November 25, 2011

FDA Revokes Avastin Approval as Breast Cancer Treatment

The FDA has finally pulled the plug on approval of the biotech drug Avastin for treating advanced breast cancer. Avastin is a monoclonal antibody which works by targeting and shrinking the blood vessels required for tumor growth.  What was interesting about this drug was that it was approved on the FDA fast track in 2008 at a time when it looked to be a promising therapy for the treatment of advanced breast cancer.  In June, an FDA advisory committee recommended that the FDA remove its endorsement for use in metastatic breast cancer, citing studies in which Avastin had shown very little effect on survival time. What is important about this whole episode from the regulatory perspective are several facets: the use of a fast track FDA approval process to capture a promising lead on a biotech drug while minimizing delay in clinical studies, hence the initial approval in 2008; the promise to condition final approval on studies which more thoroughly teased out whether the drug did significantly lengthen survival time (the studies did not support the promised effect) and the extensive public scrutiny of the FDA decision by a powerful patient constituency (pro-approval petition by some breast cancer advocates) and a biotech company (Genentech) which surely did not want to lose its FDA imprimatur and actively campaigned to keep drug approval. But Commissioner Margaret Hamburg sided with the advisory committee in ending the FDA approval, publishing a lengthy document which outlines the reasoning for the decision. Of course, physicians may continue to prescribe Avastin off-label for treatment of breast cancer, but the drug can no longer be legally advertised for such use. Notably, not all breast cancer advocates opposed the FDA's decision; the National Breast Cancer Coalition expressed support. Of most immediate concern for breast cancer patients who still want to receive Avastin is that the lack of FDA endorsement will cause most insurance plans to not cover the cost of the drug (about $88,000 per year). What's also interesting about Avastin (and potentially other biotech drugs which target the support system for cancer cells) is that its mechanism would appear to have wide applicability (be able to generally limit tumor growth) but in actual clinical trials, the effects may be quite heterogeneous (Avastin retains FDA approval for use in treating colon, lung, kidney, and brain cancers).

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