ViewRay, Inc. announced that findings from the phase III randomized controlled MIRAGE trial (NCT04384770) were published on January 12 in JAMA Oncology. The MIRAGE trial compared MRI-guided and CT-guided stereotactic body radiation therapy (SBRT) for localized prostate cancer and found MRI-guided radiation therapy -- delivered with MRIdian -- to be superior in substantially reducing acute genitourinary (GU) and gastrointestinal (GI) toxicity. MRI-guided radiation was also associated with significantly better patient- reported quality of life metrics.

The MIRAGE trial was led by Amar Kishan, M.D. (first author) and Michael L. Steinberg, M.D. (senior author) at the University of California, Los Angeles (UCLA). The study was independently designed, conducted, and analyzed exclusively by UCLA. In this trial, the investigator team randomized 156 patients to receive either MRI-guided SBRT or CT-guided SBRT.

Acute grade >=2 GU toxicity rates were significantly lower with MRI guidance vs. CT guidance (24.4% in the MRI group vs. 43.4% in the CT group).

Acute grade >=2 GI toxicity rates were also significantly lower with MRI guidance (0.0% in the MRI group vs. 10.5% in the CT group). On multivariate analysis, which controls for differences in the use of a rectal spacer, prostate size, and baseline urinary symptoms, the MRI-guided arm was associated with a 60% reduction in odds of grade >=2 GU toxicity.

More notably, there were improvements in multiple patient-reported outcomes. Significantly more patients receiving CT- guided SBRT experienced large increases in urinary symptoms, as measured by a >15 points increase in International Prostate Symptom Score (IPSS) (6.8% in the MRI group vs. 19.4% in the CT group).

Similarly, a significantly greater percentage of patients experienced a clinically notable decrease in bowel-related quality of life with CT-guided, as measured by the Expanded Prostate Cancer Index Composite-26 (EPIC-26) survey (25.0% in the MRI group vs. 50.0% in the CT group). Finally, though it is too early to conclude, as more than 2/3rds of men on the trial received hormonal therapy, exploratory analysis in men who did not receive hormonal therapy showed that patient-reported sexual-function scores (by EPIC-26) decreased more in men receiving CT-guided SBRT.

To date, more than 27,000 patients have been treated with MRIdian. Currently, 56 MRIdian systems are installed at hospitals around the world where they are used to treat a wide variety of solid tumors and are the focus of numerous ongoing research efforts. MRIdian has been the subject of hundreds of peer-reviewed publications, scientific meeting abstracts, and presentations.