The new method could revolutionise the treatment of brain cancers and neurodegenerative diseases.
The new technique of guided ultrasound (Magnetic Resonance-guided Focused Ultrasound - MrgFUS) allows the temporary opening of blood vessels in a specific area of the brain, so that the drug can reach the cancer cells in the brain through the bloodstream. Four women with primary breast cancer that had metastasised to the brain saw their brain tumours shrink when the anti-cancer drug (Herceptin) was administered by the new method.
The blood-brain barrier is a cellular «wall» that prevents various substances such as toxins, viruses and microbes from entering the brain through the blood, so that they do not damage sensitive brain tissue. However, in the case of brain cancers or diseases such as Alzheimer's and Parkinson's, this barrier also makes drug therapy difficult, as few drugs (e.g. antidepressants) can cross the barrier.
The new technique, using focused ultrasound, causes tiny bubbles of a substance previously injected into the patient to oscillate in such a way that the blood-brain barrier cells move away from each other, so that the cancer drug can now pass into the brain. This is a temporary procedure that allows the barrier to open for less than 24 hours.
The researchers, led by Dr Nir Lipsman of the Sunnybrook Health Sciences Centre and the University of Toronto, who conducted the phase 1 clinical trial and published the results in the journal Science Translational Medicine, successfully delivered the monoclonal antibody trastuzumab (Herceptin) to the brains of four women with brain cancer. Their tumours shrunk by 21% on average and no patients experienced serious side effects. Antibody therapy helps the immune system fight cancer and is often used in combination with radiotherapy and chemotherapy.
As Lipsman said, «Herceptin is a huge substance, so if we can get that into the brain, we can safely assume that we will be able to do something similar with other substances that are large or smaller with the help of focused ultrasound.».
