Vaccine Therapy Plus Interleukin-12 in Treating Patients With Metastatic Prostate Cancer That Has Not Responded to Hormone Therapy

DISEASE CHARACTERISTICS:

* Histologically confirmed metastatic adenocarcinoma of the prostate
* HLA-A2 positive
* Progressive measurable systemic disease

  * PSA at least 5 ng/mL with 2 consecutive rising PSA levels at least 1 week apart and no measurable disease OR
  * Objective evidence of disease progression by a 20% increase in the sum of longest diameter of all target lesions or evidence of new lesions by CT or bone scan regardless of PSA status
  * Lesions must be at least 1 cm to be considered measurable
  * Progressive systemic disease after discontinuation of anti-androgen therapy
* Previously treated with orchiectomy (testosterone less than 50 ng/mL) OR luteinizing hormone-releasing hormone (LHRH) analogue therapy with or without anti-androgens

  * If on LHRH analogue therapy, must continue therapy during study
* Brain metastases allowed if previously treated, clinically stable, and weaned from prior corticosteroids

PATIENT CHARACTERISTICS:

Age:

* Over 18

Performance status:

* Karnofsky 70-100%

Life expectancy:

* At least 12 weeks

Hematopoietic:

* Absolute neutrophil count greater than 1,500/mm\^3
* Hemoglobin greater than 9 g/dL
* Platelet count greater than 100,000/mm\^3
* No active gastrointestinal bleeding

Hepatic:

* Bilirubin less than 1.5 times upper limit of normal (ULN)
* SGPT normal
* Hepatitis B surface antigen negative

Renal:

* Creatinine less than 1.5 times ULN
* Calcium less than 11 mg/dL

Cardiovascular:

* No significant cardiovascular disease
* No cardiac arrhythmia requiring therapy

Other:

* Fertile patients must use effective barrier contraception
* No intrinsic immunosuppression
* HIV negative
* No serious concurrent infection
* No psychiatric illness that would preclude study compliance
* No clinically significant autoimmune disease
* No uncontrolled peptic ulcer disease
* No history of inflammatory bowel disease

PRIOR CONCURRENT THERAPY:

Biologic therapy:

* At least 4 weeks since prior biologic therapy

Chemotherapy:

* Not specified

Endocrine therapy:

* See Disease Characteristics
* At least 4 weeks since prior flutamide
* At least 6 weeks since prior bicalutamide or nilutamide
* No concurrent systemic corticosteroids except physiologic replacement doses

Radiotherapy:

* Not specified

Surgery:

* See Disease Characteristics

Other:

* No concurrent immunosuppressive drugs (e.g., cyclosporine)