Capecitabine, Oxaliplatin and Trastuzumab in Treating Patients With HER2 Positive Metastatic Breast Cancer

OUTLINE: This is a multi-center study. * CAPOX-T (21 day cycle):Capecitabine 825 mg/m2 orally twice daily Days 1-14Oxaliplatin 100 mg/m2 intravenously Day 1 * Trastuzumab : 6 mg/kg intravenously Day 1.8mg/kg loading dose should be given in cycle 1 for patients without previous trastuzumab therapy only. Patients may continue combination therapy until progression or toxicity intervenes. Patients who discontinue either or both cytotoxic agents due to toxicity may, at the investigators discretion, continue therapy with the remaining agents on study until progressive disease ECOG performance status 0 or 1 Hematopoietic:· * ANC \> 1,200/mm3· * Platelets \> 100,000/mm3 Hepatic:· * Total bilirubin \< 1.5 x ULN· * AST \< 2 x ULN (up to 5 x ULN in patients with known liver involvement) Renal:· * Serum creatinine \< 1.5 x ULN and estimated creatinine clearance \>50ml/min as calculated with Cockroft-Gault equation Cardiovascular:· * No clinically significant cardiac disease (e.g. congestive heart failure, symptomatic coronary artery disease and cardiac arrhythmias not well controlled with medication) or myocardial infarction within the last 12 months.· * LVEF \> LLN by MUGA or ECHO