(i) Histologically-confirmed breast cancer that is metastatic or locally recurrent (7th Edition of the AJCC TNM System) and measurable and/or evaluable or non-measurable by RECIST 1.1 criteria with HER2/neu overexpression by immunohistochemistry (2+,3+) or FISH+ and progressive disease despite having received at least 1 prior FDA approved HER2 targeted (e.g. trastuzumab, trastuzumab plus pertuzumab, T-DM1, or lapatinib) (determined by their physician).*