Elan and Biogen Idec will submit additional safety information to US regulators in hopes of returning their drug Tysabri to market as a treatment for multiple sclerosis.
Shares of the companies plunged in February when they voluntarily suspended sales of the injectable medicine after one multiple sclerosis patient died following treatment with Tysabri in combination with Biogen Idec's widely used Avonex drug.
The patient died from a rare brain infection known as PML and another patient at the time was suspected of having the condition. Another case was identified in March, and two of the three patients have died.
Industry analysts hailed the drug as a potential blockbuster when it was launched in November 2004 because clinical data suggested it was far more effective than existing treatments for multiple sclerosis.
Elan and Biogen said in August that no new cases of PML were seen in an updated safety evaluation of Tysabri.
A Biogen Idec spokeswoman said last night the drug "never lost" its original approval from the US Food and Drug Administration, although it was pulled from the market.
The spokeswoman said her company and Elan now plan to submit the updated safety information on Tysabri to the FDA, as a possible prelude to re-launching the drug.
The partners also said in a release that they plan in coming weeks to complete a safety evaluation of Tysabri as a possible treatment for Crohn's disease - an inflammatory bowel ailment - and rheumatoid arthritis. Both diseases are caused by overactive immune systems that harm tissue.
Shares of Biogen Idec rose to $40.60 on the Inet electronic brokerage system, from their close of $40.23 on the Nasdaq. Elan was trading at $8.46 on Inet, from its close of $8.31 on the New York Stock Exchange.