FDA Panel: Bring Back Risky MS Drug

Multiple Sclerosis Drug Tysabri to Return to Market Despite Risk of Rare Disease

Medically Reviewed by Louise Chang, MD on March 08, 2006
From the WebMD Archives

March 8, 2006 -- Despite estimates that it kills one patient in a thousand, an FDA expert panel today unanimously recommended bringing back the multiple sclerosis drug Tysabri.

In February 2005, Tysabri manufacturer Biogen voluntarily stopped sales of the drugstopped sales of the drug after three patients developed a rare brain disease called progressive multifocal leukoencephalopathy -- or PML. Two of the patients died from the devastating, incurable disease.

Tysabri can be a huge benefit for some patients with MS. Patients who respond to the drug stop the inexorable downward spiral that characterizes relapsing MS. During the two-day panel meeting, patients described in dramatic detail how getting the drug changed their lives -- and how losing it affected their hopes.

But it was facts and not emotion that carried the day, insists panel chairman Karl Kieburtz, MD, MPH, a renowned neurologist at the University of Rochester in New York.

Risks vs. Benefits

"There is a human face behind every illness," Kieburtz said at a news conference. "That was articulated poignantly in the public hearing. ... But the decision really went around the evidence regarding benefits and the evidence regarding risk."

The benefit: Tysabri works at least twice as well as other first-line treatments for relapsing MS.

The risk: PML is an extraordinarily dangerous, if rare, side effect. Its early symptoms are hard to tell from worsening MS.

"It may not kill all the time, but it leaves you in terrible shape. It is very bad," Robert Temple, MD, director of the FDA's Center for the Office of Drug Evaluation, said at the news conference.

If the FDA follows the panel's advice, patients will get their monthly infusions of Tysabri only at registered infusion centers. Stringent safeguards will ensure that patients fully understand the risks of taking the drug and that the drug was properly prescribed.

Patients also must enroll in follow-up studies that will track them for any sign of PML. The idea is to know as soon as possible whether the true risk of PML is greater or less than one in a thousand.

"We may learn that the true risk is lower or higher," Kieburtz said. "If the risk is higher, the agency or committee will reassess the recommendation."

If the FDA follows the panel's recommendation -- and there is every sign that it will -- it will be only the second time in history that the FDA has returned a drug to market after it was pulled for safety reasons. In June 2002, the irritable bowel syndrome drug Lotronex returned to market. Lotronex was linked to blocked blood flow to the intestine that caused death in some patients and permanent disability in others.