HER2 (human epidermal growth factor receptor 2) is a protein that promotes the growth of cancer cells. Approximately 15-20% of breast cancers are HER2-positive, meaning the cancer cells have extra copies of the HER2 gene or overexpress the HER2 protein.
HER2-targeted therapies include trastuzumab (Herceptin), pertuzumab, ado-trastuzumab emtansine (T-DM1), trastuzumab deruxtecan (T-DXd), and lapatinib. These drugs have dramatically improved outcomes for patients with HER2-positive breast cancer.
Treatment typically involves a combination of HER2-targeted therapy and chemotherapy, and the specific regimen depends on the stage of disease and prior treatments.