REGENXBIO, Novartis and Dyne Therapeutics are advancing toward regulatory submissions for new therapies targeting muscular dystrophies, according to information released on May 26. The developments follow a year marked by significant events in the field, including Novartis’ $12 billion acquisition of Avidity Biosciences and ongoing challenges with Sarepta Therapeutics’ Elevidys gene therapy.
Michael Kelly, chief scientific officer at CureDuchenne, said the year has started well for companies developing Duchenne muscular dystrophy (DMD) treatments. He listed recent catalysts such as positive data from Avidity’s exon-44-skipping therapy del-zota and Capricor’s cell therapy deramiocel regaining FDA review after a prior rejection. Kelly also highlighted upcoming FDA submissions from Dyne Therapeutics for its exon 51 skipper DYNE-251, and REGENXBIO’s plans to launch RGX-202 in 2027.
Despite these advances, safety concerns have emerged. REGENXBIO reported two serious adverse events—one case of liver injury and one case of myocarditis—in its Phase 3 trial for RGX-202. While both were managed and resolved within weeks, the news caused a significant drop in company stock value. Chief Medical Officer Steve Pakola described the correlation between microdystrophin expression and functional improvements as a “landmark distinction” among DMD gene therapies.
Novartis is awaiting key data from Avidity’s DM1 program following last year’s acquisition. Oppenheimer analyst Kostas Biliouris said that results from an upcoming Phase 3 trial could largely determine the success of the deal: “This is perhaps 80% of the acquisition.” However, Kelly argued that Novartis acquired Avidity for its broader platform potential beyond any single asset.
Other companies are also making progress. Solid Biosciences has begun dosing patients in a Phase 3 study of SGT-003 gene therapy for DMD; analysts noted this marks an important step toward potential accelerated approval. Meanwhile, Sarepta is seeking full approval conversions for Amondys 45 and Vyondys 53 despite previous confirmatory trial failures blamed partly on pandemic disruptions.
