Tysabri approved as Crohn's treatment

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The FDA today approved Elan and Biogen IDEC's supplemental biologics license application for Tysabri to treat Crohn's disease, a chronic and progressive disease marked by inflammation of the bowel.

The companies anticipate Tysabri to be available to Crohn's patients by the end of February 2008. About 600,000 Americans have the disease.

The companies said the FDA granted approval based on its review of Tysabri clinical trial data and overall safety data. It was not immediately clear if there were any conditions attached to Tysabri's approval.

Tysabri was originally approved as a multiple sclerosis (MS) treatment in November 2004 but was pulled off the US market in February 2005, after three patients developed a rare and potentially deadly brain infection, progressive multifocal leukoencephalopathy (PML).

That FDA allowed Tysabri back on the market in June 2006 under a restricted distribution program dubbed the “Tysabri Outreach: Unified Commitment to Health” (TOUCH) prescribing program.

Before Tysabri treatment for MS can start, patients must undergo a magnetic resonance imaging scan. Then, patients on Tysabri are to be evaluated at three and six months after the first infusion, and every six months after that, with their status being reported directly to Biogen IDEC.

Biogen Idec said more than 21,000 patients are using Tysabri and so far there haven't been any additional reports of PML.

Tysabri for Crohn's is expected to compete with Remicade, the leading treatment in the category, made by Johnson and Johnson.

Friedman, Billings, Ramsey, & Co. analyst David Amsellem wrote in a note to investors that Elan and Biogen IDEC's long-term 100K patient target looks aggressive.

“Biogen Idec suggested that nearly 10% of the 100K target could come from Crohn's disease.,” he said.

“We believe peak usage in Crohn's disease of 3,500 to 4,000 is more realistic. In MS, there were around 21,000 patients on Tysabri at the end of 2007. Most MS doctors we have talked with are currently using the drug in less than 5% of the MS patients they treat and do not expect to use Tysabri in more than 10% of their patients. The 100K target translates to nearly 25% of treated MS patients. Even if we do not see new PML cases in the near term, we believe doctors will continue to be cautious in patient selection for Tysabri.”

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