Interferon beta, the most commonly prescribed drug to treat multiple sclerosis (MS), did not delay progression of the disease in relapsing patients, according to a recent study.
The study, published in the Journal of the American Medical Association, looked at data on 868 MS patients treated with interferon beta and compared their outcomes to 1,788 patients who never took the drug. The researchers found that treated patients were no less likely than their untreated counterparts to develop long-term disabilities, such as needing a cane to walk 100 meters — a standard marker of MS progression on a widely used scale.
“The ultimate goal of treatment for MS is to prevent or delay long-term disability. Our findings bring into question the routine use of interferon beta drugs to achieve this goal in MS,” write the authors from the University of British Columbia in Vancouver.
The findings don’t necessarily mean that interferon beta drugs offer no benefit for MS patients. They have been shown to reduce both relapses and lesions in the brain. It just hasn’t been clear whether interferon beta can also prevent the disease from progressing into permanent disability. Some previous research has found that interferon beta does help prevent disease progression, but the authors of the current study say methodological problems — such small sample sizes, insufficient follow-up or the inclusion of patients who were already too ill to start taking medication in the control group — weaken those findings.
About 400,000 Americans are living with MS and about 200 people are newly diagnosed each week, according to the National Multiple Sclerosis Society. The disease is characterized by its unpredictability, and its symptoms vary widely, from mild to severe; they can include numbness, tremors, difficulty walking, paralysis, bowel and bladder problems, depression, problems with attention and reasoning, speech problems and vision loss. The disease commonly relapses.
MS is an autoimmune disease that causes the body to attack the myelin sheath that surrounds and protects nerve fibers of the central nervous system. When disrupted, signals between the brain and spinal cord are interrupted, resulting in symptoms.
Although the disease can be severely disabling for some and has no cure, many patients live normal, productive lives for decades, using drugs to control symptoms or to try to help slow the progression of the disease.
The results of the new study disappointed other researchers in the field. Dr. Claire Riley, director of the Multiple Sclerosis Clinical Care and Research Center at Columbia University, told the New York Times:
It’s a little dispiriting to see this well-designed, well-conducted assessment showing no association between reduction of disability progression and interferon use. … But the key is that all M.S. is not created equal, and we now have eight approved drugs in four different classes that allow us to better react to patients who are not having a response to therapy.
Especially for those patients taking interferon, the new study shouldn’t encourage them to stop. “If patients are taking the existing disease-modifying therapies [such as interferon beta] they should continue to take them,” Timothy Coetzee, chief research officer for the National MS Society, told HealthDay. “Those drugs were approved for treating MS based on strong clinical trial results that found over a two- to three-year period, people did better with the drugs.”
Interferon beta drugs currently on the market include Betaseron, Avonex and Rebif.