An advisory panel for the US Food and Drug Administration (FDA) says the drug Avastin (bevacizumab) should not be approved for breast cancer treatment.

The Oncology Drug Advisory Committee recommended against FDA approval by a 5-4 vote Wednesday, noting that Avastin does not help breast cancer patients live longer and can cause severe side effects. The FDA often follows the recommendations of its advisory panels, but does not have to. A final decision by the agency is expected by late February 2008.

Avastin is approved to treat colon cancer and lung cancer. Studies have shown that Avastin helps patients with these cancers live longer. Even if the FDA does not approve it for treatment of breast cancer, some doctors may still prescribe it "off label" for this use, although insurance reimbursement might be an issue.

In making its recommendation, the advisory panel reviewed the results of a clinical trial involving 722 women with breast cancer that had returned after initial treatment or that had spread to other parts of their body. The women were randomly assigned to receive either Avastin plus the chemotherapy drug paclitaxel, or paclitaxel alone.

Adding Avastin to paclitaxel kept the cancer from growing for an average of 11.3 months, compared to 5.8 months for the women getting paclitaxel alone. But overall survival was not significantly better, and women who received Avastin had more serious side effects compared to those who got paclitaxel alone. Those included high blood pressure, blood clots, heart problems, holes forming in the colon (bowel perforation) and high levels of protein in the urine, which is a sign of kidney damage. These are all known side effects of Avastin.

In a report prepared for the panel, the FDA also said Avastin treatment may have caused as many as 6 deaths. However, Avastin's manufacturer, Genentech, disagreed with that assessment. The company's analysis attributed all those deaths to breast cancer or other causes, not to treatment with Avastin.

The advisory panel also reviewed the results of another clinical trial of Avastin in women who had previously been treated for metastatic breast cancer. In that study, the 462 patients received either Avastin in combination with the chemotherapy drug capecitabine, or capecitabine alone. Avastin did not significantly improve survival, or the time it took for the cancer to start growing again.

Genentech executives said they were "disappointed" by the committee's vote and will continue working with the FDA to get Avastin approved for breast cancer.