Dyne Therapeutics shared promising clinical trial updates from two of its experimental RNA medicines for myotonic dystrophy type 1 (DM1) and Duchenne muscular dystrophy.
The update, announced Monday, includes a first look at six patients in a Phase 1/2 study who received a high dose of Dyne’s myotonic dystrophy therapy called DYNE-101. It showed a dose-dependent increase in splicing correction — measured on a panel of 22 genes — compared to earlier cohorts that received lower doses of the therapy. Researchers and analysts look for dose dependency because that’s a sign that a treatment has an effect.
The high-dose group saw a mean 27% splicing correction from baseline at three months.
In myotonic dystrophy, patients experience muscle loss and weakness over time, as well as myotonia, which is the inability to relax voluntary muscles.
On a hand-opening test, which is used to evaluate myotonia, participants who received DYNE-101 showed an improvement in the time it takes to release their hand grip. The six participants in the high-dose cohort had a mean 4.5-second improvement on the test at three months.
In the Phase 1/2 study in Duchenne muscular dystrophy, Dyne reported that levels of dystrophin expression jumped in six patients who received its exon 51 skipping treatment at 10 mg/kg. In the small cohort of patients, the treatment led to higher levels of dystrophin expression at lower dosing compared to Sarepta’s approved treatment Exondys 51. Exondys 51 is given once a week, while Dyne’s treatment was administered once every four weeks.
The data updates sent Dyne’s shares $DYN up about 25% on Monday morning.
“The data are so striking that we felt obligated to share them with the field earlier than planned,” CEO John Cox said Monday during an investor call. Cox joined Dyne in March after Joshua Brumm, who was CEO since 2019, left to pursue a career in healthcare investing.
The company is hoping to apply for accelerated approval for both therapies, and it said it plans to share additional details on its regulatory filing plans later this year.
The “DM1 data now look best-in-class, while [Dyne] now also has a commercially viable exon skipper in DMD, even as they still dose-escalate,” Stifel analyst Paul Matteis wrote in a note. In myotonic dystrophy, Matteis told investors that “the data also offer optionality on the regulatory front.”
Dyne “remains confident that there’s a potential path to market in DM1 using splicing, after additional conversations with FDA,” he added.