Biotechnology company PepGen Inc (Nasdaq: PEPG) on Monday announced positive initial results from its ongoing FREEDOM-DM1 Phase 1 trial, evaluating PGN-EDODM1 for myotonic dystrophy type 1 (DM1). The 5 mg/kg and 10 mg/kg dose cohorts showed a mean splicing correction of 12.3% and 29.1%, respectively, 28 days post-dose.

Dose-dependent increases in muscle tissue concentrations of PGN-EDODM1 were observed, with favorable safety data emerging from both cohorts. Most treatment-related adverse events were mild or moderate, with one serious event of abdominal pain in the 10 mg/kg cohort.

The investigational treatment, which aims to restore normal splicing function by addressing cytosine-uracil-guanine (CUG) repeat expansions, showed positive early trends in functional outcome measures, although improvements were not seen with single doses. PepGen plans to report results from the 15 mg/kg cohort in the second half of 2025 and from the FREEDOM2 5 mg/kg cohort in early 2026.

PGN-EDODM1 has received Orphan Drug and Fast Track Designations from the U.S. FDA for DM1. The ongoing multinational trial will continue to assess safety, splicing correction and functional outcomes with additional dose escalation in future cohorts.