['metastatic breast cancer']
['paclitaxel', 'paclitaxel']

        Inclusion Criteria:

          -  Histologically confirmed diagnosis of breast cancer.

          -  Presence of metastatic disease.

          -  Documentation of HER2 gene amplification or overexpression.

          -  Available tumor tissue for central review of HER2 status.

          -  At least 1 measurable lesion as defined by RECIST 1.1.

          -  Eastern Cooperative Oncology Group status of 0 to 2.

          -  Left ventricular ejection fraction within institutional range of normal, measured by
             either two dimensional echocardiogram or multigated acquisition scan.

        Exclusion Criteria:

          -  Relapse within 1 year of last dose of previous adjuvant (including neoadjuvant)
             treatment (except endocrine therapy) and within 1 year before randomization.

          -  Prior systemic therapy for metastatic disease (except endocrine therapy).

          -  Prior cumulative dose of doxorubicin of >400 mg/m2, epirubicin dose >800 mg/m^2, or
             the equivalent dose for other anthracyclines or derivatives (eg, 72 mg/m^2 of
             mitoxantrone). If the patient has received more than one anthracycline, then the
             cumulative dose must not exceed the equivalent of 400 mg/m^2 of doxorubicin.

          -  Inflammatory breast cancer.

          -  Active uncontrolled or symptomatic central nervous system metastases.
      