DISEASE CHARACTERISTICS: Histologically or cytologically confirmed prostate carcinoma Metastatic disease Documented progression of prostate cancer while receiving androgen ablative therapy (i.e., surgical or chemical castration and a serum testosterone level in the castrate range) Documented hormone therapy resistance defined as: PSA rise on 3 occasions not less than 4 weeks apart Any evidence of progressive measurable disease PSA must be above 20 ng/mL prior to study entry No brain metastases

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Hemoglobin at least 9.0 g/dL Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL SGOT/SGPT no greater than 2 times upper limit of normal (ULN) (5 times ULN if liver metastases present) Renal: Creatinine no greater than 1.5 mg/dL Cardiovascular: No active congestive heart failure No uncontrolled angina No myocardial infarction within the past 6 months Other: Fertile patients must use effective contraception No uncontrolled pain requiring irradiation No concurrent serious infection No other malignancy within the past 5 years except nonmelanoma skin cancer No overt psychosis, mental disability, or incompetence

PRIOR CONCURRENT THERAPY: Biologic therapy: No prophylactic colony stimulating factors to prevent neutropenia No concurrent biologic therapy Chemotherapy: No more than 1 prior cytotoxic chemotherapy regimen No concurrent cytotoxic chemotherapy Endocrine therapy: See Disease Characteristics At least 6 weeks since prior peripheral antiandrogens (e.g., flutamide) No concurrent steroid therapy initiated within past 2 months Current LHRH agonist therapy should continue through study Radiotherapy: At least 4 weeks since prior radiotherapy (except low dose, non myelosuppressive) and recovered No prior irradiation to greater than 25% of bone marrow No prior strontium chloride Sr 89 or samarium Sm 153 lexidronam pentasodium No concurrent radiotherapy Surgery: See Disease Characteristics At least 4 weeks since prior major surgery and recovered No concurrent surgery Other: No other concurrent anticancer treatment At least 28 days since investigational drugs, including analgesics or antiemetics No other investigational drugs during and for 28 days after study No concurrent drugs that induce or inhibit CYP3A enzyme No concurrent herbal preparations (e.g., PC-SPES)