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

May 28, 2026 updated by: Dyne Therapeutics

A Phase 3, Randomized, Double-Blind, 48-Week Placebo-Controlled Study to Assess the Efficacy, Safety, and Tolerability of DYNE-101 Administered to Participants With Myotonic Dystrophy Type 1

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).

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

The study consists of three periods: a Screening period (up to 8 weeks), Placebo-Controlled Period (48 weeks) and a Long-Term Extension Period (24 weeks).

An Independent Data Monitoring Committee (IDMC) comprised of members independent and external to the Sponsor will review safety and tolerability data of this study at regular intervals.

Study Type

Interventional

Enrollment (Estimated)

150

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Japan
    • Osaka
      • Toyonaka-Shi, Osaka, Japan, 560-8552
    • Yamaguchi
      • Ube-Shi, Yamaguchi, Japan, 755-8505
  • United States
    • Georgia
    • Missouri
      • Columbia, Missouri, United States, 65211
    • North Carolina
      • Hillsborough, North Carolina, United States, 27278
    • Texas
      • San Antonio, Texas, United States, 78229
        • Recruiting
        • The University of Texas Health Science Center at San Antonio
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • 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).

Exclusion Criteria:

  • 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.

Note: Other inclusion and exclusion criteria may apply.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Placebo-Controlled Period: DYNE-101
Participants will be randomized to receive DYNE-101, once every 8 weeks (Q8W) for up to 48 weeks.
Drug: zeleciment basivarsen (DYNE-101)
Administered by IV infusion
Placebo Comparator: Placebo-Controlled Period: Placebo
Participants will be randomized to receive DYNE-101 matching placebo, Q8W for up to 48 weeks.
Drug: Placebo
Administered by IV infusion
Experimental: Long-Term Extension Period: DYNE-101

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: Placebo
Administered by IV infusion
Drug: zeleciment basivarsen (DYNE-101)
Administered by IV infusion

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
5 Times Sit-To-Stand (5×STS) Time
Time Frame: Baseline, Week 49
Baseline, Week 49

Secondary Outcome Measures

Outcome Measure
Time Frame
Video Hand Opening Time (vHOT) [Middle Finger]
Time Frame: Baseline, Week 49
Baseline, Week 49
Quantitative Muscle Testing (QMT) Total
Time Frame: Baseline, Week 49
Baseline, Week 49
Clinician Global Impression of Change (CGI-C)
Time Frame: Week 49
Week 49
10-Meter Walk/Run Test (10-MWRT) Velocity (m/s)
Time Frame: Baseline, Week 49
Baseline, Week 49
Patient Global Impression of Change (PGI-C)
Time Frame: Week 49
Week 49
DM1-ACTIV^C Total Score
Time Frame: Baseline, Week 49
Baseline, Week 49
Myotonic Dystrophy Health Index (MDHI) Total
Time Frame: Baseline, Week 49
Baseline, Week 49
Patient Global Impression of Severity (PGI-S)
Time Frame: Baseline, Week 49
Baseline, Week 49
Clinician Global Impression of Severity (CGI-S)
Time Frame: Baseline, Week 49
Baseline, Week 49
9-Hole Peg Test (9-HPT) Time
Time Frame: Baseline, Week 49
Baseline, Week 49
Myotonic Dystrophy Health Index (MDHI) Subscale Scores
Time Frame: Baseline, Week 49
Baseline, Week 49
Maximum Observed Plasma Drug Concentration (Cmax) of DYNE-101
Time Frame: Pre-dose, and at multiple time points up to Week 73
Pre-dose, and at multiple time points up to Week 73
Time to Maximum Concentration (tmax) of DYNE-101
Time Frame: Pre-dose, and at multiple time points up to Week 73
Pre-dose, and at multiple time points up to Week 73
Area Under the Concentration-Time Curve (AUC) from Hour 0 to the Last Measurable Concentration (AUC0-tlast) of DYNE-101
Time Frame: Pre-dose, and at multiple time points up to Week 73
Pre-dose, and at multiple time points up to Week 73
Area Under the Concentration-Time Curve Extrapolated to Infinity (AUC0-∞) of DYNE-101
Time Frame: Pre-dose, and at multiple time points up to Week 73
Pre-dose, and at multiple time points up to Week 73
Apparent Terminal Elimination Rate Constant (λZ) of DYNE-101
Time Frame: Pre-dose, and at multiple time points up to Week 73
Pre-dose, and at multiple time points up to Week 73
Apparent Terminal Elimination Half-Life (t½) of DYNE-101
Time Frame: Pre-dose, and at multiple time points up to Week 73
Pre-dose, and at multiple time points up to Week 73
Plasma clearance (CL) of DYNE-101
Time Frame: Pre-dose, and at multiple time points up to Week 73
Pre-dose, and at multiple time points up to Week 73
Volume of Distribution at the Terminal Phase (Vz), if Appropriate of DYNE-101
Time Frame: Pre-dose, and at multiple time points up to Week 73
Pre-dose, and at multiple time points up to Week 73
Volume of Distribution at Steady State (Vss), if Appropriate of DYNE-101
Time Frame: Pre-dose, and at multiple time points up to Week 73
Pre-dose, and at multiple time points up to Week 73
Number of Participants With Antidrug Antibodies (ADAs)
Time Frame: Up to Week 73
Up to Week 73

Other Outcome Measures

Outcome Measure
Time Frame
Fatigue and Daytime Sleepiness Scale (FDSS)
Time Frame: Up to Week 73
Up to Week 73
Cognitive function as measured by individual and composite Cogstate cognition scores
Time Frame: Up to Week 73
Up to Week 73
Digital functional assessments as measured by the ActiGraph LEAP® wearable device
Time Frame: Up to Week 73
Up to Week 73

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Dyne Therapeutics

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

April 1, 2026

Primary Completion (Estimated)

July 1, 2028

Study Completion (Estimated)

January 1, 2029

Study Registration Dates

First Submitted

March 17, 2026

First Submitted That Met QC Criteria

March 17, 2026

First Posted (Actual)

March 23, 2026

Study Record Updates

Last Update Posted (Actual)

June 1, 2026

Last Update Submitted That Met QC Criteria

May 28, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • DYNE101-DM1-301
  • 2025-522957-20-00 (Ctis)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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