Summary: A new study shows that primary brain tumors called gliomas respond well to targeted drug delivery using focused ultrasound (FUS) combined with microbubbles, and that an MRI-based approach can precisely track blood-brain barrier (BBB) opening and drug transport inside the tumor microenvironment.
Researchers developed a high-resolution MRI protocol to visualize how focused ultrasound opens the BBB and moves therapeutic molecules into tumor tissue. Their results challenge previous concerns that the mutated, irregular vasculature of gliomas would block sound-wave-mediated delivery. Instead, focused ultrasound retained—sometimes even improved—performance in tumor tissue, and the team identified a “Goldilocks” molecular size window that maximizes uptake into tumor cells.
Key Facts
- Enhanced Barrier Permeation: Glioma tissue showed equal or greater susceptibility to focused-ultrasound-mediated BBB opening compared with normal brain tissue, rather than resistance caused by chaotic tumor vasculature.
- MRI-Integrated Tracking: The study combined high-resolution MRI with focused ultrasound to map intra-tumoral drug accumulation dynamics with precise spatial detail.
- Molecular Size “Goldilocks” Window: Delivery efficiency depended strongly on payload size: medium-sized therapeutic molecules accumulated more effectively than very small or very large compounds.
- Non-Invasive, Localized Delivery: Microbubble-assisted FUS uses low-frequency acoustic waves to transiently and reversibly open the BBB at targeted coordinates without surgery.
- Translational Infrastructure: The addition of an Insightec MRI-guided focused ultrasound system at UVA will accelerate the translation of this work toward clinical trials in glioblastoma immunotherapies and gene therapies.
Source: UVA Health
Overview
UVA Health researchers report that gliomas—primary brain tumors that include the aggressive glioblastoma subtype—may be even more receptive than healthy brain tissue to targeted drug delivery using focused ultrasound with microbubbles. This result eases a key clinical concern: that the altered blood-brain barrier within tumors would prevent consistent, localized delivery of therapeutic agents.
Tumor development alters both the structure and function of the BBB, producing heterogeneous and unpredictable permeability. That variability raised questions about whether the mechanical action of microbubbles—driven by focused sound—would reliably open the barrier and allow drugs to reach tumor cells. To address that uncertainty, the researchers integrated a new MRI approach directly with FUS to measure drug delivery at high spatial resolution inside glioma tissue.
According to Richard J. Price, PhD, co-director of the Focused Ultrasound Cancer Immunotherapy Center at UVA, the MRI-integrated method provides unprecedented insight into how molecules move from blood vessels into the tumor microenvironment during and after BBB opening. The results indicate focused ultrasound delivery is preserved in gliomas and can be optimized for particular therapeutic agents.
Better Brain Cancer Treatments
Gliomas are the most common primary brain tumors in adults and include glioblastoma, which remains highly lethal despite current therapies. One major obstacle is safely delivering drugs across the BBB. The barrier protects the brain from pathogens and toxins, so clinicians must balance effective drug access against the risk of allowing unwanted material into the brain.
Microbubble-assisted focused ultrasound provides a solution: intravenous microbubbles and externally applied, focused low-frequency sound waves temporarily loosen the tight junctions of cerebral blood vessels at precise coordinates. The BBB opening is short-lived and localized, enabling therapeutic molecules to enter tumor tissue without invasive surgery or a craniotomy.
In preclinical glioma models, the UVA team observed that medium-sized molecules accumulated most efficiently after FUS-mediated BBB opening. Very small molecules tended to pass through too rapidly and did not localize effectively inside tumor cells, while very large molecules encountered transport limitations. Identifying this intermediate “Goldilocks” size range helps guide the design and selection of drugs, antibodies, and gene-delivery vectors for maximum tumor uptake.
The potential of FUS to enhance immunotherapy and gene therapy for brain tumors motivated UVA to establish the Focused Ultrasound Cancer Immunotherapy Center in 2022. Strengthening that initiative, the new Insightec MRI-guided focused ultrasound system at UVA provides high-fidelity magnetic-resonance imaging paired with precise ultrasound delivery. This integrated platform lets researchers both administer treatments and monitor their biological effects in real time.
James Stone, MD, PhD, of UVA Health notes that combining accurate delivery with exceptional imaging will speed optimization of therapeutic protocols and support the transition of promising approaches into clinical trials. UVA leadership emphasizes ongoing collaboration between investigators, funding agencies, and industry to advance focused ultrasound research and bring better therapies to patients.
While further studies are needed, these findings are encouraging for research teams at UVA Cancer Center and the Paul and Diane Manning Institute of Biotechnology, which aim to accelerate new treatment options for people with brain cancers.
“Advanced MR imaging methods can improve focused ultrasound delivery in the clinic,” Price said, highlighting the potential to combine these tools with emerging gene therapies and immunotherapies under development at the Manning Institute and partner organizations.
Findings Published
Price and collaborators published their results in Radiology. The research team included Matthew R. Hoch, Victoria R. Breza, G. Wilson Miller, and Richard J. Price. Price holds appointments in UVA’s Department of Biomedical Engineering, as well as the Department of Radiology and Medical Imaging in the School of Medicine.
Funding: The research was supported by the National Institutes of Health (grants R01EB030409, R01EB030744, R21NS118278, and R01CA226899) and by the UVA Focused Ultrasound Cancer Immunotherapy Center.
Key Questions Answered
A: High-grade gliomas alter BBB structure and function in complex ways. Scientists were concerned that this disordered vasculature could reduce the mechanical effectiveness of microbubbles and limit consistent drug entry into tumor tissue.
A: Delivery efficiency depended on molecular size: very small molecules tended to wash through too quickly without effective cellular uptake, while very large molecules faced transport barriers. Medium-sized therapeutics achieved the best balance for tumor accumulation.
A: Injected microbubbles circulating in the bloodstream vibrate when targeted by focused sound waves. This acoustic cavitation transiently loosens tight junctions between endothelial cells, allowing therapeutic agents to pass from blood into brain tissue at the targeted site.
Editorial Notes
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full.
- Additional context was added by staff to clarify translational implications and imaging advances.
About this brain cancer and neurotech research news
Author: Josh Barney
Source: University of Virginia Health System
Contact: Josh Barney – University of Virginia Health System
Image: Image credited to Neuroscience News
Original Research: Findings published in Radiology