A drug licensed to treat a type of leukemia appears to reduce the damaging effects of multiple sclerosis in its early stages, researchers said Thursday.

In a three-year study published in the New England Journal of Medicine, alemtuzumab reduced clinical relapses and the development of new disability compared with those who received a current treatment.

MS is a neurodegenerative disease in which the immune system attacks nerve fibres and their protective insulation, resulting in physical and intellectual disabilities and symptoms ranging from tingling to blindness and paralysis.

'The patients on alemtuzumab have an increase in brain volume, which means the brain is repairing itself.'— Study author Dr. Alasdair Cole

"The most remarkable thing is if you look at the disability of all the patients at the end of the treatment, the people on the standard treatment were more disabled," said study author Dr. Alasdair Cole, a neurologist at the University of Cambridge.

"The patients on alemtuzumab have an increase in brain volume, which means the brain is repairing itself."

The study, which was funded by Genzyme Corp. and Bayer Schering Pharma AG, involved 334 men and women who were diagnosed with early-stage active relapsing-remitting multiple sclerosis that was not previously treated.

In this form of the MS, flare-ups of numbness, vision loss and other problems may last for weeks or months. Relapsing-remitting MS accounts for 85 per cent of people who are first diagnosed with MS, according to the MS Society.

Better disability scores

About two-thirds of participants received intravenous cycles of alemtuzumab and the rest received conventional interferon-beta therapy.

The rate of sustained accumulation of disability among those receiving alemtuzumab was 9 per cent, compared with 26 per cent among those receiving the conventional treatment, the researchers said.

The annualized rate of relapse was 0.10 for alemtuzumab compared with 0.36 for interferon-beta.

The mean disability score improved by 0.39 point on a 10-point scale for the alemtuzumab group, it worsened by 0.38 point in the interferon beta group.

From month 12 to month 36, brain volumes also increased in the alemtuzumab group but decreased in the other group.

Side-effect concerns

Alemtuzumab works by destroying lymphocytes, a type of white blood cell. By shutting down this part of the immune system, the drug seems to block the damage to brain tissue that occurs in MS.

But three per cent of those taking alemtuzumab in the trial developed a life-threatening autoimmune condition.

During the trial, 20 per cent of those treated with alemtuzumab developed an over- or under-active thyroid gland.

Three per cent of those in the alemtuzumab group developed a low platelet count that increases vulnerability to bleeding — a complication that can be easily treated if recognized early, the researchers said, but that led to one death during the study.

"The data convincingly demonstrate that intensive immunosuppression can dramatically reduce the accumulation of new inflammatory lesions and focal [neuron] scarring and the rate of clinical relapse in patients with recent-onset multiple sclerosis," neurologist Dr. Stephen Hauser wrote in an editorial accompanying the study.

The findings highlight the value of very aggressive therapy at the beginning of the disease and helps medical researchers address the relationship between the inflammatory and degenerative phases of the disease, Hauser added.

The researchers did not test alemtuzumab against natalizumab, sold as Tysabri, a newer drug for MS that is considered more effective but carries safety concerns.

The safety and effectiveness of alemtuzumab need to be determined over longer terms. Alemtuzumab is about to go into Phase III clinical trials, and if those are successful, it could sold as a treatment for MS in four years, Cole said.

With files from Reuters