Phase 1/2 Study in Boys With Duchenne Muscular Dystrophy

Part A was a 1-week, open-label study to assess safety, tolerability, pharmacokinetics and
biomarkers for three dose levels of edasalonexent and is now complete.

Part B was a randomized, double-blind, placebo-controlled, multiple dose study to evaluate
the safety, efficacy, PK, and PD of edasalonexent over 12 weeks. Patients who participated in
Part A also participated in Part B, along with newly enrolled patients. Patients received
either edasalonexent 67 mg/kg/day, edasalonexent 100 mg/kg/day, or placebo in Part B. Part B
is now complete.

Following completion of Part B, patients receive edasalonexent for 138 weeks in Part C, the
open-label portion of the MoveDMD study. Patients on the 67 mg/kg/day treatment moved to the
100 mg/kg/day treatment. Patients on the 100 mg/kg/day treatment remained on the 100
mg/kg/day treatment. If clinically indicated, concomitant treatment with eteplirsen (Exondys
51™) may be acceptable in patients with amenable gene mutations during Part C after the
patient has been exposed to edasalonexent for 6 months.

**Following completion of MoveDMD Part C, access to edasalonexent will continue through a new
open-label extension study. Families currently enrolled in MoveDMD Part C are encouraged to
speak with their trial site for additional information.**

Inclusion Criteria:

- Written informed consent from parent or legal guardian prior to participation and, for
patients who are 7 years of age, written assent from patient

- Diagnosis of DMD based on a clinical phenotype with increased serum CK and the
presence of a mutation in the dystrophin gene known to be associated with a DMD
phenotype

- Ability to walk independently (assistive devices are permitted)

- Adequate immunization for influenza and varicella

Exclusion Criteria:

- Use of corticosteroids within prior 6 months of treatment initiation or planning to
initiate steroid therapy within the next 6 months

- Other prior or ongoing significant medical conditions

- Exposure to another investigational drug (such as eteplirsen or idebenone) within 28
days prior to start of study treatment or ongoing participation in any other
therapeutic clinical trial

- Note: There are separate criteria for patients who participated in Part A versus
newly enrolling patients. New patients must meet all of the Part A entry criteria
to participate in Part B.

Patients who participated in Part A must meet the following criteria to participate in Part
B:

- Completed Part A

- Continue to meet all of the Part A entry criteria, including an absence of safety
concerns (however, patients may be ≥8 years of age)

There are no entry criteria for Part C; all patients who complete Part B will automatically
continue in Part C