No Accelerated FDA Approval For Edgewise's Rare Muscular Disease Drug; Shares Fall

Edgewise Therapeutics, Inc. EWTX, a biotechnology company focused on developing treatments for rare muscle disorders, recently unveiled promising results from its sevasemten program for Becker muscular dystrophy (BMD) and Duchenne muscular dystrophy (DMD).

Both are progressive genetic disorders characterized by muscle weakness and degeneration, with DMD typically being more severe and having an earlier onset than BMD.

On Thursday, the company announced data from MESA. This open-label extension trial provides continued access to sevasemten to participants with Becker who were previously enrolled in ARCH or completed CANYON, GRAND CANYON, or DUNE.

Also Read: Edgewise Therapeutics Sees Meaningful HCM Treatment Gains With EDG-7500 In Phase 2 Study

As of the March 2025 data cut, 99% of eligible participants (n=85) are enrolled in MESA. The MESA data demonstrated sustained disease stabilization.

CANYON participants who rolled over to MESA showed increased North Star Ambulatory Assessment (NSAA) scores over 18 months (0.8 point improvement from baseline), with a trend toward improvement in placebo participants switching to sevasemten (0.2 point improvement since initiation of sevasemten).

NSAA measures functional motor abilities in ambulant (who can walk) children with Duchenne. During the 18 months of sevasemten treatment, participants’ NSAA scores continued to diverge relative to the expected functional declines seen in multiple Becker natural history studies.

Further, NSAA scores for ARCH participants who rolled over to MESA remained stable after three years of treatment. Sevasemten demonstrates a favorable safety profile after up to three years of treatment. 

Edgewise recently completed a Type C meeting with the U.S. Food and Drug Administration (FDA).

While the FDA deemed the CANYON data insufficient for accelerated approval, the Agency reiterated that NSAA is a clinically meaningful endpoint for traditional approval.

Accelerated approval is an FDA pathway that allows for earlier approval of drugs for serious conditions that fill an unmet medical need, based on a surrogate endpoint (a measure that is reasonably likely to predict clinical benefit).

However, it requires confirmatory trials post-approval. Traditional approval, on the other hand, typically requires more extensive clinical trial data demonstrating direct clinical benefit.

GRAND CANYON is highly powered to show a statistically significant difference in NSAA versus placebo over 18 months and is on track for topline data in the fourth quarter of 2026. 

The company also announced topline data from its Phase 2 Duchenne trials, LYNX and FOX.

The goals were to explore a range of doses to assess safety and identify a potentially beneficial dose for Phase 3. Across both studies, sevasemten was well-tolerated at target doses.

LYNX is an ongoing Phase 2 trial to evaluate the effect of sevasemten on safety, biomarkers of muscle damage, and function in four- to nine-year-old participants with Duchenne treated with sevasemten.

The company identified a dose of 10 mg to evaluate in Phase 3. 

Similar to the LYNX design, FOX is an ongoing Phase 2 trial to evaluate the effect of sevasemten on safety, biomarkers of muscle damage, and function in six- to 14-year-old participants with Duchenne who have been previously treated with gene therapy.

The company plans to meet with the FDA in the fourth quarter of 2025 to discuss a Phase 3 design, including input on the patient population and endpoints, with plans to initiate the pivotal study in 2026.

Price Action: EWTX stock is down 11.6% at $12.68 at last check Thursday.

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