Sevasemten for Becker Muscular Dystrophy Associated with Stabilized Ambulatory Function
Key Takeaways
- Sevasemten treatment was associated with stable NSAA scores for up to 3.5 years in those with Becker muscular dystrophy.
- Ambulatory scores increased in the first year for participants who transitioned from placebo to sevasemten.
- Sevasemten is designed to protect muscle from contraction-induced damage by inhibiting fast skeletal myosin.
Treatment with sevasemten (Edgewise Therapeutics, Boulder, CO), an investigational oral fast skeletal myosin inhibitor, was associated with stabilization of motor function in individuals with Becker muscular dystrophy (BMD) compared with predicted natural history decline. In data from the MESA open-label extension (OLE) study (NCT06066580), presented at the 2026 Muscular Dystrophy Association Clinical and Scientific Conference, ambulatory function remained stable for up to 3.5 years among participants treated with sevasemten. BMD is a progressive neuromuscular disorder characterized by gradual loss of motor function and currently has no approved disease-modifying therapies.
The ongoing OLE study enrolled 52 ambulatory adults and adolescents with BMD who had previously participated in the phase 1b ARCH trial (NCT05160415; n=12) or phase 2 placebo-controlled CANYON trial (NCT05291091; n=40). The primary end point was safety, and motor function was tracked using the North Star Ambulatory Assessment (NSAA). To contextualize treatment effects, investigators developed a validated predictive model of individual NSAA trajectory based on published BMD natural history data, which estimates an average annual NSAA decline of 1 to 1.7 points.
Key results from the OLE include:
- After 3.5 years, the mean NSAA change in the ARCH cohort was +0.1 points vs a predicted decline of -5.3 points (Δ, +5.4).
- After 2 years, the mean NSAA change in the CANYON cohort was +0.1 points vs a predicted decline of -2.9 points (Δ, +3).
- CANYON participants who switched from placebo to sevasemten showed an upward trend in NSAA scores in the first year of treatment.
- No new safety signals emerged with extended exposure; the most common treatment-emergent adverse events were falls (17%), arthralgia (12%), dizziness (12%), and headache (12%).
- 99% of eligible participants from prior sevasemten studies opted to enroll in MESA.
Sources: Edgewise Therapeutics. Edgewise announces positive long-term sevasemten data demonstrating sustained functional stabilization in Becker muscular dystrophy through 3.5 years of follow-up. Press release. Published March 10, 2026. Accessed March 15, 2026. https://www.prnewswire.com/news-releases/edgewise-announces-positive-long-term-sevasemten-data-demonstrating-sustained-functional-stabilization-in-becker-muscular-dystrophy-through-3-5-years-of-follow-up-302708743.html
McDonald C, Phan H, Kushlaf H, et al. Long-term stabilization of function in Becker: sevasemten prevented functional decline up to 3.5 years with MESA open-label extension. Poster presented at: 2026 MDA Clinical and Scientific Conference; March 8-11, 2026; Orlando, Florida, USA.