Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed prostate cancer

- Disease progression after primary surgery (radical prostatectomy) or radiotherapy
with or without prior neoadjuvant androgen ablation

- Minimum of 3 rising PSA values, taken at least 2 weeks apart, with more than a
50% rise in PSA level above the baseline value (1.0 ng/mL post -prostatectomy or
2.0 ng/mL post-radiotherapy)

- Received prior intermittent hormonal therapy after prior primary therapy

- Non-castrate levels of testosterone (more than 50 ng/mL)

- Evaluable disease (by serial changes in PSA)

- No radiographic evidence of metastatic disease

- No active CNS or epidural tumor

- No soft tissue and/or bone disease

- No androgen-independence with no evidence of radiographic disease

- May not be symptomatic or anticipated to develop symptoms within 6 months of study
entry

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- Karnofsky 70-100%

Life expectancy:

- At least 6 months

Hematopoietic:

- WBC at least 3,500/mm^3

- Platelet count at least 100,000/mm^3

Hepatic:

- Bilirubin less than 2.0 mg/dL

- SGOT less than 3 times upper limit of normal

Renal:

- Creatinine no greater than 2.0 mg/dL OR

- Creatinine clearance at least 40 mL/min

Cardiovascular:

- No clinically significant cardiac disease (New York Heart Association class III or
IV)

Pulmonary:

- No severe debilitating pulmonary disease

Other:

- No allergy to seafood (shellfish)

- No other active malignancy within the past 5 years except nonmelanoma skin cancer

- No infection requiring antibiotics

- No narcotic-dependent pain

- No positive stool guaiac unless associated with hemorrhoids or prior documented
radiation-induced proctitis

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- Not specified

Chemotherapy:

- At least 4 weeks since prior chemotherapy

Endocrine therapy:

- See Disease Characteristics

- See Chemotherapy

- At least 2 weeks since change in hormonal therapy (e.g., prednisone or dexamethasone)
except to maintain castrate levels of testosterone

Radiotherapy:

- See Disease Characteristics

- At least 4 weeks since prior radiotherapy

- No concurrent irradiation of only measurable lesion

Surgery:

- See Disease Characteristics

- No concurrent surgery of only measurable lesion

Other:

- Recovered from prior therapy

- At least 8 weeks since prior suramin and/or documented plasma concentration of
suramin if less than 50 micrograms/mL (replacement hydrocortisone allowed)

- No other concurrent oncolytic agents

- No concurrent immunosuppressive therapy