It was a close-run thing but Genentech and Roche have seen their bid to get blockbuster Avastin approved for breast cancer suffer a setback at the hands of a US advisory committee.

The US Food and Drug Administration’s Oncologic Drugs Advisory Committee has voted five to four that the data provided by Genentech are not sufficient to establish a favourable risk/benefit analysis for the use of Avastin (bevacizumab), in combination with paclitaxel, for the treatment of patients who have not received chemotherapy for their locally recurrent or metastatic HER2-negative breast cancer. The agency, which is not bound by the recommendations of its advisory committees, will make a final decision before February 23, but the odds are not good.

The panel took the same line as FDA staffers who, before the review, had noted that while the data from a 722-patient trial showed that median progression-free survival (PFS) was 11.3 months in patients who received Avastin in combination with paclitaxel compared to 5.8 months for chemotherapy on its own, overall survival was not extended. Furthermore, those in the Avastin group suffered a 20% rise in serious side effects including hypertension, blood clots and heart attacks. Six of the 363 patients who took Avastin died from side effects, compared with none of the 348 people on chemotherapy.

The vote was a close one, however. The panel’s chairwoman, Maha Hussain, an oncologist at the University of Michigan, said that that the side effect problem was sufficient to vote against approval and argued that Genentech’s data did not show that patients are living better or longer. However, slowing tumours improves quality of life for patients, claimed fellow committee member Eric Winer, an oncologist at Dana-Farber Cancer Institute in Boston, who said that should be enough for approval.

Susan Desmond-Hellmann, Genentech’s president of product development, said “we are disappointed by the split vote”, adding that the addition of Avastin to chemotherapy “showed the longest reported PFS in any first-line clinical trial of patients with advanced breast cancer, and we believe PFS is a meaningful endpoint". She added that “we remain committed to working with the FDA to make Avastin a viable treatment option for these patients”.

Genentech sales took a bashing on the news and ended the day down 8.4% to $66.64, with trading having been halted earlier. However analysts believe that the drug, which is currently approved for colorectal and lung cancers and had third-quarter sales of $597 million, still has a future in breast cancer. Genentech is conducting two additional Phase III trials on the drug in breast cancer and that data may see Avastin get approval in the future.