Inclusion Criteria:

          -  Patients must have histologically or cytologically confirmed invasive cancer of the
             breast

          -  Patients must have documented locally advanced/metastatic disease, defined by the
             investigator, which is not amenable to resection with curative intent.

          -  Patients must have HER2-positive breast cancer as defined by ASCO/CAP 2013 guidelines
             that is confirmed by a Sponsor-designated central laboratory

          -  Patients must have progressed on, or be intolerant to pertuzumab in the LABC/MBC
             setting or had disease recurrence within 12 months of pertuzumab treatment in the
             neoadjuvant or adjuvant setting.

          -  Patients must have progressed on, or be intolerant to ado-trastuzumab emtansine in the
             LABC/MBC setting

          -  Patients must have been previously treated with trastuzumab in any setting (which may
             have been previously administered with or without pertuzumab)

          -  ECOG Performance Status of 0 or 1

        Exclusion Criteria:

          -  Patients who have previously been treated with doxorubicin, liposomal doxorubicin,
             epirubicin, mitoxantrone, or any other anthracycline derivative

          -  Subjects with central nervous system (CNS) metastases, unless they have been treated
             and are stable without symptoms for 4 weeks after completion of treatment and must be
             off steroids for at least 4 weeks prior to enrollment

          -  Patients with any class of New York Heart Association (NYHA) CHF or heart failure with
             preserved ejection fraction (HFPEF)

          -  Patients with a history of known coronary artery disease or a myocardial infarction
             within the last 12 months

          -  Patients with a known history of serious cardiac arrhythmias requiring treatment
             (exception: controlled atrial fibrillation, paroxysmal supraventricular tachycardia)

          -  Patients who previously discontinued trastuzumab due to unacceptable cardiac toxicity

          -  Patients with a history of LVEF decline to below 50% during or after prior
             trastuzumab/lapatinib or other HER2 directed therapy.