Dyne Therapeutics has reported positive early results for its investigational therapy zeleciment rostudirsen in the treatment of Duchenne muscular dystrophy (DMD). According to analysts from Stifel, the therapy not only increased dystrophin levels but also led to significant functional improvements, which they described as the “best ever” seen for an exon-skipping treatment in this condition.
Stifel analysts stated, “The regulatory precedent is overwhelmingly in DYN’s favor,” pointing out that previous therapies for Duchenne have received approval based on “marginal” increases in dystrophin and with “limited evidence of clinical efficacy.” The analysts also confirmed with Dyne that analyses for functional outcomes in this study were conducted according to standards expected of registrational trials.
In Dyne’s Phase I/II DELIVER study, patients who received a monthly dose of 20-mg/kg zeleciment rostudirsen showed mean dystrophin expression at 5.46% of normal, adjusted for muscle content. This marks about a sevenfold increase at six months. Stifel highlighted this result as giving the therapy a “highly differentiated” efficacy profile compared to existing treatments.
The report noted that these dystrophin levels are much higher than those achieved by Sarepta Therapeutics’ Exondys 51, which reached only 0.3% of normal at six months. However, Stifel cautioned that no direct comparison studies have been conducted between Exondys 51 and zeleciment rostudirsen, so cross-study comparisons may not fully reflect their relative effectiveness.
Functional improvements observed included better time-to-rise and 10-meter walk/run results compared to placebo. Patients also experienced improved stride velocity, upper limb performance, and lung function after six months on zeleciment rostudirsen. The DELIVER study was not designed to statistically assess these functional benefits versus placebo, but posthoc analysis showed nominally significant effects.
Based on these findings, Dyne plans to submit a biologics license application in the second half of 2026 and is seeking accelerated approval from regulators. If successful and if granted priority review by the FDA, the company anticipates launching the drug in early 2027. Additionally, Dyne intends to start a Phase III program for zeleciment rostudirsen in the second quarter of next year to further validate clinical benefit and support global regulatory submissions.
A correction issued December 8 clarified that the Phase III program is scheduled to begin in Q2 2026 rather than later in the year.
