Breaking through the blood-brain barrier to treat brain cancer
CANCER DIGEST – May 6, 2023 – Using an implantable ultrasound device, researchers have successfully opened the blood-brain barrier to allow more potent chemotherapy to treat brain cancers, a new clinical trial shows.
The new treatment approach was described in a May 2, 2023 Lancet Oncology article showing preliminary results of an early stage clinical trial aimed at determining the optimal chemotherapy dose to treat glioblastoma, a highly aggressive type of brain cancer with a poor prognosis.
The blood-brain barrier, which normally protects the brain from toxins, also makes it difficult for chemotherapy drugs to penetrate the brain. This means that traditional chemotherapy treatments are often ineffective against glioblastoma resulting in a high mortality for patients with this cancer.
The study, which was conducted by researchers from the Northwestern University, Feinberg School of Medicine, involved 17 patients (nine men and eight women) with recurrent glioblastoma who had previously undergone standard treatment with surgery, radiation therapy, and chemotherapy.
Following surgery to remove the brain tumor, patients were implanted with an ultrasound device that could be activated to temporarily disrupt the blood-brain barrier, allowing chemotherapy injections to reach the brain.
The results of the study were highly encouraging. Of the 17 patients in the trial, the average uptake of the chemotherapy by the portion of the brain targeted by the ultrasound waves was three to seven times higher than in the portions that did not receive ultrasound.
“This is potentially a huge advance for glioblastoma patients,” said lead investigator Dr. Adam Sonabend, in a press release. He is also an associate professor of neurological surgery at the Feinberg School of Medicine. “While we have focused on brain cancer (for which there are approximately 30,000 gliomas in the U.S.), this opens the door to investigate novel drug-based treatments for millions of patients who suffer from various brain diseases,” he said.
The chemotherapy drug used in the study was albumin-bound paclitaxel, which has been shown to be effective against glioblastoma in preclinical studies. Albumin is a natural protein made by the liver that makes the paclitaxel less toxic to healthy tissues.
The drug was administered intravenously following transmission of ultrasound waves by the implanted device to the area of the brain tumor. The chemotherapy was delivered twice a week for three weeks at three dose levels for three subgroups of patients in order to assess the optimal, least toxic dose.
The trial primarily evaluated toxicity and did not measure effectiveness. Side effects included loss of white and red blood cells and high blood pressure. No treatment-related deaths occurred.
The trial also showed that the ultrasound-induced opening in the blood-brain barrier is temporary, lasting about an hour following the ultrasound transmission.
A phase 2 trial combining the ultrasound and chemotherapy will be tested in a larger number of patients to evaluate effectiveness. That trial (NCT04528680) is currently enrolling patients.
The researchers caution that this was a small, phase 1 trial and that further studies are needed to confirm the safety and effectiveness of the treatment. However, the results suggest that this approach could be a promising new way of treating glioblastoma, a disease that has long been a challenge for oncologists.