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Long-term safety and efficacy study of elexacaftor/tezacaftor/ivacaftor treatment in people with cystic fibrosis who have non-F508del genetic mutations

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What is this trial about?

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

This study investigates the long-term safety and effectiveness of a medication called elexacaftor/tezacaftor/ivacaftor for people with cystic fibrosis. Cystic fibrosis is a genetic disease that affects multiple organs, primarily the lungs and digestive system, causing thick, sticky mucus to build up, which leads to breathing difficulties and other health problems. The study specifically focuses on individuals who have genetic variants of cystic fibrosis that do not include the F508del mutation.

The purpose of this research is to evaluate how safe and effective this medication combination is when used over an extended period. Participants in the study will take the medication and attend scheduled follow-up visits where various assessments will be performed. These assessments will monitor lung function, weight changes, quality of life, and the amount of salt in sweat (a marker used to evaluate cystic fibrosis severity).

The study is designed in two parts (Part A and Part B), allowing for continuous evaluation of the medication's effects. Throughout the study, participants will maintain their regular cystic fibrosis treatments (except for other CFTR modulators, which are medications that target the underlying cause of cystic fibrosis by improving the function of the defective protein responsible for the disease).

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment in the Long-term Safety Study

    After signing the informed consent form, you will be enrolled in this long-term study that evaluates the safety and effectiveness of a medication combination for cystic fibrosis.

    This study is specifically for people with cystic fibrosis who do not have the F508del genetic mutation.

    The study consists of two parts: Part A and Part B, which will evaluate how well you tolerate the medication combination over an extended period.

  2. Step 2

    Medication Regimen

    You will take a combination of three medications called elexacaftor/tezacaftor/ivacaftor (also known as ELX/TEZ/IVA or by the brand name Kaftrio).

    Depending on your age and weight, you will receive either Kaftrio 37.5 mg/25 mg/50 mg film-coated tablets or Kaftrio 75 mg/50 mg/100 mg film-coated tablets.

    You will also take ivacaftor (brand name Kalydeco) as either 75 mg or 150 mg film-coated tablets.

    These medications will be taken daily according to the schedule provided by your study doctor.

  3. Step 3

    Regular Study Visits

    Throughout the study, you will attend scheduled clinic visits to monitor your health and response to treatment.

    During these visits, the study team will perform various assessments to track your progress.

    You must maintain your regular cystic fibrosis treatments (except for other CFTR modulators, which are medications that target the defective protein in cystic fibrosis) throughout the study period.

  4. Step 4

    Health Assessments

    The study team will regularly monitor your health through several tests:

    Lung function tests to measure your FEV1 (the amount of air you can forcefully exhale in one second)

    Sweat chloride tests to measure the amount of salt in your sweat, which is typically elevated in people with cystic fibrosis

    Completion of the CFQ-R questionnaire, which asks about your respiratory symptoms and quality of life

    Measurements of your weight and BMI (body mass index, which is a calculation based on your height and weight)

    Tracking of any pulmonary exacerbations (episodes when your lung symptoms get worse)

  5. Step 5

    Safety Monitoring

    Throughout the study, your safety will be closely monitored through:

    Adverse event reporting (any unexpected medical problems you experience)

    Blood tests and other laboratory assessments

    ECGs (electrocardiograms, which record the electrical activity of your heart)

    Vital signs measurements (like blood pressure and heart rate)

    Pulse oximetry (measuring the oxygen level in your blood)

  6. Step 6

    Transition from Part A to Part B

    After completing Part A of the study, if you meet the criteria, you will continue to Part B.

    Part B will follow a similar format to Part A, continuing to evaluate the long-term safety and effectiveness of the medication.

  7. Step 7

    Study Completion

    The study is scheduled to run until April 2027.

    Upon completion of the study, your study doctor will discuss next steps for your cystic fibrosis treatment.

Who can join the trial?

7 criteria

  • You must sign an informed consent form (and an assent form if appropriate). If you're under 18, your parent or legal guardian will need to sign.
  • You must be willing and able to follow the study schedule, including visits, treatment plan, restrictions, laboratory tests, and contraceptive guidelines (if applicable).
  • If you're under 18, your parent or guardian must understand the study requirements and be able to help you complete the study as planned.
  • You must not have withdrawn consent from the previous study you participated in (called the parent study).
  • For Part A of the study: You must have either completed the treatment in the parent study OR had interruptions but still completed all scheduled visits during the treatment period.
  • For Part B of the study: You must have either completed the treatment in Part A OR had interruptions but still completed all scheduled visits during the treatment period of Part A.
  • You must be willing to stay on your stable cystic fibrosis (CF) treatment plan (except for CFTR modulators - medications that target the defective protein in CF) throughout the study.

Who cannot join the trial?

12 criteria

  • Children or people under 12 years old cannot participate.
  • People who have abnormal liver function (problems with how well the liver works) shown in blood tests.
  • People with a history of alcohol or drug abuse within the past year.
  • People who have a history of organ transplantation (surgical procedure where an organ is removed from one person and placed in another).
  • People with unstable lung disease (lung condition that is not stable or is getting worse).
  • People who had a respiratory infection (infection affecting the lungs or airways) within 4 weeks before starting the study.
  • People who cannot perform the required breathing tests properly.
  • People who have abnormal kidney function (problems with how well the kidneys work) shown in blood tests.
  • People who have taken part in another clinical trial within 30 days.
  • Pregnant women or women who are breastfeeding.
  • People who are allergic to the study medications or any of their ingredients.
  • People with severe medical conditions that might interfere with the study or put them at risk.
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Investigated drugs

Elexacaftor/Tezacaftor/Ivacaftor is a combination medication used to treat cystic fibrosis. It works by improving the function of a defective protein called CFTR (cystic fibrosis transmembrane conductance regulator) in people with certain genetic mutations. This medication helps thin the mucus in the lungs and other organs, which can help reduce infections and improve breathing in people with cystic fibrosis.

What is already known about the treatment

  • Elexacaftor

    This medication is administered orally as part of a triple combination therapy for cystic fibrosis. It is FDA-approved and widely supported in medical literature as an effective treatment for specific genetic variants of cystic fibrosis, particularly in patients with non-F508del CFTR genotypes. Elexacaftor works at the molecular level by improving the processing and function of defective CFTR protein, helping to increase chloride transport in cells lining the lungs and other organs. It belongs to the class of CFTR modulators, specifically acting as a CFTR corrector that helps the abnormal protein fold properly and reach the cell surface.

  • Tezacaftor

    This oral medication is part of a triple combination therapy used in treating cystic fibrosis patients with specific genetic mutations. It has established efficacy in clinical trials and is approved for use in combination with other CFTR modulators for treating cystic fibrosis. Tezacaftor works by helping the defective CFTR protein fold correctly and move to the cell surface, addressing the underlying cause of cystic fibrosis rather than just treating symptoms. Pharmacologically, it is classified as a CFTR corrector that works synergistically with other modulators to improve lung function and reduce pulmonary exacerbations in patients with specific CFTR mutations.

  • Ivacaftor

    This oral medication is a well-established treatment for cystic fibrosis, used alone or in combination therapies depending on a patient's specific genetic mutation. It has been extensively studied in clinical trials and was the first CFTR modulator approved, revolutionizing cystic fibrosis treatment by targeting the underlying cause of the disease. Ivacaftor works at the molecular level by increasing the open time of the CFTR protein channel at the cell surface, allowing better chloride ion flow, which helps thin mucus in the lungs and other organs. It belongs to the class of CFTR modulators known as potentiators, which enhance the function of the CFTR protein once it reaches the cell surface.

Investigated diseases

Cystic Fibrosis is a genetic disorder that affects the cells that produce mucus, sweat, and digestive fluids, causing these secretions to become abnormally thick and sticky. In the lungs, this thick mucus clogs the airways and traps bacteria, leading to infections, inflammation, and respiratory problems that progressively worsen over time. The digestive system is also affected, as the thick secretions block ducts in the pancreas, preventing digestive enzymes from reaching the intestines to help break down food. As the disease progresses, patients experience decreased lung function, malnutrition due to poor nutrient absorption, and other complications such as sinus infections and diabetes. Cystic fibrosis is caused by mutations in the CFTR gene, which regulates salt and water movement in and out of cells.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-515637-14-00Protocol codeVX21-445-125Estimated enrolment323 patientsSponsorVertex Pharmaceuticals Inc.

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