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Viewray: ViewRay Announces Results of the First Prospective Clinical Trial on MR-guided Radiation Treatment for Prostate Cancer Without Implanted Markers

Date: Thursday, 10 October 2019

ViewRay announced the acceptance of publication by the International Journal of
Radiation Oncology, Biology and Physics of the first prospective clinical
trial of MR-guided radiation therapy (MRgRT) in patients with localized
prostate cancer. This robust study of clinician and patient reported outcomes
demonstrated zero CTCAE v4 grade 3 or higher gastrointestinal (GI) and
genitourinary (GU) toxicity and even lower incidence of grade 2 toxicity than
investigators hypothesized. It is also one of the first prospective clinical
trials to study SBRT in a mix of intermediate- and high-risk prostate cancer
patients, a challenging patient population to treat. The journal is the
official scientific journal of the American Society for Radiation Oncology.

Researchers from Amsterdam University Medical Center enrolled 101 patients
with intermediate- or high-risk prostate cancer in a prospective phase II
clinical trial. All patients received MRgRT in five fractions of 7.25 Gy to
the target volume using on-table adaptive techniques. The trial did not use
implanted markers or tissue spacers because treatments were delivered under
MR-guidance, thereby eliminating an invasive procedure, potentially associated
complications, and implantation costs.

Results at three months showed that no early CTCAE v4.0 grade 3 GU or GI
toxicity was observed, and the maximum cumulative grade 2 early GU and GI
toxicity measured by any symptom at any study time point was 23.8% (study
hypothesis 40%) and 5.0% (study hypothesis 15%). These results were obtained
in a complex clinical cohort (59.4% high-risk patients) and are comparable to
what would be typically observed in lower-risk populations, pointing to the
potential benefits of MR-guided SBRT in this higher risk group. Additionally,
the low incidence of early GI toxicity, despite the inclusion of the base of
the seminal vesicles in 96 percent of patients, illustrates the benefit of
MR-guidance and on-table adaptive re-planning. This technology facilitates
smaller treatment margins while minimizing damage to surrounding tissue and
critical structures, such as urethra, rectum, and bladder. The publication
noted that incontinence was uncommon, reported by 4% of patients at the end of
MRgRT and decreasing over time.

"SBRT offers significant promise in the treatment of prostate cancer. Our
clinical trial takes that a step further in showcasing its value in patients
with intermediate- and high-risk disease, with a focus on evaluating
associated toxicities and quality of life outcomes," said principal
investigator Anna Bruynzeel, M.D., Ph.D., Radiation Oncologist at Amsterdam
UMC. "We see a lower incidence of GI and GU toxicity with MR-guidance as
compared to similar SBRT prostate cancer studies. The results reinforce the
value of MRIdian's real-time on-table adaptive treatment with automatic beam
gating for prostate patients."

"This promising data in the treatment of prostate cancer with SBRT, enabled by
the unique combination of MRIdian's ability to see, shape, and strike, is
notable for patients and physicians," said Scott Drake, President and CEO.
"MRIdian is providing physicians the confidence and tools they need to deliver
ablative radiation doses both precisely and accurately while sparing sensitive
structures near the target, in order to achieve better patient outcomes. We
are pleased to add this prospective trial to our clinical data compendium and
thank the team at Amsterdam UMC for their work to improve the lives of cancer
patients.

The article in press can be viewed at
https://www.redjournal.org/article/S0360-3016(19)33640-5/fulltext