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Study on the Safety and Effectiveness of BI 3720931 for Adults with Cystic Fibrosis Who Cannot Use CFTR Modulators

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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 the effects of a new treatment for cystic fibrosis, a genetic condition that affects the lungs and digestive system. The treatment being tested is called BI 3720931, which is an inhaled gene therapy. Gene therapy is a technique that uses genes to treat or prevent disease. In this study, the therapy is delivered through a nebulizer, a device that turns liquid medicine into a mist to be inhaled into the lungs.

The purpose of the study is to evaluate the safety, tolerability, and effectiveness of a single dose of BI 3720931 in adults with cystic fibrosis who cannot use other treatments known as CFTR modulators. The study will begin with an open-label phase, where all participants will receive the treatment to determine the best dose. This will be followed by a randomized, double-blind phase, where participants will receive either the treatment or a placebo without knowing which one they are getting. This helps to ensure that the results are not biased.

Participants will be monitored for changes in their lung function, specifically looking at a measure called FEV1, which stands for forced expiratory volume in one second. This is a common test to see how well the lungs are working. The study will also track any side effects that occur after receiving the treatment. The trial is expected to continue until 2027, with recruitment starting in late 2024.

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, eligibility is confirmed based on specific criteria related to cystic fibrosis diagnosis and lung function.

    Participants must have a stable condition and meet certain health standards before proceeding.

  2. Step 2

    Phase I: Initial treatment

    Participants receive a single inhaled dose of BI 3720931, a gene therapy designed for cystic fibrosis.

    The medication is administered through inhalation, using a nebulizer solution.

  3. Step 3

    Monitoring and assessment

    Participants are monitored for any drug-related side effects up to 24 weeks after receiving the dose.

    Lung function is assessed by measuring the forced expiratory volume (FEV1pp) at various intervals, including weeks 4, 6, 8, and 24.

  4. Step 4

    Phase II: Randomized treatment

    Participants may receive a higher dose of BI 3720931 or a placebo, depending on random assignment.

    The goal is to evaluate the effectiveness of the higher dose in improving lung function compared to the placebo.

  5. Step 5

    Final evaluation

    The primary outcome is the change in lung function from the start of the study to week 8.

    Secondary outcomes include further assessments of lung function and any side effects up to week 24.

Who can join the trial?

8 criteria

  • Must be a male or female who cannot have children and has a type of cystic fibrosis that affects the lungs, with a confirmed diagnosis of cystic fibrosis.
  • Must have a positive sweat test result, which is a test that measures the amount of salt in sweat, showing 60 or more units, or have two known genetic mutations causing cystic fibrosis with certain symptoms if the sweat test result is between 30 and 59 units.
  • Must not be eligible for a specific cystic fibrosis treatment due to their genetic makeup and not expected to become eligible during the study.
  • Must be able to perform breathing tests properly according to specific standards set by health organizations.
  • Must have a lung function test result (FEV1pp) between 50% and 100% of what is considered normal for their age and size.
  • Must have stable cystic fibrosis with no worsening of lung symptoms for at least 4 weeks before the study starts and during the initial screening period, and must have stable treatment for cystic fibrosis during this time.
  • Can either have never received gene therapy or have received gene therapy for cystic fibrosis before. If they have had gene therapy, they must not have any ongoing side effects from it, and there must be a gap of 6 months since the last non-viral gene therapy or 24 months since the last viral gene therapy.
  • Additional criteria may apply.

Who cannot join the trial?

7 criteria

  • Patients who have a history of severe allergic reactions to any of the ingredients in the study medication.
  • Patients who are currently participating in another clinical trial or have participated in one within the last 30 days.
  • Patients with a history of lung transplant.
  • Patients who have a significant medical condition that the study doctor believes could interfere with the study results.
  • Patients who are pregnant or breastfeeding.
  • Patients who have a history of drug or alcohol abuse within the past year.
  • Patients who are unable to comply with the study procedures or follow-up visits.
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Investigated drugs

BI 3720931 is an inhaled gene therapy being studied for its potential to help people with cystic fibrosis who cannot use other treatments called CFTR modulators. This therapy uses a lentiviral vector, which is a type of delivery system that helps introduce new genetic material into the body. The goal of this treatment is to improve lung function by delivering a single dose directly to the lungs. The trial is designed to assess how safe and tolerable this therapy is, as well as how effective it might be in improving breathing in patients.

What is already known about the treatment

BI 3720931 – This medication is administered as an inhaled treatment and is currently being studied in clinical trials for its potential use in treating cystic fibrosis, particularly in patients who cannot use CFTR modulators. It is in the early stages of research, with ongoing evaluations of its safety, tolerability, and effectiveness. The main therapeutic indication is cystic fibrosis, a genetic disorder affecting the lungs. BI 3720931 works by delivering a lentiviral vector gene therapy directly to the lungs, aiming to correct the underlying genetic defect at the molecular level. It is classified as a gene therapy, which represents a novel approach in the pharmacological treatment of genetic diseases.

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, leading to digestive problems and poor nutrient absorption. The disease is progressive, meaning symptoms typically worsen over time. It is most commonly diagnosed in childhood, but symptoms can vary widely among individuals.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase I/IITrial ID2023-503281-23-00Protocol code1504-0001Estimated enrolment27 patientsSponsorBoehringer Ingelheim Espana S.A.

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