Avastin, in combination with chemotherapy (paclitaxel), was approved in February 2008 under the FDA's accelerated approval program, based on the results of a clinical trial known as "E2100," which evaluated the drug in patients who had not received chemotherapy for their metastatic HER2-negative breast cancer. Under the accelerated approval program, a drug may be approved based on clinical data that suggest the drug has a meaningful clinical benefit, with more information being needed to confirm this.  The program provides earlier patient access to promising new drugs to treat serious or life-threatening conditions while confirmatory clinical trials are conducted.

After the accelerated approval of Avastin for breast cancer, Genentech completed additional clinical trials and submitted the data from those studies to the FDA. These data showed only a small effect on "progression-free survival" without evidence of an improvement in overall survival or a clinical benefit to patients sufficient to outweigh the risks. The small increase in "progression-free survival" reflects a small, temporary effect in slowing tumor growth.

Avastin has also been associated with several other serious and potentially life-threatening side effects including the risk of stroke, wound healing complications, organ damage or failure; and the development of a neurological condition called reversible posterior leukoencephalopathy syndrome (RPLS), characterized by high blood pressure, headaches, confusion, seizures, and vision loss from swelling of the brain.

On the basis of all available data relating to the use of Avastin to treat metastatic breast cancer, the agency has determined that the risks of the drug outweigh the benefits for this use.

FDA is open to working with Genentech on any proposals to conduct additional studies of Avastin in patients with metastatic breast cancer designed to identify a population of patients in which the drug's benefits exceed the risks.