Inclusion Criteria:

1. Histologic diagnosis (recent or remote) of prostate adenocarcinoma.

2. Progressive, castrate metastatic carcinoma of the prostate defined by presence of
metastatic disease on imaging and:

- progressive tumor lesions on CT or MRI and/or

- new osseous lesions on bone scan and/or

- rising PSA

3. Rising PSA on 3 serial determinations over a period of ≥ 2 weeks.

4. If patient is being treated with an LHRH analog, the drug:

- must be maintained for the duration of this study or

- must be terminated ≥ 10 weeks prior to entry (for 28 day depot preparations) or
24 weeks (for 3 month depot preparations) or 32 weeks (for 4 month depot
preparation).

5. Platelet count > 150,000/mm3.

6. Absolute neutrophil count (ANC) ≥ 2,000/mm3

7. Normal coagulation profile (PT, PTT), unless on a stable anticoagulation regimen

8. Hematocrit > 30% or Hemoglobin > 10g/dL without blood transfusion dependency

9. Patients of child bearing potential must agree to use an effective method of
contraception.

10. Patient must have progressed following discontinuation of anti-androgen therapy, if
received.

11. Serum testosterone < 50 ng/ml.

Exclusion Criteria:

1. Prior aspirin and/or non-steroidal anti-inflammatory agents within 1 week of study
treatment.

2. Prior corticosteroids and/or adrenal hormone inhibitors within 4 weeks of treatment,
except for low dose maintenance prednisone or hydrocortisone (i.e. for adrenal
insufficiency) on a stable dose at the investigator's discretion.

3. Prior cytotoxic chemotherapy and/or radiation therapy within 4 weeks of treatment.

4. Prior radiation therapy encompassing >25% of expected red marrow distribution.

5. Prior treatment with 89Strontium (Metastron®) or 153Samarium (Quadramet®). CNS
metastasis.

6. History of seizure and/or stroke within past 2 years

7. History of HIV

8. Serum creatinine > 2.0

9. SGOT > 2x ULN

10. Bilirubin (total) >1.5x ULN

11. Serum calcium > 12.5

12. Active infection

13. Active angina pectoris or NY Heart Association Class III-IV.

14. Karnofsky Performance Status < 60; ECOG Performance Status > 2.

15. Life expectancy < 6 months

16. Other serious illness(es) involving the cardiac, respiratory, CNS, renal, hepatic or
hematological organ systems which might preclude completion of this study or
interfere with determination of causality of any adverse effects experienced in this
study.

17. Prior treatment with monoclonal Ab J591 labeled with therapeutic doses of 177Lu or
90Y

18. Other investigational therapy within 4 weeks of treatment