(1888PressRelease)
June 20, 2009 - A suspected link to progressive multifocal leukoencephalopathy, or PML, led to Tysabri being pulled from the market for 18 months beginning in 2005. Prior to Friday, the company has reported that eight people had confirmed cases of PML, with one dying, since the relaunch. The most recent case was reported one week ago.
Biogen closed Friday down 32 cents at $51.67, while Elan fell 5 cents to $7.36.
The drug was allowed back on the market in 2006 because of its effectiveness in fighting the degenerative disease and the incidence of PML remains well below the long-projected risk of one in 1,000 patients developing the infection.
"PML is still very rare in Tysabri-treated patients," said Biogen spokeswoman Shannon Altimari.
The patient with the latest confirmed PML case took 34 doses of the monthly medication and was located overseas. Only two of the nine cases since last July were located in the U.S.
Altimari said Biogen doesn't know why confirmed cases of the condition are more common overseas, but that the company is constantly performing research to better understand the infection.
Much is unknown about PML, but it is thought to be caused when the JC virus, which most people carry, attacks the central nervous system in those with weakened immune systems, often leading to an irreversible decline in neurologic function and death.
It is thought that Tysabri patients with PML have had a better prognosis because of earlier detection and treatment with plasmapharesis, a process that removes large molecules from the blood, speeding up Tysabri's removal and allowing the immune system to fight the infection.
Tysabri is one of several immune-system-suppressing therapies that have been linked to PML, including Rituxan, sold by Biogen with Roche Holding AG (RHHBY) unit Genentech, and Raptiva, a psoriasis drug that Genentech pulled from the market earlier this year because of the issue.
Earlier this year, Biogen retreated from its long-held goal to reach 100,000 patients on Tysabri by the end of 2010. As of the end of March, about 40,000 patients were using Tysabri, up from 37,600 patients at the end of December.
Some believe that the duration of therapy plays a role in Tysabri's risk. About 6,800 patients have used the drug for more than two years, as of the end of March.
Biogen is posting a case update on the Internet every Friday at 4:30 p.m. EDT until July 24 - the third anniversary of the drug's relaunch - by which time it expects the risk/benefit profile of Tysabri to be clearer.
Tysabri had 2008 sales of $813 million, but the longer-term sales trajectory, which is key to Biogen's future growth, will depend on the true incidence of PML, which is still coming into focus.
http://www.biogenidec.com
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