Furthermore, the emergence of targeted therapies, such as monoclonal antibodies and small molecule inhibitors, has revolutionised breast cancer treatment.12 In the past two decades, two HER2-targeted monoclonal antibodies (mAbs), trastuzumab and pertuzumab, have been approved as adjuvant treatments for HER2+ breast cancer and metastatic breast cancer. The gene discussed is ERBB2; the disease is breast cancer.