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FDA cites concerns on monitoring drug's safety
By Jeffrey Krasner, Globe Staff | March 23, 2006

The Food and Drug Administration yesterday delayed by up to three months its decision on whether to return the multiple sclerosis drug Tysabri to the market, citing concerns about plans to safeguard patients from potentially deadly side effects.

Biogen Idec of Cambridge and Elan Corp. of Ireland, the drug's makers, said the FDA may take until June 28 to review a risk management plan intended to prevent further cases of a rare brain disease found in three patients taking the drug in trials. The disease, called progressive multifocal leukoencephalopathy, caused Tysabri to be pulled from the market in February 2005, after just three months on sale.

The companies have proposed mandatory enrollment in a registry for patients taking Tysabri and for physicians administering the treatment. Doctors will also test for signs of PML. But the plan, put together in the days leading up to an FDA advisory committee meeting this month, may not be stringent enough to satisfy regulators.

On March 8, after dozens of patients testified in favor of Tysabri, the committee voted unanimously to recommend that the FDA allow its return to the market. It also voted 7-to-5 in favor of it being taken by patients who have not tried existing MS treatments.

Yesterday's news led several analysts to lower their 2006 revenue estimates for Biogen Idec and Elan.

''We're disappointed," said Amy Brockelman, a Biogen Idec spokeswoman. ''At the advisory committee meeting, we heard patients speak very passionately about the unmet medical need in multiple sclerosis. We're continuing to work around the clock to make Tysabri available as quickly as possible."

After an extensive safety review, only three cases of PML were found among thousands of patients who took Tysabri in clinical trials and commercially. At issue in the delay is how the companies will monitor patients for signs of PML and otherwise reduce the risk of an infection or death.

In addition to proposing the mandatory registry, the companies also recommend that patients be required to give informed consent to be treated with a drug with potentially fatal side effects, and that they undergo MRI scans. Should a patient come down with PML, the images could be used to help show the progress of the disease.

''A delay is bad," said Art Mellor, chief executive of the Accelerated Cure Project, a nonprofit in Waltham that promotes MS research and possible treatments. ''But it would be much worse if Tysabri came back, and they weren't able to monitor for something, and the drug got pulled again. If it gets pulled again, it's never coming back."

Mellor said he would like the final risk management plan to spell out steps to be taken if a patient is diagnosed with PML.

Both firms' shares dropped sharply on the early morning disclosure, but recovered some throughout the day. Elan shares ended down 55 cents at $13.80. Biogen Idec shares fell 21 cents.

Analysts said the delay and the possibility of stricter patient monitoring could slow the acceptance of Tysabri if it returns, limiting sales for both firms, which share Tysabri revenues.

Joel Sendek, an analyst with Lazard Capital Markets, reduced his estimate of 2006 Tysabri sales in the United States from $48 million to $28 million. But he left his long-term targets unchanged, with sales reaching $216 million by 2009. ''If the FDA felt comfortable approving the drug, they would have done it by the original deadline," said Sendek. ''Something's come up that caused them to reassess what that approval will entail. But we still think the drug will come back and get an approval in June."

Jeffrey Krasner can be reached at krasner@globe.com.



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