Canadians with multiple sclerosis gain access to new drug

Health Canada has approved a new drug to treat the most common form of multiple sclerosis, despite concerns it cancause a rare but fatal brain infection.

The regulator fast-tracked approval for Tysabri(natalizumab) because there are so few treatment options for people with relapsing-remitting MS, a progressive neurodegenerative disease. Canada has one of the highest rates of MS, andan estimated 55,000 to 75,000 Canadians have the disease.

In an international clinical trial, the medication was found to reduce the rate of relapse by 68 per cent compared with the placebo, and the risk of disability progression by 42 per cent.

Tysabri is a leap forward in treatment that could allow one out of every four or five patients to improve, compared to one out of nine from current drugs, said Dr. Virender Bhan, director of an MS clinic in Halifax.

Tysabri was approved in the U.S. in 2004, but the manufacturer withdrew it when three patients developed a rare brain disorder known as PML while taking another drug at the same time. Two of them died.

After a review, the U.S. Food and Drug Administration determined the risk of the brain infection is about one in 1,000. Under pressure from patients, the FDA allowed it to return to the market last spring, with the recommendation that it not be taken with other MS drugs containing interferon.

On Wednesday, Biogen Idec Canada and Elan Corp. said Health Canada has approved it as a single therapy. It is taken intravenously once a month.

Patients watched closely

In the U.S., all patients taking the drug and their doctors must be enrolled in a registration program so that signs of the brain disease are detected early.

Health Canada has not made the monitoring program mandatory, but Canadian neurologists will be watching patients closely, said Dr. Paul O'Connor, who treats MS patients in Toronto.

Despite the risks, Blake Maybank, 51, of Halifax, said he is relieved Tysabri is available again.Maybank received the drug earlier in a clinical trial, and believes it kept his MS in check.

"During the time I was on the drug, not only did I have no episodes but MRIs showed I'd had no further scarring," Maybank said.

Now that the drug is approved, Tysabri's manufacturer will apply to provincial drug plans to have the drug costs covered. Based on the price in the U.S., it is expected to cost $30,000 per patient per year.

The drug is designed to work by preventing the body's affected immune cells from migrating from the bloodstream into the brain, where they can cause problems of MS, such as inflammation and damage to nerve fibres and their myelin coating.