Bevacizumab is an anti-VEGF antibody used as a chemotheraputic agent. VEGF is a growth factor in the body that promotes the growth of new blood vessels. The antibody is marketed as Avastin and has on-label approval in a number of cancers. Initially approved for colon cancer it is now used in lung and renal and, for our purposes in this post, glioblastoma multiforme. GBM is an aggressive primary brain tumor. It is what Ted Kennedy passed from.
Avastin got quick approval for GBM from the FDA based on limited studies and results that showed it delayed progression once patients had progressed on traditional chemotherapy.
Well now at the American Society for Clinical Oncology meeting two phase III randomized studies have shown somewhat disappointing results for Avastin in terms of prolonging overall survival in patients with GBM. Both the Radiation Therapy Oncology Group protocol and the AV Aglio trial put Avastin with Temodar and radiation therapy at diagnosis to see if such improved survival versus simply temodar and radiation, a more traditional therapy. Perhaps no surprise as phase II trials had shown similiar prior to these two large trials but there was no improvement in overall survival.
Avastin didn’t prolong life when used as a first treatment for people with brain tumors like the one U.S. Sen. Edward Kennedy died of several years ago, two studies found. In one, patients who were expected to benefit the most from Avastin based on genetic testing had the worst survival rates. Side effects also were more common with Avastin.
That might not be so horrible, since Avastin’s current approval is essentially as salvage, but the side effects were much more significant when Avastin was added to Temodar as a first line agent.
Avastin used to have approval for use in breast cancer but something very simliar had to the data with Avastin in breast cancer that prompted the FDA to pull approval.
Avastin received Food and Drug Administration approval after studies suggested it delayed disease progression. But when later research showed it didn’t prolong life and brought more side effects, its approval for breast cancer was revoked.
I would argue, and clinicians more in the know than myself however are already as well, that progression free survival in brain tumors is something different than progression free survival in breast cancer patients.
[B]ecause of the cramped quarters of the brain, progressive disease almost always has immediate effects on cognitive and motor functions. Other studies have shown that patients receiving Avastin are more likely to be able to live independently, and have less need for corticosteroid drugs.
If Avastin does indeed produce very quantifiable quality of life benefits, potentially mostly in terms of preserved cognition and functional ability, then it would obviously be a potentially well worth therapy, at least as continued second line therapy, even with its known potential side effects.