"Elan and Biogen on Tuesday said they expected within weeks to submit additional safety information to U.S. regulators in hopes of returning their drug Tysabri to market as a treatment for multiple sclerosis. Irish drugmaker Elan and Biogen Idec, which is based in Cambridge, Massachusetts, in August said no new cases of PML were seen in an updated safety evaluation of Tysabri.

Biogen Idec spokeswoman Amy Brockelman on Tuesday said the drug "never lost" its original approval from the U.S. Food and Drug Administration, although it was withdrawn from the market.

She 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 for treating multiple sclerosis. The data involves more than 3,000 patients with multiple sclerosis, Crohn's disease and rheumatoid arthritis that have taken Tysabri in past trials.

Some patients in the two late-stage multiple sclerosis trials took Tysabri by itself, while others took it in combination with Avonex, Brockelman said.

"At this point, we do not expect we will need to conduct additional multiple sclerosis trials to return Tysabri to market," Brockelman said.

Elan and Biogen Idec 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." Reuters.com