Long-Term Outcomes of Ataluren in Duchenne Muscular Dystrophy

This study is a randomized, double-blind, placebo-controlled, 72-week study followed by a
72-week open-label period. The purpose is to characterize the long-term effects of
ataluren-mediated dystrophin restoration on disease progression. Participants will be
randomized in a 1:1 ratio to ataluren or placebo. Participants will receive blinded study
drug three times daily (TID) at morning, midday, and evening for 72 weeks, after which all
participants will receive open-label ataluren for an additional 72 weeks (144 weeks in
total). Study assessments will be performed at clinic visits every 12 weeks during the
double-blind period and every 24 weeks during the open-label period. The total sample size of
~250 subjects will include ~160 subjects who meet the criteria for inclusion in the primary
analysis population (age 7 to 16 years old, baseline six minute walk distance (6MWD) greater
than or equal to (>=) 300 meters, supine to stand >= 5 seconds). The study will be conducted
in the United States and other countries around the world.

Inclusion Criteria -

- Male sex.

- Age ≥5 years.

- Phenotypic evidence of Duchenne Muscular Dystrophy

- Nonsense point mutation in the dystrophin gene

- Use of systemic corticosteroids (prednisone/prednisolone or deflazacort)for a minimum
of 12 months immediately prior to start of study treatment, with no significant change
in dosage or dosing regimen for a minimum of 3 months immediately prior to start of
study treatment

- 6MWD ≥150 meters

- Ability to perform timed function tests within 30 seconds

- Willingness and ability to comply with scheduled visits, drug administration plan,
study procedures, laboratory tests, and study restrictions.

Exclusion Criteria:

- Any change in prophylaxis treatment for cardiomyopathy within 1 month prior to start
of study treatment.

- Ongoing intravenous (IV) aminoglycoside or IV vancomycin therapy.

- Prior or ongoing therapy with ataluren.

- Known hypersensitivity to any of the ingredients or excipients of the study drug

- Exposure to another investigational drug within 6 months prior to start of study
treatment, or ongoing participation in any interventional clinical trial.

- History of major surgical procedure within 12 weeks prior to start of study treatment,
or expectation of major surgical procedure during the 72-week placebo-controlled
treatment period.

- Requirement for daytime ventilator assistance or any use of invasive mechanical
ventilation via tracheostomy.

- Uncontrolled clinical symptoms and signs of congestive heart failure

- Elevated serum creatinine or cystatin C at screening.