Two-fraction Versus Five-fraction Stereotactic Radiotherapy for Localized Prostate Cancer (SABR-Dual)

November 13, 2024 updated by: Rabin Medical Center

Two-fraction Versus Five-fraction Stereotactic Radiotherapy for Localized Low- and Favorable Intermediate-risk Prostate Cancer: SABR-Dual

The goal of this clinical trial is to compare two dose schedules of stereotactic radiation therapy in patients with localized prostate cancer. Historically, external beam radiation to treat localized prostate cancer was given in small treatments over a period of multiple weeks. Recent studies have shown that with newer technologies and better understanding of how prostate cancer responds to radiation, the same effective dose can be given in as few as 5 treatments. This study is comparing this newer standard course of 5 treatments with an even shorter course of just 2 treatments. The dose for the 2 treatments is based on a form of internal radiation called brachytherapy, but in this study, that dose will be given using external radiation, without the need for invasive procedures.

In order to make sure that the radiation therapy is given in a way that minimizes the risk of side effects to the surrounding organs, including the rectum and bladder, prior to radiation a hydrogel material will be inserted behind the prostate in order to distance the rectum further from the prostate gland, and small gold markers will be inserted into the prostate to decrease any possible movement during treatment.

The main questions are whether 2-treatment radiation is tolerated as well and is as effective at treating prostate cancer, compared to the standard 5-treatment course of radiation.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Following publication of multiple prospective clinical trials demonstrating the biochemical progression free survival (bPFS) benefits of high dose radiation for the curative treatment of localized prostate cancer, typical external beam radiotherapy (EBRT) courses ranged from 38-45 daily fractions delivered over 7.5-9 weeks. Over the past two decades, monumental advances in EBRT have been achieved, allowing significant shortening of the standard radiotherapy course. With diagnostic, imaging, and technological developments, the ability to deliver higher doses per fraction further expanded and an improved radiobiologic understanding of the response of prostate adenocarcinoma revealed that ultrahypofractionated regimen could take advantage of the comparatively low a/b ratio of prostate cancer cells. As a result of these two streams of development, stereotactic ablative radiation therapy (SABR) emerged as an accepted standard of care for definitive treatment in the low- and favorable intermediate-risk settings.

At both the individual and systems levels, efficient delivery of patient care and prudent utilization of medical resources is at the forefront. Given the ubiquity of prostate cancer and high volumes of patients in treatment centers across the globe, there remains meaningful potential for substantial improvements in patient throughput and cost of care. Presently, the shortest treatment courses for low- and favorable intermediate-risk prostate cancer are radical prostatectomy and low-dose-rate (LDR) brachytherapy, which offer an excellent likelihood of cure but entail degrees of invasiveness that may not be appropriate, feasible, or desirable for all patients, and include additional costs associated with operating room facilities and anesthesia. Surgical patients typically require a brief inpatient hospital stay. A comparable radiation therapy treatment course could help address many of these concerns and offer effective and efficient patient care.

A strong and mature precedent for a two-fraction course of high dose radiation can be found in the realm of high-dose-rate (HDR) brachytherapy. Under anesthesia, a radioactive source is programmed to traverse catheters that have been transperineally inserted into the prostate in order to produce a desired dose deposit. bPFS rates range between 91%-97% in the modern literature. While attempts were made to deliver single-fraction HDR brachytherapy (typical dose of 19 Gy), trials resulted in inferior oncologic outcomes, and to date, standard HDR treatment courses are comprised of two-fraction definitive treatment or single-fraction combined with EBRT. Radiobiologically, based on the particularly low a/b of prostate cancer cells and unique cell cycling, there is suggestion that at least two fractions are necessary for complete tumor eradication.

There exists, to date, limited data on the safety and effectiveness of prostate SABR delivered in fewer than five fractions. A recent proof-of-concept study by Greco et al compared single-dose SABR of 24 Gy to 5 fractions of 9 Gy in favorable intermediate and unfavorable intermediate risk patients. The results demonstrated comparable four-year prostate specific antigen outcomes for favorable intermediate disease though inferior PFS for unfavorable intermediate disease. Objective and patient reported genitourinary and gastrointestinal toxicities were not significantly different, though one of the 15 patients in the single-fraction arm experienced delayed grade 3 urethral stenosis. Magli et al published acceptable 1-year toxicity outcomes for a novel three-fraction regimen of SABR for low- and favorable intermediate-risk patients, to a dose of 40 Gy. MRI based planning was utilized, gold fiducials and a hydrogel spacer were placed, and a catheter was inserted in the bladder for each fraction. They observed rates of 11.9% and 1.7% acute grade 2 and 3 urinary toxicity, respectively, and 8.5% acute grade 2 rectal toxicity, all of which resolved by 12 months. Alayed et al published safety and efficacy results of their prospective single-cohort study of low- and intermediate-risk patients undergoing a two-fraction SABR regimen to a dose of 26 Gy. On their sample of 30 patients, they reported no acute grade 3+ gastrointestinal or genitourinary toxicity, and one instance each in later follow up, comparable or even slightly better than that from five-fraction protocols.

Multiple questions remain regarding the potential role for and safety of delivering SABR in fewer than five fractions. These include optimal patient selection, ideal dose fractionation, proper techniques to assure necessary avoidance of surrounding normal tissue, and how to balance dose to organs at risk with the accepted requirement of a planning target volume (PTV) to account for inevitable setup uncertainty. Importantly, recent endoscopic reports reveal notably high rates of rectal ulceration after dose-escalated SABR, and placement of a hydrogel spacer has been demonstrated to significantly reduce this risk. Placement of a resorbable hydrogel spacer to displace the rectum away from the high dose region, allowing for a posterior safety margin to account for potential intra-fractional motion, instead of a rectal balloon, is essential for accomplishing rectal sparing while facilitating additional assurance regarding treatment accuracy.

In the context of modern dose escalation, and in lieu of a strong body of HDR-brachytherapy data supporting a two-fraction approach to ultra-high dose treatment with initial experiences of two-fraction SABR, direct comparison of a non-invasive and broadly generalizable two-fraction SABR regimen to the standard approach of five-fraction regimen is logical. Institutional studies have emerged in the recent years demonstrating evidence for safety of ultra-hypofractionated regimen in fewer than five fractions of SABR, and large-scale randomized data is much needed. Aided by the ability to achieve necessary rectal dose constraints through placement of a rectal hydrogel, this approach may serve as an appropriate balance between minimizing the number of treatments necessary while allowing for delivery of the higher dose needed to optimize likelihood of cure.

Study Type

Interventional

Enrollment (Estimated)

562

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Israel
      • Petah Tikva, Israel, 49100
        • Recruiting
        • Davidoff Cancer Center, Rabin Medical Center
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion:

  • Male patients ≥18 years

  • Diagnosis of low- or favorable intermediate-risk prostate adenocarcinoma

    • T1-T2c
    • Prostate specific antigen < 20
    • Gleason 6 or 7 (3+4)
    • Cannot had multiple intermediate-risk factors consistent with unfavorable intermediate risk disease
  • Prostate gland < 60 cc (can include following cytoreductive androgen deprivation)
  • International Prostate Symptom Score < 15 (unaided by a-adrenergic inhibitor or anticholinergic drugs)

Exclusion:

  • Unfavorable intermediate-risk disease and above
  • Chronic inflammatory bowel condition (IBD, Crohn's disease, Sarcoidosis, Rheumatic disease)
  • Chronic immunosuppression
  • Contraindications to hydrogel spacer placement
  • Contraindications to a prostate MRI
  • Any prior prostate cancer treatment
  • Prior pelvic radiotherapy
  • Previous transurethral resection of the prostate (TURP) within 12 months
  • Hip prosthesis
  • Prior use of therapeutic androgen deprivation therapy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Two-fraction stereotactic radiotherapy
Participants receive stereotactic ablative radiotherapy in two treatments to a dose of 27 Gy, with the options to boost a high-grade lesion to 30 Gy
Radiation: Two-fraction stereotactic radiotherapy
Definitive prostate radiotherapy will be delivered to a dose biologically comparable to 40 Gy in 5 treatments, but in only 2 treatments
Active Comparator: Five-fraction stereotactic radiotherapy
Participants receive stereotactic ablative radiotherapy in five treatments to a dose of 40 Gy, with the options to boost a high-grade lesion to 45 Gy
Radiation: Five-fraction stereotactic radiotherapy
Definitive prostate radiotherapy will be delivered to a standard stereotactic dose of 40 Gy in 5 treatments

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Biochemical Progression Free Survival
Time Frame: five-year
Phoenix definition
five-year

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Freedom From Progression
Time Frame: five-year
biochemical failure, clinical failure, death from any cause
five-year
Distant metastasis free survival
Time Frame: five-year
Survival without development of distant metastatic disease
five-year
Prostate cancer specific survival
Time Frame: five-year
Survival with cause of death or censoring without residual or recurrent prostate cancer
five-year
Time to salvage treatment
Time Frame: five-year
Time interval until need for salvage treatment for residual or recurrent disease
five-year
Physician-reported Genitourinary/Gastrointestinal toxicity
Time Frame: Every 3 months until 24 months
Toxicity caused by the intervention as graded by the physician
Every 3 months until 24 months
Patient-reported Genitourinary/Gastrointestinal toxicity
Time Frame: Every 3 months until 24 months
Toxicity caused by the intervention as graded by the patient
Every 3 months until 24 months
Time to prostate specific antigen nadir (< 0.2) - Longitudinal response
Time Frame: five-year
Biochemical prostate specific antigen response over time
five-year

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Rabin Medical Center

Investigators

  • Principal Investigator: Elisha T Fredman, MD, Davidoff Cancer Center, Rabin Medical Center

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 29, 2022

Primary Completion (Estimated)

December 1, 2027

Study Completion (Estimated)

December 1, 2032

Study Registration Dates

First Submitted

August 31, 2023

First Submitted That Met QC Criteria

August 31, 2023

First Posted (Actual)

September 7, 2023

Study Record Updates

Last Update Posted (Actual)

November 15, 2024

Last Update Submitted That Met QC Criteria

November 13, 2024

Last Verified

August 1, 2024

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • RMC-0199-22
  • MOH_2022-08-30_012007 (Registry Identifier: Israel Ministry of Health)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

All individual participant data used in the results publication will be provided with participating researchers

IPD Sharing Time Frame

Individual participant data and supporting information will be made upon request through final publication of the study results

IPD Sharing Access Criteria

Access will be granted by the leading study PI upon request by participating researchers, based on the needs and length of time necessary.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF
  • ANALYTIC_CODE
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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