- Patients must have metastatic and/or recurrent (distant or locoregionally recurrent) breast cancer and be HER2 non-over expressing per 2013 American Society of Clinical Oncology (ASCO)-College of American Pathologists (CAP) HER testing guidelines (0 or 1+ by immunohistochemistry [IHC]; and/or HER2 ratio < 2.0 and HER2 copy number < 4 signals/cell by in-situ hybridization [ISH])