Efficacy, Safety, and Tolerability of Zeleciment Rostudirsen (DYNE-251) Administered Intravenously Every 4 Weeks in Ambulatory Participants With Duchenne Muscular Dystrophy (FORZETTO)

NCT07608432 | Recruiting Phase 3 DMC FDA Drug

• 2 other identifiers: DYNE251-DMD-3012025-524096-23-00
• Study Type: interventional
• Target: 90
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of the study is to assess the efficacy, safety, and tolerability of zeleciment rostudirsen (DYNE-251) administered intravenously (IV) every 4 weeks to ambulatory Duchenne muscular dystrophy (DMD) participants, 4 to 18 years of age, with dystrophin mutations amenable to exon 51 skipping.

Conditions

Duchenne Muscular Dystrophy (DMD); Muscular Dystrophy, Duchenne; Muscular Dystrophy (DMD); DMD; Muscular Dystrophies; Muscular Dystrophy in Children; Muscular Dystrophy, Duchenne Type; Muscular Dystrophy, Duchenne and Becker Types; Muscular Dystrophies (Duchenne, Becker, Myotonic Dystrophy); Genetic Disease, Inborn; Genetic Disease, X-Linked; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Neuromuscular Diseases (NMD)

Keywords

Ambulatory; DMD; Duchenne Muscular Dystrophy; Duchenne; Dyne; Dyne Therapeutics; DYNE-251; Dystrophy; Exon Skipping; Exon 51; FORZETTO; Pediatric; PMO; Muscle Function; Muscular Dystropy, Duchenne; Rise From Floor; RFF; RFF Velocity; Rostudirsen; Time to rise; TTR; TTR Velocity; Zeleciment rostudirsen; Z-rostudirsen

Outcome Measures

Primary Outcomes (1)

• Rise From Floor (RFF) velocity

  Baseline, Week 73

Secondary Outcomes (21)

• RFF (Rise From Floor) velocity

  Baseline, up to Week 169

• Stride Velocity 95th Percentile (SV95C)

  Baseline, Week 73, up to Week 169

• North Star Ambulatory Assessment (NSAA) Total Score

  Baseline, Week 73, up to Week 169

• 10-Meter Walk/Run (10MWR) Velocity

  Baseline, Week 73, up to Week 169

• 4-Stair Climb (4SC) velocity

  Baseline, Week 73, up to Week 169

Study Arms (3)

Placebo-Controlled Period: Zeleciment Rostudirsen (DYNE-251)

EXPERIMENTAL

Participants will be randomized to receive zeleciment rostudirsen, once every 4 weeks (Q4W) for up to 72 weeks.

Drug: Zeleciment Rostudirsen (DYNE-251)

Placebo-Controlled Period: Placebo

PLACEBO COMPARATOR

Participants will be randomized to receive placebo, Q4W for up to 72 weeks.

Drug: Placebo

Open-Label Long-Term Extension Period: Zeleciment Rostudirsen (DYNE-251)

EXPERIMENTAL

All participants who complete the Placebo-Controlled Period of the study will receive zeleciment rostudirsen administered Q4W for up to 96 weeks.

Drug: Zeleciment Rostudirsen (DYNE-251)

Interventions

Zeleciment Rostudirsen (DYNE-251) DRUG

Administered by IV infusion

Open-Label Long-Term Extension Period: Zeleciment Rostudirsen (DYNE-251); Placebo-Controlled Period: Zeleciment Rostudirsen (DYNE-251)

Placebo DRUG

Administered by IV infusion

Placebo-Controlled Period: Placebo

Eligibility Criteria

• Age: 4 Years - 18 Years
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• Ambulatory male with confirmed diagnosis of DMD and with a mutation in the dystrophin gene characterized by exon deletion amenable to exon 51 skipping .
• Rise From Floor (RFF) time must be \< 10 seconds for both screening assessments .
• Receiving a stable daily or weekend dosage of glucocorticoids for at least 24 weeks prior to randomization with the expectation of maintaining a stable dose during the Placebo-Controlled Period of the study (unless dose adjustment is required by weight change)

You may not qualify if:

• Receipt of ongoing immunosuppressive therapy (other than glucocorticoids) within 12 weeks prior to randomization
• Use of any pharmacologic treatment (other than glucocorticoids) that may have an effect on muscle strength or function within 12 weeks prior to randomization
• Any change in prophylaxis/treatment for congestive heart failure (CHF) within 12 weeks prior to randomization
• Receipt of eteplirsen within 1 week prior to randomization
• Receipt of alternative exon-skipping or dystrophin-modifying therapy or zeleciment rostudirsen within 24 weeks prior to randomization
• Receipt of givinostat within 12 weeks prior to randomization
• Receipt of gene therapy at any time

Sponsors & Collaborators

• Dyne Therapeutics: lead

Study Sites (1)

Rare Disease Research, LLC

Hillsborough, North Carolina, 27278, United States

RECRUITING

MeSH Terms

Conditions

Muscular Dystrophy, Duchenne; Muscular Dystrophies; Myotonic Dystrophy; Genetic Diseases, Inborn; Genetic Diseases, X-Linked; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Neuromuscular Diseases

Condition Hierarchy (Ancestors)

Muscular Disorders, Atrophic; Muscular Diseases; Musculoskeletal Diseases; Nervous System Diseases; Myotonic Disorders; Heredodegenerative Disorders, Nervous System; Neurodegenerative Diseases

Central Study Contacts

Dyne Clinical Trials

CONTACT

+1-781-317-1919; clinicaltrials@dyne-tx.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 20, 2026
• First Posted: May 27, 2026
• Study Start: June 1, 2026
• Primary Completion (Estimated): December 1, 2030
• Study Completion (Estimated): October 1, 2032
• Last Updated: May 27, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)