An experimental drug used to treat multiple sclerosis has been shown to significantly reduce the number of relapses suffered by patients, according to two major studies.

The studies, both published in the New England Journal of Medicine on Wednesday, show that the drug BG-12 also reduces the number of brain lesions that are found in MS patients.

BG-12 was long used in Europe to treat psoriasis, a skin condition that causes redness and irritation. The new studies show that when MS patients used the drug, the annualized rate of relapses dropped by 45 to 50 per cent, compared to patients who were given a dummy pill.

"That is a very robust reduction in relapses," said Dr. Robert Fox, a principal investigator of one of the studies. "It's not a cure. None of our therapies is a cure for MS at this point. But it appears to be a greater reduction than what we see with injectable therapies, which (offer) roughly a 30 per cent reduction in the annualized relapse rate."

Fox said patients in the studies who were randomly assigned to receive BG-12 also had a 70 to 90 per cent reduction in brain lesions.

"What this drug appears to provide is a significant step forward in the combination of efficacy, safety and tolerability," said Fox. "So it appears to be more effective than our standard first-line injectable therapies."

While promising, BG-12 must be approved by government regulatory bodies such as the U.S. Food and Drug Administration (FDA) and Health Canada before it can be used to treat patients.

Canada has one of the highest rates of MS in the world with an estimated 75,000 people suffering from the incurable disease.

The chronic, inflammatory disease targets the central nervous system by disrupting communication between the brain and other parts of the body, affecting patients’ vision, hearing, memory, balance and mobility.

Most people with MS experience relapses that are followed by recovery periods. However, over time recovery periods could be incomplete, leading to a progressive decline.

Dr. Paul O'Connor, director of the multiple sclerosis clinic and MS research at St. Michael's Hospital in Toronto, said the efficacy and safety of BG-12 "look pretty good."

O'Connor, who was not involved in either study, said that if approved, BG-12 would be "another tool in the toolbox" for doctors to prescribe to patients with relapsing-remitting MS.

MS drugs approved for use

In Canada, the only MS oral drug approved for widespread use is Gilenya, which has been associated with heart-rate and heart-rhythm irregularities in some patients.

Last week the FDA approved a new, once-a-day tablet for adults suffering from MS.

The drug, Aubagio, is shown to lower the relapse rate in MS patients by 30 per cent.

“In trials to date, Aubagio was generally safe and well tolerated,” said a news release issued by The Multiple Sclerosis Society of Canada.

While the drug is not available in Canada, the MS Society said U.S. researchers worked with Canadian scientists, clinicians and MS patients during the trial phase of the drug.

A spokesperson from the Multiple Sclerosis Society of Canada said the agency will continue to monitor the drug’s status in the U.S.

According to the society, MS is most often diagnosed in young adults between the ages of 15 and 40. Women are more than three times more likely to develop the disease than men.

With files from The Canadian Press