Safety, Tolerability, Pharmacodynamic, Efficacy, and Pharmacokinetic Study of DYNE-101 in Participants With Myotonic Dystrophy Type 1

• Status: Not yet recruiting
• Trial end date: 2026-07-01
• Target enrollment: 0
• Participant gender: All

Summary

The primary purpose of the study is to evaluate the safety and tolerability of multiple intravenous (IV) doses of DYNE-101 administered to participants with Myotonic Dystrophy Type 1 (DM1).

The study consists of 4 periods: A Screening Period (up to 6 weeks), a multiple-ascending dose (MAD) Placebo-Controlled Period (24 weeks), a Treatment Period (24 weeks) and a Long-Term Extension (LTE) Period (96 weeks).

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

Details

• Lead Sponsor: Dyne Therapeutics

Criteria

Inclusion Criteria:

• Diagnosis of DM1 with trinucleotide repeat size >100.

• Age of onset of DM1 muscle symptoms ≥12 years.

• Clinically apparent myotonia equivalent to hand opening time of at least 2 seconds in the opinion of the Investigator.

• Hand grip strength and ankle dorsiflexion strength averaged from both sides ≥20th and ≤80th percentile for age, sex, and height at screening.

• Able to complete 10MWT, stair ascend/descend, and 5×STS at screening without the use of assistive devices such as canes, walkers, or orthoses.

Exclusion Criteria:

• History of major surgical procedure within 12 weeks prior to the start of investigative product administration or an expectation of a major surgical procedure (eg, implantation of cardiac defibrillator) during the study.

• History of anaphylaxis.

• Medical condition other than DM1 that would significantly impact ambulation or participation in functional assessments.

• Treatment with medications that can improve myotonia within a period of 5 half-lives of the medication prior to performing screening assessments.

• Electrocardiogram (ECG) with the corrected QT interval by Fridericia's Formula (QTcF) ≥450 milliseconds (ms) in men and QTc ≥460 in women, PR ≥240 ms, left bundle-branch block, or a conduction defect, which is clinically significant in the opinion of the Investigator.

• Percent predicted forced vital capacity (FVC) <50%.

• History of tibialis anterior biopsy within 3 months of Day 1 or planning to undergo tibialis anterior biopsies during study period for reasons unrelated to the study.

Note: Other inclusion and exclusion criteria may apply.