Capecitabine and Oxaliplatin in Treating Patients With Metastatic Breast Cancer

In vitro data suggest synergy between oxaliplatin and 5-FU. The combination of oxaliplatin with 5-fluorouracil produced objective response rates ranging from 27-34% in two studies of patients with prior chemotherapy. Capecitabine was designed as an orally administered, tumor selective fluoropyrimidine, preferentially converted to 5-FU at the tumor site by the higher levels of pyrimidine nucleoside phosphorylase (PyNPase) in tumor tissues compared to normal tissues. The end result is higher concentrations of 5-fluorouracil in tumor relative to surrounding normal tissue. This trial will investigate the activity of this novel capecitabine/oxaliplatin (CAPOX) combination in patients with advanced disease. In addition, an exploratory analysis will correlate response with thymidine synthase and thymidine phosphorylase expression in primary tumor samples.

OUTLINE: This is a multi-center study. CAPOX (21 day cycle): * Capecitabine 825 mg/m2 orally twice daily Days 1-14. * Oxaliplatin 100 mg/m2 intravenously Day 1 Patients may continue combination therapy until progression or toxicity intervenes. Patients who discontinue either agent due to toxicity may, at the investigators discretion, continue therapy with the remaining single agent on study. 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.