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A Study of ADX-324 to Prevent Attacks in Patients With Hereditary Angioedema

Fast replyInvestigationalNo placebo
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What is this trial about?

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

This study is looking at a condition called Hereditary Angioedema, which is a rare genetic disorder that causes repeated episodes of severe swelling in different parts of the body such as the hands, feet, face, intestinal tract, and airways. These swelling episodes, called attacks, can be painful and potentially dangerous, especially when they affect the throat and airways. The study will test a medication called ADX-324, which is given as an injection under the skin, against placebo to see if it can help prevent these swelling attacks from happening. The purpose of the study is to find out if ADX-324 works to prevent swelling attacks in people with this condition.

The study is designed so that participants will be randomly assigned to receive either ADX-324 or placebo. The study is double-blind, which means that neither the participants nor the doctors will know who is receiving the actual medication or placebo during the treatment period. Before starting the treatment, there will be a screening period lasting up to eight weeks to confirm that participants have the right type of condition and experience swelling attacks frequently enough to be part of the study. During this screening time, doctors will check medical history and confirm the diagnosis through specific blood tests that measure certain proteins and complement levels in the blood.

The treatment period will last for 25 weeks, during which participants will receive regular injections of either ADX-324 or sterile normal saline, which is the placebo. Throughout the study, participants will need to keep track of any swelling attacks they experience and will have access to rescue medication that they have used before to treat attacks when they occur. The study will measure how many swelling attacks occur during the treatment period, how many attacks require the use of rescue medication, and how many participants remain free from attacks. Doctors will also look at the severity of any attacks that do occur and compare the results between those receiving ADX-324 and those receiving placebo.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Screening period

    During the first 4 to 8 weeks, your condition will be monitored to confirm eligibility for the trial. The screening period lasts either 4 weeks if you experience at least 1 confirmed attack, or 8 weeks if you experience at least 2 confirmed attacks.

    This period serves to establish your baseline attack rate, which refers to how often you experience episodes of swelling.

  2. Step 2

    Random assignment to treatment group

    You will be randomly assigned to one of two groups. One group will receive ADX-324, which is the medication being tested. The other group will receive a placebo, which is a sterile salt water solution (0.9% sodium chloride) that contains no active medication.

    Neither you nor the medical staff will know which treatment you are receiving. This is called a double-blind study design.

  3. Step 3

    Treatment period with injections

    You will receive injections under the skin (subcutaneous injections) of either ADX-324 or placebo.

    The treatment period will last for 25 weeks.

    The injections will be administered according to a schedule determined by the study protocol. The exact frequency of injections will be provided during the trial.

  4. Step 4

    Monitoring from day 22 onwards

    Starting from day 22 of treatment until the week 25 visit, the number and severity of your swelling attacks will be carefully monitored and recorded.

    This period is the main evaluation phase where the effectiveness of the treatment is assessed.

    You will continue to have access to your usual emergency medication to treat any swelling attacks that occur during the trial. This may include treatments such as C1-inhibitor concentrate (a protein replacement therapy) or bradykinin B2-receptor antagonist (a medication that blocks certain chemical signals causing swelling).

  5. Step 5

    Regular assessments and visits

    Throughout the 25-week treatment period, you will attend scheduled visits where the medical team will assess your condition.

    During these visits, information about any swelling attacks, their severity, and whether you needed emergency medication will be collected.

    The medical team will also monitor your safety and any potential side effects from the injections.

  6. Step 6

    Final assessment at week 25

    At the end of the 25-week treatment period, a final assessment will be conducted.

    The total number of swelling attacks you experienced from day 22 to week 25 will be calculated and compared between the treatment groups.

    Additional evaluations will include how many attacks required emergency treatment, how many were moderate or severe, and whether you remained free of attacks during the monitoring period.

Who can join the trial?

7 criteria

  • You must be 18 years of age or older.
  • You must have a confirmed diagnosis of Hereditary Angioedema type 1 or type 2, which is a rare condition that causes episodes of swelling in different parts of the body. This diagnosis must be supported by:
    • A medical history showing symptoms consistent with this condition.
    • Laboratory test results that confirm at least 2 of the following: low levels of a protein called C1-INH (either the amount of the protein or how well it works), or specific genetic changes, or low levels of a blood component called complement factor C4.
    • At least one of the following: your symptoms started before age 30, or you have family members with the same condition, or normal levels of another blood component called complement component 1q.
    • You must experience at least 1 attack of swelling confirmed by the study doctor during the first 4 weeks of the screening period, or at least 2 attacks confirmed by the study doctor during 8 weeks of the screening period.
    • You must have access to and be able to use emergency medication to treat sudden swelling attacks, which has worked for you in the past.
    • Your doctor must determine that using medication only when attacks occur, rather than taking daily preventive medication, is appropriate for your medical situation.

Who cannot join the trial?

3 criteria

  • The source data does not provide specific exclusion criteria for this clinical trial
  • Exclusion criteria are reasons why a person cannot take part in a study, but these details were not included in the available information
  • Without the complete list of exclusion criteria, it is not possible to determine which conditions or situations would prevent participation in this study
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Investigated drugs

  • ADX-324

    is an experimental medication being tested in this study. It works by using a technology called siRNA to target a protein called prekallikrein in the body. This medication is being studied to see if it can help prevent attacks in people with hereditary angioedema, which is a condition that causes sudden swelling in different parts of the body.

  • Placebo

    is an inactive substance that looks like the real medication but contains no active treatment. It is used in this study to compare against the experimental medication to help determine if the medication is truly effective.

What is already known about the treatment

ADX-324 – ADX-324 is an experimental medication currently being studied in Phase 3 clinical trials for the prevention of attacks in people with Hereditary Angioedema, a rare genetic condition that causes sudden swelling in various parts of the body. This medication works by using small interfering RNA (siRNA) technology to target and reduce the production of prekallikrein, a protein in the blood that plays a key role in triggering the swelling episodes characteristic of this disease. The drug is being tested in a controlled study to determine if it can effectively reduce the frequency of these potentially dangerous swelling attacks compared to a placebo treatment.

Investigated diseases

Hereditary Angioedema – Hereditary Angioedema is a rare genetic disorder that causes episodes of swelling in various parts of the body. The swelling most commonly affects the skin, digestive system, and airways. These swelling attacks occur because the body does not properly regulate certain proteins that control inflammation. Episodes can happen without warning or may be triggered by stress, illness, or minor injuries. The swelling typically develops over several hours and can last for several days before gradually resolving. Between attacks, people with this condition usually have no symptoms and appear healthy.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-521352-38-00Protocol codeADX-324-301Estimated enrolment89 patientsSponsorAdarx Pharmaceuticals Inc.

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).