The use of Avastin alone to treat a subgroup of recurrent Grade 3 brain tumors showed it was safe and effective at delaying tumor progression, according to a retrospective study of 22 patients conducted by a researcher at the Seattle Cancer Care Alliance.
The patients all had a recurrent malignant glioma known as alkylator-refractory anaplastic oligodendroglioma (AO), for which there is no existing standard therapy. Oligodendrogliomas begin in brain cells called oligodendrocytes, which provide support around nerves by building a sheath of myelin and facilitating electrical nerve impulses. The relatively uncommon tumor affects about 2,000 persons annually in the U.S. Most are under age 50.
Avastin, known generically as bevacizumab, is the first approved therapy designed to inhibit angiogenesis, the process by which new blood vessels develop and carry vital nutrients to a tumor. It is approved so far to treat certain metastatic colon cancers and non-small cell lung cancer.
"Bevacizumab is an important drug for us," said Marc Chamberlain, M.D., author of the study published in the April 15 edition of the journal Cancer. "Of all of the targeted therapies for gliomas, this has been the most promising. And this is practice changing."
Therapy for treating recurrent high-grade gliomas is palliative. All patients with these high-grade tumors eventually die of their cancer. However, bevacizumab has the potential to be the best palliative treatment, according to Chamberlain, who is director of the Neuro-oncology Program at the SCCA and a professor of neurology and neurological surgery at the University of Washington School of Medicine.
Chamberlain said he expects that patients treated with the drug will have a marked improvement in their quality of life because the use of steroids, a common treatment that has significant side effects, can be greatly reduced or even eliminated.
"While treatment with Avastin does dramatically improve survival time, the time that patients have left is of better quality and less about living with the disease itself," Chamberlain said. In this study, the patients, ages 24-60, received an infusion of bevacizumab every two weeks for an average of 14.5 cycles (range was two to 39 cycles). Fourteen (64 percent) patients showed a partial response to the medicine as shown on radiographic scans. Two patients had stable disease and six had progressive disease. Progression-free survival ranged from three to 18 months and survival for the entire group of patients was three to 19 months.
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