Study of VX-809 Alone and in Combination With VX-770 in Cystic Fibrosis (CF) Patients Homozygous or Heterozygous for the F508del-CFTR Mutation

Inclusion Criteria:

- Male or female participants with confirmed diagnosis of CF

- Must have the F508del-CFTR mutation on at least 1 allele.

- FEV1 greater than equal (>=) 40% of predicted normal for age, gender, and height
(Knudson standards)(Cohort 1, 2, and 3); FEV1 40-90% of predicted normal for age,
gender, and height (Hankinson standards (Cohort 4)

- Participant of child-bearing potential and who are sexually active must meet the
contraception requirements

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 (e.g., cirrhosis with portal hypertension).

- An acute illness including acute upper or lower respiratory infection, pulmonary
exacerbation or changes in therapy (including antibiotics) for pulmonary disease
within 14 days (Cohort 1, 2, and 3) or 28 days (Cohort 4) before receiving the first
dose of study drug.

- History of solid organ or hematological transplantation.

- History of alcohol abuse or drug addiction in the past year, including cannabis,
cocaine, and opiates.

- Ongoing participation in another therapeutic clinical study, or prior participation
in an investigational drug study without appropriate washout

- Pregnant or nursing females; females of childbearing potential who are unwilling or
unable to use an acceptable method of non-hormonal contraception

- Participants enrolled in Cohort 1 or Cohort 2 will not be eligible for Cohort 3

- Ongoing or prior participation in an investigational drug study within 30 days of the
Screening Visit

- Heterozygous participants who participated in Cohort 2 and meet the eligibility
criteria for Cohort 4 may participate in Cohort 4

- Evidence of lens opacity or cataract as determined by the ophthalmologic examination
(Cohort 4 only)