Safety, Tolerability, Pharmacodynamic, Efficacy, and Pharmacokinetic Study of DYNE-251 in Participants With Duchenne Muscular Dystrophy Amenable to Exon 51 Skipping

• Status: Recruiting
• Trial end date: 2026-11-01
• Target enrollment: 0
• Participant gender: Male

Summary

The primary purpose of this study is to evaluate the safety, tolerability, and dystrophin protein levels in muscle tissue following multiple intravenous (IV) doses of DYNE-251 in participants with Duchenne muscular dystrophy (DMD) amenable to exon 51 skipping.

The study consists of 3 periods: a multiple-ascending dose (MAD) / placebo-controlled period (24 weeks), an open-label period (24 weeks) and a long-term extension period (96 weeks).

• Phase: Phase 1/Phase 2
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Dyne Therapeutics

Criteria

Inclusion Criteria:

• Age 4 to 16 years inclusive, at the time of informed consent/assent.

• Male with a confirmed DMD mutation in the dystrophin gene characterized by exon deletion amenable to exon 51 skipping.

• Upper extremity muscle group that is amenable to muscle biopsy.

• Brooke Upper Extremity Scale score of 1 or 2.

• Ambulatory or non-ambulatory. A non-ambulatory participant must have been non-ambulatory for <2 years before enrolment.

• Receiving a stable dosage of glucocorticoids for at least 12 weeks prior to the start of study drug administration.

• Left ventricular ejection fraction of ≥50% by echocardiogram or ≥55% by cardiac magnetic resonance imaging (MRI).

Exclusion Criteria:

• Uncontrolled clinical symptoms and signs of congestive heart failure (CHF).

• Any change in prophylaxis/treatment for CHF within 3 months prior to the start of study treatment.

• History of major surgical procedure within 12 weeks prior to the start of study drug administration or an expectation of a major surgical procedure during the study.

• Requirement of daytime ventilator assistance.

• Percent predicted FVC <40 % (applies only for participants who are age ≥7 years).

• Receipt of eteplirsen, or alternative exon-skipping/dystrophin-modifying therapy, within 12 weeks of randomization.

• Receipt of non-exon skipping investigational drug within 4 months before the start of study drug administration.

• Receipt of gene therapy at any time.

Other inclusion and exclusion criteria may apply.