Posted: Jul 16, 2008 11:48 PM
June 3, 2008 (Chicago) -- After Sen. Edward Kennedy recuperates from surgery for brain cancer at Duke University Medical Center he will begin targeted radiation and chemotherapy.
Kennedy, 76, has a type of brain tumor called a malignant glioma. The standard treatment for glioblastoma, the most common form of glioma, is the chemotherapy drug Temodar during and after radiation.
Studies have shown that half of people given the combination of radiation and Temodar live nearly 15 months vs. 12 months for radiation alone. But the range is variable, says Mark R. Gilbert, MD, professor and deputy chairman of the department of neuro-oncology at the University of Texas M.D. Anderson Cancer Center in Houston.
At the annual meeting of the American College of Society Oncology (ASCO) here this week, Gilbert and other brain cancer specialists reported on some experimental therapies that Kennedy and his doctors may also be looking into.
One possibility is experimental treatment with a cancer vaccine that bolsters the patient's immune system to attack the tumor.
Patients given the vaccine, known as CDX-110, typically live twice as long as those not given the vaccine, according to the results of two small studies.
One study involved 23 patients with newly diagnosed glioblastoma tumors who had undergone surgery, radiation, and Temodar treatment.
Half of patients treated with the injectable vaccine lived an average of 33.1 months. In contrast, people receiving standard treatment typically live for an average of 14 or 15 months, says John H. Sampson, MD, a neurosurgeon at Duke University.
The study also showed the vaccine extended the time to tumor recurrence after surgery. Tumors came back an average of 16.6 months later in the vaccine group vs. the standard 6.4 months for patients given radiation and chemo, Sampson says.
The vaccine was generally well tolerated, with the most common side effect being soreness at the site of injection he says.
In the second study, half of the 21 patients given the vaccine lived for 26 months, says Sampson.
The findings are promising enough that researchers plan to move to the next stage -- a larger trial comparing patients given the vaccine to those who don't get it. The trial will involve about 90 patients at more than 20 cancer centers across North America.
"The data are very striking, but it's very preliminary," says Gilbert, who participated in the research. He notes that to qualify for the study, there has to be no signs of tumor regrowth on an imaging scan after surgery, radiation, and chemo.
"The problem with glioblastoma is that some patients do very well and some do very poorly. By definition, the patients in this study are good-prognosis patients in that they had no signs of tumor growth after standard therapy. So until the larger head-to-head comparison is done, we can't say with certainly that the vaccine extends lives," he tells WebMD.
Another possibility is adding the targeted cancer drug Avastin to standard treatment.
Avastin prevents tumors from growing new blood vessels, thereby choking them to death. It is approved to treat metastatic breast cancer as well as metastatic colorectal cancer and advanced lung cancer.
A study revealed at the ASCO meeting this week involved 167 people with glioblastoma who suffered a recurrence after standard treatment. They face a worse prognosis than people with newly diagnosed brain cancer.
The study was funded by Genentech, which makes Avastin.
Results showed that the median overall survival time was 9.2 months in those who received Avastin alone and 8.7 months in those who got Avastin plus the chemo drug with Camptosar.
The most common severe side effects were high blood pressure and convulsions, similar to those observed in other studies of Avastin.
"This is better than anything we have tried before for this group of patients," says researcher Timothy Cloughesy, MD, director of the neuro-oncology division at UCLA.
Based on the results, doctors hope to launch a study of Avastin in newly diagnosed patients in the fall, Gilbert says.
But even before then, doctors can prescribe the drug "off-label" -- that is, for purposes other than its FDA-approved uses -- for patients with newly diagnosed brain cancer if they think it will help, doctors say.
Massachusetts General Hospital, where Kennedy is scheduled to have his follow-up treatment, is participating in a study designed to see "whether giving more Temodar over a longer period of time can make these cancers even more treatable and further improve survival," Gilbert says.
It's already been proven that women undergoing chemotherapy for breast cancer live longer and suffer fewer recurrences if the drugs are given more frequently than had been standard practice, he explains.
And while there were worries that the regimen would prove more toxic, that was not the case, researchers say.
"We've shown it works with breast cancer. Now we're hoping it will work in brain cancer as well," Gilbert says.
The study is being conducted in newly diagnosed glioblastoma patients, he says.
Yet another possibility is treatment with a novel drug called talampanel. The use of talampanel follows discovery that brain tumor cells release a lot of a substance called glutamate. Talampanel may prevent brain tumor growth by blocking the effect of glutamate.
Stuart Grossman, MD, at John Hopkins and colleagues studied 72 patients with newly diagnosed glioblastoma. Patients were given talampanel in addition to standard chemo and radiation.
The participants lived an average of 18 months, "which is striking," Gilbert says. "This is a strategy well worth pursuing."
The researchers hope to start a larger long study pitting talampanel plus chemotherapy and radiation vs. chemo and radiation alone in the near future.