RESEARCH - Two studies show withdrawn multiple sclerosis drug is safe

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Withdrawn multiple sclerosis drug is safe -studies

01 Mar 2006 22:00:56 GMT

Source: Reuters

By Gene Emery

BOSTON, March 1 (Reuters) - Tysabri, withdrawn last year because of fears it

might cause an often-deadly brain disorder, slows the progression of

multiple sclerosis and seems to pose little risk, two studies showed on

Wednesday.

The studies were financed by the drug's manufacturers and come as a U.S.

Food and Drug Administration advisory panel is to meet on March 7 to discuss

whether Tysabri should go back on the market.

The drug, also known by the generic name natalizumab, was removed by Biogen

Idec Inc. <BIIB.O> and its marketing partner Elan Corp. <ELN.I>, just over a

year ago after three patients developed a rare brain disease known as

progressive multifocal leukoencephalopathy (PML).

It appears when a common but usually dormant virus is reactivated and

infects the nervous system. Studies have shown that 10 percent of AIDS

patients get PML.

The studies, published in this week's New England Journal of Medicine,

reported no additional cases of PML and " provide reassurance that the risk

of PML is small with relatively brief use, " said Allan Ropper, chief of

neurology at the Caritas St. Medical Center, in a Journal

editorial.

Conventional treatment with interferon beta and glatiramer acetate typically

reduces the relapse rate of multiple sclerosis -- a serious disease in which

the immune system attacks the brain and spinal cord -- by about a third.

RELAPSE LIKELIHOOD FELL

Researchers in the first study found that Tysabri cut the likelihood of a

relapse by 68 percent in 627 patients, compared to the 315 patients who got

a placebo. Both groups received intravenous injections every four weeks.

In addition, the number of abnormalities found on individual MRI scans of

the brain or spinal cord was 92 percent lower among the Tysabri recipients.

" Natalizumab may offer greater benefit to patients with relapsing multiple

sclerosis than the other therapies, " said the research team led by Chris

Polman of the Vrije University Medical Center in Amsterdam.

The second study looked at 1,171 volunteers who had suffered a recent

relapse despite treatment with interferon beta.

Among the 582 patients who were receiving just interferon, 32 percent did

not have a relapse after two years. The rate was 54 percent among the 589

who also got Tysabri.

" It is tempting to project these improvements over a patient's lifetime, "

said Ropper, " but there are no data yet to support such a view. "

The drug is also being tested against Crohn's disease, which is an

inflammation of the digestive tract, and rheumatoid arthritis.

A Biogen executive told Reuters last week that Tysabri will likely only be

approved as a stand-alone treatment if U.S. regulators allow it to be

reintroduced.

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