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Study on the Effects of Dirocaftor, Posenacaftor, and Nesolicaftor for Adults with Cystic Fibrosis

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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 condition that affects the lungs and digestive system. The study will evaluate the effectiveness and safety of three investigational treatments: Dirocaftor (also known as PTI-808), Posenacaftor (PTI-801), and Nesolicaftor (PTI-428). These treatments are being tested to see if they can help improve the health of individuals with cystic fibrosis by targeting specific genetic mutations associated with the disease.

The purpose of the study is to assess how well these treatments work over a period of 8 weeks. Participants will be randomly assigned to receive either the investigational treatments or a placebo. The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving the actual treatment or the placebo. This helps ensure that the results are not biased. The study will follow a crossover design, which means that participants will have the opportunity to receive both the investigational treatments and the placebo at different times during the study.

Throughout the study, participants will have regular check-ups to monitor their health and assess the effects of the treatments. These check-ups will include measurements of lung function, sweat chloride levels, and weight, as well as questionnaires about respiratory symptoms. The study aims to provide valuable information on the potential benefits of these treatments for people with cystic fibrosis, particularly those with rare genetic mutations. The total duration of the study is expected to be 16 weeks, with participants receiving treatment for 8 weeks and then switching to the other treatment option for another 8 weeks.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Beginning of the trial

    Upon joining the study, you will be randomly assigned to receive either the study medication or a placebo. A placebo is a substance with no active medication, used to compare the effects of the actual medication.

    The study is designed to be double-blind, meaning neither you nor the study team will know which treatment you are receiving. This helps ensure the results are unbiased.

  2. Step 2

    Medication administration

    You will take the study medication or placebo orally in the form of a hard capsule. The medications involved in the study are dirocaftor, posenacaftor, and nesolicaftor.

    The treatment period lasts for 8 weeks, during which you will follow the prescribed dosage and frequency as instructed by the study team.

  3. Step 3

    Regular assessments

    Throughout the study, you will undergo regular assessments to monitor your health and the effects of the treatment. These assessments include measuring your lung function, specifically the forced expiratory volume in one second (FEV1), which is a test to see how well your lungs are working.

    Additional assessments will include measuring your sweat chloride levels, weight, and completing a questionnaire about your respiratory health.

  4. Step 4

    End of treatment evaluation

    At the end of the 8-week treatment period, you will have a final evaluation to assess the overall effects of the medication. This will include the same tests and measurements conducted during the study.

    The results will help determine the efficacy and safety of the study medication for individuals with cystic fibrosis.

Who can join the trial?

13 criteria

  • Must be a male or female who completed the HIT-CF Organoid Study and is 18 years of age or older.
  • Must have a confirmed diagnosis of Cystic Fibrosis (CF), which includes:
    • A sweat chloride value of 60 mmol/L or higher (a test to measure salt in sweat) OR
    • Two CF-causing genetic mutations AND
    • Chronic lung or sinus problems, or digestive/nutritional issues.
    • Must have clinically stable CF as judged by the study doctor, with no major health changes in the last 28 days.
    • Must have a lung function test result (FEV1) between 40% and 90% of what is predicted for their age and size.
    • Must have a Body Mass Index (BMI) between 16 kg/m² and 30 kg/m².
    • Must be a non-smoker and not use any tobacco products for at least 30 days before the study starts, and agree not to use them during the study.
    • If able to have children, must meet the study's contraception requirements.
    • Must be willing to stay on a stable medication plan for CF from 28 days before the study starts until the end of the study.
    • Must be willing and able to follow the study's schedule, treatment plan, and other requirements.
    • Must be selected by the study team based on specific criteria or randomly.
    • Must sign and date an informed consent form to participate in the study.

Who cannot join the trial?

4 criteria

  • Patients who do not have Cystic Fibrosis cannot participate. Cystic Fibrosis is a genetic condition that affects the lungs and digestive system.
  • Patients who are not within the specified age range cannot participate. The study is open to children and adults.
  • Both male and female patients can participate, but those who do not identify as either may not be eligible.
  • Patients who are considered part of a vulnerable population cannot participate. This means groups who may need special protection, like pregnant women or people unable to give consent.
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Investigated drugs

  • Dirocaftor

    is a medication being studied for its potential to help people with cystic fibrosis, a condition that affects the lungs and digestive system. It works by targeting a specific protein in the body that is not functioning properly in people with this condition. The goal of this medication is to improve the function of this protein, which may help improve lung function and overall health in patients.

  • Posenacaftor

    is another medication included in the study for cystic fibrosis. Like Dirocaftor, it aims to help correct the function of a faulty protein in the body. By doing so, it may help reduce the symptoms of cystic fibrosis, such as breathing difficulties and frequent lung infections, and improve the quality of life for those affected by the condition.

  • Nesolicaftor

    is the third medication being tested in this clinical trial for cystic fibrosis. It is designed to work alongside Dirocaftor and Posenacaftor to enhance their effects. Together, these medications aim to improve the function of the defective protein in cystic fibrosis patients, potentially leading to better lung function and fewer health complications related to the disease.

What is already known about the treatment

Dirocaftor/Posenacaftor/Nesolicaftor – This medication is administered orally and is currently being studied in clinical trials for its effectiveness in treating cystic fibrosis, a genetic disorder that affects the lungs and other organs. The medication is in the experimental stage and is being evaluated for its ability to improve symptoms in patients with specific genetic mutations related to cystic fibrosis. It works by targeting and enhancing the function of a protein called CFTR, which is defective in cystic fibrosis patients, helping to improve the flow of salt and fluids in the cells. This combination of drugs is classified as a CFTR modulator, aiming to correct the underlying cause of cystic fibrosis rather than just alleviating symptoms.

Investigated diseases

Cystic Fibrosis – Cystic Fibrosis is a genetic disorder that affects the respiratory, digestive, and reproductive systems. It is characterized by the production of thick and sticky mucus that can clog the airways and lead to respiratory issues. Over time, this mucus buildup can cause persistent lung infections and damage to the lungs. In the digestive system, the thick mucus can block the ducts of the pancreas, preventing digestive enzymes from reaching the intestines and leading to malnutrition. The disease progresses with increasing respiratory difficulties and frequent lung infections. It is a lifelong condition that requires ongoing management to address the symptoms and complications.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2022-500410-26-00Protocol codeHIT-CF-001Estimated enrolment41 patientsSponsorUniversitair Medisch Centrum Utrecht

sourced from the EU Clinical Trials Register and site verification

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