PoC Study to Assess Activity and Safety of SMT C1100 (Ezutromid) in Boys With DMD

This is a Phase 2, open-label, study to assess the activity and safety of utrophin modulation
with SMT C1100 (ezutromid) administered orally bid in ambulatory paediatric male subjects
with DMD. Approximately 40 subjects with DMD will be enrolled in this study.

This study will be conducted in a multi-centre setting in both the United Kingdom and the
United States of America and comprises of a Screening and Baseline Phase of up to 28 days, a
48-week open label Treatment Phase, and either a 30-day Safety Follow up Phase or an optional
extension phase where study treatment is provided until discontinuation of the program or
regulatory approvals as applicable.

Inclusion Criteria:

- Male

- Age ≥5 and <10 years (from 5th birthday to 10th birthday)

- DMD diagnosis

- Willing and able to comply with study procedures, including 2 muscle biopsy procedures

- Able to undergo MRI

- Have used at least 6 months stable dose systemic corticosteroids

- Ability to walk 300 metres unassisted and below 80% predicted 6MWD

Exclusion Criteria:

- Uncontrolled congestive heart failure (CHF) or recent change in CHF
prophylaxis/treatment

- Use of beta blockers, herbal supplements, BCRP substrates, SNRIs, SSRIs, tricyclic
antidepressants, or ADHD treatments such as methylphenidate or PEA.

- Use of over the counter, herbal or prescription CYP2B6, CYP1A1 or CYP1A2 inhibitors,
inducers or substrates.

- Exposure to other investigational drug or DMD interventional agent within 3 months
(except FOR-DMD Study participants are permitted)

- Require daytime ventilator assistance

- Be dairy or lactose intolerant

- Be a smoker, use other tobacco or nicotine products or be exposed to daily passive
smoking

- Use of an approved DMD medication or anticipate use during the study (other than
steroids)