Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed adenocarcinoma of the prostate

- Progressive disease after androgen deprivation AND meets 1 of the following criteria:

- Measurable disease

- Measurable lesions ≥ 10 mm with spiral CT

- Up to 5 lesions per organ and 10 lesions total should be identified as
target lesions

- No measurable disease

- Patients with prostate-specific antigen (PSA)-only disease must have an
elevated PSA

- PSA evidence for progressive disease consists of a PSA level of ≥ 5
ng/mL that has risen on ≥ 2 successive occasions, ≥ 2 weeks apart

- Patients with a positive bone scan must also have an elevated PSA

- Patients who received prior antiandrogen as a part of primary androgen ablation
therapy must demonstrate disease progression after discontinuation of the
antiandrogen

- Disease progression after antiandrogen withdrawal is defined as 2 consecutive
rising PSA values obtained ≥ 2 weeks apart, or documented osseous or soft tissue
progression

- Patients receiving flutamide must have had ≥ 1 of the PSA values obtained ≥
4 weeks after flutamide discontinuation

- Patients receiving bicalutamide or nilutamide must have had ≥ 1 of the PSA
values obtained ≥ 6 weeks after antiandrogen discontinuation

- Testosterone < 50 ng/dL

- PSA ≥ 5 ng/mL

PATIENT CHARACTERISTICS:

- Karnofsky performance status 60-100%

- No serious intercurrent infections or nonmalignant uncontrolled medical illnesses

- No psychiatric illnesses OR social situations that would limit compliance

- No active or uncontrolled autoimmune disease

- ALT and AST normal

- Bilirubin normal

- Absolute neutrophil count ≥ 1,500/mm³

- Platelet count ≥ 100,000/mm³

- Creatinine ≤ 1.5 times upper limit or normal (ULN)

- Hemoglobin ≥ 8 g/dL

- No other currently active malignancy except for nonmelanoma skin cancer

- No currently active malignancy defined as therapy completed with ≤ 30% risk of
relapse

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- Patients must continue primary androgen deprivation therapy with a
luteinizing-hormone releasing-hormone (LHRH) analogue if they have not undergone
orchiectomy

- No prior systemic chemotherapy for prostate cancer

- All other systemic chemotherapy must have been completed ≥ 2 years prior to
study

- No other concurrent chemotherapy, immunotherapy, or radiotherapy

- Major surgery or radiation therapy completed ≥ 4 weeks prior to study

- No other concurrent corticosteroids, including routine use antiemetics

- No prior ketoconazole, aminoglutethimide, or corticosteroids for treatment of
progressive prostate cancer

- No prior immunotherapy (e.g., vaccines or sargramostim GM-CSF)

- Patients receiving any other hormonal therapy (e.g., megestrol, finasteride, herbal
product known to decrease PSA levels [e.g., saw palmetto or PC-SPES], or any systemic
corticosteroid) must discontinue the agent ≥ 4 weeks prior to enrollment and
progressive disease must be documented after discontinuation

- No initiation of bisphosphonate therapy within 1 month prior to starting study
therapy

- Patients on stable doses that show tumor progression are allowed to continue
bisphosphonate

- No concurrent supplements or complementary medicines/botanicals, except any
combination of the following:

- Conventional multivitamin supplements

- Selenium

- Lycopene

- Soy supplements

- Vitamin E

- At least 8 weeks since prior radiopharmaceuticals (strontium chloride Sr 89, samarium
Sm 153 lexidronam pentasodium)

- No other concurrent investigational or commercial anticancer agents or therapies