THURSDAY, July 30, 2009 (HealthDay News) -- A new way to predict which brain cancer patients will respond to the drug Avastin has been developed by U.S. researchers.
Avastin, which shrinks tumors by cutting off their blood supply, was approved this spring by the U.S. Food and Drug Administration for treatment of aggressive brain cancer. However, half of those with the cancer don't respond to the drug, which can cost up to $10,000 a month, according to a news release from the University of California, Los Angeles.
UCLA researchers examined 82 people who had surgery and radiation to treat glioblastoma, the most common and deadly form of adult brain cancer. Half of them were given infusions of Avastin every two weeks, and all had monthly MRI brain scans to monitor changes.
An analysis of the scans showed that there was greater water movement in the tumors of people who later had the best response to Avastin. By using MRI to measure the amount of water motion within the tumor, the researchers were able to predict with 70 percent accuracy which tumors would progress within six months and which would not.
Increased water movement in tumors is linked with higher levels of a growth factor called VEGF, which is secreted by a tumor to promote the growth of new blood vessels that provide the tumor with oxygen and nutrients. Avastin blocks VEGF, the researchers explained.
"When we realized that high levels of VEGF are linked to greater cell death and increased water movement, we were able to predict the patients' response to Avastin before they began treatment," lead author Dr. Whitney Pope, assistant professor of radiological sciences at UCLA's David Geffen School of Medicine, said in the news release.
"We were correct 70 percent of the time," Pope said. "Previously, identifying which patients would respond was like flipping a coin. This is a huge improvement."
The study appears in the July issue of Radiology.
"Knowing this information ahead of time will help doctors personalize therapy for each patient and decrease exposure to side effects," Pope said.
He and a co-author are consultants for Genentech, which makes Avastin, and are working with the company on several research studies.
The U.S. National Cancer Institute has more about brain tumors.