Yesterday on BioNews Texas, we reported on how the research community is debating the efficacy of Avastin for treating brain cancer. This follow-story reports on a new study conducted by researchers at The University of Texas MD Anderson Cancer Center, which suggests that newly diagnosed patients of glioblastoma are more likely to get positive results with bevacizumab (Avastin-) therapy.
According to the phase III clinical trial of Radiation Therapy Oncology Group (RTOG) 0825 that was conducted to study the efficacy of bevacizumab (when added to standard chemoradiation regimen with maintenance temozolomide therapy), researchers reported worsening of symptoms and cognitive decline with bevacizumab as compared to placebo group, with improvements in the area of disease progression. The Texas MD Anderson researchers conducted the study to determine the ideal patient population that can likely benefit from bevacizumab therapy.
Glioblastoma is one of the most aggressive brain tumors with a bad prognosis and high risk of recurrence after initial therapy.
The lead author and assistant professor in MD Anderson’s Department of Radiation Oncology, Erik Sulman, M.D. Ph. D commented:
“In general, glioblastomas are heterogeneous and no drug has been found that benefits every patient. We wanted to determine which patients are most likely to benefit from bevacizumab and use that information to develop a diagnostic tool that can predict which patients may be good candidates for the drug.”
The role of bevacizumab as an anti- tumor agent:
Bevacizumab exerts its action as a monoclonal antibody that has the ability to bind with the vascular endothelial growth factor, an essential requirement of all tumor cells. The ability of Bevacizumab to prevent the formation of new blood vessels to supply growing tumor cells leads to ischemic necrosis. Prior studies suggest prolong symptom-free survival and decreased intensity of symptoms.
The researchers at MD Anderson conducted this study to identify the role of genetic expression in gauging response to the Bevacizumab therapy.
The tissue samples of 637 randomized patients from RTOG 0825 were sent for molecular analysis. Degree of gene enrichment was also measured by molecular stratification to identify genes that are required for the formation of new blood vessels. After thorough observational studies, researchers identified the association between lower mesenchymal signature and better drug response in promoting survival in patients consuming bevacizumab.
Researchers formulated a novel gene expression after studying the association and expression of 43 genes as a predictor of outcome to bevacizumab therapy.
Dr. Sulman commented:
“One of the key things about this predictor is that it’s designed to be used on standard, archival tumors found in most clinical pathology labs. It doesn’t require fresh tissue.”
The research team is conducting further studies to determine the extent to which this gene expression is predictive of the actual prognosis. The results and recommendations of the study were presented at the annual meeting of American Society of Clinical Oncology.