A Prospective, Randomized Multicenter, Open-label Comparison of Preoperative Trastuzumab Emtansine (T-DM1) With or Without Standard Endocrine Therapy vs. Trastuzumab With Standard Endocrine Therapy Given for Twelve Weeks in Patients With Operable HER2+/HR+ Breast Cancer Within the ADAPT Protocol. (ADAPT; T-DM1)

Inclusion Criteria:

• Female patients, age at diagnosis 18 - 75 years
• Histologically confirmed unilateral primary invasive carcinoma of the breast
• Clinical T1 - T4 (except inflammatory breast cancer)
• All clinical N (cN)
• No clinical evidence for distant metastasis (M0)
• Known HR status and HER2 status (local pathology) Tumor block available for central pathology review
• Performance Status ECOG ≤ 1 or KI ≥ 80%
• Negative pregnancy test (urine or serum) within 7 days prior to start of inducion treatment in premenopausal patients
• Written informed consent prior to beginning specific protocol procedures, including expected cooperation of the patients for the treatment and follow-up, must be obtained and documented according to the local regulatory requirements
• The patient must be accessible for treatment and follow-up

Additional Inclusion criteria for participation in the HER2+/HR+ sub-protocol:

• Confirmed ER and/or PR positive and HER2+ by central pathology
• Clinical cT1c - T4a-c (participation of patients with tumors >cT2 is strongly recommended)
• All clinical N (participation of patients with cN0, if cT1c is strongly recommended)
• Patients must qualify for neoadjuvant treatment
• LVEF > 50%; LVEF within normal limits of each institution measured by echocardiography and normal ECG (within 42 days prior to induction treatment)

Exclusion Criteria:

• Known hypersensitivity reaction to the compounds or incorporated substances
• Prior malignancy with a disease-free survival of < 10 years, except curatively treated basalioma of the skin, pTis of the cervix uteri
• Non-operable breast cancer including inflammatory breast cancer
• Previous or concurrent treatment with cytotoxic agents for any reason after consultation with the sponsor
• Concurrent treatment with other experimental drugs. Participation in another clinical trial with any investigational not marketed drug within 30 days prior to study entry
• Male breast cancer
• Concurrent pregnancy; patients of childbearing potential must implement
• a highly effective (less than 1% failure rate) non-hormonal contraceptive measures during the study treatment
• Breast feeding woman
• Sequential breast cancer
• Reasons indicating risk of poor compliance Patient not able to consent

Additional Exclusion Criteria for participation in the HER2+/HR+ sub-protocol:

• Known polyneuropathy ≥ grade 2
• Severe and relevant co-morbidity that would interact with the application of cytotoxic agents or the participation in the study
• Inadequate organ function (e.g. hepatic impairment, pulmonary disease, etc.)
• Uncompensated cardiac function (current unstable ventricular arrhythmia
• requiring treatment, history of symptomatic CHF NYHA classes II-IV), history of myocardial infarction or unstable angina pectoris within 6 months of enrollment, history of severe hypertension, CAD - coronary artery disease)
• Severe dyspnea
• Pneumonitis

Abnormal blood values:

• Thrombocytopenia > CTCAE grade 1
• Increases in ALT/AST > CTCAE grade 1
• Hypokalaemia > CTCAE grade 1
• Neutropenia > CTCAE grade 1
• Anaemia > CTCAE grade 1