Avastin Blood Clot Safety Warning

November 2008

The Food and Drug Administration (FDA) is being advised to give its strongest warning, a black box warning, to the blockbuster cancer drug Avastin. According to a report in the Journal of the American Medical Association, the potentially dangerous medication increases the risk of developing serious blood clots.

Avastin is part of a group of drugs called "targeted therapies" that have been praised for being safer and gentler than traditional chemotherapy. However, the report says that about 12 percent of people who take Avastin develop blood clots in their veins, a rate that is 30 percent higher than among cancer patients not taking the drug. Blood clots can be deadly if they travel to the lungs and are one of the leading causes of sickness and death among cancer patients.

Doctors did not know the degree of Avastin's risks until now because earlier studies were too small to produce clear results, says co-author Shenhong Wu of New York's Stony Brook University. Wu says his study is particularly strong because he combined the results of 15 well-designed trials involving nearly 8,000 patients.