Why Is Rare Muscle Disease-Focused Dyne Therapeutics Stock Soaring Today?

Dyne Therapeutics Inc DYN released initial clinical data from its ACHIEVE trial of DYNE-101 in patients with myotonic dystrophy type 1 (DM1) and its DELIVER trial of DYNE-251 in patients with Duchenne muscular dystrophy (DMD) who are amenable to exon 51 skipping.

Phase 1/2 ACHIEVE Trial of DYNE-101 in DM1: The initial efficacy assessment of the DYNE-101 ACHIEVE trial is based on data from 32 adult DM1 patients enrolled.

• DYNE-101 demonstrated dose-dependent splicing correction, muscle delivery, and DMPK knockdown.
• The 3.4 mg/kg Q4W group had a 40% mean DMPK knockdown from baseline compared to 25% in patients in the 1.8 mg/kg Q4W group at three months.
• Evaluable patients treated with 3.4 mg/kg Q4W of DYNE-101 had a 19% mean splicing correction from baseline across a broad, 22-gene panel at three months, with all evaluable participants experiencing an improvement. Patients in the 1.8 mg/kg Q4W group at three months had a 13% mean splicing correction.
• Patients treated with 1.8 mg/kg of DYNE-101 Q4W had a mean 3.8-second benefit in myotonia (prolonged muscle contractions) and improvement in fatigue.

Phase 1/2 DELIVER Trial of DYNE-251 in DMD: Initial efficacy assessment is based on 6-month data from 6 male patients enrolled in the 5 mg/kg (approximate PMO dose) cohort

• Muscle delivery: DYNE-251 showed a mean 657 ng/g PMO muscle drug concentration at six months.
• DYNE-251 demonstrated a mean absolute exon skipping level of 0.90% and a 0.80% change from baseline at 6 months. The current standard of care, eteplirsen, administered weekly, showed a 0.59% mean absolute exon skipping level and a 0.40% change from baseline at six months. 
• DYNE-251-treated patients had a mean absolute dystrophin level of 0.88% of normal and a 0.28% change from baseline at six months. Eteplirsen reached a mean absolute dystrophin level of 0.30% of normal and a 0.06% change from baseline at six months.
• DYNE-251 demonstrated a 22.2% mean level of dystrophin-positive fibers and a 19.8% change from baseline at 6 months. Eteplirsen showed a 19.6% mean level of PDPF and a 10.7% change from baseline at six months.

The favorable safety profile for DYNE-101 and DYNE-251 supports dose escalation. Enrollment is complete in the 5.4 mg/kg cohort of the ACHIEVE trial and the 20 mg/kg cohort of the DELIVER trial.

Dyne anticipates providing its next clinical data update from both trials in 2H of 2024.

Price Action: DYN shares are up 41.50% at $18.49 during the premarket session on the last check Wednesday.