Science News: REACH Trial Finds No Clinical Benefit for Losmapimod in FSHD

Submitted by: Shaohua Xu, MD, PhD

Edited by: Rebecca O'Bryan, MD

Citation: Voermans NC, Statland JM, Haywayd LJ, et al, A randomized, double-blind, placebo-controlled study of losmapimod in patients with facioscapulohumeral muscular dystrophy: Results of the REACH study, Journal of Neuromuscular Disease, 2026 Feb 6:22143602261419558. doi: 10.1177/22143602261419558.

Summary:
This phase 3 REACH trial evaluated the p38α/β MAPK inhibitor losmapimod in 260 adults with genetically confirmed facioscapulohumeral muscular dystrophy (FSHD1 or FSHD2) over 48 weeks and found no significant improvement in the primary endpoint—reachable workspace (RSA)—or in secondary measures of muscle composition, strength, or quality of life compared with placebo.

Losmapimod was well tolerated, with mostly mild adverse events and a safety profile consistent with prior studies. Although the drug did not demonstrate clinical efficacy, the study provides important insights for future FSHD therapeutic trials, including the challenges of placebo effects, endpoint sensitivity, disease heterogeneity, and trial duration, and highlights the need for improved biomarkers and functional outcome measures in FSHD research.

Comments:
The REACH study is significant because it represents one of the largest, most rigorously designed phase 3 clinical trials ever completed in facioscapulohumeral muscular dystrophy (FSHD), and its results reshape how the field thinks about therapeutic development. Even though losmapimod did not meet its primary or secondary efficacy endpoints, the study provides several important contributions.

The negative efficacy results help redirect the field away from p38 inhibition as a therapeutic strategy. The study provides a rich dataset that will inform endpoint selection, trial duration, patient stratification, and biomarker development for future FSHD therapies.

Why is this article interesting/relevant to the AANEM audience?
This article is highly relevant to the AANEM audience because it delivers one of the most comprehensive, methodologically rigorous datasets ever generated in facioscapulohumeral muscular dystrophy (FSHD)—a disease that neuromuscular clinicians diagnose, monitor, and counsel regularly—while also exposing the challenges that remain in developing meaningful clinical endpoints for slowly progressive myopathies.