Trastuzumab Emtansine for HER2-Positive Advanced Breast Cancer

Amplification of human epidermal growth factor receptor 2 (HER2, also called ErbB2) occurs in approximately 20% of breast cancers and is associated with shortened survival.1?3 Combining HER2-targeted agents with standard chemotherapy is an effective therapeutic approach for patients with HER2-positive metastatic breast cancer. When combined with first-line chemotherapy, trastuzumab increases the time to progression and overall survival among patients with metastatic disease.4,5 The addition of lapatinib to capecitabine increases the time to progression in patients previously treated with trastuzumab, an anthracycline, and a taxane,6 and this combination is a standard option for disease progression with trastuzumab. Trastuzumab emtansine . . .