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Study on Long-Term Safety of Donidalorsen for Patients with Hereditary Angioedema

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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 Hereditary Angioedema (HAE), a rare genetic condition that causes sudden swelling in various parts of the body, such as the face, hands, and feet. The study will use a treatment called Donidalorsen, which is an injection designed to help prevent these swelling attacks. Donidalorsen is a type of medication known as an antisense oligonucleotide, which works by targeting specific genetic material to reduce the frequency of HAE attacks.

The purpose of this study is to evaluate the long-term safety of using Donidalorsen in patients with HAE. Participants in the study will receive regular injections of Donidalorsen and will be monitored over an extended period to assess how well the treatment works and to identify any potential side effects. The study will also track the number of HAE attacks participants experience each month and how the treatment affects their quality of life.

Throughout the study, participants will have regular check-ups with healthcare professionals to ensure their safety and to gather information on the effectiveness of the treatment. The study aims to provide valuable insights into the long-term use of Donidalorsen for managing Hereditary Angioedema and to improve the overall understanding of this condition.

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, participants must provide a written and signed informed consent form. This is a document that confirms understanding and agreement to participate in the study.

    Participants must have access to at least one medication to treat angioedema attacks, such as plasma-derived or recombinant C1-INH concentrate or a bradykinin receptor antagonist.

  2. Step 2

    Eligibility confirmation

    Participants must have completed a previous study with the medication ISIS 721744 through Week 25 or have an acceptable safety profile if exiting early.

    Participants must be at least 12 years old and have a documented diagnosis of hereditary angioedema (HAE) type 1 or 2.

    Participants must be on a stable dose of prophylaxis treatment with lanadelumab, berotralstat, or C1-esterase inhibitor for at least 12 weeks before the screening period.

  3. Step 3

    Treatment administration

    The medication used in this study is called donidalorsen, also known as ISIS 721744. It is administered as a subcutaneous injection, which means it is injected under the skin.

    The study aims to evaluate the safety of long-term dosing with donidalorsen in patients with hereditary angioedema.

  4. Step 4

    Monitoring and evaluation

    The primary focus is on the incidence and severity of any adverse events that occur during treatment.

    Secondary evaluations include the frequency of hereditary angioedema attacks, the percentage of attack-free patients, and the quality of life over the course of 53 weeks.

  5. Step 5

    Study duration

    The study is expected to continue until November 6, 2026.

    Participants will be monitored throughout the study to ensure safety and to assess the effectiveness of the treatment.

Who can join the trial?

6 criteria

  • Participants and, if needed, their legally authorized representatives (like a parent or legal guardian) must provide a written and signed informed consent form. This means they agree to join the study after understanding what it involves.
  • Participants must have access to and be able to use at least one medication to treat sudden swelling attacks. This is for those who are already part of the Open-Label Extension group.
  • Participants must have successfully completed a previous study called ISIS 721744-CS5 through Week 25, or be allowed to leave that study with a good safety and tolerability profile. This is for new participants who have not used donidalorsen before.
  • Participants must be at least 12 years old at the time they give their consent to join the study.
  • Participants must have a documented diagnosis of **Hereditary Angioedema** (HAE), specifically types HAE-1 or HAE-2.
  • Participants must have been on a stable dose of preventive treatment with medications like lanadelumab, berotralstat, or C1-esterase inhibitor for at least 12 weeks before the screening period of the study.

Who cannot join the trial?

4 criteria

  • Patients who do not have **Hereditary Angioedema** cannot participate. **Hereditary Angioedema** is a rare genetic condition that causes sudden swelling in different parts of the body.
  • Patients who are not within the specified age ranges cannot participate. The age ranges include children, teenagers, and adults.
  • Both **male** and **female** patients are considered for participation, so gender is not an exclusion criterion.
  • Patients who are part of a **vulnerable population** may not be eligible. A **vulnerable population** includes groups like children, pregnant women, or those unable to give consent.
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Investigated drugs

Donidalorsen is a medication being studied for its ability to prevent attacks in patients with Hereditary Angioedema (HAE). This trial aims to assess the long-term safety and effectiveness of using donidalorsen regularly to reduce the frequency and severity of HAE episodes.

What is already known about the treatment

Donidalorsen – Donidalorsen is administered as an injection, typically under the skin, and is currently being studied in clinical trials for its long-term safety and effectiveness in treating hereditary angioedema (HAE). This medication is not yet widely available in medical practice, as it is still under investigation. It is primarily indicated for the prophylactic treatment of HAE, a condition characterized by recurrent episodes of severe swelling. Donidalorsen works by targeting specific molecules involved in the inflammatory process that leads to swelling, helping to prevent these episodes. It falls under the pharmacological classification of antisense oligonucleotides, which are designed to interfere with the production of proteins that contribute to disease symptoms.

Investigated diseases

Hereditary Angioedema – Hereditary Angioedema is a rare genetic disorder characterized by recurrent episodes of severe swelling. This swelling can affect various parts of the body, including the hands, feet, face, and airway. The condition is caused by a deficiency or dysfunction of a protein called C1 inhibitor, which leads to an overproduction of bradykinin, a peptide that increases blood vessel permeability. Swelling episodes can be triggered by stress, trauma, or hormonal changes, but they often occur without a clear cause. The frequency and severity of attacks can vary widely among individuals. Swelling in the airway can be particularly dangerous, requiring immediate medical attention.
Trial detailsLast updated 4 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-509201-77-00Protocol codeISIS 721744-CS7Estimated enrolment55 patientsSponsorIonis Pharmaceuticals Inc.

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