A Study to Evaluate the Safety and Efficacy of VX-121 Combination Therapy in Subjects With Cystic Fibrosis

The purpose of this study is to evaluate the safety, tolerability and efficacy of VX-121 combination therapy in subjects with cystic fibrosis (CF).

Key Inclusion Criteria:

* Part 1: Heterozygous for F508del and an MF mutation (F/MF)
* Part 2: Homozygous for F508del (F/F)
* FEV1 value ≥40% and ≤90% of the predicted mean for age, sex, and height

Key Exclusion Criteria:

* History of clinically significant cirrhosis with or without portal hypertension
* Lung infection with organisms associated with a more rapid decline in pulmonary status
* History of solid organ or hematological transplantation

Other protocol-defined Inclusion/Exclusion criteria may apply