Blood-brain barrier breached for first time to treat cancer

TORONTO: For the first time, scientists have successfully breached the human blood-brain barrier non-invasively to effectively deliver cancer-fighting drugs into the brain of a patient.

Each person has a protective blood barrier lining the blood vessels in the brain to restrict the passage of large toxic substances from the bloodstream into the brain.

"The blood-brain barrier (BBB) has been a persistent obstacle to delivering valuable therapies to treat disease such as tumours," said Dr Todd Mainprize, principal investigator of the study and Neurosurgeon at Sunnybrook Health Sciences Centre in Canada.

"We are encouraged that we were able to temporarily open this barrier in a patient to deliver chemotherapy directly to the brain tumour," said Mainprize.

The research team infused a chemotherapy drug and tiny, microscopic bubbles, into the bloodstream of the patient who had a malignant brain tumour.

The microbubbles were smaller than red blood cells and pass harmlessly through the circulation.

The researchers then used MRI-guided focused low-intensity ultrasound waves to target blood vessels in the blood-brain barrier (BBB) area near the tumour.

The waves repeatedly compress and expand the microbubbles, causing them to vibrate and loosen tight junctions of the cells comprising the BBB.

Once the barrier was opened, the chemotherapy flowed through and deposited into the targeted regions.

"Some of the most exciting and novel therapeutics for the treatment of malignant brain tumours are not able to reach the tumour cells because of the blood brain barrier," said Mainprize, also an Assistant Professor at University of Toronto.

"This technique will open up new opportunities to deliver potentially much more effective treatments to the targeted areas," said Mainprize.

Less than 24 hours after breaching the blood brain barrier, the tumour and some surrounding tissues were surgically removed and sent to pathology to measure differences in the concentration of chemotherapy that deposited in the area treated by the focused ultrasound and the area not treated.

"Breaching this barrier opens up a new frontier in treating brain disorders," said Neal Kassell, chairman of the Focused Ultrasound Foundation, a US-based non-profit organisation.

The success of this research opens up the potential for delivering drug therapies to parts of the brain protected by the blood brain barrier, including researching treatments for patients with various kinds of brain tumours, Alzheimer's disease, and some psychiatric conditions.

The case was the first of up to 10 participants in this study, which is testing for feasibility, safety and preliminary efficacy.

The participants are those already scheduled for traditional neurosurgery to remove parts of their brain tumour.