Inclusion Criteria:

- Completed a full course of radiation therapy for prostate cancer at least 2 years
before enrollment.

- Biochemical failure at screening as determined by either the ASTRO or the Phoenix
definitions.

- At least 5 available PSA readings after completion of radiation therapy and prior to
screening.

- PSA level of not greater than 10 ng/mL.

- PSA doubling time of at least 9 months at screening.

- Biopsy-proven recurrent localized prostate cancer.

- Tumor stage T1C to T2C.

- Prostate volume estimated at 40 mL or less as determined by TRUS.

- ECOG performance score 0 to 2.

- Serum testosterone of at least 1 ng/dL.

Exclusion Criteria:

- Prior history of metastatic prostate cancer.

- Salvage external beam therapy and/or salvage brachytherapy prior to enrollment.

- Biological, immunological, chemotherapeutic treatment or cryotherapy after completing
radiation.

- Androgen ablation therapy within 12 months prior to enrollment.

- Recurrence of prostate cancer within 18 months of definitive primary radiotherapy.

- Other medication for prostate cancer.

- Presence of active malignancy other than prostate cancer.

- Treatment with other investigational therapies within 12 months prior to enrolment.

- Presence of a chronic indwelling Foley catheter for obstructive uropathy.

- Previous transurethral resection of the prostate (TURP), transurethral resection of
the bladder neck, photo-selective vaporization of the prostate (PVP) or other
resection surgery in the urinary tract.

- Previous treatment with PRX302.

- Any evidence of metastatic disease on bone scan, CT or magnetic resonance imaging
(MRI) within 3 months prior to enrollment.