Main Session
Sep 30
PQA 07 - Genitourinary Cancer, Patient Safety, Nursing/Supportive Care

3193 - Pre-Formed Radiopaque Hydrogel for Perirectal Spacing in Subjects with Low to Intermediate Risk Prostate Cancer Undergoing External Beam Radiotherapy (EBRT): A Multicenter, Randomized, Controlled Clinical Study (HYDROSPACE)

12:45pm - 02:00pm PT
Hall F
Screen: 3
POSTER

Presenter(s)

Brian Baumann, MD - Springfield Clinic, Springfield, IL

B. C. Baumann1,2, N. B. Desai3, S. P. Collins4, M. Pinkawa5, D. Vannan6, K. Rainbow6, R. Rao6, P. O'Connor6, D. Qi6, and J. E. Sylvester7; 1Springfield Clinic, Springfield, IL, 2University of Pennsylvania, Philadelphia, PA, 3Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, 4Department of Radiation Oncology, University of South Florida (USF) Health Morsani College of Medicine, Tampa, FL, 5Department of Radiation Oncology, RWTH Aachen University Hospital, Aachen, Germany, 6Boston Scientific, Marlborough, MA, 7Atlantic Urology Clinics, Myrtle Beach, SC

Purpose/Objective(s):

While radiation therapy (RT) is a well-established and widely used treatment for prostate cancer, it has the limitation of increasing the risk of both acute and late toxicity to rectal and bladder tissues. Polyethylene glycol (PEG)-based hydrogel spacing has been used to increase separation between the anterior rectal wall and the prostate, in order to mitigate the risk of toxicity associated with RT.

A next generation pre-formed iodinated absorbable PEG-based hydrogel is designed with radiopacity for visibility under ultrasound, MRI, CT and cone beam CT. Different from commercially available PEG-based hydrogels, this new spacer is manufactured as a pre-polymerized hydrogel. The main trial objective is to demonstrate the safety and effectiveness of the next generation perirectal hydrogel spacer in subjects undergoing external beam RT (EBRT) to treat prostate cancer.

Materials/Methods:

This is a prospective, multi-center, multinational randomized control trial (NCT06451614). Up to 35 sites in the US and Canada have been or are expected to be authorized to enroll. The primary safety endpoint is an evaluation of acute Grade 3 or greater AEs inclusive of all AEs listed on the commercially available hydrogel perirectal spacer labels, that arise within 90 days of the index procedure. The primary effectiveness endpoint is a clinically relevant dose reduction defined as a 25% reduction in the volume of the rectum receiving 90% of prescribed radiation dose in subjects receiving the pre-formed radiopaque perirectal hydrogel spacer. Based on the sample size calculation for the primary safety endpoint, approximately 230 subjects with a diagnosis of low to intermediate risk prostate cancer, indicated for EBRT, will be randomized (1:1) to the pre-formed iodinated hydrogel intervention (n~115) or the commercially available PEG-based hydrogel control group (n~115). All subjects will undergo transperineal injection of 10 mL of the hydrogel. Dosimetric comparisons before and after spacer placement will be made using dedicated treatment planning imaging. Over 2-year follow-up, subjects will be assessed for spacer effectiveness and absorption, GI and GU toxicity (NCI CTCAE) and quality of life (EQ-5D-5L, EPIC-26, & WPAI questionnaires). Enrollment began in October 2024 and is anticipated to complete in 2026, with final endpoint results available 24 months following the end of enrollment.

Results: TBD

Conclusion:

This study is designed to demonstrate the clinical utility and dosimetric benefit of using a pre-formed radiopaque perirectal hydrogel spacer for perirectal spacing in patients receiving EBRT for prostate cancer. Long-term follow-up including patient-reported outcomes is intended to provide insight into how space creation with this technology may reduce toxicity and be associated with maintained quality-of-life.