Natalizumab reduces MS relapses and disability--Cochrane review

Dr Doug Brown, Head of Biomedical Research at theMS Society, said, "Natalizumab is a licensed treatment for MS in the UK and we have known for some time that it reduces relapse rates and progression of disability in people with relapsing remitting MS; it’s nice to see these findings confirmed in this review.”

MS is a disease that causes inflammation and damages the myelin sheath, a membrane that protects the nerve fibers of the central nervous system.

It can lead to vision problems, muscle weakness and cognitive decline. Over time the disease has the tendency to develop into a permanent disability.

Relapsing-remitting MS is the most common type of multiple sclerosis. Symptoms of the devastating disease fade away partially or completely during the remitting phase only to return aggressively during the relapse period.

Review of 3 trials
In order to assess the efficacy and safety of natalizumab in people with highly active relapsing remitting multiple sclerosis, the scientists conducted review of three trials involving 2223 patients.

The studies involved giving an infusion of at least 3 mg/kg of natalizumab intravenously once every 4 weeks.

Findings of the study
The analysis revealed that natalizumab was well tolerated for a period of two years.

Treatment with the drug lowered the risk of experiencing a new relapse by about 40 percent.

Moreover, the investigators found natalizmab helped to slow the progression of multiple sclerosis by approximately 25 percent.

Additionally, magnetic resonance imaging showed that natalizumab had lessened the disease activity.

Adverse effects
A number of common side effects including infusion reactions, anxiety, sinus congestion, lower limb swelling, rigors, vaginitis, and menstrual disorders were perceived.

In addition, two cases of a serious condition called progressive multifocal leukoencephalopathy (PML) which is caused by a viral infection in the brain occurred.

Among them, one patient had received 29 doses of the drug, while the second case which was fatal had received 37 doses.

Lead author of the study, Eugenio Pucci, of the neurological unit in Macerata, Italy stated, "Various factors seem to increase the risk of developing PML, including the number of natalizumab infusions a person receives, whether the patient has had previous immunosuppressive treatment, and if their blood contains antibodies against [John Cunningham virus]."

A word of caution
Given, the risks involved, experts feel the drug should be administered only by skilled neurologists in MS centres under national or international surveillance programs.

Moreover, Dr Pucci believes there is need for further studies to determine which MS patients would gain maximum benefits from natalizumab.

Pam Macfarlane, Chief Executive of the Multiple Sclerosis Trust stated, "The Cochrane review of natalizumab (NTZ)/(Tysabri) is useful and supports what we know about the drug so far.

“Natalizumab is an important treatment option for people with highly active relapsing remitting MS, but as the report highlights it is not without risk.

"People considering this treatment need full information and specialist support to assess the risks and benefits for themselves."

The findings of the review are published in the latest edition of The Cochrane Library.