Inclusion Criteria

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 corticosteroids 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
started < 2 months before first planned AdV-tk or placebo injection and 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