Dyne Therapeutics is seeking US accelerated approval of its Duchenne muscular dystrophy (DMD) drug after it met its endpoints in a Phase I/II trial.
The randomised, placebo-controlled DELIVER study (NCT05524883) met its primary endpoint, demonstrating a statistically significant increase in muscle content-adjusted dystrophin expression to 5.46% of normal relative to baseline after six months of treatment with Dyne’s zeleciment rostudirsen in the registrational expansion cohort (REC).
Improvement after treatment with zeleciment rostudirsen relative to placebo was also seen in key secondary endpoints, including time to rise (TTR) and 10m walk / run (10MWR).
Lung function, the loss of which is a leading cause of mortality in DMD, as measured by forced vital capacity (FVC), was also preserved at six months compared to a decline in placebo.
The six-month portion of the trial enrolled 32 ambulant and non-ambulant males with DMD who have mutations amenable to exon 51 skipping. Of these, 24 were randomised to receive the study drug while eight received placebo.
Longer-term data showed a sustained functional improvement in TTR, 10MWR, and FVC after up to 24 months of treatment.
The drug has continued to demonstrate a favourable safety profile, with most related treatment-emergent adverse events (TEAEs) being mild or moderate. The most commonly reported related TEAEs were pyrexia (fever) and headache. There were no serious TEAEs in the main six-month cohort; however, two were reported in the open-label extension (OLE) and long-term extension (LTE) portion of the trial.
Based on the DELIVER trial, Dyne CMO Dr Doug Kerr said the company will be seeking accelerated approval in the US in Q2 2026, with hopes for a Q1 2027 approval. The company will also initiate a global Phase III trial to further support accelerated approvals and other approval pathways.
Dyne president and chief executive officer John Cox said: “With this clinical validation, we are now in a position to leverage these capabilities and relationships in DMD to advance a broader portfolio of potential exon-skipping therapies with a total population of more than 4,000 individuals.”
Cox added that beyond DMD, the trial data shows the potential of its platform in developing other products in alternative neuromuscular diseases, but he did not specify which disease these could include.
After announcing the data, Dyne’s stock rose 9.47%, with shares selling at $20.28 on 5 December at market close, compared with $22.20 at market close on 8 December. Since the markets opened on 9 December, this rise slightly reduced in magnitude.
The positive data comes just days after Capricor also scored a win with its DMD cell therapy deramiocel in a Phase III trial, which sent the company’s stock soaring by 370%.
DMD market poised for growth
These successes come at a time when the DMD market is set for growth, with GlobalData predicting sales in the seven major markets (7MM: The US, France, Germany, Italy, Spain, the UK, and Japan) to grow from $2.3bn in 2023 to $5.2bn in 2033. This is driven by approvals of Sarepta Therapeutics and Roche’s Elevidys (delandistrogene moxeparvovec), and Santhera Pharmaceuticals’ Agamree (vamorolone).
Currently, exon-skipping therapies dominate the DMD therapeutic landscape, generating approximately $1bn in sales in the 7MM in 2023.
GlobalData healthcare analyst Asiyah Nawab said: “The DMD treatment landscape is evolving with the emergence of novel therapies such as exon-skipping and gene therapies.
"However, gene therapies in particular, compared to exon-skipping, will have less of an impact due to the small patient share eligible for treatment, in addition to the high cost of these medicines limiting patients’ access. By 2033, GlobalData forecasts gene therapies to contribute $821m to the DMD market, a lower figure relative to exon-skipping therapies.”
GlobalData is the parent company of Clinical Trials Arena.
