Genentech’s blockbuster cancer drug Avastin (bevacizumab) is to come before a US Food and Drug Administration advisory panel in December as a first-line treatment for advanced breast cancer, according to press reports, following the August resubmission of its Biologics License Application in this indication. The move surprised some investors and analysts, sending the firm's shares down marginally on the New York Stock Exchange last week.

Currently approved for colorectal and lung cancers, Genentech is hoping a 'yes' in breast cancer will help send sales of Avastin – already standing at $564 million in the second quarter alone – even higher.

Genentech sought approval for the use of Avastin in combination with Bristol-Myers Squibb’s Taxol (paclitaxel) in May 2006, for use in patients who have not yet received chemotherapy. A final decision on approvability is expected by February next year.

But it has not been an entirely smooth ride. In September last year, the FDA requested additional information from the trials, including an independent, blinded review of patient scans for progression-free survival the primary endpoint of the trial. Genentech says the findings of this review are consistent with the initial findings – presented in 2005 at the American Society of Clinical Oncology meeting – that patients treated with Avastin plus paclitaxel experienced a near doubling in median PFS compared to those treated with paclitaxel alone (11 months versus six months). Furthermore, it stresses, no new safety signals emerged outside of those known to be associated with Avastin.

According to the American Cancer Society, an estimated 178,000 women will be diagnosed with breast cancer and approximately 40,000 will die from the disease in the United States in 2007. Among women, breast cancer is the most common form of the disease, excluding skin cancer, and the second leading killer after lung cancer.

Avastin, a therapeutic antibody designed to specifically inhibit vascular endothelial growth factor – a protein that builds the new blood vessels that supply oxygen and nutrients to the tumour - is also being investigated in more than 20 different tumor types, including for its potential use in adjuvant and metastatic colorectal, renal cell, breast, pancreatic, non-small cell lung, prostate and ovarian cancers.