Safety Study of Eteplirsen to Treat Advanced Stage Duchenne Muscular Dystrophy

This is an open-label, multi-center study to explore the safety and tolerability of
eteplirsen injection in participants with advanced stage DMD with confirmed genetic mutations
amenable to treatment by exon 51 skipping.

Participants will be evaluated for inclusion during a Screening/Baseline period of up to 4
weeks. Eligible participants will receive once weekly intravenous (IV) infusions of 30 mg/kg
eteplirsen for 96 weeks, followed by a safety extension (not to exceed 48 weeks).

Safety will be regularly assessed throughout the study via the collection of adverse events
(AEs), laboratory tests, electrocardiograms (ECGs), echocardiograms (ECHOs), vital signs, and
physical examinations.

Inclusion Criteria:

- Male 7 - 21 years of age

- Diagnosis of DMD with a mutation that is amenable to exon 51 skipping, confirmed by a
genetic report

- Stable dose of oral corticosteroids for at least 24 weeks or has not received
corticosteroids for at least 24 weeks

- Non-ambulatory, or incapable of walking ≥300 meters on the 6-Minute Walk Test (6MWT).

- Score of ≤4 on the Brooke Score for Arms and Shoulders.

- Stable cardiac and pulmonary function

- Use of contraceptives for sexually active males throughout the study

- Willing to provide consent and comply with the study

Exclusion Criteria:

- Use of any pharmacologic treatment (other than corticosteroids) within 12 weeks that
may have an effect on muscle strength or function (e.g., growth hormone, anabolic
steroids).

- Previous treatment with SMT C1100/BMN 195 at any time.

- Previous treatment with drisapersen (PRO051) within the last 6 months.

- Participation in any other DMD interventional clinical study within 12 weeks

- Major change in physiotherapy regimen within the past 3 months

- Major surgery within 3 months

- Presence of other clinically significant illness

- Use of an aminoglycoside antibiotic within 12 weeks or the need for this antibiotic or
statin during study

- Forced vital capacity % predicted [FVC % predicted] <40%, or requiring daytime
ventilation.

- Require antiarrhythmic and/or antidiuretic therapy for heart failure.

- Have a left ventricular ejection fraction (LVEF) of <40%.

- Prior or ongoing medical condition that could adversely affect the safety of the
patient, make it unlikely that the course of treatment would be completed, or impair
the assessment of study results.