A Study of Trastuzumab Emtansine in Comparison With Treatment of Physician's Choice in Participants With HER2-positive Breast Cancer Who Have Received at Least Two Prior Regimens of HER2-directed Therapy

Inclusion Criteria

• •Adult participants ≥ 18 years of age.
• •Histologically or cytologically documented breast cancer.
• •Metastatic or unresectable locally advanced/recurrent breast cancer.
• •HER2-positive disease by prospective laboratory confirmation.
• •Disease progression on the last regimen received as defined by the investigator.
• •Prior treatment with an trastuzumab, a taxane, and lapatinib.
• •Disease progression after at least two regimens of HER2-directed therapy in the metastatic or unresectable locally advanced/recurrent setting.
• •Adequate organ function, as evidenced by laboratory results.
• •Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2.
• •Left ventricular ejection fraction (LVEF) ≥ 50% by echocardiogram or multi gated acquisition scan.