Patients with Duchenne muscular dystrophy (DMD) have seen an “unprecedented and sustained” functional improvement in a Phase I/II trial examining Dyne Therapeutics’ DYNE-251.
Announced as part of the Muscular Dystrophy Association (MDA) 2025 meeting, taking place from 16 to 19 March in Dallas, Texas, the ongoing Deliver trial (NCT03619213) investigated the company’s intravenous (IV) therapy in patients who are likely to experience exon 51 skipping.
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Results at 12 months and six months saw improvements from baseline in multiple functional endpoints in both the selected registrational dose of 20mg/kg, as well as an additional dosing arm of 10mg/kg.
DMD is a progressive, inherited muscle-wasting disease primarily affecting boys, caused by a lack of the protein dystrophin. According to the company, DYNE-251 demonstrated unprecedented near-full-length dystrophin expression as measured by Western blot for patients with DMD who are amenable to exon 51 skipping. At the six-month mark patients treated with 20 mg/kg of DYNE-251 had a mean absolute dystrophin expression of 8.72% above baseline.
Additional endpoints examining patient movement speed by way of the Stride Velocity 95th Centile (SV95C) system, North Star Ambulatory Assessment (NSAA), 10m Walk/Run Time and time taken to rise from the floor, all saw changes in the baseline.
Dyne is hoping that a further readout later in 2025 will set the company up to submit for accelerated approval in early 2026 with the US Food and Drug Administration (FDA).
Dyne CEO John Cox said: “With DYNE-251, we have the opportunity to deliver a durable and redosable therapy demonstrating clinically meaningful and sustained functional improvement in DMD. The consistency of these new data across multiple endpoints and time points underscores the potential of DYNE-251 to meaningfully address the significant unmet need in Duchenne despite available therapies.
“We are rapidly advancing DYNE-251 toward a readout later this year with the potential to submit for US accelerated approval in early 2026 based on a well-established regulatory pathway leveraging dystrophin expression as a surrogate endpoint. If approved, we believe there is an opportunity for rapid adoption by physicians and currently treated patients, as well as those naïve to therapy.”
The Phase I/II trial enrolled 88 patients at 33 sites across the US, Europe and Asia with patients split into three arms, receiving either 20mg or 10mg of DYNE-252, or a placebo.
Research by GlobalData’s Pharmaceutical Intelligence Center estimates that should DYNE-252 make it to market, it is predicted to bring in $5m by the end of this year with that figure predicted to rise to $48m by the end of 2028, continuing on to $129m by the end of 2030.
GlobalData is the parent company of Clinical Trials Arena.
Elsewhere in the field of DMD, PepGen is pausing the initiation of a new Phase I trial as it awaits data from an ongoing Phase II trial. Meanwhile, the US Food and Drug Administration (FDA) has lifted its two-year clinical hold over Entrada Therapeutics therapy, ENTR-601-44.
