Biogen Idec, Elan Shares Plummet on News of Two PML Cases With Tysabri

8/1/08Follow @xconomy

Shareholders in Biogen Idec (NASDAQ: BIIB) and its partner Elan are getting pounded today. The Cambridge, MA-based biotech’s shares fell 25 percent, to $52.05 at 10:11 a.m. today after it reported two new cases of a rare, often fatal brain infection called PML, among patients taking its multiple-sclerosis drug Tysabri. Shares of Ireland-based Elan (NYSE: ELN) were hit even harder, down 45 percent to $11.10.

Analysts grilled this company this morning on a conference call about the cases, which we reported on yesterday. “We worry that this may be just the beginning of confirmed PML cases, possibly prompting some physicians to re-think this therapeutic option,” said Christopher Raymond, an analyst with Robert W. Baird in Chicago, in a note to clients before the call.

Biogen and Elan avoided any talk about long-term financial impact from the cases, so their forecast of getting 100,000 patients on the drug by the end of 2010 remains intact until further notice. The company has said that forecast always assumed some level of PML risk. “We believe Tysabri’s risk management profile continues to be favorable, offering new hope for patients,” said Cecil Pickett, Biogen’s president of research and development, on the call.

The association with PML has long dogged Tysabri. Biogen and Elan pulled the drug off the market in February 2005 after two cases of the brain disease were confirmed among patients taking the drug; a month later, a third case was confirmed. The FDA allowed Tysabri to return to the market in July 2006 after determining the drug’s benefits outweighed the risks, since it is the most effective medicine yet at reducing the risk of multiple sclerosis flare-ups. This January, the agency approved the drug for the treatment of Crohn’s disease as well. Tysabri’s prescribing information includes language stating that the risk of PML is at about 1 in 1,000 users.

The two new cases of PML were confirmed in patients in Europe, Biogen and Elan said. About 31,800 patients were taking Tysabri worldwide when Biogen reported earnings last week; 13,900 of them have been taking it for a year or more, and 6,600 have been on it for 18 months or more. One of the patients diagnosed with PML had been taking the drug for 17 months, the other had been on it 14 months. Biogen declined to speculate whether the risk of getting PML increases as patients remain on the drug for longer periods of time.

If patients are diagnosed with PML, doctors can perform a blood-exchange procedure to wash the Tysabri out of their system, which the companies described this spring in a presentation at the American Academy of Neurology meeting. Whether that really helps these two patients with PML will go a long way toward determining how big of an impact this news has on Tysabri’s future.

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  • america

    i would like to know if they r anymore pml patients my son was just comfrimed to have the virus he used the monthly med for four yrs about four yrs