In the phase 2 clinical trial, 8 of 35 participants treated with the drug — which has been used for years to treat malaria, a mosquito-borne disease, and is also used to treat some autoimmune inflammatory rheumatoid diseases, including rheumatoid arthritis and lupus — experienced clinically significant worsening of disability between 6 and 18 months after starting treatment, the study found. On the basis of prior study data, 10 were expected to show signs of worsening disability, according to the University of Calgary researchers, who didn’t respond to requests for comment.
How Disability Progression Was Measured
Study participants were given one 200 milligram (mg) tablet of the drug twice daily, and they were evaluated using several standard measures for MS progression, including an Expanded Disability Status Scale (EDSS) score, contrast magnetic resonance imaging (MRI), timed 25-foot walk test, the Nine-Hole Peg Test, and the Symbol Digit Modalities Test, the researchers say. For the purposes of the study, those with a 20 percent or more decline in performance on the timed 25-foot walk test were considered to have worsening disability. RELATED: Speaking Multiple Sclerosis: A Glossary of Common Terms
Safety and Side Effects
In addition to appearing to slow progression, hydroxychloroquine was generally safe, the study authors wrote. In all, 15 participants experienced drug-related side effects, with six reporting vivid dreams, three developing nausea, three indicating upset stomach, and three reporting tinnitus, or ringing in the ears. Six participants developed serious side effects, but none were linked with hydroxychloroquine, the researchers noted.
Results Support Further Research, Says Expert
Although the drug was associated with less disability worsening in people with PPMS in the study, larger trials of the drug in people with the condition are needed to confirm the results, according to Jeffrey Cohen, MD, the director of the experimental therapeutics program at the Cleveland Clinic’s Mellen Center for Multiple Sclerosis Treatment and Research in Ohio. The immunologic properties of hydroxychloroquine that make it an effective treatment for malaria also work against several biologic processes in MS that cause disability progression, including damage to the cells of the central nervous system, Dr. Cohen says. But “showing that 8 participants worsened instead of the predicted 10 is only modestly convincing,” says Cohen, who was not part of this study. “Further investigation would be reasonable, but these results are very preliminary and do not support use of hydroxychloroquine to treat PPMS outside of studies.”
