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    Warning Issued for Cancer Drug Avastin

    Cancer Drug May Increase the Risk of Stroke, Heart Attack Especially in Elderly
    WebMD Health News

    Aug. 13, 2004 -- The recently approved cancer drug Avastin may increase the risk of serious and potentially deadly blood clots in up to 5% of people who use it, according to a drug warning issued today.


    The drug's manufacturer, Genentech, Inc., and the FDA sent a letter warning health care providers with new information about the potential side effect yesterday. Avastin was approved in February for the treatment of advanced colorectal cancer that has spread to other parts of the body.


    In the letter, Genentech officials say there is evidence of an increased risk of developing clots within blood vessels and arteries that could become dislodged and travel to the heart or brain and lead to serious complications, such as stroke or heart attack, associated with the use of Avastin.


    People who experience blood clots during treatment are advised to stop taking the drug.

    Avastin Linked to Blood Clots

    In randomized clinical trials with advanced colorectal cancer patients, the risk of serious blood clot-related events was nearly twice as high in patients receiving Avastin in addition to standard chemotherapy vs. those receiving chemotherapy alone. The estimated overall rate of these adverse events was up to 5%.


    The risk of these side effects was higher in people with a prior history of blood clots in the arteries and those over age 65.


    Genentech says it is currently developing revised labeling information for the drug to include details on these risks. Genentech is a WebMD sponsor.


    Avastin is the first of a new class of drugs known as angiogenesis inhibitors to be approved by the FDA. The drugs work by preventing the formation of new blood vessels, a key factor in preventing the spread of cancer as well other diseases.


    Avastin is given by injection. The antibodies target a protein called vascular endothelial growth factor (VEGF) that plays a role in making new blood vessels for tumors (a process called angiogenesis). When Avastin binds to the protein, it stops the growth of new blood vessels, which eventually starves the tumor of the blood, oxygen, and other elements needed for growth.

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