If approved, Dyne Therapeutics’ zeleciment rostudirsen could “capture the majority” of the exon-51 Duchenne muscular dystrophy market, given its better efficacy and dosing profile versus Sarepta Therapeutics’ exon-skipping therapy Exondys 51, the current standard of care, according to Oppenheimer.
The FDA has accepted Dyne Therapeutics’ application for its investigational Duchenne muscular dystrophy therapy, setting a target action date of Jan. 21, 2027.
“We anticipate a smooth approval,” Oppenheimer told investors in a note on Monday, adding that the therapy, dubbed zeleciment rostudirsen (z-rostudirsen) is poised to “capture the majority of market share,” given stronger dystrophin benefits and a more convenient dosing profile than the current standard treatment.
Outside of symptomatic management through corticosteroids, Sarepta Therapeutics’ Exondys 51 is a standard of care regimen for patients with Duchenne muscular dystrophy (DMD) who are amenable to exon 51 skipping. Dyne, however, could challenge Exondys with z-rostudirsen, which in the Phase 1/2 DELIVER trial outperformed Sarepta’s asset, Jefferies said in a Monday note, adding that the early data cut looks “best-in-class.”
Exondys is dosed weekly, while z-rostudirsen is designed to be given once every four weeks—a “convenient” profile, the firm noted. Given its convenience and efficacy advantages, “z-rostudirsen could command a pricing premium” if approved, Jefferies continued. The analysts added that they expect uptake to be “robust” across three key patient subgroups: those who have yet to undergo Exondys treatment, those who have discontinued Sarepta’s therapy and those who are currently receiving it.
Dyne is seeking accelerated approval for z-rostudirsen in patients with DMD who are amenable to exon 51 skipping, according to a company release on Monday. Topline data from the registrational cohort of DELIVER, released December 2025, showed a 5.46% increase at six months in concentrations of the dystrophin protein, a key disease marker.
Patients also saw improvements in key functional measures, including time-to-rise velocity and the 10-meter walk/run test. Lung function, a major driver of death in DMD, was preserved at six months.
The FDA does not plan on holding an advisory committee meeting for z-rostudirsen, according to Dyne.
Jefferies models more than $500 million in peak sales for z-rostudirsen, calling this estimate “conservative.” Oppenheimer, on the other hand, did not provide a peak forecast for the z-rostudirsen, only noting that Dyne’s therapy could secure a “majority” of the $1.5 billion exon-51 DMD market.
In DMD, a rare and progressive neuromuscular disorder, mutations to the dystrophin protein render it dysfunctional or completely absent. Under healthy conditions, dystrophin plays a crucial role in maintaining the structure and function of muscles. Z-rostudirsen works by restoring the expression of near-full-length dystrophin, in turn restoring the function of the protein.
A key player in the DMD space is Sarepta, which aside from Exondys owns the gene therapy Elevidys. Last year, two patients died after receiving Elevidys, which ultimately forced the FDA to slap a boxed warning on the product’s label and limited its use to ambulatory patients four years and up.
Sarepta also owns Amondys 45 and Vyondys 53—both exon-skipping drugs like Exondys—which in November 2025 failed to elicit significant motor function improvements in the confirmatory Phase 3 ESSENCE study. Sarepta has nevertheless pushed for full approval of these products, with the FDA setting a decision date of Feb. 28, 2027.
