Tysabri Still Down, But Not Out
Matthew Herper, 08.09.05, 10:50 AM ET
After months of waiting, Biogen Idec (nasdaq: BIIB - news - people ) and Elan (nyse: ELN - news - people ) are finally having a good day--but investors should be careful not to be too exuberant about hopes for their beleaguered drug.
The two biotech firms have finished their safety review of Tysabri, the multiple sclerosis drug that the companies pulled from the market on Feb. 28 after it was linked to a rare brain disorder. They say that there have been no new cases of progressive multifocal leukoencephalopathy (PML), the brain disorder. In all, they say, there have been three confirmed cases of PML in Tysabri patients, two of them in subjects with multiple sclerosis and one in a subject with Crohn's disease, a gastrointestinal ailment. In all, 2,000 patients multiple sclerosis patients were included in the review.
That means that several other cases that were reported in the press were not confirmed in the final review.
Biogen and Elan say that they are taking preliminary steps to restart clinical trials of Tysabri in MS, which were stopped in February. Executives on a conference call were optimistic that Tysabri might return to the market for some patients. James Mullen, chief executive of Biogen Idec, said that he was "encouraged" that the companies have a handle on what the Tysabri risk is. "We're encouraged that it will be coming back to the market," says Mullen.
Despite Mullen's optimism, there is still room for doubt on Tysabri. On a conference call with analysts at Sanford C. Bernstein last week, Daniel Wynn, a multiple sclerosis investigator, said that most patients being evaluated for safety were not given spinal taps--the most conclusive test for PML and the virus that causes it. Based on today's conference call with the companies, Wynn appears to have been correct.
"I think they are being very cautious on their language," says Geoffrey Porges, the biotech analyst at Bernstein. "The companies have said that there are no new confirmed cases, not no new potential cases."
Porges says he would still like to know how many patients who did not have spinal taps had suspected cases of PML. "I think we are still several steps away from a final decision," Porges says, "but this is now set up for a showdown with the regulatory agencies with patients and the companies on one side and safety oversight and caution on the other side."
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