FDA approves Antegren under a new name

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FDA News

FOR IMMEDIATE RELEASE

P04-107

November 23, 2004

Media Inquiries: 301-827-6242

Consumer Inquiries: 888-INFO-FDA

http://www.fda.gov/bbs/topics/news/2004/NEW01141.html

First Monoclonal Antibody Treatment For Multiple Sclerosis Approved

FDA today licensed a new biologic approach to treat patients with

relapsing forms of multiple sclerosis (MS) to reduce the frequency of

symptom flare-ups or exacerbations of the disease. MS is a chronic,

often disabling disease of the brain and spinal cord.

Natalizumab, the new product, is a monoclonal antibody bioengineered

from part of a mouse antibody to closely resemble a human antibody.

It is being marketed under the tradename Tysabri. The product is

given intravenously once a month in a physician's office.

According to the Multiple Sclerosis Association of America,

approximately 350,000 individuals have been diagnosed with MS in the

U.S., with an estimated 10,000 new cases diagnosed each year. The

most common form of MS at the time of initial diagnosis is a

relapsing-remitting form, in which acute symptoms or worsening of

neurologic function (referred to as " relapses, " " attacks, "

or " exacerbations " ) occur intermittently. The symptoms can diminish

or disappear for months or years between relapses.

Although the cause of MS is unknown, it is widely considered to be an

autoimmune disease in which the person's immune system attacks the

brain and/or spinal cord. Tysabri appears to work by binding to these

immune system cells, thus preventing them from traveling to the brain

where they can cause damage.

Antibodies are proteins produced by a person's immune system to fight

foreign substances, such as infections. Monoclonal antibodies, such

as natalizumab, can be produced in large quantities in cell culture

in a laboratory setting. They can be designed to bind to proteins on

the body's normal cells. By recognizing and attaching to these

proteins, monoclonal antibodies can interfere with (or alter) normal

or abnormal cellular responses. In this way, monoclonal antibodies

may be useful in the treatment of certain diseases such as MS.

" This innovative treatment for multiple sclerosis represents a new

approach to treating MS -- exciting news for patients with this

serious disease, " said Dr. Lester M. Crawford, Acting FDA

Commissioner. " While we eagerly await long-term results from ongoing

clinical trials, we have reason to believe that Tysabri will

significantly reduce relapses in MS. "

The approval of Tysabri is based on positive results seen in patients

after one year of treatment. This product received accelerated

approval because it appears to provide substantial benefit for

patients with a serious disease. As part of that approval, the

manufacturer has committed to continuing its trials of this product

for another year.

Tysabri was evaluated for safety and efficacy in two ongoing

randomized, double-blind, placebo-controlled trials in patients with

relapsing forms of MS. In the first clinical trial of the product's

safety and efficacy, the drug reduced the frequency of relapses by 66

percent relative to placebo.

In a second trial, patients who had been treated with Avonex

(interferon beta-1a), an approved treatment for MS, but who had

experienced one or more relapses while on Avonex, were randomized to

receive Tysabri or placebo. Avonex was continued throughout the study

for both groups. In this trial, natalizumab reduced the frequency of

relapses by 54 percent relative to placebo.

The most frequently reported serious adverse reactions were

infections, including pneumonia, temporary hypersensitivity reactions

(such as rash, fever, low blood pressure, and chest pain),

depression, and gallstones. These serious adverse reactions were

uncommon. Common adverse reactions were generally

mild and included non-serious infections (such as urinary tract,

lower respiratory tract, GI system, and vaginal infections),

headache, depression, joint pains, and menstrual disorders.

Tysabri is marketed by Biogen Idec, Inc., of Cambridge,

Massachusetts, and Elan Pharmaceuticals, Inc., of Dublin, Ireland.