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Study on Long-term Safety of VX-121, Tezacaftor, and Deutivacaftor in Patients with Cystic Fibrosis

Verified siteRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying Cystic Fibrosis, a genetic disorder that affects the lungs and other organs. The study will use a combination therapy involving three medications: Tezacaftor, Deutivacaftor, and Vanzacaftor, which are taken as a film-coated tablet. These medications are designed to work together to help improve the function of certain proteins in the body that are affected by cystic fibrosis.

The purpose of the study is to evaluate the long-term safety and tolerability of this combination therapy in individuals with cystic fibrosis. Participants will take the medication over a period of time and will have regular check-ups to monitor their health. These check-ups will include assessments of vital signs, laboratory tests, and other evaluations to ensure the treatment is safe and well-tolerated.

Throughout the study, researchers will also look at how the treatment affects lung function, measured by a test called percent predicted forced expiratory volume in 1 second (ppFEV1), and the level of sweat chloride, which is a marker of cystic fibrosis. Additionally, the study will track the number of lung infections, known as pulmonary exacerbations, that participants experience. This information will help determine the effectiveness of the treatment in managing cystic fibrosis symptoms over the long term.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, the participant will have signed an informed consent form. This indicates understanding and agreement to participate in the study.

    The participant must be willing and able to comply with scheduled visits, treatment plans, study restrictions, laboratory tests, and other study procedures.

  2. Step 2

    Treatment regimen

    The participant will receive a combination therapy consisting of tezacaftor, deutivacaftor, and vanzacaftor. These are active substances in the form of a film-coated tablet.

    The medication is taken orally. The specific dosage and frequency will be determined by the study protocol and communicated to the participant by the study team.

  3. Step 3

    Monitoring and assessments

    Throughout the study, the participant's health will be monitored through various assessments. These include checking for any adverse events, conducting clinical laboratory tests, and measuring vital signs.

    Additional assessments will include electrocardiograms (ECGs) and pulse oximetry to ensure the participant's safety and the treatment's tolerability.

  4. Step 4

    Evaluation of treatment effects

    The study will evaluate the effects of the treatment on lung function, specifically the change in percent predicted forced expiratory volume in one second (ppFEV1).

    Other evaluations include changes in sweat chloride levels and the number of pulmonary exacerbations experienced by the participant.

  5. Step 5

    Completion of study participation

    The study is estimated to conclude by November 11, 2025. Participants are expected to remain on a stable cystic fibrosis treatment regimen throughout the study duration.

    Upon completion, participants will have contributed valuable data regarding the long-term safety and efficacy of the VX-121 combination therapy.

Who can join the trial?

6 criteria

  • The patient or their legally authorized representative must sign and date an informed consent form. If needed, a form for minors, called an assent form, should also be signed.
  • The patient must be willing and able to attend scheduled visits, follow the treatment plan, adhere to study restrictions, undergo laboratory tests, follow contraceptive guidelines, and participate in other study procedures.
  • The patient must not have withdrawn consent from a previous related study, known as a parent study.
  • The patient must meet at least one of the following conditions:
    • Completed the study drug treatment in a parent study.
    • Had interruptions in the study drug during a parent study but did not permanently stop the study drug and completed all scheduled visits during the treatment period of the parent study.
    • The patient must be willing to continue their current treatment plan for **Cystic Fibrosis** until the end of their participation in the study.
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Investigated drugs

  • VX-121

    is a medication being studied for its potential to help people with cystic fibrosis. It is part of a combination therapy aimed at improving lung function and overall health in patients with this condition.

  • Tezacaftor

    is another component of the combination therapy. It works by helping certain proteins function better in the cells of people with cystic fibrosis, which can lead to improved lung function and fewer symptoms.

  • Deutivacaftor

    is the third part of the combination therapy. It is designed to enhance the activity of the proteins affected by cystic fibrosis, working together with VX-121 and tezacaftor to provide better health outcomes for patients.

What is already known about the treatment

VX-121/tezacaftor/deutivacaftor – This medication is administered orally and is currently being studied in clinical trials for its long-term safety and effectiveness in treating cystic fibrosis. It is not yet fully approved for general medical use, but it is being evaluated for its potential benefits in medical literature. The main therapeutic indication for this combination therapy is cystic fibrosis, a genetic disorder affecting the lungs and other organs. At the molecular level, the medication works by improving the function of the CFTR protein, which is defective in cystic fibrosis patients, thereby enhancing chloride transport across cell membranes. It is classified pharmacologically as a CFTR modulator, aiming to correct the underlying protein defect in cystic fibrosis.

Investigated diseases

Cystic Fibrosis – Cystic fibrosis is a genetic disorder that affects the respiratory and digestive systems. It is caused by mutations in the CFTR gene, leading to the production of thick and sticky mucus. This mucus can clog the airways, causing breathing difficulties and frequent lung infections. Over time, the buildup of mucus can also affect the pancreas, hindering the digestion and absorption of nutrients. The disease progresses with recurring respiratory infections and can lead to lung damage. It is a lifelong condition that requires ongoing management to maintain quality of life.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-514173-22-00Protocol codeVX20-121-104Estimated enrolment844 patientsSponsorVertex Pharmaceuticals Inc.

sourced from the EU Clinical Trials Register and site verification

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