Study of Ivacaftor in Cystic Fibrosis Subjects 2 Through 5 Years of Age With a CFTR Gating Mutation

Inclusion Criteria:

- Male or female with confirmed diagnosis of CF

- Must have a CFTR gating mutation in at least 1 allele

- Aged 2 through 5 years at screening and Day 1

- Weight >= 8 kg at screening and Day 1

- Hematology, serum chemistry, coagulation, and vital signs results at screening with
no clinically significant abnormalities that would interfere with the study
assessments, as judged by the investigator

Exclusion Criteria:

- History of any illness or condition that, in the opinion of the investigator, might
confound the results of the study or pose an additional risk in administering study
drug to the participant

- An acute upper or lower respiratory infection, or pulmonary exacerbation, or changes
in therapy for pulmonary disease within 4 weeks before Day 1

- Abnormal liver function, at screening

- History of solid organ or hematological transplantation

- Use of any moderate or strong inducers or inhibitors of cytochrome P450 (CYP) 3A
within 2 weeks before Day 1

- Participation in a clinical study involving administration of either an
investigational or a marketed drug within 30 days or 5 terminal half-lives before
screening