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NCT Number: NCT05524883

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

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 (LTE) period (192 weeks).

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This study is active but is not currently recruiting participants.

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Key information

Conditions

Duchenne Muscular Dystrophy (DMD) Congenital, Hereditary, and Neonatal Diseases and Abnormalities Genetic Diseases, Inborn Genetic Diseases, X-Linked Muscular Diseases Muscular Disorders, Atrophic Muscular Dystrophies Muscular Dystrophy, Duchenne Musculoskeletal Diseases Nervous System Diseases Neuromuscular Diseases

Age range

4 year–16 year

Sex eligibility

Male

Study type

Interventional

Phase

Phase 1 / Phase 2

Primary location

Children's Hospital at Westmead, Westmead, New South Wales, Australia

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age 4 to 16 years inclusive, at the time of informed consent/assent.
  • Male with a confirmed diagnosis of DMD and with a 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 enrollment.
  • Receiving a stable dosage of glucocorticoids for at least 12 weeks prior to the start of study drug administration, with the expectation of maintaining a stable dose during the Placebo-Controlled and Open-Label Periods of the study (unless dose adjustment is required by weight change).
  • 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.

Treatment and study plan

DYNE-251

Drug

Administered by IV infusion

Placebo

Drug

Administered by IV infusion

Primary outcomes

  1. Number of Participants With Treatment-Emergent Adverse Events (TEAEs)

    Time frame: Through study completion, up to Week 241

  2. Change From Baseline in Dystrophin Protein Levels in Muscle Tissue at Week 25

    Time frame: Baseline, Week 25

Secondary outcomes

  1. Change From Baseline in Muscle Tissue Exon 51 Skipping Levels at Week 25 For Participants Dosed at Q4W or Q8W Interval With a Second Biopsy Performed at Week 25

    Time frame: Baseline, Week 25

  2. Change From Baseline in Muscle Tissue Percent Dystrophin-Positive Fiber (PDPF) at Week 25 For Participants Dosed at Q4W or Q8W Interval With a Second Biopsy Performed at Week 25

    Time frame: Baseline, Week 25

  3. Change From Baseline in Blood Creatine Kinase (CK) Levels up to Week 241 For Participants Dosed at Q4W or Q8W Interval With a Second Biopsy Performed at Week 25

    Time frame: Baseline, up to Week 241

  4. Change From Baseline in Dystrophin Protein Level in Muscle Tissue as Determined by Western Blot at Week 49 For Participants Dosed at Q8W Interval With a Second Biopsy Performed at Week 49

    Time frame: Baseline, Week 49

  5. Change From Baseline in Muscle Tissue Exon 51 Skipping Levels at Week 49 For Participants Dosed at Q8W Interval With a Second Biopsy Performed at Week 49

    Time frame: Baseline, Week 49

  6. Change From Baseline in Muscle Tissue PDPF at Week 49 For Participants Dosed at Q8W Interval With a Second Biopsy Performed at Week 49

    Time frame: Baseline, Week 49

  7. Change From Baseline in Blood CK Levels up to Week 241 For Participants Dosed at Q8W Interval With a Second Biopsy Performed at Week 49

    Time frame: Baseline, up to Week 241

  8. Change From Baseline in North Star Ambulatory Assessment (NSAA) Total Score in Ambulatory Participants up to Week 241

    Time frame: Baseline, up to Week 241

    The NSAA is a 17-item functional scale used to measure functional motor abilities in ambulant participants with DMD and monitor progression of the disease and treatment effects in each of the items. The items are graded on a 3-point scale: 0=unable to achieve independently, 1=modified method but achieves goal with no physical assistance, and 2=normal, no obvious modification of activity. Total score range is 0 to 34.

  9. Change From Baseline in Time to Rise From Floor in Ambulatory Participants up to Week 241

    Time frame: Baseline, up to Week 241

  10. Change From Baseline in 10-Meter Run/Walk (10MRW) Time in Ambulatory Participants up to Week 241

    Time frame: Baseline, up to Week 241

  11. Change From Baseline in Performance Upper Limb (PUL) Scale Version 2.0 Score up to Week 241

    Time frame: Baseline, up to Week 241

    The PUL scale is a validated tool specifically designed for assessing upper limb function in ambulant and non-ambulant individuals with DMD. It includes an entry item to define the broad starting functional level and 22 items subdivided into 3 areas indicative of upper limb strength as, shoulder level, midlevel, and distal level. The global score is a combination of the 3 areas and ranges from 0 to 42. Lower scores indicate higher disability.

  12. Change From Baseline in Percent Predicted Forced Vital Capacity (FVC) up to Week 241

    Time frame: Baseline, up to Week 241

  13. Change From Baseline in Stride Velocity 95th Centile (SV95C) in Ambulatory Participants up to Week 241

    Time frame: Baseline, up to Week 241

  14. Maximum Observed Plasma Drug Concentration of DYNE-251 (Cmax)

    Time frame: Through study completion, up to Week 241

  15. Time to Maximum Observed Plasma Drug Concentration of DYNE-251 (tmax)

    Time frame: Through study completion, up to Week 241

  16. Area Under the Plasma Drug Concentration-Time Curve From Time 0 to the Last Quantifiable Concentration of DYNE-251 in Plasma (AUC0-tlast)

    Time frame: Through study completion, up to Week 241

  17. Area Under the Plasma Drug Concentration Versus Time Curve From Time 0 (Dosing) Extrapolated to Time Infinity of DYNE-251 (AUC∞)

    Time frame: Through study completion, up to Week 241

  18. Apparent Terminal Phase Elimination Rate Constant of DYNE-251 in Plasma (λz)

    Time frame: Through study completion, up to Week 241

  19. Apparent Terminal Elimination Half-Life of DYNE-251 in Plasma (t½)

    Time frame: Through study completion, up to Week 241

  20. Total Body Clearance (CL) of DYNE-251

    Time frame: Through study completion, up to Week 241

  21. Volume of Distribution at the Terminal Phase of DYNE-251 in Plasma (Vz)

    Time frame: Through study completion, up to Week 241

  22. Volume of Distribution at Steady State of DYNE-251 in Plasma (Vss)

    Time frame: Through study completion, up to Week 241

  23. Tissue Phosphorodiamidate Morpholino Oligomer (PMO) Concentration of DYNE-251 in Muscle Tissue

    Time frame: Through study completion, up to Week 241

  24. Percentage of Participants With Antidrug Antibodies (ADAs)

    Time frame: Through study completion, up to Week 241

Sponsors and collaborators

Lead sponsor

Dyne Therapeutics

Industry

Registry information

Official study title

A Randomized, Double-Blind, Placebo-Controlled, Multiple Ascending Dose Study Assessing Safety, Tolerability, Pharmacodynamics, Efficacy, and Pharmacokinetics of DYNE-251 Administered to Participants With Duchenne Muscular Dystrophy Amenable to Exon 51 Skipping

Acronym: DELIVER

Important dates

Study start
2022
Primary completion
2029
Study completion
2029
First posted
Sep 1, 2022
Registry last updated
Aug 13, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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