Sorafenib in Treating Patients With Metastatic or Recurrent Prostate Cancer

DISEASE CHARACTERISTICS: Histologically confirmed adenocarcinoma of the prostate Metastatic or recurrent disease No curative standard therapy exists Hormone-refractory disease Evidence of prostate-specific antigen (PSA) progression during androgen ablation therapy, including medical or surgical castration Documented PSA progression after completion of prior peripheral anti-androgens At least a 25% increase (≥ 5 ng/mL) over a reference value PSA with 2 consecutive rising PSAs taken ≥ 1 week apart Castrate level of testosterone ≤ 1.7 nmol/L for patients on medical androgen ablation Patients receiving luteinizing hormone-releasing hormone agonist therapy must continue this treatment during study participation PSA ≥ 10 ng/mL at the time of study entry Primary tumor tissue (paraffin embedded) must be available for immunohistochemistry Minimal symptomatic disease No requirement for morphine or equivalent dose > 30 mg/day to control pain No known brain metastases PATIENT CHARACTERISTICS: Age 18 and over Performance status ECOG 0-1 Life expectancy At least 12 weeks Hematopoietic Absolute granulocyte count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 No evidence of bleeding diathesis Hepatic Bilirubin normal AST and ALT ≤ 2.5 times upper limit of normal Renal Serum creatinine normal OR Creatinine clearance ≥ 60 mL/min Cardiovascular No myocardial infarction within the past 6 months No congestive heart failure No unstable angina No active cardiomyopathy No unstable ventricular arrhythmia No uncontrolled hypertension Other No serious infection No active peptic ulcer disease No upper gastrointestinal or other condition that would preclude study compliance with oral medication No uncontrolled psychotic disorder No history of allergic reaction attributed to compounds of similar chemical or biologic composition to sorafenib or other study agents No other serious illness or medical condition that would preclude study participation No other malignancy within the past 5 years except adequately treated non-melanoma skin cancer or other curatively treated solid tumor PRIOR CONCURRENT THERAPY: Biologic therapy Concurrent prophylactic filgrastim (G-CSF), sargramostim (GM-CSF), or other growth factors allowed for the management of adverse events only Chemotherapy No prior chemotherapy No other prior cytotoxic chemotherapy Endocrine therapy See Disease Characteristics Concurrent steroids allowed provided there has been no increase in steroid requirements within the past 4 weeks AND no increase in dose is planned Radiotherapy At least 4 weeks since prior external-beam radiotherapy except low-dose non-myelosuppressive radiotherapy Concurrent low-dose non-myelosuppressive palliative radiotherapy allowed Surgery Not specified Other No prior investigational anticancer agents No concurrent therapeutic anticoagulation Concurrent prophylactic low-dose warfarin for venous or arterial access devices allowed No concurrent combination antiretroviral therapy for HIV-positive patients No other concurrent anticancer therapy No other concurrent investigational therapy No concurrent grapefruit juice Concurrent bisphosphonates allowed