Study of Ataluren (PTC124) in Cystic Fibrosis

Key Inclusion Criteria:

• Ability to provide written informed consent (parental/guardian consent and participantassent if less than [<] 18 years of age).

• Evidence of completed participation in the double-blind study, PTC124-GD-009-CF (Study 009).

• Body weight greater than or equal to (≥) 16 kilograms (kg).

• Performance of a valid, reproducible spirometry test using the study-specificspirometer during the screening period.

• Confirmed laboratory values within the central laboratory ranges at screening.

• In male and female participants who are sexually active, willingness to abstain fromsexual intercourse or employ a barrier or medical method of contraception during thestudy drug administration and 60-day follow-up period.

• Willingness and ability to comply with all study procedures and assessments, includingscheduled visits, drug administration plan, laboratory tests, and study restrictions.

Key Exclusion Criteria:

• Chronic use of systemic tobramycin within 4 weeks prior to screening.

• Evidence of pulmonary exacerbation or acute upper or lower respiratory tract infection (including viral illnesses) within 3 weeks prior to screening or between screening andrandomization.

• Any change (initiation, change in type of drug, dose modification, schedulemodification, interruption, discontinuation, or re-initiation) in a chronictreatment/prophylaxis regimen for CF or for CF-related conditions within 4 weeks priorto screening and randomization.

• Known hypersensitivity to any of the ingredients or excipients of the study drug.

• Exposure to another investigational drug within 4 weeks prior to screening.

• Treatment with intravenous antibiotics within 3 weeks prior to screening.

• History of solid organ or hematological transplantation.

• Ongoing immunosuppressive therapy (other than corticosteroids).

• Positive hepatitis B surface antigen, hepatitis C antibody test or humanimmunodeficiency virus (HIV) test.

• Known portal hypertension.

• Pregnancy or breast-feeding.