Dyne is eyeing an accelerated approval filing for DYNE-251 in early 2026 that would pit the asset against Sarepta’s Exondys 51 in a patient population amenable to exon 51 skipping.
Dyne Therapeutics’ investigational oligomer therapy DYNE-251 maintained its functional benefits through 18 months of follow-up in patients with Duchenne muscular dystrophy, according to a Sunday release from the company. Dyne remains on track for a regulatory submission in early 2026.
In a Sunday note, BMO Capital Markets analysts wrote that these findings are “supportive” of the asset’s accelerated approval in Duchenne muscular dystrophy (DMD).
The data come from a long-term readout of Dyne’s Phase I/II DELIVER trial, testing the asset in patients who are amenable to exon 51 skipping. This represents about 13% of the DMD population.
The results, which will be presented at the 2025 Clinical & Scientific Conference of the Muscular Dystrophy Association, showed that the 10-mg/kg dose of DYNE-251, given once every four weeks, could maintain multiple functional improvements through 18 months.
Meanwhile, patients treated with the selected registrational dose, once-monthly 20-mg/kg, saw slightly shorter-term functional improvements through 12 months.
DELIVER found DYNE-251 to be tolerable, with no new documented serious adverse events or safety signals of concern.
In a note to investors on Sunday, Stifel analysts said the readout “continues to support a real and differentiated clinical effect for DYNE-251.” The analysts also called out “compelling dystrophin data.”
In its press release on Sunday, Dyne reported that dystrophin expression in patients treated with the registrational dose of DYNE-251 reached 8.72% of normal expression levels, a “high single-digit increase,” according to the Stifel note.
Taken together, DYNE-251’s functional and biomarker data “demonstrate a consistent/sustained treatment benefit and acceptable safety,” the BMO analysts wrote. DYNE-251 could also have a convenience edge over other approved oligomer therapies for DMD, which could help distinguish the treatment in an increasingly crowded space, according to the analysts, who called its once-per-month dosing schedule an “attractive regimen,” in comparison to similar drugs that are taken weekly.
Sarepta Therapeutics’ antisense oligonucleotide Exondys 51 captures around 25% to 40% of the market in the Duchenne patients targeted by Dyne’s molecule, as per the BMO note. With these data, BMO forecasts around a 20% penetration for DYNE-251. Dyne could encounter additional headwinds from Sarepta’s gene therapy Elevidys, which was approved by the FDA in 2023 and according to the analysts could be given to “most” eligible patients by around 2030.
