Mitoxantrone and G-CSF in Treating Patients With Metastatic Prostate Cancer

OBJECTIVES: I. Study the effectiveness of mitoxantrone in patients with metastatic, hormone refractory prostate cancer. II. Assess the side effects of mitoxantrone in this patient population. III. Determine whether filgrastim (granulocyte colony-stimulating factor; G-CSF) treatment can overcome chronic bone marrow suppression and facilitate a dose intensive mitoxantrone chemotherapy regimen in this patient population. OUTLINE: This is a dose escalation study. Patients receive a 30 minute intravenous infusion of mitoxantrone once a week on day 1. On days 2-6 of each week, patients receive subcutaneous filgrastim (granulocyte colony-stimulating factor; G-CSF). Treatment continues for patients who respond to therapy and exhibit no disease progression. Dose escalation proceeds until the maximum tolerated dose (MTD) of mitoxantrone with G-CSF support is determined. The MTD is defined as the dose preceding that at which 2 or more patients experience dose limiting toxicity. After the MTD is determined, an additional 20-40 patients are enrolled at this dose level to examine their response to this therapy. PROJECTED ACCRUAL: Approximately 12-24 patients will be accrued for the phase I portion of this protocol. An additional 20-40 patients may be accrued for the phase II portion of this study.