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.