Wednesday February 12, 5:51 pm ET
By Hollister H. Hovey
Dow Jones Business News
The Food and Drug Administration has asked Biogen Inc. to notify doctors that in a small number of cases, patients taking blockbuster multiple-sclerosis drug Avonex developed rare blood diseases after taking the drug.
The Cambridge, Mass., biotech company plans to change the label on Avonex, which garnered over $1 billion in sales last year, to say that a small number of patients taking the drug developed pancytopenia, a condition in which the bone marrow has a difficult time making red blood cells, and thrombocytopenia, an abnormal drop in platelet count, which affects the blood's ability to clot.
The label change comes after the company on Friday released the results of a three-year study that led the FDA to approve Avonex as an early treatment of multiple sclerosis, which will be added to the drug's label. Prior to that, the drug was only approved in the U.S. as a therapy for relapsing forms of the disease.
While the FDA doesn't require a company to put every instance of an adverse side effect into a drug's label as they crop up, it's standard to review the historic safety data of the drug when the company plans to change the label or package insert anyway, spokeswoman Amy McKnight said.
Ms. McKnight said she wasn't sure how many cases of the blood disorders
showed up over the seven years the drug's been on the market, but she did
say the incidences were rare.
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