MRI-guided focused ultrasound to treat pain from bone metastases

InSightec Ltd, the leader in magnetic resonance imaging guided Focused Ultrasound therapy (MRgFUS), announced that the results of its ExAblate® Phase III clinical trial for treating painful bone metastases have been published online in the JNCI, Journal of National Cancer Institute.

This is the first completed phase III clinical trial of the use of MRgFUS in oncology. It was an international, multi-center, randomized study of MRI-guided focused ultrasound to treat pain from bone metastases in patients who do not respond or cannot undergo radiation treatment for their pain. The results formed the basis for the  Pre-Market Approval (PMA) by the US Food and Drug Administration (FDA) . In total 147 patients were enrolled in the study.

Bone metastases occur when cancer cells spread from their primary site to other parts of the body. According to the American Cancer Society, more than two-thirds of  breast and prostate cancers spread to the bones as well as lung, bladder and thyroid cancers.  Pain is the most common and severe symptom, for which pain medications and palliative radiation therapy are the most common treatments prescribed. However, up  to 30% percent of patients with bone metastases either do not respond to radiation therapy or are unable to undergo radiation for pain relief.

"The results of this trial demonstrate a role for MR guided focused ultrasound in cancer-related bone pain," says Mark Hurwitz, M.D., Director of Thermal Oncology and Vice Chair for Quality, Safety and Performance Excellence of the Department of Radiation Oncology at Thomas Jefferson University in Philadelphia and principal investigator of the study. "Response to MRgFUS was rapid and durable, with two-thirds of responses seen within days after treatment. Additionally, 47% of the patients treated by MRgFUS reduced (21%) or completely stopped (26%) consumption of medications. The impact on patient functioning, which often influences quality of life, is an important additional finding of the study. MRgFUS thus contributes to the well-being of these patients."

ExAblate combines therapeutic acoustic ultrasound waves and continuous guidance and treatment monitoring with an MRI. Physicians use the MRI to plan and guide the therapy and monitor treatment outcome. The focused ultrasound acoustic energy destroys the nerves causing the pain, resulting in rapid reduction in pain.

Over 17 leading centers participated  in the study including Fox Chase Cancer Center, Stanford University, University of California at San Diego, University of Virginia, Moffitt, and Brigham and Women's Hospital in the US as well as University of Toronto, La Sapienza University in  Rome, Sheba and Rambam Medical Centers in Israel,  Petrov Research Institute of Oncology and Rostov Medical University in Russia.

ExAblate is the only FDA-approved MRI-guided focused ultrasound system for treating uterine fibroids and bone metastases related pain management. It has also received European CE marking for uterine fibroids, bone metastases, and neurological disorders such as essential tremor and tremor from Parkinson's disease.

The paper concludes that, MRgFUS provides durable pain relief and improved function in patients who failed radiation or those who are not candidates for or declined radiation. Given the impact of these clinically significant results, coupled with a favorable side effect profile, MRgFUS should be considered a viable treatment option for painful bone metastases.