FDA Grants Hearing on Proposed Withdrawal of Marketing Approval for Avastin

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The FDA proposes to withdraw approval for a breast cancer treatment, with hearing scheduled for June.

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The Food and Drug Administration (FDA) is moving forward with a process to withdraw approval for marketing Genentech’s Avastin (bevacizumab) as a first-line treatment for metastatic breast cancer, a type of cancer that spreads to other organs.

Avastin, an antibody that blocks new blood vessel formation and thus may prevent tumor growth, already has FDA’s approval as a treatment for colorectal, lung, and kidney cancers. Last December, the agency proposed withdrawing approval for also listing the treatment of breast cancer on Avastin’s label.

The FDA’s proposal marks the first step in the withdrawal process.  Genentech has filed a request for a hearing, which the FDA has scheduled for June 28-29, 2011. The hearing will take place before the Oncologics Drug Advisory Committee (ODAC), an expert panel recruited by the FDA to provide recommendations.  This same committee voted twelve to one in July, 2010, to recommend removing breast cancer from the Avastin label.

The FDA has based its proposed withdrawal on a review of four clinical trials which it claims have failed to provide convincing evidence of Avastin’s efficacy in treating breast cancer.  The agency also cited “substantial adverse reactions” associated with Avastin’s use.

To obtain FDA approval to market drugs for treatment of specific diseases, manufacturers are required to conduct “Phase III trials” — large, randomized studies of a drug’s safety and effectiveness.

The FDA’s ODAC initially voted five to four against the use of Avastin to treat breast cancer in 2007 when it reviewed an initial Phase III study.  Notwithstanding the ODAC’s 2007 recommendation, the FDA in 2008 granted accelerated approval of Avastin, finding some potentially meaningful results in the initial study.  Accelerated approval allows use of drugs that demonstrate potentially greater clinical benefit for serious illnesses over existing treatment options but have yet to satisfy the criteria for full approval.

However, the FDA conditioned its accelerated approval on the results of additional phase III clinical studies.  The ODAC and the FDA have stated that the results of these additional studies provide the basis for their more recent recommendations to withdraw approval.