Avastin halts brain cancer
Posted on: 03/04/2007
Avastin halts brain cancer
By Steve Mitchell Feb 20, 2007, 18:43 GMT
WASHINGTON, DC, United States (UPI) -- Genentech may get a boost from a new pilot study showing its drug Avastin slows the growth of the most common and deadly form of brain cancer.
Avastin, which is approved for treating lung and colorectal cancers, either shrank tumors or halted their growth for up to three months longer than other therapies in patients with a form of brain cancer known as recurrent glioma.
'It's pretty promising,' Dr. James Vredenburgh, a brain-cancer specialist at Duke's Preston Robert Tisch Brain Tumor Center and lead researcher on the study, told United Press International.
In fact, Genentech, which partially funded the study along with the National Institutes of Health, liked the results so much, they're already launched a larger trial involving 160 patients to determine if the beneficial effects were due to Avastin alone. The patients in the pilot trial were also given another chemotherapy drug known as irinotecan along with Avastin.
Vredenburgh, who has no connection to Genentech, said the study has completed enrollment and will now begin treating the patients and following them.
Genentech did not respond to UPI's request for comment.
Kate Carr, president and chief executive officer of Accelerate Brain Cancer Cure, a not-for-profit organization that has worked in collaboration with Genentech to examine Avastin's potential for treating brain cancer, applauded the pilot study and the larger study now under way.
'The results of this initial study are very encouraging,' Carr said. 'We are now excited to learn the findings of the larger study, that, it is hoped, will lead to an approved therapy for patients with brain cancer,' she added.
In the pilot study, which appears in the Feb. 20 issue of Clinical Cancer Research, Vredenburgh's team administered Avastin in conjunction with irinotecan to 32 patients with stage III or IV forms of recurrent glioma. The tumors shrank by at least 50 percent in 63 percent of the patients, and 38 percent were progression-free at six months.
The findings may offer hope for patients who would otherwise have no options. Life expectancy for recurrent glioma is three to nine months, and there are no drugs approved for treating it.
It also could be a boon for Genentech because the current gold standard of treatment only extends survival by two months. And that's under the best-case scenario in patients who have just been diagnosed. In the current study, Avastin offered a longer time of progression-free survival in patients with advanced disease.
Vredenburgh thinks beginning the drug when they're first diagnosed may yield even better benefits.
'If we get to them earlier, I think we're finally going to improve survival of disease,' he said. 'We haven't done that in the last two decades.'
However, the drug will have to overcome two barriers: cost and the risk of bleeding.
Insurance companies currently won't cover the expense of the glioma Avastin course, which runs about $20,000 every two weeks. Considering the patients were treated for approximately a year in this study, that comes out to more than $500,000.
Insurance companies consistently denied coverage of the drug for patients in the trial even though it appeared to be their best option, Vredenburgh said. So without being enrolled in a trial like this, they usually can't afford the drug, he said.
The risk of bleeding almost made it impossible to get the pilot trial started in the first place.
Both the Food and Drug Administration and Genentech were resistant to the idea of using Avastin to treat patients with gliomas because the drug's labeling warns against the risk of bleeding and specifically refers to patients with brain metastases.
'The risk of central nervous system (CNS) bleeding in patients with CNS metastases receiving AVASTIN has not been evaluated because these patients were excluded from late stage clinical studies following development of CNS hemorrhage in a patient with a CNS metastasis in a Phase 1 study,' the labeling states.
But Vredenburgh said he was convinced by the basic science that Avastin should work in this form of cancer because it has one of the highest concentrations of VEG-F, which is what the drug targets. VEG-F, or vascular endothelial growth factor, is a protein that plays a role in enabling tumors to grow. Shutting down VEG-F shrinks or halts tumor growth.
It took some pleading, but Vredenburgh was finally able to persuade the FDA and the company to allow him to proceed with the study.
'Both of them thought I was crazy,' he said.
Vredenburgh conceded the risk of bleeding may be slightly increased with Avastin but said it is very difficult to tell because about 40 percent of brain-tumor patients develop bleeding problems anyway. The larger trial that's already completed enrollment may help elucidate which glioma patients are most at risk and whether some should not receive the drug.
But in the case of glioma, which is nearly always fatal, the risk may be worth it, he said.
Copyright 2007 by United Press International
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