The experimental therapy DYNE-251, developed by Dyne Therapeutics for treating Duchenne muscular dystrophy (DMD), has received a Breakthrough Therapy designation from the U.S. Food and Drug Administration (FDA), according to a recently published press release. This designation is expected to expedite the drug’s development.
DYNE-251 is an exon-skipping therapy intended for those amenable to exon 51 skipping. The drug’s active component binds to transferrin receptor 1 (TfR1), enabling the production of nearly full-length dystrophin in muscle cells — thus addressing the dystrophin deficiency that causes the characteristic clinical manifestations of DMD.
What is dystrophin?
Dystrophin is the protein that mutates and leads to DMD. It is found in small quantities in muscle cells, where its role is to protect the cell from daily damage.
When it mutates, it causes muscle cell degeneration and inflammation, leading to damage in the tissue of the bones, lungs and heart.
The Breakthrough Therapy designation will allow Dyne Therapeutics to accelerate the development process through increased FDA support, including senior-level involvement and eligibility for Rolling Review and Priority Review. These mechanisms are expected to expedite the drug’s regulatory approval process.
The breakthrough designation was granted while the drug is being evaluated in the Phase 2 DELIVER clinical trial. The study currently has an enrollment of 86 patients, some of whom are receiving DYNE-251, while others are receiving a placebo.
The trial’s primary outcome measures are changes in dystrophin expression after six months of treatment and the identification of any adverse effects associated with the therapy. Secondary outcome measures include improvements in muscle function (assessed by the North Star Ambulatory Assessment), upper limb performance and data on the drug’s absorption, metabolism and elimination.
“This Breakthrough Therapy Designation for DYNE-251 is a testament to its potential as a next-generation therapy designed to bring meaningful functional improvement to individuals with DMD for whom exon 51 skipping can lead to the production of near full-length dystrophin,” said Dr. Doug Kerr, chief medical officer of Dyne. “As we’ve previously disclosed, DYNE-251 has demonstrated sustained functional improvement over eighteen months, as assessed by key measures such as time to rise and stride velocity at the 95th percentile. The level of near-full-length dystrophin expression observed marks a significant step forward in potentially delivering meaningful benefits to patients.”
DYNE-251 previously received Orphan Drug designation and Rare Pediatric Disease designation from the FDA.
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