FDA Approves Restricted Return of Tysabri
FDA on Monday approved a restricted market return for multiple sclerosis drug Tysabri, despite the drug's risk of causing an often-fatal brain infection, the New York Times reports (Pollack, New York Times, 6/6). FDA approved Tysabri in November 2004, but drugmakers Biogen Idec and Elan withdrew the medication from the market in 2005 after three patients -- two of whom died - developed progressive multifocal leukoencephalopathy, a rare brain disease.
An FDA advisory committee in March voted unanimously to recommend the return of Tysabri to the market. Studies have found that Tysabri is about twice as effective as available medications in the prevention of MS recurrences and appears to delay the progression of the disease (American Health Line, 3/23).
FDA, Biogen and Elan have agreed to a risk-management plan that will require doctors and other medical professionals to obtain additional training in order to provide the treatment. Doctors will counsel patients on the risks of PML before they begin treatment and will be required to obtain consent from patients acknowledging the risk (Krasner, Boston Globe, 6/6). Doctors at authorized infusion centers will go through a checklist with patients before each monthly infusion of the drug to determine whether patients show early signs of PML.
Doctors are required to examine patients for signs of PML after three months and six months of initial treatment, to be followed by PML assessments every six months thereafter. FDA and the companies hope that "if PML can be detected early enough and the drug stopped, the patient can recover," the New York Times reports (New York Times, 6/6).
Doctors must provide Biogen and Elan with an MRI scan of patients' brains taken before they start using Tysabri, so any changes resulting from PML can be more easily examined, FDA said. The drug will carry a black box warning about the risk of PML (Pagan Westphal, Wall Street Journal, 6/6).
Tysabri is approved for use only as a stand-alone treatment that cannot be administered in conjunction with additional MS treatments. Combining other therapies with Tysabri might increase the risk of PML (New York Times, 6/6). FDA said Tysabri "is generally recommended for patients who have had an inadequate response to, or are unable to tolerate, alternate multiple sclerosis therapies."
The Globe reports that FDA's "wording makes it likely Tysabri will be a second-line treatment," but the agency "has left the door open for doctors to prescribe it as a front-line drug" (Boston Globe, 6/6).
Steven Galson, director of the FDA Center for Drug Evaluation and Research, said, "In this case, we made the assessment that the benefits of this drug outweigh the risks for MS. We are certain that patients are willing to take this risk because of the potential benefits of the drug" (Crabtree, San Diego Union-Tribune, 6/6).
Russell Katz, director of the FDA Division of Neurology Products, said, "We expect, yes, that there will be other cases [of PML] and, yes, there will be additional deaths. This is balanced against the significant benefit we believe the drug confers" (Bridges, AP/Philadelphia Inquirer, 6/6).