Dyne Therapeutics, Inc. (Nasdaq: DYN) has officially initiated the Phase 3 HARMONIA trial for zeleciment basivarsen (z-basivarsen, also known as DYNE-101), marking a significant step forward in the treatment of myotonic dystrophy type 1 (DM1). The trial, designed to evaluate the multi-system efficacy, safety, and tolerability of z-basivarsen, is now open for enrollment at its first sites.
A Comprehensive Trial Design
The HARMONIA trial is a global, randomized, placebo-controlled, double-blind study that will enroll approximately 150 participants aged 16 and older. Participants will be randomized 1:1 to receive either 6.8 mg/kg of z-basivarsen or a placebo every eight weeks for 48 weeks. Those who complete the placebo-controlled period will have the option to join a 24-week long-term extension, during which all participants will receive z-basivarsen.
The trial’s primary endpoint focuses on the change from baseline in the five times sit-to-stand (5xSTS) test at week 49. This test is a reliable measure of DM1-related impairments, such as lower extremity strength, balance, and trunk strength, which are critical for daily activities. Secondary endpoints include video hand opening time, quantitative muscle testing, the 10-Meter Walk/Run test, the Myotonic Dystrophy Health Index, and additional patient- and clinician-reported outcomes. The trial also incorporates exploratory endpoints to assess the central nervous system (CNS) impact of DM1.
FDA Alignment and Global Goals
Dyne Therapeutics has worked closely with the U.S. Food and Drug Administration (FDA) to align the HARMONIA trial design and protocol. The trial is intended to serve as a confirmatory study to support the conversion of Accelerated Approval to traditional approval in the U.S. and to back marketing applications outside the U.S.
Dr. Doug Kerr, Chief Medical Officer of Dyne, emphasized the importance of this trial, stating, “We are proud to contribute to key advances in myotonic dystrophy clinical research with a field-defining Phase 3 study. HARMONIA is designed to demonstrate the broad potential benefits of z-basivarsen, building on the ongoing registrational expansion cohort of the Phase 1/2 ACHIEVE trial. This study reinforces the best-in-class potential of z-basivarsen, leveraging our FORCE platform to deliver therapeutics to a wide range of muscle systems and the CNS.”
About Zeleciment Basivarsen (Z-Basivarsen)
Z-basivarsen is an investigational therapeutic currently being evaluated in the Phase 1/2 ACHIEVE trial for DM1. It consists of an antisense oligonucleotide (ASO) conjugated to an antigen-binding fragment (Fab) that targets the transferrin receptor 1 (TfR1). This design enables delivery to both muscle and CNS tissues, aiming to reduce toxic nuclear DMPK RNA, release splicing proteins, and restore normal mRNA processing.
The FDA has granted z-basivarsen Breakthrough Therapy, Orphan Drug, and Fast Track designations. Additionally, it has received Orphan Drug designation from the European Medicines Agency (EMA) and Japan’s Ministry of Health, Labour and Welfare (MHLW) for the treatment of DM1.
Understanding Myotonic Dystrophy Type 1 (DM1)
DM1 is a rare, progressive genetic neuromuscular disease that affects approximately 40,000 people in the U.S. and 55,000 in the EU. Symptoms, which vary in severity and progression, can include muscle weakness, myotonia, excessive daytime sleepiness, cognitive impairments, cardiac arrhythmias, and respiratory issues. Despite a well-understood genetic cause, there are currently no approved disease-modifying treatments for DM1.
Dyne’s Commitment to Neuromuscular Diseases
Dyne Therapeutics is dedicated to delivering functional improvements for individuals living with genetically driven neuromuscular diseases. In addition to its DM1 programs, the company is advancing clinical programs for Duchenne muscular dystrophy (DMD) and preclinical programs for facioscapulohumeral muscular dystrophy (FSHD), Pompe disease, and multiple DMD mutations.
With the launch of the HARMONIA trial, Dyne continues to push the boundaries of innovation in neuromuscular disease treatment, aiming to bring transformative therapies to patients and their families. For more investor relations information, visit www.investors.dyne-tx.com.
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