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