A U.S. Food and Drug Administration panel is advising the agency to revoke Roche's right to market Avastin as a treatment for metastatic breast cancer after additional trial data convinced it that the biologic's risks might outweigh its benefits. The recommendation could put a $1 billion dent in Avastin's global sales some reports say, slicing as much as a sixth off Roche's $6 billion take from the drug in 2009 and opening up fears that European regulators may also revisit their approval of the drug's use in treating advanced breast cancer.

“We are disappointed by the committee's recommendation and believe Avastin should continue to be an option for women with this incurable disease,” says Sandra Horning, global head of clinical development in hematology and oncology for Genentech, the Roche subsidiary that developed Avastin.

The Oncology Drug Advisory Committee's near-unanimous vote was 12-1 in favor of reversing an accelerated approval granted to Roche by the FDA in 2008. That approval was granted on the basis of initial clinical data showing the drug, in combination with another cancer medicine, paclitaxel, could help extend the lives of those taking it by an average five and a half months. Data from two new studies showed Avastin, in combination with other standard chemotherapeutic regimens, didn't extend survival as much as the initial study had suggested it might.

The panel was also swayed by data showing that the addition of Avastin, known generically as bevacizumab, to chemotherapy resulted in an increased rate of serious adverse events, such as gastrointestinal perforation and pulmonary hemorrhage.

Breast cancer is the number one cause of cancer in women in the United States, with an estimated 192,300 new cases of breast cancer and 40,000 deaths related to breast cancer in 2009, according to the panel's report. About ten percent of the patients will have the terminal, metastatic form of the disease at the time of the diagnosis and nearly half of patients treated for apparently localized breast cancer develop metastatic disease, the report's authors say.