Study of the Effect of Ivacaftor on Lung Clearance Index in Subjects With Cystic Fibrosis and the G551D Mutation

A Phase 2, Randomized, Double-Blind, Placebo-Controlled, Crossover Study to Evaluate the Effect of VX-770 on Lung Clearance Index in Subjects With Cystic Fibrosis, the G551D Mutation, and FEV1 >90% Predicted

The purpose of this study is to evaluate the effect of ivacaftor (VX-770) on lung clearance index (LCI) in subjects aged 6 years and older with cystic fibrosis (CF) who have the G551D-CFTR mutation on at least 1 allele.

Currently, limited objective measures are available to quantify lung function in CF patients with mild lung disease. Lung clearance index (LCI) derived from inert gas multiple-breath washout (MBW) testing hold considerable promise to evaluate early lung disease as studies have detected abnormalities in a high percentage of CF patients with normal spirometry in both infants and children.

This study explored the effect of ivacaftor on LCI and the efficacy of ivacaftor on other clinical and biomarker endpoints of CF lung disease in subjects aged 6 years and older with CF who have the G551D-CFTR mutation on at least 1 allele.

Inclusion Criteria:

• Male or female subjects with confirmed diagnosis of CF
• Must have the G551D-CFTR mutation in at least 1 allele
• FEV1 >90% of predicted normal for age, gender, and height

Exclusion Criteria:

• Ongoing participation in another therapeutic clinical study or prior participation in an investigational drug study within the 30 days prior to screening
• Use of inhaled hypertonic saline treatment within 2 weeks of the Period 1, Day 1 visit