Inclusion Criteria:

          1. Patients ≥ 18 years of age with histologically, and radiographically confirmed
             non-metastatic ER-positive (defined as ≥30% of positive cells) and HER2-positive
             (defined as overexpression by immunohistochemistry (3+) or 2+ and positive by defined
             by fluorescence or dual in situ hybridization.) breast cancer with minimal tumor size
             over 2 cm (≥T2 lesion) to receive neoadjuvant chemotherapy recommended by the treating
             physician

          2. Eastern Cooperative Oncology Group (ECOG) performance status score < 1

          3. Absolute neutrophil count > 1500 mm3, platelet count ≥ 100×109 L, hemoglobin ≥ 8.5
             g/dL

          4. Serum creatinine ≤1.5 times the upper limit of the normal range, total bilirubin ≤ 1.5
             X ULN (≤ 3 mg/dL if clinically diagnosed with Gilbert syndrome) AST/ALT ≤ 2.5 X ULN
             (AST/ALT ≤ 5X ULN if clinically diagnosed with Gilbert syndrome)

          5. Women of child-bearing potential (i.e., women who are pre-menoposaul or not surgically
             sterile) must have a negative serum pregnancy test within 2 weeks prior to beginning
             treatment

        Exclusion Criteria:

          1. Uncontrolled cardiac disease, such as angina, hypertension or significant arrhythmias

          2. LVEF (left ventricular ejection fraction) < 50% on any prior assessment. Note:
             Assessment of LVEF is done before and after trastuzumab-based chemotherapy as standard
             of care

          3. Pregnant or lactating females

          4. Inability to complete informed consent process and adhere to the protocol treatment
             plan and follow-up requirements

          5. Concurrent severe illness such as active infection, or psychiatric illness/social
             situations that would limit safety and compliance with study requirements