Extension Study of Ataluren (PTC124) in Cystic Fibrosis

This Phase 3, open-label, safety and efficacy study will be performed at sites in North
America, Europe, and Israel. The study will enroll up to approximately 208 patients with
nonsense mutation CF who participated in a previous Phase 3 study of ataluren (PTC124)
(PTC124-GD-009-CF, NCT00803205). Subjects will receive study drug 3 times per day (at
breakfast, lunch, and dinner) for approximately 48 weeks (approximately 1 year). Study
assessments will be performed at clinic visits every 8 weeks.

Inclusion Criteria:

- Completion of blinded study drug treatment in the previous Phase 3 study
(PTC124-GD-009-CF).

- Ability to provide written informed consent (parental/guardian consent if
applicable)/assent (if <18 years of age).

- In subjects who are sexually active, willingness to abstain from sexual intercourse or
employ a barrier or medical method of contraception during ataluren administration and
the 4-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 (list
provided at study sites).

- Current pregnancy or lactating, or pregnancy or lactating during the previous Phase 3
study.

- Ongoing participation in any other therapeutic clinical trial.

- Prior or ongoing medical condition (eg, 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.