Roll-Over Study of Ivacaftor in Cystic Fibrosis Pediatric Subjects With a CF Transmembrane Conductance Regulator Gene (CFTR) Gating Mutation

A Phase 3, 2-Arm, Roll-Over Study to Evaluate the Long-term Safety and Pharmacodynamics of Ivacaftor Treatment in Pediatric Subjects With Cystic Fibrosis and a CFTR Gating Mutation

The purpose of this study is to provide information regarding the long-term safety and pharmacodynamics of ivacaftor treatment in the pediatric population younger than 6 years of age with Cystic Fibrosis (CF) who have a CFTR gating mutation in at least 1 allele and will further explore the efficacy of long-term ivacaftor treatment in this population of patients with CF.

Inclusion Criteria (Ivacaftor Arm):

1. Completed the last study visit of the treatment period of the previous study (NCT01705145)
2. Hematology, serum chemistry, and vital signs results on Day 1 with no clinically significant abnormalities that would interfere with the study assessments, as judged by the investigator
3. As judged by the investigator, parent or legal guardian must be able to understand protocol requirements, restrictions, and instructions and the parent or legal guardian should be able to ensure that the subject assents to participation in the study to the degree the subject can assent, and that the subject will comply with and is likely to complete the study as planned

Inclusion Criteria (Observational Arm):

1. Subjects who completed their assigned study drug treatment in the previous study (NCT01705145) and elected not to enroll in the ivacaftor arm and subjects who prematurely discontinued treatment in the previous study and received at least 1 dose of study drug treatment in the previous study will be eligible for enrollment in the observational arm.

Exclusion Criteria (Ivacaftor Arm):

1. Subjects who prematurely discontinued from the previous study
2. 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 subject
3. Subjects with a history of study treatment intolerance as observed in their previous study that, in the opinion of the investigator, might pose an additional risk in administering study drug to the subject
4. Subjects receiving commercially-available ivacaftor treatment
5. Subject was unable to complete an adequate slit-lamp examination at the last ophthalmologic examination in the previous study

Exclusion Criteria: (Observational Arm)

1. Subjects receiving ivacaftor treatment will not be eligible for enrollment in the observational arm.