All patients will be properly consented. 4.1.1 Patient selection 20 Protocol: 2014-0443 Version 2.1 Version Date: 11 April 2016 Potentially eligible patients, specifically patients with high-risk HER2-positive breast cancer will be identified by staff in the medical and surgical and/or the hematology/oncology clinics at the individual study sites. High-risk HER2- positive is defined as those that receive neoadjuvant therapy with an approved regimen that includes trastuzumab and at least four cycles (12 weeks) of taxane- containing chemotherapy and fail to achieve a pCR or those who undergo surgery as a first intervention and are found to be pathologically node-positive. For clarity, standard of care pertuzumab is allowed.