Current Environment:


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.


Cystic Fibrosis

Recruitment Status


Eligibility Criteria

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: ≥ 40% 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.


Intervention Type

Intervention Name


VX-522 mRNA therapy




Phase 1, Phase 2



Min Age

18 Years

Max Age

65 Years

Download Date

April 12, 2024

Principal Investigator

Ahmet Uluer

This field has been modified from to show a contact specific to Boston Children's.

Primary Contact Information

Robert Fowler

This field has been modified from to show a contact specific to Boston Children's.

For more information on this trial, visit


For more information and to contact the study team:

A Phase 1/2 Study of VX-522 in Participants With Cystic Fibrosis (CF) NCT05668741 Robert Fowler