Multiple sclerosis patients taking Tysabri experienced significant improvements in their quality of life, including a lower relapse rate and a reduced risk of their disease progressing, according to trial data presented at a recent medical meeting.

Tysabri, a drug from

Biogen Idec

(BIIB) - Get Report

and

Elan

(ELN)

, was taken off the market early last year after concerns were raised about its connection to a severe and sometimes deadly brain disease.

The latest study results also showed that patients taking Tysabri had better dexterity and cognitive functions, Biogen said Thursday. In a study dubbed Affirm, treatment with Tysabri led to a 42% reduction in the risk of MS worsening when compared with a placebo, and it meaningfully delayed patients' need for canes, crutches or braces.

At a meeting of a Food and Drug Administration advisory committee

last month, a number of former Tysabri users offered compelling testimony about how much the drug improved their lives while it was available. The committee decided that the drug was safe enough to return to the market, and Biogen and Elan expect the full FDA to make a decision by June 28.

"MS is a debilitating disease that significantly reduces the quality of patients' lives by causing symptoms like fatigue, pain and diminished emotional well-being," said Dr. Richard Rudick, an MS researcher at the Cleveland Clinic, who presented the study findings at a neurology conference in San Diego. "We have never before observed positive findings on our quality of life measures in a phase III MS study."

Biogen's shares were gaining 25 cents, or 0.6%, to $45.25, and Elan was rising 20 cents, or 1.4%, to $14.35.

The companies halted sales of Tysabri in February 2005 after it was linked to a central nervous system disease called progressive multifocal leukoencephalopathy. The disease was ultimately found in two MS patients who had taken Tysabri and Avonex, another Biogen drug, and in one Crohn's disease patient who had previously received an immunosuppressant. Two of the cases were fatal.