Efficacy, Safety, and Tolerability of Zeleciment Basivarsen (DYNE-101) in Participants With Myotonic Dystrophy Type 1

NCT07486934 | Recruiting Phase 3 DMC FDA Drug

• 2 other identifiers: DYNE101-DM1-3012025-522957-20-00
• Study Type: interventional
• Target: 150
• Locations: 2 countries
• Sites: 4

Brief Summary

The purpose of the study is to assess the efficacy, safety, and tolerability of zeleciment basivarsen (DYNE-101) for the treatment of myotonic dystrophy 1 (DM1).

Conditions

Myotonic Dystrophy Type 1 (DM1); DM1; Myotonic Dystrophy; Steinert Disease; Steinert

Keywords

DM1; Myotonic Dystrophy; Myotonic Dystrophy 1; Myotonia; Myotonic Dystrophy Type 1 (DM1); Dystrophy Myotonic; Myotonic Disorders; Steinert Disease; Steinert; Myotonic Muscular Dystrophy; HARMONIA; Dyne Therapeutics; Dyne; DYNE-101; zeleciment basivarsen; z-basivarsen

Outcome Measures

Primary Outcomes (1)

• 5 Times Sit-To-Stand (5×STS) Time

  Baseline, Week 49

Secondary Outcomes (21)

• Video Hand Opening Time (vHOT) [Middle Finger]

  Baseline, Week 49

• Quantitative Muscle Testing (QMT) Total

  Baseline, Week 49

• Clinician Global Impression of Change (CGI-C)

  Week 49

• 10-Meter Walk/Run Test (10-MWRT) Velocity (m/s)

  Baseline, Week 49

• Patient Global Impression of Change (PGI-C)

  Week 49

Other Outcomes (3)

• Fatigue and Daytime Sleepiness Scale (FDSS)

  Up to Week 73

• Cognitive function as measured by individual and composite Cogstate cognition scores

  Up to Week 73

• Digital functional assessments as measured by the ActiGraph LEAP® wearable device

  Up to Week 73

Study Arms (3)

Placebo-Controlled Period: DYNE-101

EXPERIMENTAL

Participants will be randomized to receive DYNE-101, once every 8 weeks (Q8W) for up to 48 weeks.

Drug: zeleciment basivarsen (DYNE-101)

Placebo-Controlled Period: Placebo

PLACEBO COMPARATOR

Participants will be randomized to receive DYNE-101 matching placebo, Q8W for up to 48 weeks.

Drug: Placebo

Long-Term Extension Period: DYNE-101

EXPERIMENTAL

Participants who receive DYNE-101 in Placebo-Controlled Period will continue to received DYNE-101, Q8W for up to 24 weeks. Participants who received placebo in Placebo-Controlled Period will receive DYNE-101, Q8W for up to 24 weeks.

Drug: zeleciment basivarsen (DYNE-101); Drug: Placebo

Interventions

Placebo DRUG

Administered by IV infusion

Long-Term Extension Period: DYNE-101; Placebo-Controlled Period: Placebo

zeleciment basivarsen (DYNE-101) DRUG

Administered by IV infusion

Long-Term Extension Period: DYNE-101; Placebo-Controlled Period: DYNE-101

Eligibility Criteria

• Age: 16 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• Diagnosis of DM1 confirmed by molecular genetics with trinucleotide repeat size greater than (\>) 100. Historical results from clinical testing are acceptable.
• Able to walk 10 meters and complete 5 times sit to stand independently (inserts or supports that don't go above the ankle are allowed).
• Body mass index (BMI) less than (\<) 35 kilograms per meter square (kg/m\^2).

You may not qualify if:

• A known diagnosis of congenital DM1.
• History of major surgical procedure (based on Investigator judgment) within 12 weeks prior to the start of screening, with the exception of implanted pacemaker or defibrillator.
• Use of glucagon-like peptide 1 (GLP-1) agonist/incretin medications including semaglutide, dulaglutide, liraglutide, exenatide, or tirzepatide within a period of 5 half-lives of the medication prior to performing screening assessments.

Sponsors & Collaborators

• Dyne Therapeutics: lead

Study Sites (4)

Rare Disease Research, LLC

Atlanta, Georgia, 30329, United States

RECRUITING

Rare Disease Research, LLC

Hillsborough, North Carolina, 27278, United States

RECRUITING

The University of Texas Health Science Center at San Antonio

San Antonio, Texas, 78229, United States

RECRUITING

Yamaguchi University Hospital

Ube-Shi, Yamaguchi, 755-8505, Japan

RECRUITING

MeSH Terms

Conditions

Myotonic Dystrophy; Myotonia; Myotonic Disorders

Condition Hierarchy (Ancestors)

Muscular Dystrophies; Muscular Disorders, Atrophic; Muscular Diseases; Musculoskeletal Diseases; Heredodegenerative Disorders, Nervous System; Neurodegenerative Diseases; Nervous System Diseases; Neuromuscular Diseases; Genetic Diseases, Inborn; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Neuromuscular Manifestations; Neurologic Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

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: March 17, 2026
• First Posted: March 23, 2026
• Study Start: April 1, 2026
• Primary Completion (Estimated): July 1, 2028
• Study Completion (Estimated): January 1, 2029
• Last Updated: April 16, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

US (3); JP (1)