Dyne Therapeutics, Inc. (NASDAQ:DYN) on Monday revealed topline results from the Registrational Expansion Cohort (REC) of its Phase 1/2 DELIVER trial evaluating zeleciment rostudirsen (z-rostudirsen, also known as DYNE-251) for Duchenne muscular dystrophy (DMD) amenable to exon 51 skipping.
The REC met its primary endpoint, demonstrating a statistically significant increase in muscle content-adjusted dystrophin expression to 5.46% of normal relative to baseline at six months.
Dystrophin is a protein located primarily in muscles used for movement.
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These results replicate the 7-fold increase in muscle-content adjusted dystrophin expression at six months reported previously from participants receiving 20 mg/kg z-rostudirsen Q4W in the multiple-ascending dose (MAD) portion of the DELIVER trial.
When unadjusted for muscle content, the mean absolute dystrophin expression among patients treated with 20 mg/kg z-rostudirsen Q4W was 2.87% of normal, approximately 10-fold higher than the 0.3% of normal reported in a clinical trial of the weekly standard of care for DMD exon 51 in the U.S., Sarepta Therapeutics Inc.’s (NASDAQ:SRPT) Exondys 51 (eteplirsen).
In addition, improvement relative to placebo was observed across all six prespecified functional endpoints from the topline readout of the REC. Two of these measures, Time to Rise (TTR) Velocity and 10-Meter Walk/Run (10MWR) Velocity, both improved relative to placebo at six months with a nominal p<0.05, even though the study was not powered to demonstrate statistical significance in any of the functional measures.
Lung function loss, which is a leading cause of mortality in DMD, as measured by Forced Vital Capacity Percent Predicted (FVC%p), was preserved at 6 months compared to a decline in placebo.
Long-Term Data And Safety Profile
Additionally, Dyne announced new positive long-term clinical data from the ongoing open-label extension (OLE) and long-term extension (LTE) portions of DELIVER.
Z-rostudirsen continued to demonstrate a favorable safety profile, and most related treatment-emergent adverse events (TEAEs) were mild or moderate. The most commonly reported related TEAEs were pyrexia (fever) and headache.
Upcoming Milestones
Dyne plans to submit a BLA (Biologics License Application) for U.S. Accelerated Approval in the second quarter of 2026, with potential U.S launch in the first quarter of 2027.
The company plans to initiate a global Phase 3 clinical trial of z-rostudirsen in the second quarter of 2026.
DYN Price Action: Dyne Therapeutics shares were up 6.78% at $21.65 at the time of publication on Monday, according to Benzinga Pro data.
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