According to earlier phase 1 and 2 clinical trials, ExAblate provides substantial relief from painful metastatic bone tumors.

Those findings were confirmed by a newly-reported randomized, sham treatment-controlled phase 3 trial headed up by Dr. Hurwitz. (He conducted the study during his tenure as Director of Regional Program Development at the Department of Radiation Oncology at Brigham and Women’s Hospital and Associate Professor of Radiation Oncology at Harvard Medical School.)


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In Dr. Hurwitz’s phase 3 trial of the ExAblate MRgFUS system, patients with painful bone metastasis with a self-reported numeric self-reported pain intensity (NRS) score of ≥4 on a scale of 0-10 were randomized 3:1 to receive MRgFUS or sham treatment. (Sham treatment-arm subjects were allowed to cross over to MRgFUS after 2 weeks if their pain did not improve.)

Dr. Hurwitz’s team followed patients’ pain intensities, quality of life (QOL), and safety for 3 months. They reported that MRgFUS resulted in superior and significant 3-month reductions in pain scores, defined as a decrease in worst pain NRS scores ≥2 from baseline (67% of 100 MRgFUS-arm patients vs 21% of 34 sham treatment-arm patients (P<0.0001).

MRgFUS patients’ median pain scores dropped from a baseline of 7.0 to a 3-month median score of 2.0, whereas patients receiving sham treatments saw a much more modest decline in median pain scores, from 7.0 to 6.5, Dr. Hurwitz said.

“MRgFUS results in excellent rates of durable pain relief, improvement in QOL, and subject-assessed well-being and function for patients with metastatic bone pain who are not candidates for radiotherapy,” they concluded. “Given these excellent results coupled with a favorable side-effect profile, MRgFUS should be considered a primary choice for eligible patients when RT is contraindicated in treatment of painful bone metastases.”

The findings are “not just statistically significant, but clinically significant,” Dr. Hurwitz said, offering patients “quick and durable responses.”

“Having a second-line option that is highly effective for quality of life and pain, from a clinical standpoint, that is a very important development,” he said. “And for patients, it’s a very significant advance.”

One of Dr. Hurwitz’s patients, who suffered painful metastatic pelvic-bone tumors from prostate cancer, had undergone three courses of radiation treatment without relief, Dr. Hurwitz noted. “He went on to receive ExAblate treatment and experienced a complete response; he’d had pain of 8 out of 10 on the numeric rating scale – severe pain – but 1 week later he came in for follow-up and was pain free. He remained pain free at the 3-month follow-up.”

Asked if there are skeletal regions for which ExAblate palliation of bone can be challenging or should not be attempted, Dr.Hurwitz told The Advisor Blog: “This was an initial foray and there were several sites excluded,” including the L3 vertebral column, in order to protect the spinal cord.

“Disease within 1 cm of critical organs and blood vessels were excluded, and cranial lesions were excluded, as well,” he added.

The safety profile is “excellent,” Dr. Hurwitz said. “We’ve had no significant complications.”

Transient discomfort during the procedure was the main problem, he said.

ExAblate has previously been approved by the FDA and in Europe for treating uterine fibroids. The system is in clinical use for bone metastasis pain palliation in 20 hospitals in Europe and Asia, InsighTec reports.

ExAblate “typically involves a team approach between a radiologist and a radiation oncologist,” Dr. Hurwitz said. “For a center that doesn’t have the technology, that’s something that can be learned relatively rapidly with some mentoring.”


Readers, we want to hear from you!

  • Would you consider this new palliative therapy for your patients with bone metastasis?
  • Do you think that MRgFUS thermoablation system has the potential to replace narcotic analgesics in your patients with bone metastasis?