Phase 3 Study of ProstAtak® Immunotherapy With Standard Radiation Therapy for Localized Prostate Cancer (PrTK03)

A Randomized Controlled Trial of ProstAtak® as Adjuvant to Up-front Radiation Therapy For Localized Prostate Cancer

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.

Study Overview

• Status: Active, not recruiting
• Conditions: Prostate Cancer
• Intervention / Treatment: Biological: Aglatimagene besadenovec + valacyclovir; Biological: Placebo + valacyclovir

• Study Type: Interventional
• Enrollment (Estimated): 711
• Phase: Phase 3

Contacts and Locations

Study Locations

• Puerto Rico
  • San Juan, Puerto Rico, 00921
    • VA Caribbean Healthcare System
• United States
  • Arizona
    • Gilbert, Arizona, United States, 85297
      • Arizona Center for Cancer Care - Gilbert
    • Glendale, Arizona, United States, 85308
      • Arizona Urology Specialists
    • Multiple Locations, Arizona, United States, 85260
      • Arizona Oncology Services Foundation
    • Peoria, Arizona, United States, 85381
      • Arizona Center for Cancer Care - Peoria
    • Phoenix, Arizona, United States, 85027
      • Arizona Center for Cancer Care - Deer Valley
    • Scottsdale, Arizona, United States, 85251
      • Arizona Center for Cancer Care - Osborne
    • Scottsdale, Arizona, United States, 85258
      • Arizona Center for Cancer Care - Shea
    • Surprise, Arizona, United States, 85374
      • Arizona Center for Cancer Care - Surprise
    • Tucson, Arizona, United States, 85723
      • Southern Arizona VA Health Care System
  • California
    • Mather, California, United States, 95655
      • VA Northern California Health Care System
    • Tustin, California, United States, 92780
      • Precision Radiation Oncology
  • Colorado
    • Glenwood Springs, Colorado, United States, 81601
      • Valley View Hospital
    • Lakewood, Colorado, United States, 80228
      • Colorado Clinical Research
    • Parker, Colorado, United States, 80134
      • Advanced Urology
  • District of Columbia
    • Washington, District of Columbia, United States, 20016
      • Sibley Memorial Hospital
  • Florida
    • Fort Lauderdale, Florida, United States, 33324
      • 21st Century Oncology
    • Lakewood Ranch, Florida, United States, 34202
      • 21st Century Oncology
    • Naples, Florida, United States, 34102
      • 21st Century Oncology
    • Plantation, Florida, United States, 33324
      • 21st Century Oncology
    • Pompano Beach, Florida, United States, 33060
      • Clinical Research Center of Florida
    • Tampa, Florida, United States, 33615
      • Florida Urology Partners
    • Tampa, Florida, United States, 33612
      • James A. Haley Veteran's Hospital
  • Illinois
    • Chicago, Illinois, United States, 60637
      • The University of Chicago
    • Chicago, Illinois, United States, 60612
      • Jesse Brown VA Medical Center
    • New Lenox, Illinois, United States, 60451
      • Silver Cross Hospital
  • Louisiana
    • New Orleans, Louisiana, United States, 70119
      • Southeast Louisiana Veterans Health Care System
  • Maryland
    • Baltimore, Maryland, United States, 21201
      • VA Maryland Health Care System
    • Baltimore, Maryland, United States, 21204
      • Chesapeake Urology Research Associates
    • Baltimore, Maryland, United States, 21231
      • The Johns Hopkins University School of Medicine, The Sidney Kimmel Comprehensive Cancer Center
    • Bethesda, Maryland, United States, 20889
      • Walter Reed National Military Medical Center
  • Massachusetts
    • Worcester, Massachusetts, United States, 01605
      • University of Massachusetts Medical School
  • Missouri
    • Kansas City, Missouri, United States, 64128
      • Kansas City VA Medical Center
  • Nebraska
    • Omaha, Nebraska, United States, 68114
      • Adult & Pediatric Urology, P.C.
  • Nevada
    • Las Vegas, Nevada, United States, 89144
      • Sheldon Freedman MD, Ltd.
    • Reno, Nevada, United States, 89502
      • VA Sierra Nevada Health Care System
  • New Jersey
    • Cherry Hill, New Jersey, United States, 08003
      • New Jersey Urology - Cherry Hill
    • Englewood, New Jersey, United States, 07631
      • New Jersey Urology - Englewood
    • Millburn, New Jersey, United States, 07041
      • New Jersey Urology - Milburn
    • Saddle Brook, New Jersey, United States, 07663
      • New Jersey Urology - Saddle Brook
    • West Orange, New Jersey, United States, 07052
      • New Jersey Urology - West Orange
  • New Mexico
    • Albuquerque, New Mexico, United States, 87131
      • University of New Mexico Cancer Center
    • Albuquerque, New Mexico, United States, 87109
      • New Mexico Oncology Hematology Consultants (NMOHC)
  • New York
    • Bronx, New York, United States, 10468
      • James J. Peters VA Medical Center
    • North Hills, New York, United States, 11042
      • Advanced Radiation Centers of New York (Integrated Medical Professionals)
    • Syracuse, New York, United States, 13210
      • Associated Medical Professionals of NY, PLLC
  • North Carolina
    • Durham, North Carolina, United States, 27705
      • Durham VA Health Care System
  • Ohio
    • Cincinnati, Ohio, United States, 45220
      • Cincinnati VA Medical Center
  • Oregon
    • Portland, Oregon, United States, 97239
      • VA Portland Health Care System
    • Springfield, Oregon, United States, 97477
      • Oregon Urology Institute
  • Pennsylvania
    • Bala-Cynwyd, Pennsylvania, United States, 19004
      • MidLantic Urology
    • Philadelphia, Pennsylvania, United States, 19111-2497
      • Fox Chase Cancer Center
  • South Carolina
    • Charleston, South Carolina, United States, 29401
      • Ralph H. Johnson Veterans Affairs Medical Center
    • Myrtle Beach, South Carolina, United States, 29572
      • Carolina Urologic Research Center, LLC
  • Texas
    • Austin, Texas, United States, 78705
      • Urology Austin
    • Austin, Texas, United States, 78758
      • Austin Urology Institute
    • Austin, Texas, United States, 78759
      • Austin Urology Institute - Northwest Austin Cancer Center
    • Dallas, Texas, United States, 75216
      • VA North Texas Health Care System
    • Dallas, Texas, United States, 75231
      • Urology Clinics of North Texas
    • Houston, Texas, United States, 77030
      • Dr. Irving Fishman's Office
    • Houston, Texas, United States, 77070
      • Houston Willowbrook Radiation Oncology
    • Houston, Texas, United States, 77074
      • Dr. Ned Stein's Office
    • San Antonio, Texas, United States, 78229
      • The University of Texas Health Science Center at San Antonio
    • San Antonio, Texas, United States, 78229-4404
      • South Texas San Antonio VA Healthcare System
    • The Woodlands, Texas, United States, 77385
      • Texas Urology Specialists-The Woodlands
    • The Woodlands, Texas, United States, 77385
      • The Methodist Hospital - The Woodlands
    • Tomball, Texas, United States, 77375
      • Texas Urology Specialists
  • Virginia
    • Alexandria, Virginia, United States, 22311
      • Potomac Urology Center
    • Richmond, Virginia, United States, 23249
      • Hunter Holmes McGuire VA Medical Center
    • Salem, Virginia, United States, 24153
      • Salem VA Medical Center
    • Virginia Beach, Virginia, United States, 23462
      • Urology Of Virginia, Pllc
  • Washington
    • Gig Harbor, Washington, United States, 98335
      • MultiCare Regional Cancer Center - Gig Harbor
    • Tacoma, Washington, United States, 98405
      • MultiCare Regional Cancer Center - Tacoma

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: ProstAtak®; Aglatimagene besadenovec (CAN-2409) + valacyclovir + radiation therapy +/- ADT	Biological: Aglatimagene besadenovec + valacyclovir; Patients will receive three courses of ProstAtak® each consisting of aglatimagene besadenovec injection + oral valacyclovir. AdV-tk injection will be delivered to the prostate via trans-rectal ultrasound guided injection as follows: The first injection will be given at least 15 days and not more than 8 weeks before starting radiation.; The second injection will be 0-3 days before initiation of radiation therapy.; The third injection will be 15-22 days after the 2nd injection. The prodrug, valacyclovir, will be administered at a fixed dose for 14 days after each AdV-tk injection. Standard external beam radiation therapy will be delivered to the prostate. Short-term androgen deprivation therapy (maximum of 6 months) is optional but must be decided before enrollment to allow for stratification.; Other Names: CAN-2409; AdV-tk
Placebo Comparator: Control; Placebo + valacyclovir + radiation therapy +/- ADT	Biological: Placebo + valacyclovir; Patients will receive three courses each consisting of placebo injection + oral valacyclovir. Placebo injection will be delivered to the prostate via trans-rectal ultrasound guided injection as follows: The first injection will be given at least 15 days and not more than 8 weeks before starting radiation.; The second injection will be 0-3 days before initiation of radiation therapy.; The third injection will be 15-22 days after the 2nd injection. The prodrug, valacyclovir, will be administered at a fixed dose for 14 days after each placebo injection. Standard external beam radiation therapy will be delivered to the prostate. Short-term androgen deprivation therapy (maximum of 6 months) is optional but must be decided before enrollment to allow for stratification.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Disease free survival defined as the time from randomization until the date of the first failure event will be compared for the ProstAtak® arm versus the placebo control arm. The analyses will be based on the intent to treat population.	Assessed at each visit every 6 months through year 5 until event occurs.

Secondary Outcome Measures

Outcome Measure	Time Frame
Prostate cancer specific survival and overall survival will be compared for the ProstAtak® arm versus the placebo control arm.	Assessed at each visit every 6 months through year 5 after which long-term follow up of general health status will continue yearly.
PSA nadir will be compared for the ProstAtak® arm versus the placebo control arm.	Assessed at each visit every 6 months through year 5.
Patient reported Health Related Quality of Life outcomes will be collected using the Expanded Prostate Cancer Index Composite (EPIC-26) questionnaire. The change in QOL over time will be compared for the ProstAtak® arm versus the placebo control arm.	Assessed at baseline and at 3, 6, 12, 18 and 24 months after completion of radiation.
The safety profile will be characterized by collection of adverse event information and laboratory values during the treatment phase (until the completion of radiation). Data on late effects will be collected after radiation completion.	Assessed at each visit and continuously throughout the study.

Collaborators and Investigators

• Sponsor: Candel Therapeutics, Inc.

Study record dates

Study Major Dates

• Study Start: September 1, 2011
• Primary Completion (Actual): August 1, 2024
• Study Completion (Estimated): December 1, 2030

Study Registration Dates

• First Submitted: September 19, 2011
• First Submitted That Met QC Criteria: September 19, 2011
• First Posted (Estimated): September 20, 2011

Study Record Updates

• Last Update Posted (Actual): July 30, 2025
• Last Update Submitted That Met QC Criteria: July 28, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: immunotherapy, cytotoxicity, tumor vaccine, prostate cancer, radiotherapy
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Genital Diseases, Male; Prostatic Diseases; Male Urogenital Diseases; Prostatic Neoplasms; Anti-Infective Agents; Antiviral Agents; Valacyclovir
• Other Study ID Numbers: PrTK03