Phase 2B Extension Study of Ataluren (PTC124) in Duchenne/Becker Muscular Dystrophy (DMD/BMD)

A Phase 2B Extension Study of PTC124 in Subjects With Nonsense-Mutation-Mediated Duchenne and Becker Muscular Dystrophy

Duchenne/Becker muscular dystrophy (DMD/BMD) is a genetic disorder that develops in boys. It is caused by a mutation in the gene for dystrophin, a protein that is important for maintaining normal muscle structure and function. Loss of dystrophin causes muscle fragility that leads to weakness and loss of walking ability during childhood and teenage years. A specific type of mutation, called a nonsense (premature stop codon) mutation is the cause of DMD/BMD in approximately 10-15% of boys with the disease. Ataluren (PTC124) is an orally delivered, investigational drug that has the potential to overcome the effects of the nonsense mutation. This study is a Phase 2b extension trial that will evaluate the long-term safety of ataluren (PTC124) in boys with nonsense mutation DMD/BMD, as determined by adverse events and laboratory abnormalities. The study will also assess changes in walking, muscle function, and other important clinical and laboratory measures.

This is a Phase 2b, international, multicenter, open-label extension study for participants who successfully completed blinded study drug in Study 007. This extension study will evaluate the long-term administration of ataluren administered 3 times per day (TID) at morning, midday, and evening doses of 20, 20, and 40 milligrams/kilogram (mg/kg), respectively, in participants with nonsense mutation Duchenne/Becker muscular dystrophy (nmDBMD).

Inclusion Criteria:

• Completion of blinded study drug treatment in the previous Phase 2b study (PTC124-GD-007-DMD).
• Ability to provide written informed consent (parental/guardian consent if applicable)/assent (if less than [<]18 years of age).
• In participants who are sexually active, willingness to abstain from sexual intercourse or employ a barrier or medical method of contraception during PTC124 administration and the 6-week follow up period.
• Willingness and ability to comply with scheduled visits, drug administration plan, study procedures, laboratory tests, and study restrictions.

Exclusion Criteria:

• Known hypersensitivity to any of the ingredients or excipients of the study drug (Litesse® UltraTM [refined polydextrose], polyethylene glycol 3350, Lutrol® micro F127 [poloxamer 407], mannitol 25C, crospovidone XL10, hydroxyethyl cellulose, vanilla, Cab-O-Sil® M5P [colloidal silica], magnesium stearate).
• Ongoing participation in any other therapeutic clinical trial.
• Prior or ongoing medical condition (for example, concomitant illness, psychiatric condition, behavioral disorder, alcoholism, drug abuse), medical history, physical findings, ECG findings, or laboratory abnormality that, in the investigator's opinion, could adversely affect the safety of the subject, makes it unlikely that the course of treatment or follow up would be completed, or could impair the assessment of study results.