Only Half of MS Patients Respond to Interferon Therapy
WEDNESDAY Nov. 12, 2008 -- New research suggests that treating multiple sclerosis with the drug interferon only works for about half of patients.
Interferon works by reducing inflammation and can reduce the relapse rate of multiple sclerosis (MS) while slowing the progression of disability.
Dr. Moses Rodriguez, a professor of neurology and immunology at the Mayo Clinic, who was not involved with the study, thinks the finding provides more evidence that MS is not one disease.
"This finding fits well with our results and fits our clinical observation," Rodriguez said. "We see that there are four distinct patterns of MS. Two of the patterns are associated with inflammation, and two of the patterns are not associated with very much inflammation."
The new interferon study supports that finding, Rodriguez said, adding, "You have either responders or non-responders."
This is true for all current MS treatments, Rodriguez explained. For the type of multiple sclerosis called chronic progressive MS, there is no treatment, he noted. "There are probably a number of diseases hiding under this umbrella we call MS," he said.
The interferon report was published online Nov. 10 in Archives of Neurology and was expected to be published in the January 2008 print issue of the journal.
For the study, researchers led by Dr. Francesca Bagnato, of the U.S. National Institute of Neurological Disorders and Stroke, looked at brain MRI scans of 15 MS patients who were given shots of interferon -- a standard MS treatment -- every other day over 36 months.
The researchers found that eight patients saw a 60 percent reduction in their brain lesions, which are typical of MS; these patients were classified as "responders." Among the seven "non-responders," three had an initial reduction in lesions, two never reached the 60 percent reduction level, and two did not respond during the first six months of therapy but did reach a 60 percent reduction in lesions later on.
Moreover, three patients who responded to interferon therapy had at least one relapse, as did all seven of the non-responding patients, the researchers found.
"To our knowledge, our descriptive study provides for the first time a detailed long-term analysis of MRI patterns of patients undergoing long-term interferon beta-1b therapy. The results show that on close monthly MRI inspection, approximately half of the patients fail therapy from an MRI perspective," the researchers wrote.
Rodriguez thinks that one day doctors will be able to distinguish the various types of MS and develop specific treatments for each type. "For each type, we find the same thing -- certain patients are responders, and certain patients are non-responders. Different groups respond to different forms of therapy," he said.
Patricia O'Looney, director of biomedical research programs at the National Multiple Sclerosis Society, said she thought the study was too small to draw definitive conclusions.
"It is a challenge to know who is going to respond to interferon," O'Looney said. "It would be interesting if there are some markers of who will respond to one therapy versus another."
O'Looney noted that there are different disease courses to MS. "The challenge is to find a marker, something that we can measure, that can predict the disease course and progression of an individual," she said.
That ability could translate into individualized therapy, O'Looney said. "We could be more aggressive in our treatment," she added.
The U.S. National Institutes of Health calls MS an unpredictable disease of the central nervous system that can range from relatively benign to somewhat disabling to devastating, as communication between the brain and other parts of the body is disrupted. Many researchers suspect that MS is an autoimmune disease, meaning the body's immune system attacks its own tissues. In the case of MS, it is myelin -- the insulating layer around nerves, including those in the brain and spinal cord -- that comes under assault.
For more on MS, visit the U.S. National Institute of Neurological Disorders and Stroke.
Posted: November 2008