Avastin Helps Slow Late Breast Cancer

Dec. 27, 2007 -- Combination treatment with Avastin and Taxol slows the spread of metastatic breast cancer but does not improve overall survival.

The finding comes from a clinical trial that played a role in this month's 5-4 vote by an FDA advisory panel recommending against approving Avastin for metastatic breast cancer.

Avastin is a remarkable drug that chokes tumors by preventing them from growing new blood vessels. It's approved in the U.S. for patients with late-stage colorectal cancer or late-stage non-small-cell lung cancer. It's also approved in Europe for metastatic breast cancer; the FDA has not announced its final decision on this use.

In the clinical trial, Indiana University researcher Kathy Miller, MD, and colleagues randomly assigned 722 women with metastatic breast cancer to receive either Taxol alone or combination treatment with Avastin and Taxol.

The Avastin combination significantly extended patients' "progression-free survival" -- that is, the time it took for their disease to start getting worse -- from about six months to about a year.

However, the combination did not significantly extend the women's overall survival. After beginning treatment, the average patient getting the Avastin/Taxol combination lived 26.7 months. The average patient getting Taxol alone lived 25.2 months.

About 2% of the women taking the Avastin suffered reduced blood flow to parts of the brain; this did not happen to anyone in the Taxol-alone group. But overall, such events were rare. Even though patients taking the Avastin/Taxol combination had more side effects such as high blood pressure and headache, they reported the same quality of life as those taking Taxol alone.

Why did treatment with Avastin slow disease yet fail to improve survival? Miller and colleagues note that most of the patients' spreading cancers were already too well established in various parts of their bodies. These tumors likely already had a good blood supply, so stopping the growth of new blood vessels did not kill them.

Miller and colleagues report their findings in the Dec. 27 issue of the New England Journal of Medicine.