A Study Of PF-05280014 [Trastuzumab-Pfizer] Or Herceptin® [Trastuzumab-EU] Plus Paclitaxel In HER2 Positive First Line Metastatic Breast Cancer Treatment (REFLECTIONS B327-02)

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.