Dyne Therapeutics’ DYNE-251 in DMD shows efficacy in Phase 1/2 trial

Dyne Therapeutics announced new clinical data from its ongoing Phase 1/2 DELIVER trial of DYNE-251 in patients with Duchenne muscular dystrophy – DMD – who are amenable to exon 51 skipping demonstrating unprecedented dystrophin expression and functional improvement in multiple cohorts. DYNE-251 demonstrated dose dependent exon skipping and dystrophin expression and improvement in multiple functional endpoints in both cohorts. Key findings include: DYNE-251 demonstrated unprecedented dystrophin expression as measured by Western blot. Patients treated with 20 mg/kg of DYNE-251 Q4W had a mean absolute dystrophin expression of 3.71% of normal, more than 10-fold higher than the 0.3% reported in a clinical trial of the weekly standard of care, eteplirsen. When adjusting for muscle content, the DYNE-251 treated group reached 8.72% mean absolute dystrophin, which is greater than levels reported by peptide conjugate PMOs in clinical development. Meaningful improvements in multiple functional endpoints were observed in both the 20 mg/kg and 10 mg/kg DYNE-251 Q4W groups. The 10 mg/kg cohort showed continued improvement in all reported measures from 6 months to 12 months. DYNE-251 demonstrated a favorable safety profile and the majority of treatment emergent adverse events were mild or moderate. Based on these data and regulatory interactions, Dyne is initiating registrational cohorts in the DELIVER trial and plans to provide an update on the path to registration by the end of 2024. The company continues to engage with global regulators, including the FDA, and plans to provide an update on the path to registration for DYNE-101, including additional clinical data, by the end of 2024.