Shares of Elan Corp. and Biogen Idec Inc. jumped Thursday after the New England Journal of Medicine published comments online that might suggest a way for Tysabri, the companies' troubled multiple sclerosis drug, to return to the market.
Dublin, Ireland-based Elan's shares rose 77 cents to $7.37; Biogen closed up $1.78 at $35.13.
Doctors at Biogen, based in Cambridge, Mass., said in the medical journal that it might be possible to make an early diagnosis of a deadly infection linked to the drug and stop Tysabri treatment in time to allow patients to recover.
Tysabri was pulled from the market earlier this year after two patients from clinical trials were diagnosed with progressive multifocal leukoencephalopathy, or PML, a debilitating and often deadly brain infection. One of them died. A third patient, who had taken part in testing the drug for treatment of Crohn's disease and died, also was later found to have had PML.
The drug had won accelerated approval from the Food and Drug Administration and had been expected to be a blockbuster. The companies' shares have slipped dramatically in the last few months.
"We continue to believe it is still possible that Tysabri will be back on the market, given the strength of the efficacy data in MS patients and the need for a new therapy," Elise Wang, an analyst at Smith Barney Citigroup, said in a research note.
Wang said Tysabri probably would carry a warning in bold type and surrounded by a black box at the top of instructions provided to doctors if it was brought back, which could limit its sales.
Citigroup Global Markets is a market maker in Biogen's stock and owns 1% or more of the company's shares.
The New England Journal of Medicine posted the comments after a report last week that a fourth patient on Tysabri may have developed PML.