CLINICAL TRIAL / NCT02768363

Inclusion Criteria include: - Histologically confirmed adenocarcinoma of the prostate - Patients choosing active surveillance - Patients meeting definition of NCCN low risk, intermediate risk OR patients having only one NCCN high-risk feature - NCCN Low Risk is defined as having all of the following: PSA < 10 ng/ml, Gleason ≤ 6, T1-T2a - NCCN Intermediate Risk is defined as having at least one of the following and no high risk features: 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: High risk with more than 1 high risk factor; Locally advanced/very high risk=T3b-T4; Metastatic: N1 or M1 - Patients must be planning and medically able to tolerate multiple transrectal ultrasound guided injections. - ECOG Performance status 0-2 Exclusion Criteria include: - Active liver disease, including known cirrhosis or active hepatitis - Patients on systemic corticosteroids (>10 mg prednisone per day) or other immunosuppressive drugs - Known HIV+ patients - Regional lymph node involvement or distant metastases - Other current malignancy (except squamous or basal cell skin cancers) - Other serious co-morbid illness or compromised organ function that, in the opinion of the investigator, would interfere with treatment or follow up - Prior treatment for prostate cancer except TURP. If prior TURP, patients must be deemed able to receive prostate biopsy and multiple intra-prostatic injections by the investigator - Patients taking 5-alpha-reductase inhibitors (e.g. finasteride, dutasteride) - Patients who had or plan to use ADT or have history of an orchiectomy. - Patients who are planning to undergo radical treatment for prostate cancer within 12 months. - Known sensitivity or allergic reactions to acyclovir or valacyclovir