Elan and Biogen Idec say that they expect - within weeks - to submit additional safety information to US regulators in the hope of returning their drug Tysabri to the market as a treatment for multiple sclerosis.
In August, the two companies announced that they had completed the safety evaluation of Tysabri in MS, which resulted in no new confirmed cases of the potentially fatal brain disease progressive multifocal leukoencephalopathy (PML). Shares in the two companies had plunged in February when they suspended sales of the drug after one MS patient died after using Tysabri with Biogen's Avonex drug.
The patient had died from PLM 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 had hailed Tysabri as a potential blockbuster when it was launched in November 2004 after clinical data suggested that it was far more effective than existing treatments for MS.
The new safety data involved over 3,000 patients with MS, Crohn's disease and rheumatoid arthritis that have taken Tysabri in past trials. Some patients in the two late stage MS trials took Tysabri by itself, while others took it in combination with Avonex.
Elan and Biogen Idec said they also plan in coming weeks to complete a safety evaluation of Tysabri as a possible treatment for Crohn's disease and rheumatoid arthritis. Both diseases are caused by overactive immune systems that harm tissue.
Shares in Elan closed down 19 cent to €6.70 in Dublin.
