Deadly brain tumors show vulnerability to new sound wave approach

In a promising sign for the potential of focused sound waves to improve care for brain tumors, UVA Health researchers have determined that tumors called gliomas may be even more receptive to targeted drug delivery than normal brain tissue.

While the research is still in its early stages, the findings help allay concerns that brain tumors might have properties that would make them stubbornly resistant to the cutting-edge approach. The UVA scientists are using tiny “microbubbles” that are activated by sound waves to open the brain’s natural protective barrier, known as the “blood-brain barrier,” so drugs can enter exactly where needed.

Inside brain tumors, cancer cells mutate the structure of the blood-brain barrier, and its function becomes unpredictable. In turn, this raises questions about how effectively focused ultrasound can deliver therapies in the brain tumor environment and what sizes of drug molecules can be delivered most effectively. The new research from UVA Health’s Focused Ultrasound Cancer Immunotherapy Center provides important insights on both fronts.

“To address the central question, Dr. Wilson Miller worked with my graduate student, Matthew Hoch, to develop an MRI approach that would allow us to make drug-delivery measurements with unprecedented resolution. This approach had not been integrated with focused ultrasound before,” said researcher Richard J. Price, Ph.D., the center’s co-director. “The outcome is exciting because it means that focused ultrasound delivery performance is not expected to diminish in brain tumors. In fact, it may even be enhanced for some types of therapeutics.”

Better brain cancer treatments

Gliomas are the most common primary brain tumors in adults. This group includes glioblastomas, the deadliest form of brain cancer. While there are treatments that can extend survival and improve quality of life, glioblastomas are almost always fatal within 5–10 years, so new and better treatments are desperately needed. More than 10,000 people in the United States alone die from glioblastomas every year.

Part of the difficulty in treating glioblastoma is getting drugs through the brain’s natural defenses. The blood-brain barrier exists for an important reason: It keeps harmful germs and toxins out. So doctors have proceeded cautiously in trying to open the gates for fear of letting in dangerous invaders.

Focused ultrasound, however, is now letting doctors open the barrier extremely precisely and briefly so beneficial drugs can slip inside unaccompanied by unwanted companions. Price’s approach would use low-frequency sound waves to send tiny drug molecules spinning directly into tumor cells. This is done without the need to cut into the skull.

In addition to indicating that gliomas in laboratory mice are vulnerable to the approach, Price’s latest research sheds light on the sizes of molecules that would be most effective. He and his collaborators identified a “Goldilocks” size range where the molecules worked best. Very small molecules delivered the medicine less efficiently than larger ones, but very large molecules were less effective than the medium-sized ones. (This is relative, of course—all the molecules are far, far smaller than can be seen with the naked eye.)

The great promise of focused ultrasound to improve immunotherapy’s ability to treat cancer prompted UVA in 2022 to launch its Focused Ultrasound Cancer Immunotherapy Center—the world’s first center devoted specifically to that purpose.

Now UVA is bolstering its research tools with the addition of a cutting-edge MRI-guided focused ultrasound system for drug delivery to the brain. The system, by Insightec, comes equipped with an advanced magnetic resonance imaging unit that provides detailed views inside the brain. This will let the researchers better understand exactly what happens as they use sound waves to drive drug molecules into tumors.

“This new MRI-guided focused ultrasound system gives our researchers the ability to both deliver treatment and monitor its effects with exceptional precision,” said UVA Health’s James Stone, MD, Ph.D. “That combination will accelerate our understanding of how to optimize drug delivery for brain tumors and help move promising therapies closer to clinical care.”

“We have a deep commitment at UVA to advancing care for patients here and around the world through important research like this,” said Colin P. Derdeyn, MD, interim dean of the UVA School of Medicine.

While more research needs to be done, the promising results bode well for the efforts by UVA Cancer Center and UVA’s Paul and Diane Manning Institute of Biotechnology to develop new options for patients with brain cancers. (UVA’s Manning Institute has been launched specifically to fast-track new treatments and cures for the most challenging diseases to benefit patients across Virginia and beyond.)

“I am hopeful this research illustrates how advanced MR imaging methods can be used to improve focused ultrasound delivery treatments in the clinic,” Price said. “In particular, it’s exciting to think about how these technologies could be combined with future gene therapies, from Manning Institute investigators and companies, aimed at treating brain tumors.”

Price and his collaborators have published their results in the journal Radiology. The research team consisted of Matthew R. Hoch, Victoria R. Breza, G. Wilson Miller and Price. Price is part of UVA’s Department of Biomedical Engineering, a joint program of the School of Medicine and School of Engineering and Applied Science, as well as part of the School of Medicine’s Department of Radiology and Medical Imaging.

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Gaby Clark

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Robert Egan

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