Phase 2 Trial of Ibudilast in Progressive Multiple Sclerosis.

BACKGROUND: There are limited treatments for progressive multiple sclerosis. Ibudilast inhibits several cyclic nucleotide phosphodiesterases, macrophage migration inhibitory factor, and toll-like receptor 4 and can cross the blood-brain barrier, with potential salutary effects in progressive multiple sclerosis. METHODS: We enrolled patients with primary or secondary progressive multiple sclerosis in a phase 2 randomized trial of oral ibudilast (≤100 mg daily) or placebo for 96 weeks. The primary efficacy end point was the rate of brain atrophy, as measured by the brain parenchymal fraction (brain size relative to the volume of the outer surface contour of the brain). Major secondary end points included the change in the pyramidal tracts on diffusion tensor imaging, the magnetization transfer ratio in normal-appearing brain tissue, the thickness of the retinal nerve-fiber layer, and cortical atrophy, all measures of tissue damage in multiple sclerosis. RESULTS: Of 255 patients who underwent randomization, 129 were assigned to ibudilast and 126 to placebo. A total of 53% of the patients in the ibudilast group and 52% of those in the placebo group had primary progressive disease; the others had secondary progressive disease. The rate of change in the brain parenchymal fraction was -0.0010 per year with ibudilast and -0.0019 per year with placebo (difference, 0.0009; 95% confidence interval, 0.00004 to 0.0017; P=0.04), which represents approximately 2.5 ml less brain-tissue loss with ibudilast over a period of 96 weeks. Adverse events with ibudilast included gastrointestinal symptoms, headache, and depression. CONCLUSIONS: In a phase 2 trial involving patients with progressive multiple sclerosis, ibudilast was associated with slower progression of brain atrophy than placebo but was associated with higher rates of gastrointestinal side effects, headache, and depression. (Funded by the National Institute of Neurological Disorders and Stroke and others; NN102/SPRINT-MS ClinicalTrials.gov number, NCT01982942 .).

Design, rationale, and baseline characteristics of the randomized double-blind phase II clinical trial of ibudilast in progressive multiple sclerosis.

BACKGROUND: Primary and secondary progressive multiple sclerosis (MS), collectively called progressive multiple sclerosis (PMS), is characterized by gradual progression of disability. The current anti-inflammatory treatments for MS have little or no efficacy in PMS in the absence of obvious active inflammation. Optimal biomarkers for phase II PMS trials is unknown. Ibudilast is an inhibitor of macrophage migration inhibitor factor and phosphodiesterases-4 and -10 and exhibits possible neuroprotective properties. The goals of SPRINT-MS study are to evaluate the safety and efficacy of ibudilast in PMS and to directly compare several imaging metrics for utility in PMS trials. METHODS: SPRINT-MS is a randomized, placebo-controlled, phase II trial of ibudilast in patients with PMS. Eligible subjects were randomized 1:1 to receive either ibudilast (100mg/day) or placebo for 96weeks. Imaging is conducted every 24weeks for whole brain atrophy, magnetization transfer ratio, diffusion tensor imaging, cortical brain atrophy, and retinal nerve fiber layer thickness. Clinical outcomes include neurologic disability and patient reported quality of life. Safety assessments include laboratory testing, electrocardiography, and suicidality screening. RESULTS: A total of 331 subjects were enrolled, of which 255 were randomized onto active study treatment. Randomized subjects were 53.7% female and mean age 55.7 (SD 7.3) years. The last subject is projected to complete the study in May 2017. CONCLUSION: SPRINT-MS is designed to evaluate the safety and efficacy of ibudilast as a treatment for PMS while simultaneously validating five different imaging biomarkers as outcome metrics for use in future phase II proof-of-concept PMS trials.