The purpose of this study is to evaluate the safety, and tolerability and efficacy of VX-522 in participants 18 years of age and older with cystic fibrosis and a cystic fibrosis transmembrane conductance regulator (CFTR) genotype not responsive to CFTR modulator therapy.

Key Inclusion Criteria:

• Body mass index is less than (<) 30.0 kilograms per meter square (kg/m^2)

• A total body weight greater than (>) 50 kg

• Stable CF disease

• CFTR gene mutations on both alleles that are not responsive to CFTR modulator therapy

  o Example mutations include but are not limited to, mutations that do not produce CFTR protein (i.e., Class I): nonsense mutations (e.g., G542X, W1282X) and canonical splice mutations (e.g., 621+1G->T)

• Forced expiratory volume in 1 second (FEV1) value for SAD: greater than or equal to (≥)40 percent (%), MAD: ≥ 50% to less than or equal to (≤) 90%

Key Exclusion Criteria:

• History of uncontrolled asthma within a year prior to screening
• History of solid organ or hematological transplantation
• Hepatic cirrhosis with portal hypertension, moderate hepatic impairment (Child Pugh Score 7 to 9), or severe hepatic impairment (Child Pugh Score 10 to 15)
• Arterial oxygen saturation on room air less than (<) 94% at screening

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/our-science/clinical-trials-data-sharing/