Color the FDA skeptical. Agency staff said the case for Avastin use against brain cancer is less than compelling. Studies submitted in support of the new indication--treatment of the deadly glioblastoma multiforme--rely on imaging scans; patients whose tumors shrunk at least 50 percent were deemed "responsive." Genentech, Avastin's maker, said 25 percent of patients in one study and 20 percent of another responded successfully to Avastin treatment, the Associated Press reports. Based on that evidence, Genentech wants a fast-track OK for the new use.
But FDA reviewers said measuring tumor size via imaging is problematic, and they said that response rate has never been a criteria for fast-track approval. And FDA oncology panel has said that a drug would have to have a response rate above 30 percent to make up for the iffy nature of tumor imaging. Avastin didn't reach that threshold in either of the studies Genentech submitted.
The drug is up for discussion at tomorrow's oncology panel meeting. As you know, advisory panels weigh the drugmakers' data and the FDA staff's response to it--and often the FDA review points out the "con" side of the case, because drugmakers have no incentive to do so. We'll have to wait and see whether staff or Genentech wins out tomorrow.
- read the Associated Press story