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Inclusion Criteria:

* Histologically or cytologically confirmed adenocarcinoma of the breast with locally recurrent or metastatic disease that is suitable for chemotherapy
* HER2-positive metastatic breast cancer (MBC)
* Left ventricular ejection fraction (LVEF) greater than or equal to (\>=) 55 percent (%) at baseline (within 42 days of randomization)
* Eastern Cooperative Oncology Group Performance Status of 0 or 1
* Women of childbearing potential and men should agree to use an effective form of contraception and to continue its use for the duration of study treatment and for at least 7 months after the last dose of study treatment (trastuzumab and/or pertuzumab)

Exclusion Criteria:

* History of anti-cancer therapy for MBC (with the exception of one prior hormonal regimen for MBC)
* History of approved or investigative tyrosine kinase/HER inhibitors for breast cancer in any treatment setting, except trastuzumab used in the neoadjuvant or adjuvant setting
* History of systemic breast cancer treatment in the neo-adjuvant or adjuvant setting with a disease-free interval from completion of the systemic treatment (excluding hormonal therapy) to metastatic diagnosis of less than (\<) 12 months
* History of persistent Grade \>= 2 hematologic toxicity resulting from previous adjuvant therapy
* Grade \>= 3 peripheral neuropathy at randomization
* History of other malignancy within the last 5 years, except for carcinoma in situ of the cervix or non-melanoma skin carcinoma that has been previously treated with curative intent
* Current clinical or radiographic evidence of central nervous system (CNS) metastases
* History of exposure to cumulative doses of anthracyclines
* Current uncontrolled hypertension or unstable angina
* History of congestive heart failure (CHF) of any New York Heart Association (NYHA) classification, or serious cardiac arrhythmia requiring treatment
* History of myocardial infarction within 6 months of randomization
* History of LVEF decrease to \< 50% during or after prior trastuzumab neo-adjuvant or adjuvant therapy
* Current dyspnea at rest due to complications of advanced malignancy, or other diseases that require continuous oxygen therapy
* Inadequate organ function within 28 days prior to randomization
* Current severe, uncontrolled systemic disease
* Major surgical procedure or significant traumatic injury within 28 days prior to study treatment start or anticipation of the need for major surgery during the course of study treatment
* Pregnant or lactating women
* History of receiving any investigational treatment within 28 days of randomization
* Current known infection with human immunodeficiency virus (HIV), hepatitis C virus (HCV), or active hepatitis B virus (HBV)
* Receipt of intravenous (IV) antibiotics for infection within 14 days of randomization
* Current chronic daily treatment with corticosteroids (excluding inhaled steroids)
* Known hypersensitivity to any of the protocol-specified study treatments
* Concurrent participation in an interventional or noninterventional study

• Beijing, China
• Beijing, China
• Beijing, China
• Changchun, China
• Changzhou, China
• Chengdu, China
• Fuzhou, China
• Guangzhou, China
• Harbin, China
• Nanjing, China
• Nanjing, China
• Shanghai, China
• Shenyang, China
• Shenyang, China
• Zhejiang, China