A cover-story article published in the June 1 issue of the peer-reviewed Journal of Neurosurgery describes the findings, expected to serve as a basis for future clinical trials in humans.
Dr. Linda Liau, a researcher at UCLA's Jonsson Cancer Center and first author of the article, led the investigation of the vaccine. The vaccine uses powerful immune cells called dendritic cells to stimulate the immune system to attack malignant gliomas, the most deadly type of cancerous brain tumor.
"We observed significant improvements in survival rates for laboratory models treated with the vaccine as compared to untreated models. We're encouraged by our findings and believe they show promise to be translated into more effective brain cancer treatments," said Liau, an assistant professor of neurosurgery at the UCLA School of Medicine who specializes in novel treatments for cancerous brain tumors.
The vaccine eradicated tumors in 25 percent of the laboratory models injected with it. Models not exposed to the vaccine experienced rapid, unrestricted tumor growth, Liau said.
"These results provide an early example of the proof of principle behind immune-based approaches to treating brain cancer," said Dr. Darell Bigner, a cancer researcher and professor of pathology at Duke University Medical Center. "By finding ways to stimulate the immune system to target and attack cancer, Liau and her colleagues are poised to develop more effective anti-cancer therapies that could dramatically improve long-term success in treating the disease."
Liau said there is a critical need for more effective therapies for brain cancer, which affects more than 17,000 Americans each year and is almost 100 percent fatal.
"Without any treatment, patients with the most aggressive gliomas usually do not live longer than four months. Even after surgery, radiation and chemotherapy, patients usually live only for as long as two years," Liau said.
To be effective, a brain cancer treatment must be able to pass through the blood-brain barrier, a semi-permeable shield that guards brain tissue from foreign bodies such as toxins or bacteria. While immune cells circulate through most of the body to defend it against disease and help it heal from infections, the brain's fragile tissue requires the heightened security that the barrier provides.
Liau and her colleagues devised a way for dendritic cells in the vaccine to help other immune cells -- called T-cells -- cross the barrier. After entering the brain, the T-cells can seek out and destroy cancer cells.
"In brain cancer patients, the blood-brain barrier is like a double-edged sword. The barrier's filter is small enough to prevent harmful foreign agents from entering the brain but it is too fine to allow immune cells or some anti-cancer drugs such as chemotherapy to pass through and kill cancer cells that grow and develop in the brain," Liau said.
While additional studies are needed to improve effectiveness of the vaccine, Liau is optimistic that targeted approaches to treating brain cancer may hold the key to increasing survival and enhancing quality of life in patients.
"Immune-based therapies for brain tumors are very appealing because of their outstanding ability to target and attack cancer cells while avoiding normal brain tissue," Liau said.