According to an October 31, 2022 press release from muscle disease company Dyne Therapeutics, Inc. (“Dyne”), the company’s therapeutic candidate DYNE-251 earned Fast Track designation from the FDA for Duchenne muscular dystrophy (DMD) amenable to exon 51 skipping. Currently, there is a need for new and effective therapeutic options within this space. Thus, if DYNE-251 proves itself to be beneficial, it could have far-reaching implications within this realm.

So what exactly is DYNE-251? This therapy conjugates a fragment antibody (Fab) and phosphorodiamidate morpholino oligomer (PMO) which binds to TfR1. TfR1 is highly expressed on muscle tissue, allowing the treatment to be delivered in a more focused and targeted fashion. Through exon skipping, DYNE-251 also encourages muscle cells to produce dystrophin, a protein that plays a role in muscle health, function, and strength. Due to gene mutations, those with DMD are missing dystrophin in their muscle cells. So far, preclinical studies have shown DYNE-251 to be safe and effective in increasing dystrophin expression. Learn more about DYNE-251.

Fast Track designation is granted by the FDA to facilitate drug development and review for rare and severe conditions. Drugs granted this designation should fill some sort of unmet need; as descibed above, DYNE-251 does fit this. You can also learn more about what makes a drug eligible for Fast Track designation here. Fast Track designation may also allow drug developers to have more frequent FDA communication, rolling review, and Accelerated Approval/Priority Review eligibility.

Currently, Dyne is exploring the safety and tolerability of DYNE-251 in a Phase 1/2 study for pediatric patients with DMD. More data from the study should be available at some point next year.

About Duchenne Muscular Dystrophy (DMD)

Altogether, there are nine forms of muscular dystrophy; Duchenne muscular dystrophy is one of them. Inherited in an X-linked recessive pattern, Duchenne muscular dystrophy is characterized by DMD mutations that prevent the body from making enough dystrophin in the muscles. It occurs in approximately 1 in 3,500 male births and 1 in 50 million female births. Typically, the symptoms manifest before age six. These can (but do not always) include:

• Difficulty walking or moving positions
• Progressive muscle weakness which begins in the legs, pelvis, and thighs before spreading to the rest of the body
• Frequent tripping and falling
• Cardiomyopathy
• Reduced bone density and increased risk of fractures
• Developmental delays
• Speech delays
• Increased susceptibility to respiratory infections
• Fatigue
• Progression to heart disease and respiratory failure