Yesterday, a US Food and Drug Administration panel voted 6-0 to recommend overturning the approval of Avastin to treat breast cancer. The drug was given accelerated approval in February 2008 after an initial trial indicated that it helped patients live longer. Since then, however, four subsequent trials have failed to confirm these early results, and last December the FDA proposed withdrawing the drug for breast cancer. Genentech appealed this decision in January.

The agency has already green-lighted Avastin to treat other cancers. The drug can extend the lives of people fighting colon and non-small-cell lung cancers. And even though it does not do the same for glioblastoma patients, it helps alleviate symptoms of the disease, which convinced regulators that it would be worth approving for this indication. “We felt very comfortable that the risk was worth it,” Wyndham Wilson, head of lymphoma therapeutics at the US National Cancer Institute in Bethesda, Maryland and chair of the FDA’s oncology drugs advisory committee, told Nature Medicine.

If Avastin trials had shown benefit in either area — lifespan or symptoms — for breast cancer, his committee may have recommended differently, Wilson says. At the hearing, patients testified that the drug helps, but the overall picture is that “Avastin is not bringing meaningful clinical benefit to women with untreated metastatic breast cancer,” he explains.

The story is not over yet: A final decision is expected from FDA Commissioner Margaret Hamburg next month. And Genentech plans to go ahead with an additional trial to study the drug’s effects when given with a different variety of chemotherapy.

Some scientists, meanwhile, foresee a time when doctors can better predict which breast cancer patients will actually respond positively to Avastin. “As a breast cancer oncologist, I sincerely believe in coming years we will be using Avastin in metastatic breast cancer once science has revealed which minority or subsets truly do benefit from it,” says Gary Lyman, an oncologist at the Duke University Medical Center in Durham, North Carolina who sat on earlier advisory committees regarding the drug.