Attacking brain tumors head-on

According to the Pharmaceutical Research & Manufacturers of America, 34 medications are currently in clinical trials for brain tumors. More than one-third of those agents are being investigated for treatment of glioblastoma multiforme (GBM), a high-grade, aggressive form of brain cancer.

New directions, old therapies

Bevacizumab is a monoclonal antibody that inhibits activity of vascular endothelial growth factor (VEGF), an angiogenic peptide that promotes growth of new blood vessels in tumors. Via its angiostatic actions, bevacizumab disrupts a tumor's blood supply. This agent has already been shown to reduce microvascular growth and slow disease progression and is indicated for treatment of colon cancer. Also approved for colon cancer is irinotecan, an inhibitor of DNA topoisomerase. This enzyme normally repairs damaged DNA, but use of irinotecan prevents religation of broken DNA strands, thus leading to tumor cell death.

Lead investigator for the study, James Vredenburgh, M.D., at Duke University Medical Center, believes that the reason for the combination's efficacy is that bevacizumab suppresses abnormal tumor blood vessel growth, thus decreasing the interstitial pressure around the tumor, which allows more irinotecan to reach cancer cells. Bevacizumab will likely be tested in combination with both radiation therapy and temozolomide in patients with newly diagnosed GBM.