The purpose of this study is to evaluate the effectiveness of ProstAtak® immunotherapy in combination with radiation therapy for patients with intermediate-high risk localized prostate cancer. ProstAtak kills tumor cells and stimulates a cancer vaccine effect. Killing tumor cells in an immune stimulatory environment induces the body's immune system to detect and destroy cancer cells. ProstAtak has shown synergy with radiation without added toxicity and lower than expected recurrence rates in previous clinical trials. The hypothesis is that ProstAtak can lead to improvement in the clinical outcome for patients with prostate cancer. Participants will be randomized to the ProstAtak or control arm at a 2:1 ratio. Both arms receive standard external beam radiation therapy. Short-term androgen deprivation therapy may be given but is not required.

Inclusion Criteria include:

• Localized prostate cancer meeting the NCCN criteria of Intermediate Risk or patients having only one NCCN high-risk feature

  • NCCN Intermediate Risk is defined as having at least one of the following: PSA 10-20 ng/ml, Gleason score =7, T2b-T2c
  • High Risk with a single high risk feature is defined as having only one of the following: PSA>20 ng/ml, Gleason score 8-10, or T3a
  • Excluded are those in the following risk groups: Low risk; High risk with more than 1 high risk factor; Locally advanced/very high risk=T3b-T4; Metastatic: N1 or M1

• Planning to undergo standard prostate-only external beam radiation therapy

• ECOG Performance Status 0-2

Exclusion Criteria include:

• Liver disease, including known cirrhosis or active hepatitis
• Patients on systemic corticosteroids (>10mg prednisone per day) or other immunosuppressive drugs
• Known HIV+ patients
• Regional lymph node involvement or distant metastases
• Patients planning to receive whole pelvic irradiation
• Prior treatment for prostate cancer, except TURP or ADT. For ADT, it may only be given for a maximum of 6 months
• Patients who had or plan to have orchiectomy as the form of hormonal ablation
• Known sensitivity or allergic reactions to acyclovir or valacyclovir