No clear benefit to losmapimod for facioscapulohumeral muscular dystrophy
Key takeaways:
- Treatment with losmapimod and placebo had similar results with respect to primary, secondary endpoints.
- No treatment-related severe adverse events, discontinuation or deaths were recorded with losmapimod.
Treatment with losmapimod resulted in no clear benefit compared with placebo in individuals with facioscapulohumeral muscular dystrophy at 48 weeks, according to research presented at the Muscular Dystrophy Association Clinical & Scientific Conference.
“Facioscapulohumeral muscular dystrophy (FSHD) is a rare, progressive genetic muscle disorder, characterized by variable loss of skeletal muscle mass and strength with no approved therapy,” Jeffrey M. Statland, MD, professor of neurology at Kansas University Medical Center, told Healio. “Approximately 20% of patients lose the ability to walk or maintain a job.”
As losmapimod demonstrated beneficial effects on muscle function in patients with FSHD in a previous phase 2 study, Statland and colleagues sought to examine the selective inhibitor in REACH, a phase 3 clinical trial.
The double-blind, placebo-controlled study assessed the safety and efficacy of losmapimod for the treatment of FSHD in 260 adults (mean age, 43.9 years; 56% men) with the condition (FSHD1, n = 242; FSHD2, n = 18).
Participants were randomly assigned on a 1:1 basis to receive either 15 mg losmapimod or placebo orally twice per day over 48 weeks.
The primary efficacy endpoint was change in total relative surface area (RSA), with 500 g of weight placed on each participant’s wrist on a reachable work area. Secondary endpoints included change in shoulder abductor strength measured via hand-held dynamometry, muscle fat infiltration (MFI) as well as patient self-reported answers to the Neuro QOL-Upper Extremity Function (NeuroQoL-UE) and Patient Global Impression of Change (PGIC) questionnaires collected at week 48.
The researchers reported that no discernible benefit was demonstrated in patients treated with losmapimod compared with patients given placebo regarding RSA, MFI, dynamometry, or responses to NeuroQoL-UE or PGIC.
Data additionally showed that the overall rate of adverse events (AEs) was similar across both treatment cohorts; for losmapimod, no treatment-related severe adverse events or discontinuation due to AEs or deaths were recorded.
“Both losmapimod and placebo similarly improved reachable workspace area of the upper limb over 48 weeks, the primary endpoint in REACH,” Statland told Healio. “There remains an unmet need for therapies and while REACH did not meet its primary endpoint, the study design and data may be informative for future clinical development.”
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Statland JM, et al. Topline efficacy and safety results from REACH: Phase 3 placebo-controlled trial of losmapimod for Facioscapulohumeral Muscular Dystrophy (FSHD). Presented at: Muscular Dystrophy Association Clinical & Scientific Conference; March 16-19, 2025; Dallas.
