This is a phase 2, open-label, multicenter study to establish the dose regimen and evaluate the preliminary efficacy and the safety/tolerability of poziotinib in participants with HER2-positive metastatic breast cancer who have received at least two prior HER2-directed treatment regimens.~Each treatment cycle will be 21 days in duration. During each 21-day cycle, participants who are eligible for participation will receive poziotinib orally once daily.~All treated participants will be followed up until disease progression, death, intolerable adverse events or up to a maximum of 24 months whichever comes earlier.
The purpose of this study is to establish the dose regimen and evaluate the preliminary efficacy and the safety/tolerability of poziotinib in participants with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer who have received at least two prior HER2-directed treatment regimens.