Safety and efficacy of dimethyl fumarate in ALS: randomised controlled study

Abstract

Abstract Objective Neuroinflammation is an important pathogenic mechanism in amyotrophic lateral sclerosis (ALS), with regulatory T cells (Tregs) mediating a slower rate of disease progression. Dimethyl fumarate enhances Treg levels and suppresses pro‐inflammatory T cells. The present study assessed the safety and efficacy of dimethyl fumarate in ALS. Methods Phase‐2, double‐blind, placebo‐controlled randomised clinical trial recruited participants from May 1, 2018 to September 25, 2019, across six Australian sites. Participants were randomised (2:1 ratio) to dimethyl fumarate (480 mg/day) or matching placebo, completing visits at screening, baseline, weeks 12, 24 and 36. The primary efficacy endpoint was a change in Amyotrophic Lateral Sclerosis Functional Rating Scale‐Revised (ALSFRS‐R) at week 36. Secondary outcome measures included survival, neurophysiological index (NI), respiratory function, urinary neurotrophin‐receptor p75 and quality of life. Results A total of 107 participants were randomised to dimethyl fumarate (n = 72) or placebo (n = 35). ALSFRS‐R score was not significantly different at week 36 (−1.12 [−3.75 to 1.52, p = 0.41]). Dimethyl fumarate was associated with a reduced NI decline week 36 (differences in the least‐squares mean: (0.84 [−0.51 to 2.22, p = 0.22]). There were no significant differences in other secondary outcome measures. Safety profiles were comparable between groups. Interpretation Dimethyl fumarate, in combination with riluzole, was safe and well‐tolerated in ALS. There was no significant improvement in the primary endpoint. The trial provides class I evidence for safety and lack of efficacy of dimethyl fumarate in ALS.