For years, family, friends and physicians who care for people with multiple sclerosis have worried about how to slow the progression of the chronic neurological illness. MS strikes in young adulthood, slowly robbing patients of their motor skills and sometimes causing blindness.
Now a new generation of MS drugs containing the human protein beta interferon is providing the first hope that the disease may be controlled, if not conquered. The promise in interferon drugs is helping to change the public perception of a disease that affects 250,000 Americans. The latest evidence suggests that one of these interferon drugs--Avonex--can even slow the shrinkage of brain tissue that occurs in some patients.
No cure exists for MS, but since 1993, three drugs containing interferon have been approved by the Food and Drug Administration to treat the relapsing-remitting form of the disease. A team of researchers from the Cleveland Clinic reanalyzed clinical data submitted to the FDA on Avonex and found the first evidence that it can protect patients against the gradual loss of brain tissue. They presented their findings last month in Toronto at a meeting of the American Academy of Neurology.
An estimated 200 new cases of MS are detected each week in the United States, according to the National Institute of Neurological Disorders and Stroke. Women are twice as likely as men to get MS, and whites are twice as likely as people of other races to develop the disease. The illness costs an estimated $2.5 billion annually in direct medical costs, lost work and disability expenses, according to the institute.
What causes MS to occur is not known, although researchers have suspected that it may be a combination of environmental factors and genetic susceptibility. One theory is that perhaps a viral infection triggers the disease in vulnerable people.
However it begins, MS causes the body's immune system to attack nerve tissue in the brain, forming patches called plaques. As the disease progresses, the myelin sheaths that surround nerves can also be affected and gradually destroyed. Myelin is a fatty covering that insulates nerves and enables high-speed messages to move between the brain and other areas of the body. As the myelin is slowly destroyed, the MS symptoms grow worse. Motor skills are frequently affected, making walking difficult. The disease can also attack the optical nerve, resulting in vision loss and blindness.
MS is usually diagnosed between the ages of 20 and 40 years, but because symptoms can wax and wane, the disease may go undetected until later in life. The fluctuating symptoms also make assessment of treatments difficult: Researchers must be careful that therapy is the reason for improvement and not the natural cyclical course of the disease. Most patients begin with relapsing-remitting disease, a cycle marked by flare-ups then periods of remission. Many of these patients eventually develop primary progressive MS, which is characterized by gradual decline and no distinct remissions. About 20% of MS patients have a mild form of the disease, which shows little or no progression after the first attack.
The researchers from the Cleveland Clinic Foundation showed that the regular use of Avonex seems to help significantly reduce the brain shrinkage caused by MS.
In the two-year study, 70 patients with relapsing-remitting MS were given weekly intramuscular injections of Avonex and were compared with 70 similar patients who took injections with a placebo. Both groups were, in turn, compared with 16 healthy individuals.
During the study's first year, there was no difference in the amount of brain atrophy between the two groups of MS patients. But during the second year, the researchers found that Avonex reduced the amount of brain shrinkage in MS patients by 55% compared with people receiving the placebo.
"We've known for quite some time that there is a loss of brain volume as a consequence of MS," said Stephen Reinhold, vice president of research programs at the National Multiple Sclerosis Society, which helped fund the study. "It's unclear whether this loss is of nerve fibers or supportive brain tissue. This is a dramatic demonstration of this phenomenon."
How such a loss relates to more acute symptoms is not clear. The findings do, however, underscore the importance of early, aggressive drug treatment for MS, even when symptoms don't seem very significant, researchers said.
Richard Rudick, a coauthor of the study and professor of neurology at the Cleveland Clinic Foundation's Mellen Center for MS Treatment and Research, said MS patients in remission are often reluctant to take weekly injections of expensive medications. The drugs cost about $10,000 a year and can have unpleasant side effects.
The findings suggest that a destructive brain process "is ongoing in patients who are clinically stable," Rudick said. "Now we know that at least one of the available drugs is able to stop this. . . . It suggests that patients be treated proactively at early stages of the disease."