Positive results from the Phase 1/2 DELIVER trial suggest that z-rostudirsen (also called DYNE-251), an investigational treatment for Duchenne muscular dystrophy (DMD), may offer meaningful improvement in strength and daily function for patients eligible for exon 51 skipping, according to a press release published recently by the therapy’s maker, Dyne Therapeutics.
These findings could influence future care by providing a therapy that not only boosts dystrophin, the protein missing in DMD, but also helps preserve movement and lung capacity.
According to Dyne Therapeutics, the study’s main goal was met, with treated participants reaching an average muscle content-adjusted dystrophin level of 5.46% after six months. This represented a seven-fold increase from baseline and was highly statistically significant.
Even small increases in dystrophin can slow disease progression in DMD. Researchers also noted that lung function, measured by forced vital capacity, remained stable at six months, while it declined in the placebo group.
Functional measures, such as Time to Rise velocity and 10-Meter Walk/Run velocity, improved compared with placebo, even though the study was not designed to prove statistical significance for these outcomes. Improvements were also seen in upper limb strength and stride measurements. These changes suggest the therapy may help patients maintain abilities that typically worsen over time.
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Long-term data added more reassurance. Participants followed for up to 24 months continued to show gains or stability across all major measures, including walking speed, rising from the floor, arm function and breathing. This consistency is important because DMD is a progressive condition in which abilities usually decline steadily.
“With its high level of dystrophin expression, favorable safety profile, convenient monthly dosing regimen, and functional improvement as assessed by six prespecified clinical measures, z-rostudirsen has the potential to transform the care of those living with DMD amenable to exon 51 skipping,” said John Cox, president and chief executive officer of Dyne Therapeutics.
Safety findings were generally favorable. Across 86 participants and 1,441 total doses, most side effects were mild or moderate, such as fever or headache. Two serious side effects related to fever or malaise occurred in the long-term extension portion, but both participants recovered and stayed on treatment.
Dyne plans to submit the therapy for U.S. Accelerated Approval in the second quarter of 2026. If the Food and Drug Administration grants Priority Review, the company expects a possible U.S. launch in early 2027, offering families another treatment option aimed at slowing the impact of DMD.
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