Patient description: The patient is a 45-year-old postmenopausal woman with cytologically confirmed breast cancer. A core biopsy revealed a 3 cm invasive ductal breast carcinoma in the left upper outer quadrant. The tumor is HER2-positive and ER/PR negative. Axillary sampling revealed 5 positive lymph nodes. CXR was remarkable for metastatic lesions. The patient is using multivitamins and iron supplements. She does not smoke or consume alcohol. She is not sexually active and has no children. She is a candidate for tumor resection and agrees to do so prior to chemotherapy.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  HER2-positive Early Breast Cancer 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% per year, or two effective non-hormonal contraceptive methods during the treatment period and for 7 months after the last dose of HER2-targeted therapy, and agreement to refrain from donating eggs during this same period  Stage IV (metastatic) breast cancer History of invasive breast cancer History of concurrent or previously treated non-breast malignancies except for appropriately treated 1) non-melanoma skin cancer and/or 2) in situ carcinomas, including cervix, colon, and skin Have received any previous systemic therapy (including chemotherapy, immunotherapy, HER2-targeted agents, endocrine therapy [selective estrogen receptor modulators, aromatase inhibitors], and antitumor vaccines) for treatment or prevention of breast cancer, or radiation therapy for treatment of cancer Have a past history of ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS) if they have received any systemic therapy for its treatment or radiation therapy to the ipsilateral breast High-risk for breast cancer and have received chemopreventative drugs in the past Multicentric (multiple tumors involving more than one quadrant) breast cancer, unless all tumors are HER2-positive Bilateral breast cancer Have undergone an excisional biopsy of primary tumor and/or axillary lymph nodes Axillary lymph node dissection (ALND) prior to initiation of neoadjuvant therapy