PROSTVAC-VF is an investigational cancer vaccine. The vaccine is based on the theory that the immune system can be taught to fight cancer by directing the immune system to attack specific targets found on cancer cells. These targets are called Tumor Associated Antigens, or TAA's. This trial will help determine if this vaccine can help fight cancer.

This multi-center, double-blind, randomized, empty vector-controlled trial is designed to evaluate the safety and efficacy of PROSTVAC-VF/TRICOM co-administered with GM-CSF versus the empty viral vector co-administered with placebo in the treatment of patients with androgen-independent prostate cancer (AIPC).

All patients will be required to sign an informed consent prior to the performance of any on-study procedures. Patients will be screened for eligibility within 14 days prior to vaccine administration. Patients who meet all inclusion and exclusion criteria will be centrally randomized into the study and will receive a unique patient identification number and a blinded treatment assignment. The ratio of active treatment to empty vector control (placebo) is 2:1.

• Male patients > 18 years of age who have been vaccinated against smallpox;
• Histological confirmation of adenocarcinoma of the prostate with evidence of metastatic disease including either of the following: Lymph node metastasis measurable by CT and/or Bone metastasis evaluable by bone scan;
• Despite hormone therapy, there is evidence of two consecutive increases in PSA (Prostate Specific Antigen);
• Gleason Score of 7 or lower at initial diagnosis.

Please note that there are additional eligibility criteria that you must meet to qualify.

If you do qualify to participate, study personnel will explain the trial in detail and answer any questions you may have. You can then decide whether or not you wish to participate. If you do not qualify for the trial, study personnel will explain the reasons.