FDA questions Avastin endpoint in GBM

In briefing documents posted ahead of Tuesday's Oncologic Drugs Advisory Committee meeting, FDA questioned the use of objective response as an endpoint to support accelerated approval of Avastin bevacizumab from Genentech as a single agent for previously treated glioblastoma multiforme (GBM). The PDUFA date for mAb against VEGF is May 5.

FDA said objective response has not been used as the basis for approval for GBM because the tumors' irregular configuration makes it difficult to measure their size by MRI. Use of MRI is further confounded by VEGF inhibitors because the drugs' mechanism stabilizes the blood-brain barrier, leading to a reduction in edema, which in turn results in a decrease in gadolinium enhancement in the MRI scan, the agency said. ...