Evaluation of VX-828 in Healthy Participants and in Participants With Cystic Fibrosis

Key Inclusion Criteria:

Parts A-D:

• Body mass index (BMI) of 18.0 to 32.0 kilogram per meter square (kg/m^2)

• A total body weight of more than (>) 50 kg

• Nonsmoker or ex-smoker for at least 3 months before screening with currentnonsmoking status confirmed by urine or blood cotinine at screening

Part E:

• Confirmed diagnosis of CF as determined by the investigator

• A total body weight of more than or equal to (>=) 35 kg

• Participants must be heterozygous for F508del with a second CFTR allele carrying aminimal function mutation that is not responsive to ELX/TEZ/IVA therapy

• Participants must have a forced expiratory volume in 1 second (FEV1) of greater thanor equal to (≥) 40% of predicted normal for age, sex, and height

Key Exclusion Criteria:

Parts A-D:

• History of febrile illness or other acute illness within 14 days before the firstdose of study drug

• Any condition possibly affecting drug absorption

Part E:

• An acute illness not related to CF (e.g., gastroenteritis) within 14 days before thefirst dose of study drug

• History of solid organ or hematological transplantation

• History of clinically significant cirrhosis with or without portal hypertension

• Lung infection with organisms associated with a more rapid decline in pulmonarystatus

Other protocol defined Inclusion/Exclusion criteria will apply.