The makers of the multiple sclerosis drug Tysabri said yesterday that a second patient who used the drug had been confirmed to be suffering from a rare but deadly brain infection.
CLICK TO READ MORE The confirmed diagnosis is likely to somewhat diminish the chances that the drug will be able to return to the market.The brain infection, called progressive multifocal leukoencephalopathy, or P.M.L., is extremely rare, so even one confirmed case raised alarms, officials of the companies have said. The confirmation of a second case is stronger evidence that the disease is linked to the drug.
The two patients were among 500 people in a trial who had received both Tysabri and Avonex, another Biogen multiple sclerosis drug, for more than two years.
Biogen and Elan reiterated yesterday that they had received no reports of P.M.L. in patients who received Tysabri alone. Avonex has been on the market for years and has never been associated with the condition when used alone.