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Advice From Health Care Professionals Living With Multiple Sclerosis Goals of MS Therapy

Multiple Sclerosis Current Topics in Multiple Sclerosis

Natalizumab Update

Summary & Participants

After being suspended from the market for safety reasons, natalizumab is again available for the treatment of multiple sclerosis. Safeguards are in place because of a small risk in developing a serious brain infection. Should you consider taking this drug?

Medically Reviewed On: December 07, 2006

Webcast Transcript

ANNOUNCER: For most people with multiple sclerosis, medication is important to help slow the progression of the disease. In the early 2000s, clinical trial evidence was growing that a new drug might prove more effective than the medicines then currently available.

FREDERICK E. MUNSCHAUER, MD: There were two large prospective clinical trials using natalizumab, which is also known as Tysabri…And, at the end of those trials, when the patients were coming off after two years, it was quite clear that Tysabri was indeed the next generation of MS therapy.

People had fewer exacerbations, a 68% reduction in exacerbation rate, essentially twice as effective as any of the interferons or Copaxone. And a 42% reduction in the probability of going on to sustained worsening in physical impairment, as measured by one of our scales…

ANNOUNCER: The drug was approved by the FDA for use in November of 2004. But within three months, startling news led the manufacturer, following discussions with the FDA, to voluntarily withdraw natalizumab from the market.

ROBERT FOX, MD: The drug was approved in late 2004. But in February, 2005, there surfaced two reports, and these were… reported to the manufacturer of natalizumab, of a very serious brain infections. And this was a very rare brain infection that we typically don't see at all. It's an infection that is called progressive multifocal leukoencephalopathy. And that's quite a big mouthful. So we call it by its initials, or PML.

ANNOUNCER: The manufacturer and the FDA quickly began an investigation into the two cases of PML in MS patients, and in a third case, in a person with Crohn's disease who had also used natalizumab.

FREDERICK E. MUNSCHAUER, MD: So, in concert with a number of worldwide experts in progressive multifocal leukoencephalopathy and in cooperation with the FDA, the manufacturer reviewed meticulously every single person who had ever been given natalizumab or Tysabri in order to determine whether there were any other cases out there. And this process took the better part of a year.

The investigators found no more cases of PML. There were three cases among more than 3,000 people who were treated with natalizumab.

ROBERT FOX, MD: Once the surveillance was complete the question turned to well can this drug come back out on the market again. It was fairly clearly established that the risk of PML was in the area of one in a thousand MS patients that had treated over an 18 to 24 month period. And was that reasonable to allow it back out on the market, or was that too risky?

FREDERICK E. MUNSCHAUER, MD: And in the late Spring of 2006, an independent FDA advisory panel was brought together to review the results of the full safety inquiry that had been conducted over the previous sixteen, eighteen months.

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