The Duchenne muscular dystrophy (DMD) therapeutic landscape is rapidly evolving, with several biotech companies pioneering innovative approaches to address this severe genetic condition. Muscular dystrophies, including DMD, are characterized by progressive muscle weakness due to genetic mutations. DMD, one of the most severe forms, stems from mutations in the dystrophin gene, crucial for muscle fiber stability and health, affecting approximately 1 in 3,500 male births worldwide.
Wave Life Sciences: RNA-Targeted Therapies
Wave Life Sciences is advancing RNA medicines using its PRISM platform. Recent interim results from a phase trial of WVE-N531, an exon-skipping oligonucleotide, showed promise in boys with DMD amenable to exon 53 skipping. The trial reported a 5.5% mean absolute unadjusted dystrophin increase after 24 weeks, with 89% of ambulatory participants achieving at least 5% muscle content-adjusted dystrophin levels. Mean exon skipping was 57%, as measured by RT-PCR. These results followed the FDA's Rare Pediatric Disease Designation for WVE-N531. The company also completed a $200 million public offering in September.
Sarepta Therapeutics: Gene Therapy and Exon Skipping
Sarepta Therapeutics, a key player in the DMD field, received FDA approval for Elevidys, a gene therapy delivering a shortened dystrophin gene to muscles, initially for patients aged 4-5 and later expanded to all patients four and older with dystrophin gene mutations. Sarepta's earlier drug, Exondys 51, was controversially approved in 2016. The company's RNA-targeted therapy, SRP-5051 (vesleteplirsen), is currently in phase 2 trials. SRP-5051 aims to bind to exon 51 of dystrophin pre-mRNA to promote exon skipping, benefiting approximately 13% of DMD patients. Phase 2 results showed a mean dystrophin expression of 5.17% and mean exon skipping of 11.11% at 28 weeks. However, the trial reported seven serious adverse events, including hypomagnesemia and hypokalemia.
Capricor Therapeutics: Addressing Cardiomyopathy
Capricor Therapeutics is focused on treating cardiomyopathy, a leading cause of death in DMD patients. Their drug, deramiocel, composed of cardiosphere-derived cells (CDCs) with immunomodulatory, anti-inflammatory, pro-angiogenic, and anti-fibrotic properties, is in phase 3 trials. Capricor intends to file a Biologics License Application (BLA) with the FDA, potentially offering the first treatment for cardiomyopathy in DMD patients. Clinical benefits and slowed disease progression were observed, with improvements in heart function in patients with high ejection fractions at baseline. Capricor has granted commercialization rights to Nippon Shinyaku for both the U.S. and Europe.
Edgewise Therapeutics: Myosin Inhibition
Edgewise Therapeutics is developing sevasemten, a skeletal myosin inhibitor designed to protect unstable muscle against contraction-induced damage in muscular dystrophies. Currently in phase 2 trials, sevasemten has received FDA Fast Track designation for DMD. The company is set to present drug data at the 29th International Annual Congress of the World Muscle Society. In January, Edgewise secured $240 million in an offering.
Italfarmaco: HDAC Inhibition with Duvyzat
Italfarmaco's Duvyzat (givinostat), an HDAC inhibitor, received FDA approval for DMD patients aged six and older, marking the first nonsteroidal treatment for all genetic variants of DMD in the U.S. Duvyzat inhibits histone deacetylases to encourage muscle repair, regenerate muscle fibers, limit inflammation, and reduce fibrosis. The approval was based on a phase 3 trial involving 179 boys with DMD, demonstrating a statistically significant and clinically meaningful difference in the time to complete the four-stair climb assessment. This drug is anticipated to become a standard of care for DMD patients.
Avidity Biosciences: PMO Delivery
Avidity Biosciences is developing delpacibart zotadirsen (del-zota), designed to deliver phosphorodiamidate morpholino oligomers (PMOs) to skeletal muscle and heart tissue to skip exon 44 of the dystrophin gene. Phase 1/2 trial results showed a 25% increase in dystrophin production and a reduction of creatine kinase levels to near normal. The investigational drug demonstrated a 37% increase in exon 44 skipping, with up to 66% skipping at a 5 mg/kg dosage after four months. Del-zota has received Orphan, Rare Pediatric, and Fast Track designations from the FDA and EMA. Avidity closed a $345.1 million public offering in August.
The Evolving DMD Market
The global DMD treatment market, valued at $3.2 billion in 2023, is projected to reach $8.6 billion in 2032, driven by regulatory approvals of drugs like Nippon's Viltepso, Sarepta's Elevidys, Exondys 51, and Amondys 45, PTC Therapeutics' Emflaza, and Italfarmaco's Duvyzat. Other companies, including Myosana, Satellos Bioscience, and Dyne Therapeutics, are also advancing potential DMD therapies.
