Study of VX-809 in Cystic Fibrosis Subjects With the ∆F508-CFTR Gene Mutation

This was a Phase 2, randomized, double-blind, placebo-controlled, multiple-dose study of
orally-administered VX-809 in participants with CF who are homozygous for the specific CFTR
mutation known as ∆F508 or F508del. Enrollment was planned for 90 participants at
approximately 20 centers. Participants were planned to be randomized in a 4:1 ratio to
receive 1 of 4 doses of VX-809 or placebo once a day for 28 days in a parallel design.
Participants were outpatients during the study, except for overnight stays on Day 1 and 28.

Inclusion Criteria:

- Confirmed diagnosis of CF with ∆F508-CFTR mutation in both alleles

- Forced expiratory volume in 1 second (FEV1) greater than or equal to (>=) 40 percent
(%) of predicted normal for age, gender, and height

- Weight >=40 kilograms (kg) and body mass index greater than or equal to 18.5 kilogram
per square meter (kg/m^2)

- Screening laboratory values, tests, and physical examination within acceptable ranges

- Negative pregnancy test (for women of child-bearing potential)

- Able and willing to follow contraceptive requirements

- Willing to remain on a stable medication regimen for the duration of study
participation

Exclusion Criteria:

- History of any illness, or any ongoing acute illness, that could impact the safety of
the study participant or may confound results of study

- Pulmonary exacerbation or changes in therapy for pulmonary disease within 14 days
before receiving the first dose of study drug

- Impaired hepatic or renal function

- History of organ or hematological transplant