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NCT Number: NCT01436968

Phase 3 Study of ProstAtak® Immunotherapy With Standard 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.

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This study is active but is not currently recruiting participants.

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Key information

Conditions

Prostate Cancer Genital Diseases Genital Diseases, Male Genital Neoplasms, Male Male Urogenital Diseases Neoplasms Neoplasms by Site Prostatic Diseases Prostatic Neoplasms Urogenital Diseases Urogenital Neoplasms

Age range

18 year and older

Sex eligibility

Male

Study type

Interventional

Phase

Phase 3

Primary location

VA Caribbean Healthcare System, San Juan, Puerto Rico

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

aglatimagene besadenovec + valacyclovir

Biological

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: AdV-tk, CAN-2409

Placebo + valacyclovir

Biological

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.

Primary outcomes

  1. 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.

    Time frame: Assessed at each visit every 6 months through year 5 until event occurs.

Secondary outcomes

  1. Prostate cancer specific survival and overall survival will be compared for the ProstAtak® arm versus the placebo control arm.

    Time frame: Assessed at each visit every 6 months through year 5 after which long-term follow up of general health status will continue yearly.

  2. PSA nadir will be compared for the ProstAtak® arm versus the placebo control arm.

    Time frame: Assessed at each visit every 6 months through year 5.

  3. 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.

    Time frame: Assessed at baseline and at 3, 6, 12, 18 and 24 months after completion of radiation.

  4. 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.

    Time frame: Assessed at each visit and continuously throughout the study.

Sponsors and collaborators

Lead sponsor

Candel Therapeutics, Inc.

Industry

Registry information

Official study title

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

Acronym: PrTK03

Important dates

Study start
2011
Primary completion
2024
Study completion
2030
First posted
Sep 20, 2011
Registry last updated
Jul 30, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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