Irinotecan and Capecitabine in Treating Women With Advanced Breast Cancer

OBJECTIVES: * Determine the maximum tolerated dose of capecitabine and irinotecan in women with advanced breast cancer. * Determine the degree of accumulation of cells in S-phase in tumor biopsies from patients treated with this regimen. * Determine the dose-limiting toxicity and other major or unusual toxic effects of this regimen in these patients. * Determine any antitumor activity of this regimen in these patients. * Determine the pharmacokinetics of this regimen, including the active metabolite SN-38, in these patients. * Correlate pharmacokinetic parameters of this regimen with the biological changes observed in these patients. * Determine, preliminarily, the relationship of tumor response with modulation of S-phase in patients treated with this regimen. OUTLINE: This is a dose-escalation study. Patients receive irinotecan IV over 1.5 hours on days 1, 8, 22, and 29 and oral capecitabine twice daily on days 1-14 and 23-36. Treatment continues in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients receive escalating doses of irinotecan and capecitabine until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 3 or 2 of 6 patients experience dose-limiting toxicity. PROJECTED ACCRUAL: A total of 8-37 patients will be accrued for this study within 18-24 months.