Several clinicians were on hand this week in San Diego to share their experiences with the ViewRay MRIdian Linac, the only FDA-approved linear accelerator-based MR-guided radiation therapy system.

The most compelling data came from early results of a study, presented at the 59th American Society for Radiation Oncology (ASTRO) meeting, showing that use of the system to treat pancreatic cancer patients with high, targeted radiation doses led to significantly prolonged patient survival and resulted in low toxicity.

The retrospective study looked at the treatment of 42 locally-advanced pancreatic cancer patients treated with the MRIdian at Washington University, UCLA, University of Wisconsin and VU University Medical Center in Amsterdam. More than half of the patients received a biologically effective dose of greater than 90, the type of BED used to treat lung and liver cancers.

Toxicity was 0 percent in the high-dose group compared to 15.8 percent in the low-dose group and the estimated two-year survival was between 75 and 80 percent.

“For me, in this part of my career, it’s the most exciting data I’ve seen using radiation therapy for pancreas cancer,” said Dr. Parag Parikh, associate professor of radiation oncology at Washington University in St. Louis and lead investigator of the trial, presenting the results of the study at ASTRO. “If this was a drug that the medical oncology colleagues had that gave them three months, it’s a billion-dollar drug.”

The aim of the MRIdian Linac is to deliver higher, more effective doses to tumors while minimizing damage to the surrounding tissue with the ability to visualize the movement of nearby organs and make adaptive treatment changes.

During his presentation, Parikh noted the advantages of the MRIdian Linac to re-plan treatment based on changes in the body, to avoid damaging critical organs near the pancreas, such as the stomach and duodenum.

“Every time a physician used a very high dose, they have to adapt,” Parikh said. “We made sure we did not allow the high dose to go into those organs at risk.”

The results have initiated a multicenter prospective clinical trial for locally advanced unresectable pancreatic cancer, using the MRIdian.

The study will be part of ViewRay’s new Clinical Cooperative Think Tank, a group of clinicians from several institutions using the MRIdian to gather evidence on MR-guided radiation therapy. The institutions include the Dana-Farber/Brigham and Women's Cancer Center in Boston, the Henry Ford Cancer Institute in Detroit and Moffitt Cancer Center in Tampa, Florida.

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