DISEASE CHARACTERISTICS:

• Histologically confirmed metastatic adenocarcinoma of the prostate

• Unresponsive or refractory to hormonal therapy, as defined by at least 1 of the following criteria:

  • Progression of bidimensionally measurable disease
  • Progression of evaluable but not measurable disease (bone scan)
  • At least 2 consecutive rises in PSA and a PSA level of at least 5 ng/mL
• No minimum PSA required for measurable disease or non-PSA evaluable disease
• Soft tissue disease that has been irradiated within the past 2 months is not considered measurable disease
• Prior orchiectomy OR

• Medical castration using leuprolide or goserelin

  • LHRH agonist therapy must continue during study
• Prior nonsteroidal antiandrogens (flutamide, ketoconazole, bicalutamide, or nilutamide) allowed if disease progression occurred
• No third-space fluid accumulation such as ascites or symptomatic pleural effusion
• No brain metastases

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• SWOG 0-3
• Performance status 3 must be due to pain secondary to bone metastases

Life expectancy:

• Not specified

Hematopoietic:

• No hypercoagulability

Hepatic:

• Not specified

Renal:

• Creatinine no greater than 2.0 mg/dL

Cardiovascular:

• No history of myocardial infarction
• No history of congestive heart failure unless well controlled
• No history of cerebrovascular accident or atrial fibrillation
• No active thrombophlebitis
• LVEF at least 50% by MUGA scan or 2-D echocardiogram

Pulmonary:

• No history of pulmonary embolus

Other:

• Recovered from major infections
• No other significant active medical illness
• No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or stage I or II cancer currently in complete remission

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 4 weeks since prior biologic therapy and recovered
• No more than 1 prior biologic therapy regimen
• No concurrent biological response modifiers

Chemotherapy:

• At least 4 weeks since prior chemotherapy and recovered
• No more than 1 prior chemotherapy regimen
• No prior estramustine, taxanes, anthracyclines, or mitoxantrone
• No other concurrent chemotherapy

Endocrine therapy:

• See Disease Characteristics
• At least 4 weeks since prior flutamide or ketoconazole (6 weeks for bicalutamide or nilutamide)
• No concurrent corticosteroids or hormonal therapy (except megestrol for hot flashes or continuing LHRH treatment)

Radiotherapy:

• See Disease Characteristics
• Prior samarium Sm 153 lexidronam pentasodium allowed
• At least 4 weeks since prior radiotherapy and recovered
• No prior radiotherapy to 30% or more of bone marrow
• No prior strontium chloride Sr 89
• No concurrent radiotherapy

Surgery:

• See Disease Characteristics
• At least 3 weeks since prior surgery and recovered

Other:

• At least 4 weeks since prior bisphosphonates
• No prior anticoagulation therapy (i.e., warfarin), except aspirin
• No concurrent bisphosphonates