Next-Generation Prostate Cancer Radiotherapy

SpaceOAR System is the first absorbable hydrogel spacer designed to reduce unintentional rectal injury in men undergoing prostate radiotherapy (RT). Using ultrasound guidance, the hydrogel is administered as a liquid that expands the space between Denonvilliers’ fascia and the rectal wall, where it solidifies into a soft, but firm, hydrogel within 10 seconds. The hydrogel remains in place for 3 months during prostate radiotherapy, after which it liquefies by hydrolysis, and is absorbed and cleared in the patient’s urine.

MRI image showing prostate and rectum before SpaceOAR hydrogel placement
MRI image of rectum and prostate with SpaceOAR Hydrogel spacer in place
MRI image showing prostate and rectum 6 months after treatment using SpaceOAR Hydrogel

Clinical Trial Patient, MRI Images

In order to assess SpaceOAR System safety and effectiveness a prospective, randomized, controlled, patient-blinded clinical study was performed. In 20 centers a total of 222 men were randomized to receive fiducial marker and SpaceOAR System injection, or fiducial markers alone (control group). Patients then received 79.2Gy x 44 fraction IG-IMRT, and were followed weekly during RT, and at 3, 6, 12 and 15 months.

SpaceOAR Hydrogel Clinical Trial Results

Prostate-Rectal Space Pre-implant: 1.6 mm
Post-implant: 12.6 mm
Procedure Success 99% Technical Success (gel present)
Rectal V70 Dose
Pre-SpaceOAR Hydrogel: 12.4%
Post-SpaceOAR Hydrogel: 3.3%
Acute Rectal Pain AE’s
(3 mo)
Control Group: 11.1%
SpaceOAR Group: 2.7%
Late Rectal Toxicity
(1 year post RT)
Control Group: 7% (Max G3*)
SpaceOAR Group: 2% (Max G1)
Bowel QOL (EPIC)
% Patients with >10pt decline (15 mo)
Control Group: 21.4%
SpaceOAR Group: 11.6%

* Key:
Grade 1 (G1): Mild, transient
Grade 2 (G2):Moderate, requiring prescription medication
Grade 3 (G3): Additional procedure required for treatment