The purpose of this study is to evaluate the relative bioavailability of a fixed-dose combination tablet (FDC) of VX-121/tezacaftor/deutivacaftor (VX-121/TEZ/D-IVA).

This clinical trial information was submitted voluntarily under the applicable law and, therefore, certain submission deadlines may not apply. (That is, clinical trial information for this applicable clinical trial was submitted under section 402(j)(4)(A) of the Public Health Service Act and 42 CFR 11.60 and is not subject to the deadlines established by sections 402(j)(2) and (3) of the Public Health Service Act or 42 CFR 11.24 and 11.44.).

Key Inclusion Criteria:

• Body mass index (BMI) of 18.0 to 32.0 kilogram per meter square (Kg/m^2), both inclusive
• A total body weight greater than (>)50 kg

Key Exclusion Criteria:

• History of febrile illness or other acute illness that has not fully resolved within 14 days before the first dose of study drug
• Any condition possibly affecting drug absorption
• Female participants who are pregnant, nursing, or planning to become pregnant during the study or 90 days after the last dose of the study drug
• Male participants with a female partner who is pregnant, nursing, or planning to become pregnant during the study
• History of cardiovascular disease or central nervous system disease

Other protocol defined Inclusion/Exclusion criteria may apply.

Details on Vertex data sharing criteria and process for requesting access can be found at: https://www.vrtx.com/independent-research/clinical-trial-data-sharing