A promising drug slowed brain shrinkage in progressive multiple sclerosis (MS) by nearly half, according to new research led by Cleveland Clinic. Currently, very limited therapies are available for this disabling form of the disease.

The definitive results of the phase 2 trial – published in the New England Journal of Medicine – showed that the drug ibudilast decreased progression of brain atrophy in progressive MS patients by 48% versus placebo. The two-year SPRINT-MS study was conducted at 28 sites with 255 patients.

Robert Fox, MD, the study’s principal investigator and vice-chair for research in Cleveland Clinic’s Neurological Institute, said: “These findings are significant for patients with progressive MS.

“Our hope is that the benefit of ibudilast in slowing brain shrinkage will also translate to decreased progression of associated physical disabilities in a future phase 3 trial.”

Progressive MS is associated with gradual worsening of symptoms and increasing disability. It commonly follows relapsing-remitting MS, for which there are more than a dozen approved treatments. However, none of these therapies has consistently demonstrated efficacy in slowing disability progression in patients with progressive MS, particularly those without evidence for active inflammation.

Ibudilast, an oral drug with activity on several biologic pathways with potential relevance to progressive MS, was approved in Japan in 1989 for use in asthma and stroke. It is also being studied in the US for potential treatment of drug addiction and amyotrophic lateral sclerosis (ALS), also known as motor neurone disease.

Additionally, the SPRINT-MS study demonstrated the utility of advanced imaging in clinical trials to measure the impact of therapies on brain health. The potential application of imaging-based outcome measures may extend beyond progressive MS to other neurodegenerative disorders as well.

“There is a significant need for new treatment options to effectively delay disability progression for patients with progressive MS,” said Dr. Fox. “We are hopeful these findings will help us develop more therapies for progressive MS, and do so more rapidly and efficiently.”

The research, which paves the way for phase 3 testing, also determined that ibudilast is relatively safe and well tolerated. The drug has received fast-track designation from the U.S. Food & Drug Administration.

“Although a larger study is needed to confirm these findings, this promising study brings people with progressive MS, who currently do not have many treatment options, one step closer to a potential therapy,” said Robin Conwit, M.D., program director at the National Institute of Neurological Disorders and Stroke (NINDS), part of the U.S. government agency National Institutes of Health.

The study was conducted by the Network for Excellence in Neuroscience Clinical Trials (NeuroNEXT), which is sponsored by NINDS. The research was supported by NINDS, National Multiple Sclerosis Society and biopharmaceutical firm MediciNova.

“These results are a promising step toward a potential new therapy for people living with progressive forms of MS, for whom there are few treatment options,” said Bruce Bebo, Ph.D., Executive Vice President, Research, National MS Society. “It is gratifying to see our investments in progressive MS starting to pay off.”