Dyne Therapeutics Shares Rise on Positive 12-Month Data for DM1 Drug

Shares of Dyne Therapeutics (NASDAQ:DYN) gained 2.1% in after-hours trading Tuesday after the company released positive one-year data from a trial of its experimental treatment for myotonic dystrophy type 1 (DM1), z-basivarsen. The results showed sustained functional improvements in patients, supporting the drug's potential as a future therapy.

Key Trial Results

Dyne reported the data from the multiple ascending dose portion of its Phase 1/2 ACHIEVE trial. The company stated that a pooled group of 25 to 26 participants demonstrated significant improvement across multiple measures at both six and 12 months.

Key findings presented at the World Muscle Society Congress and the American Association of Neuromuscular & Electrodiagnostic Medicine Annual Meeting include:

• Video Hand Opening Time (vHOT): At six months, participants saw a mean decrease of 3.2 seconds from a baseline of 8.2 seconds. This compared favorably to a 0.4-second increase in the placebo group, representing a 3.6-second relative improvement.
• Functional Improvements at 12 Months: Patients showed a mean improvement of 1.2 seconds on the 5 times sit to stand test and 0.3 seconds on the 10-meter walk/run test, relative to baseline.
• Muscle Strength: Muscle strength scores improved by 4.8% as measured by both quantitative muscle testing and hand grip scores, showing a clear divergence from a matched natural history cohort.

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Path to Approval

The positive data reinforces the company's clinical development strategy. Dyne Therapeutics confirmed it expects to release topline data from the ACHIEVE trial's registrational expansion cohort in the first quarter of 2027. The primary endpoint for this cohort remains the change in vHOT at six months.

Based on these upcoming results, the company aims to submit z-basivarsen for potential U.S. Accelerated Approval in the third quarter of 2027. The drug continued to show a favorable safety profile, with no related serious treatment-emergent adverse events identified in the trial. Dyne is also currently enrolling participants in its global Phase 3 HARMONIA study.