Trastuzumab and Flavopiridol in Treating Patients With Metastatic Breast Cancer

PRIMARY OBJECTIVES: I. To evaluate the safety and tolerability of flavopiridol in combination with Herceptin in HER-2 positive metastatic breast cancer. SECONDARY OBJECTIVES: I. To determine the dose of flavopiridol necessary to achieve a target plasma level of 300-500 nM of flavopiridol in combination with a fixed dose of Herceptin. II. To assess the feasibility of measuring cyclin D1 in circulating tumor cells and tissue biopsies before and after therapy as a surrogate marker of flavopiridol activity. III. To monitor target activity of flavopiridol and Herceptin in plasma, circulating tumor cells and tissue biopsies from breast cancer patients. OUTLINE: This is a multicenter, dose-escalation study of flavopiridol. Patients receive trastuzumab (Herceptin) IV over 30-90 minutes on days 1, 8, and 15 followed by flavopiridol IV continuously over 24 hours on days 1 and 8. Courses repeat every 21 days in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients receive escalating doses of flavopiridol until the maximum tolerated dose is determined (MTD). The MTD is defined as the dose preceding that at which 2 of 3 or 2 of 6 patients experience dose-limiting toxicity. Once the MTD is determined, an additional cohort of 10 patients receives flavopiridol at the MTD and trastuzumab on the once weekly schedule to assess the true toxicity rate. A second cohort of 10 patients receives flavopiridol at the MTD and trastuzumab once every 21 days to assess the tolerability of this schedule. PROJECTED ACCRUAL: A total of 30-50 patients will be accrued for this study.