Global PGN-EDO51 development voluntarily discontinued by Sponsor

The study consists of 3 periods: A Screening Period (up to 45 days), a double-blind, placebo-controlled Multiple Ascending Dose (MAD) Period (28 weeks), and a Long-Term Extension (LTE) Period (108 weeks).

The primary purpose of the MAD period is to evaluate the safety and tolerability and levels of dystrophin after multiple ascending intravenous (IV) doses of PGN-EDO51 administered to participants with Duchenne muscular dystrophy (DMD). During the MAD period, participants will be randomized to either receive PGN-EDO51 or placebo in a 3:1 fashion, meaning that participants have a 75% chance of receiving PGN-EDO51 and a 25% chance of receiving placebo during this period. The primary purpose of the open-label LTE period is to evaluate the long-term safety and tolerability of PGN-EDO51 in participants who have completed the MAD period. All participants who roll-over into the LTE will receive PGN-EDO51 (no placebo in the LTE).

Inclusion Criteria:

• Confirmed diagnosis of DMD with a genetic alteration that can be treated by skipping exon 51
• Body weight at least 25kg (55lbs)
• Performance of Upper Limb (PUL) 2.0 entry score of at least 4

Exclusion Criteria:

• Known history or presence of any clinically significant conditions that may interfere with study safety assessments
• Treatment with any gene replacement therapy for the treatment of DMD at any time
• Current or recent systemic infection within 2 weeks prior to Screening or infection requiring IV antibiotics within 4 weeks prior to Screening
• Recent surgery requiring anesthesia within 3 months prior to Screening or expected surgery requiring general anesthesia during the study