Results from a clinical trial of more than 250 participants with progressive multiple sclerosis revealed that ibudilast was better than a placebo in slowing down brain shrinkage. The study showed the main side effects of ibudilast were gastrointestinal and headaches. The researchers said the trial’s results point towards a potential new therapy to help people with progressive MS.

A team of researchers across 28 clinical sites in a brain imaging study investigated whether ibudilast was better than a placebo in reducing the progression of brain atrophy, or shrinkage, in patients with progressive MS. The study was supported by the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health. In the study, 255 patients were randomized to take up to 10 capsules of ibudilast or placebo per day for 96 weeks. Every six months, the participants underwent MRI brain scans.

The study showed that ibudilast slowed down the rate of brain atrophy compared to placebo. Researchers discovered that although both groups experienced atrophy, the brains of the patients in the placebo group shrank on average 2.5 milliliters more over two years compared to the ibudilast group. The whole adult human brain has a volume of approximately 1,350 milliliters. However, it is unknown whether that difference had an effect on symptoms or loss of function.

There was no significant difference between the groups in the number of patients who reported adverse effects. The most common side effects associated with ibudilast were gastrointestinal, including nausea and diarrhea, as well as headaches and depression. 

Future research will test whether reducing brain shrinkage affects thinking, walking, and other problems in people with MS. In addition, future studies will examine whether ibudilast slows the progression of disability in MS patients.

The study was published in the New England Journal of Medicine.