specificity. Both antibodies function by binding domain IV of the HER2 receptor, inhibiting HER2-mediated signaling pathways (such as MAPK and PI3K/AKT), suppressing tumor cell growth and survival, and triggering immune-mediated cytotoxicity. This combination is investigated for potential synergy or overcoming resistance to trastuzumab, especially in trastuzumab-resistant or relapsed HER2+ breast cancer, and has shown tolerable safety in such settings.