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Evaluating VX-522 for Cystic Fibrosis Treatment

A Phase 1/2 Dose Escalation Study Evaluating the Safety, and Tolerability and Efficacy of VX-522 in Subjects 18 Years of Age and Older With Cystic Fibrosis and a CFTR Genotype Not Responsive to CFTR Modulator Therapy

Phase1; Phase2 Interventional Vertex Pharmaceuticals Incorporated · NCT05668741

This study is testing a new mRNA therapy called VX-522 to see if it can help adults with cystic fibrosis who have certain gene mutations that don’t respond to current treatments.

Quick facts

PhasePhase1; Phase2
Study typeInterventional
Enrollment39 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorVertex Pharmaceuticals Incorporated Industry-sponsored
Locations43 sites (Birmingham, Alabama and 42 other locations)
Trial IDNCT05668741 on ClinicalTrials.gov

What this trial studies

This study aims to assess the safety, tolerability, and efficacy of VX-522, an mRNA therapy, in adults with cystic fibrosis who have specific CFTR gene mutations that do not respond to existing CFTR modulator therapies. Participants will be monitored for their response to the treatment, which includes measuring lung function and overall health. The study is designed to include individuals with stable cystic fibrosis and specific genetic profiles, ensuring a targeted approach to treatment.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18 and older with cystic fibrosis and specific CFTR mutations that do not respond to current therapies.

Not a fit: Patients with uncontrolled asthma, recent organ transplants, or severe liver impairment may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a new therapeutic option for cystic fibrosis patients with non-responsive CFTR mutations.

How similar studies have performed: Other studies have shown promise with mRNA therapies for genetic conditions, but this specific approach is novel for cystic fibrosis.

Eligibility criteria

Show full inclusion / exclusion 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: ≥ 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.

Where this trial is running

Birmingham, Alabama and 42 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Cystic Fibrosis
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.