A Study Evaluating the Safety of VX-152 Combination Therapy in Adults With Cystic Fibrosis

Inclusion Criteria: * Willing and able to comply with scheduled visits, treatment pan, study restrictions, laboratory tests, contraceptive guidelines, and other study procedures. * Body weight ≥35 kg. * Sweat chloride value ≥ 60 mmol/L from test results obtained during screening. * Subjects must have an eligible CFTR genotype: * Cohorts 1A, 1B, 1C: Heterozygous for F508del and a minimal function mutation known or predicted not to respond to TEZ and/or IVA. * Cohorts 2A, 2B: Homozygous for F508del. * Subjects must have an FEV1 ≥40% and ≤90% of predicted normal for age, sex, and height at the Screening Visit. * Stable CF disease as judged by the investigator. * Willing to remain on a stable CF medication regimen through the planned end of treatment or if applicable the Safety Follow-up Visit. Exclusion Criteria: * History of any comorbidity 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. * History of cirrhosis with portal hypertension. * Risk factors for Torsade de Pointes. * History of hemolysis. * Glucose-6-phosphate dehydrogenase (G6PD) deficiency assessed at Screening. * Clinically significant abnormal laboratory values at screening. * An acute upper or lower respiratory infection, pulmonary exacerbation, or changes in therapy for pulmonary disease within 28 days before the first dose of study drug. * Lung infection with organisms associated with a more rapid decline in pulmonary status. * An acute illness not related to CF within 14 days before the first dose of study drug. * A standard digital ECG demonstrating QTc \>450 msec at screening. * History of solid organ or hematological transplantation. * History or evidence of cataract or lens opacity determined to be clinically significant by the ophthalmologist or optometrist, based on the ophthalmologic examination during the Screening Period. * History of alcohol or drug abuse in the past year, including but not limited to, cannabis, cocaine, and opiates, as deemed by the investigator. * Ongoing or prior participation in an investigational drug study with certain exceptions. * Use of commercially available CFTR modulator within 14 days before screening (applies only to Cohorts 1A, 1B, and 1C). * Pregnant or nursing females: Females of childbearing potential must have a negative pregnancy test at screening and Day 1.