Dyne Therapeutics has initiated the Phase III HARMONIA trial to evaluate the efficacy, safety, and tolerability of zeleciment basivarsen (z-basivarsen, also called DYNE-101) in individuals diagnosed with myotonic dystrophy type 1 (DM1).
The randomised, global, double-blind, confirmatory, placebo-controlled trial aims to enrol 150 participants aged 16 years and above.
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Participants will be randomised into a 1:1 ratio to receive either 6.8mg/kg of z-basivarsen or placebo by intravenous infusion every eight weeks. The first sites have been activated and are open to recruitment.
The primary endpoint of the study is the change from baseline in the five times sit to stand (5×STS) test at week 49. The test assesses reduced extremity strength, balance, and trunk strength, which are important for daily function in patients with DM1.
Secondary endpoints include quantitative muscle testing, video hand opening time, Myotonic Dystrophy Health Index, the 10m walk/run test, as well as additional patient- and clinician-reported outcomes.
Exploratory endpoints will examine multiple domains of central nervous system impact in DM1. After completing the 48-week, double-blind, placebo-controlled treatment period, participants can enter a 24-week long-term extension phase.
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By GlobalDataDyne Therapeutics has reached alignment with the US Food and Drug Administration (FDA) regarding the HARMONIA Phase III trial design and protocol.
This trial aims to provide confirmatory evidence for converting accelerated approval to traditional approval in the US and to support marketing applications internationally.
Dyne Therapeutics’ chief medical officer Doug Kerr said: “We are proud to be contributing to key advances in myotonic dystrophy clinical research with the initiation of a field-defining Phase III study designed to demonstrate the broad potential benefits of z-basivarsen.
“Building on the ongoing registrational expansion cohort of the Phase I/II ACHIEVE trial, which is utilising myotonia, as measured by video hand opening time, as an early indicator of clinical benefit for potential US accelerated approval, HARMONIA is a larger and longer-term study utilising a clinically meaningful functional measure as the primary endpoint.
“HARMONIA was designed to reinforce the best-in-class potential of z-basivarsen based on the differentiated capabilities of our FORCE platform to deliver therapeutics to a broad range of muscle systems as well as the CNS.”
In December 2025, Dyne Therapeutics sought US accelerated approval for its Duchenne muscular dystrophy (DMD) drug after it met endpoints in a Phase I/II trial.
