Elan shares jumped more than 24 per cent when trading resumed on the New York Stock Exchange after a panel of experts unanimously urged the US return of the multiple sclerosis drug Tysabri.
The panel voted 7-5 that Tysabri could be considered as an initial treatment for patients diagnosed with a relapsing form of MS, without requiring them to try another therapy first.
The FDA will make the final decision but usually follows panel recommendations. A ruling is expected by month's end.
The advisory panel said Tysabri must have mandatory controls to ensure patients know the risks and any new cases of a possibly fatal brain infection are spotted quickly.
Elan and Biogen suspended Tysabri sales in February 2005 after three patients developed an infection called progressive multifocal leukoencephalopathy, or PML. Two of them died.
Older drugs cut the number of relapses by one-third, while Tysabri reduced episodes by two-thirds in patients treated for two years. The risk of PML appeared to be about one in 1,000, but that estimate could change after more experience with the drug, FDA officials said.
There is no known treatment for PML. "If (a patient) gets this, it's going to be very bad. It's not going to be reversible. That is what the patient is going to have to weigh against the benefit," said Dr. Robert Temple, director of the FDA's medical policy office.