NeoMET Study in Neoadjuvant Treatment of Breast Cancer

Inclusion Criteria: * women aged ≥18 years and \< 70 years with life expectancy \> 12 months * Measurable disease in breast or axillary lymph node, histologically confirmed invasive breast cancer by core needle biopsy, T≥2cm or stage IIb or stage III according AJCC classification, fine-needle aspiration is encouraged to every patient with metastasis suspicious nodes; * Biopsy specimens are available for ER, PgR, Her2 and proliferation biomarker detection; * Adequate bone marrow function: Neutrophil ≥ 1.5\*109/L; Hb ≥ 100g/L; PLT ≥ 80\*109/L; * Adequate liver and renal function: * Serum AST ≤ 90U/L * Bilirubin ≤ upper limit of normal (UNL) range * Serum creatinine ≤110 umol/L，calculated creatinine clearance should be ≥ 60 mL/min; * BUN ≤ 7.1mmol/L; * Has ECOG Performance Score 0-1; * BMI ≥ 25kg/m2 or hyperglycemia or hyperlipemia or hypertension; * Willing to take biopsy before neoadjuvant chemotherapy and patients must be accessible for treatment and follow-up; * Women with potential child-bearing must have a negative pregnancy test (urine or serum) within 7 days of drug administration and agree to use an acceptable method of birth control to avoid pregnancy for the duration of the study; * Written informed consent according to the local ethics committee requirements. Exclusion Criteria: * Prior systemic or loco-regional treatment of breast cancer, including chemotherapy; * Metastatic breast cancer; * With a history of malignant tumor except uterine cervix cancer in situ or skin basal cell carcinoma; * Patients with medical conditions that indicate intolerant to neoadjuvant therapy and related treatment, including uncontrolled pulmonary disease, severe infection, active peptic ulcer, coagulation disorder, connective tissue disease or myelo-suppressive disease; * Has active hepatitis B or hepatitis C with abnormal liver function tests (LFTs) or is known to be HIV positive; * Contraindication for using dexamethasone, chemotherapy agents or metformin; * History of congestive heart failure, uncontrolled or symptomatic angina pectoris, arrhythmia or myocardial infarction; poorly controlled hypertension (systolic BP \>180mmHg or diastolic BP \>100mmHg); * Has peripheral neuropathy ≥ grade 1; * Patient is pregnant or breast feeding (not willing to stop breast feeding); * Not willing to take core needle biopsy or patients with psychiatric disorder or other diseases leading to incompliance to the therapy * Known severe hypersensitivity to any drugs in this study; * Treatment with any investigational drugs within 30 days before the beginning of study treatment. * History of lactic or other metabolic acidosis * Consumption of \> 3 alcoholic beverages per day (on average)