1. Provide signed and dated written informed consent before entering the study. The
             informed consent will cover both parts of the study (neoadjuvant part and adjuvant
             part).

          2. Female, ≥18 and ≤65 years of age.

          3. Histologically-confirmed invasive carcinoma of the breast (American Joint Committee on
             Cancer [AJCC, vs. 8.0] Stage II, IIIa).

          4. Operable breast cancer, planned surgical resection of breast tumor (mastectomy or
             lumpectomy) and sentinel or axillary lymph nodes.

          5. Unilateral, measurable tumor of the breast >2 cm in diameter.

          6. HER2 positive tumor, defined as 3+ score by IHC or fluorescence positive by FISH, as
             confirmed by central laboratory.

          7. Known estrogen receptor (ER) and progesterone receptor (PrR) status at study entry.

          8. Adequate bone marrow function, defined as granulocyte count of ≥1.500/µL, and platelet
             count of ≥100.000/µL.

          9. Adequate hepatic and renal function, defined as:

             bilirubin within normal range

             alanine aminotransferase (ALT) ≤2 x upper limit of normal (ULN)

             aspartate aminotransferase (AST) ≤2 x ULN

             gamma glutamyl transferase (GGT) ≤3 x ULN

             serum creatinine <1.5 ULN

         10. International normalized ratio ≤1.5×ULN (2 to 3×ULN if on anticoagulants) or
             prothrombin time ≤1.5×ULN; activated partial thromboplastin time ≤1.5×ULN.

         11. Hemoglobin concentrations ≥10 g/dL.

         12. Eastern Cooperative Oncology Group (ECOG) score of 0 or 1.

         13. LVEF ≥55%, measured by multiple-gated acquisition (MUGA) scan or echocardiography.

         14. Negative pregnancy test at entry, women of childbearing potential have to use
             contraceptives during the course of the study.

        Females with childbearing potential must provide a negative serum pregnancy test at
        Screening and must be using adequate birth control. Adequate birth control is defined as
        agreement to consistently practice an effective and accepted method of contraception
        throughout the duration of the study and for 7 months after study drug treatment. These
        methods include hormonal contraceptives, intrauterine device, or double barrier
        contraception (i.e., condom + diaphragm) or a male partner with documented vasectomy.

        Non-childbearing potential is defined as post-menopausal for at least 1 year or surgical
        sterilization or hysterectomy at least 3 months before study start.

        Exclusion Criteria:

          1. Bilateral breast cancer.

          2. Pregnancy or lactation or considering becoming pregnant.

          3. Metastases, other than sentinel/axillary lymph nodes.

          4. Previous treatment (chemotherapy, biologic therapy, radiation, or surgery) for
             invasive malignant disease or other concomitant malignancy, other than basal cell
             carcinoma of the skin. Previous treatment for carcinoma in situ of the cervix is
             allowed.

          5. Previous treatment with Herceptin.

          6. Angina pectoris or arrhythmia requiring medication; poorly controlled hypertension;
             history of myocardial infarction or cardiac failure, New York Heart Association (NYHA)
             class II or higher; clinically significant cardiac valvular disease; hemodynamic
             effective pericardial effusion; other cardiomyopathies; LVEF of <55%.

          7. Any investigational treatment less than 30 days prior to study entry, or within a time
             interval less than at least 5 half-lives of the investigational medicinal product,
             whichever is longer.

          8. Positive diagnostic test for hepatitis B virus (HBV), hepatitis C virus (HCV), or
             human immunodeficiency virus (HIV).

          9. History of hypersensitivity to drugs with similar chemical structures to trastuzumab.

         10. History of, or known current problems with, drug or alcohol abuse.

         11. Other serious illness, medical disorder or condition that, in the opinion of the
             Investigator, would make the patient unsuitable for participation in the study.