Real-world effectiveness of posttrastuzumab emtansine treatment in patients with HER2-positive, unresectable and/or metastatic breast cancer: A retrospective observational study (KBCSGTR 1917)

Trastuzumab emtansine (T-DM1) is a second-line standard therapy for patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. Evidence regarding post–T-DM1 treatments is currently lacking. We evaluated the effectiveness of post–T-DM1 drug therapy in patients with HER2-positive, unresectable and/or metastatic breast cancer.