A Two-Arm Study to Evaluate the Pharmacokinetics, Efficacy, and Safety of Subcutaneous Administration of the Fixed-Dose Combination of Pertuzumab and Trastuzumab in Combination With Chemotherapy in Chinese Participants With HER2-Positive Early Breast Cancer

Inclusion Criteria

• Ability to comply with the study protocol, in the investigator's judgment
• Eastern Cooperative Oncology Group (ECOG) Performance Status greater or equal to (≤)1
• Stage II-IIIC (T2-T4 plus any N, or any T plus N1-3, M0), locally advanced, inflammatory, or early-stage, unilateral, and histologically confirmed invasive breast cancer
• Primary tumor greater than (>)2 centimeters (cm) in diameter, or node-positive disease (clinically or on imaging, and node positivity confirmed with cytology and/or histopathology)
• Human Epidermal Growth Factor Receptor 2 (HER2)-positive breast cancer confirmed by a central laboratory prior to study enrollment. HER2-positive status will be determined based on pretreatment breast biopsy material and defined as 3+ by immunohistochemistry (IHC) and/or positive by HER2 amplification by in situ hybridization (ISH) with a ratio of ≥2 for the number of HER2 gene copies to the number of signals for chromosome 17 copies
• Hormone receptor status of the primary tumor, centrally confirmed
• Patient agreement to undergo mastectomy or breast conserving surgery after neoadjuvant therapy
• Availability of formalin-fixed, paraffin-embedded (FFPE) tumor tissue for central confirmation of HER2, hormone receptor status, and PIK3CA mutational analyses
• Baseline left ventricular ejection fraction (LVEF) ≥55% measured by echocardiogram (ECHO) or multiple-gated acquisition scan (MUGA)
• For women of childbearing potential (WOCBP) who are sexually active: agreement to remain abstinent (refrain from heterosexual intercourse) or use one highly effective non-hormonal contraceptive method with a failure rate of less than ( 1.5X upper limit of normal (ULN)
• Current severe, uncontrolled systemic disease that may interfere with planned treatment (e.g., clinically significant cardiovascular, pulmonary, or metabolic disease; wound-healing disorders)
• Pregnant or breastfeeding, or intending to become pregnant during the study or within 7 months after the last dose of HER2-targeted therapy
• Any serious medical condition or abnormality in clinical laboratory tests that, in the investigator's judgment, precludes the patient's safe participation in and completion of the study
• Known active liver disease, for example, active viral hepatitis infection (i.e., hepatitis B or hepatitis C), autoimmune hepatic disorders, or sclerosing cholangitis
• Concurrent, serious, uncontrolled infections, or known infection with HIV
• Known hypersensitivity to study drugs, excipients, and/or murine proteins
• Current chronic daily treatment with corticosteroids (dose >10 milligrams [mg] methylprednisolone or equivalent excluding inhaled steroids)
• History of other malignancy within 5 years prior to screening, except for appropriately treated carcinoma in situ of the cervix, colon, skin, and/or non-melanoma skin carcinoma
• History of ventricular dysrhythmias or risk factors for ventricular dysrhythmias, such as structural heart disease (e.g., severe LVSD, left ventricular hypertrophy), coronary heart disease (symptomatic or with ischemia demonstrated by diagnostic testing), clinically significant electrolyte abnormalities (e.g., hypokalemia, hypomagnesemia, hypocalcemia), or family history of sudden unexplained death or long QT syndrome