The Food and Drug Administration's (FDA) Oncologic Drugs Advisory Committee (ODAC) will examine the drug as a first-line treatment in combination with paclitaxel chemotherapy for previously untreated patients in December, with the agency expected to take a final decision on 23 February 2008.

Avastin has already been approved as a breast-cancer treatment in the European Union and received approval in the US last year to treat patients with lung cancer. The drug had already been given the nod by the FDA to treat patients with colorectal cancer back in 2004.

However, Genentech has not had to face an FDA committee review for these indications in the past.

The world's second biggest biotech firm submitted a supplemental Biologics License Application (sBLA) for Avastin in May last year, based on the results of a clinical trial known as E2100.

E2100 was a pivotal Phase III multicentre, randomised and controlled study that enrolled 722 patients with locally recurrent or metastatic breast cancer who had not received chemotherapy before. The trial was sponsored by the National Cancer Insitute and found that Avastin reduced the risk of disease progression or death by 52 per cent for patients who used the treatment with chemotherapy, compared with patients who only received chemotherapy.

The firm resubmitted the sBLA in August this year after receiving a complete response letter from the regulator requesting additional information from the trial, including an independent, blinded review of patient scans for progression-free survival (PFS), the primary endpoint.

The independent review showed a similar magnitude of benefit to the data from E2100, although overall survival - a secondary endpoint of the trial - was not improved significantly. No new safety signals related to Avastin were observed.

If the FDA gives Avastin the green light in the breast cancer setting, it could significantly boost the drug's sales which totalled $564m (€407m) in the second quarter of the year, a 33 per cent increase compared to the same quarter last year, making it the firm's second biggest earner.

Meanwhile, some analysts estimate the drug could spawn an extra $300m in its first year on the market if approved for breast cancer.