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Long‑Term Safety Study of ADX‑324 in Participants with Hereditary Angioedema (Phase 3 Extension)

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What is this trial about?

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

The study looks at a rare condition called Hereditary Angioedema, which causes sudden swelling of the face, lips, hands, or throat. The treatment being tested is a new medicine called ADX-324, which works by turning off a specific gene signal (siRNA) that can trigger swelling. Participants will receive either the study medicine by a subcutaneous injection (an injection under the skin) or a simple salt water solution called sterile normal saline that acts as a placebo. The main goal is to see how safe the medicine is when given repeatedly over a long period.

After enrollment, participants will receive the assigned injection at regular intervals for several months, and they will be asked to keep a simple diary of any swelling episodes and any side effects they notice. Doctors will check in regularly to record any adverse events and to count how many swelling attacks occur, but no detailed imaging or laboratory tests are described here. The study will continue until enough information about long‑term safety has been collected.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment confirmation

    After joining the study, you provide written consent and allow the study team to review your medical history related to hereditary angioedema.

    The study staff records baseline information, including the number of previous attacks and any current medications.

  2. Step 2

    Baseline visit

    A comprehensive medical evaluation is performed, which may include physical examination, laboratory tests, and documentation of your current health status.

    The information collected serves as a reference point for later comparisons during the study.

  3. Step 3

    First dose administration

    You receive an injection of adx-324 or, if assigned to the control group, an injection of sterile normal saline (0.9% sodium chloride solution).

    The injection is given subcutaneously, meaning it is placed just under the skin.

    The specified dose of adx-324 is 00 mg, delivered as a solution for injection.

  4. Step 4

    Post‑injection observation

    After the injection, you remain in the clinic for a short observation period, typically about thirty minutes, so that any immediate reactions can be identified and treated promptly.

  5. Step 5

    Scheduled follow‑up visits

    You attend regular clinic visits according to the study schedule, which continue throughout the extension period that runs from august 2026 to april 2030.

    At each visit, safety assessments are performed, including checks for adverse events and laboratory testing.

    You also record any hereditary angioedema attacks that occur between visits.

  6. Step 6

    Repeat dosing

    At each scheduled visit, you receive another subcutaneous injection of adx-324 (or sterile normal saline if you are in the control group) at the same dose of 00 mg.

    This repeat dosing continues for the duration of the extension study, providing long‑term exposure to the medication.

  7. Step 7

    Ongoing safety monitoring

    Throughout the study, you are asked to report any side effects, new symptoms, or changes in health status to the study staff.

    Regular laboratory tests and clinical evaluations help the investigators assess the long‑term safety of repeat dosing.

  8. Step 8

    Final visit and study completion

    At the end of the study period in april 2030, a final visit is scheduled.

    Comprehensive assessments are performed, including a summary of all recorded hereditary angioedema attacks and any adverse events that occurred.

    All study data are collected and the participant’s involvement in the trial concludes.

Who can join the trial?

5 criteria

  • You must have hereditary angioedema (HAE), a rare condition that causes sudden swelling of the skin and deeper tissues.
  • You must have received two doses of the study medication (ADX‑324 or a placebo) in the earlier study ADX‑324‑301 and completed that study, including follow‑up through week 25.
  • You must sign a written consent form and any other required legal documents, and agree to follow all study rules for the entire trial.
  • You need to have access to, and be able to use, at least one fast‑acting treatment for HAE attacks (such as a plasma‑derived or recombinant C1‑INH concentrate or a BK2‑receptor antagonist) that has worked for you before.
  • If you are a woman who could become pregnant, you must have a negative urine pregnancy test on the first day of the study and agree to use a reliable contraceptive method from the time you sign the consent until the end of the study or three months after the last dose, whichever is later. Men with partners who could become pregnant must also agree to use a reliable contraceptive method for the same period.

Who cannot join the trial?

2 criteria

  • You cannot join if you had serious side effects in a previous study, known as unacceptable toxicity. This includes a lab pattern called Hy's law, which means liver tests show ALT or AST at least three times the normal upper limit (ULN) and total bilirubin at least twice the normal level, while ALP is less than twice normal, and no other reason explains these findings; it also includes a severe allergic reaction (grade 3 or higher) to the study drug, called a hypersensitivity reaction.
  • You cannot join if you have any other health condition, abnormal lab result, heart test (ECG), vital sign (such as blood pressure or heart rate), or physical exam finding that the doctor believes would place you at an unacceptable risk for participation.
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Investigated drugs

ADX-324 is an experimental medicine that uses a small piece of genetic material called siRNA to lower the amount of a protein called prekallikrein in the body. By reducing prekallikrein, the drug aims to prevent or lessen the swelling attacks that occur in people with hereditary angioedema. In the study, participants receive ADX-324 as a liquid that is injected just under the skin. The main goal of the trial is to see how safe it is to give this medication repeatedly over a long period.

What is already known about the treatment

  • Sterile normal saline (0.9% sodium chloride solution)

    This sterile solution is given by injection, usually intravenously, to provide a safe, isotonic fluid that matches the body’s natural salt balance. It is widely used in hospitals and is considered a standard, well‑known product with no active drug ingredients, making it suitable as a placebo in clinical studies. The main use is to replace lost fluids and electrolytes, and it serves as a control to compare the effects of the test medication. It belongs to the class of isotonic crystalloid solutions.

  • ADX-324

    ADX‑324 is administered as a subcutaneous injection of a clear solution designed for patients with hereditary angioedema. It is an investigational drug currently in clinical trials and not yet approved for general medical use. The medication works by using small interfering RNA (siRNA) to lower the production of prekallikrein, a protein that contributes to swelling attacks, thereby helping to prevent episodes. It is classified as an RNA interference therapeutic targeting the immune system.

Investigated diseases

Hereditary Angioedema - Hereditary Angioedema is a genetic condition that causes sudden swelling in various parts of the body, such as the skin, gastrointestinal tract, and airways. The swelling results from excess fluid leaking into tissues due to a missing or low level of a protein that controls certain chemical reactions. Episodes can appear without warning and may last from a few hours to several days. Over time, individuals may experience more frequent attacks, and the swelling can affect different areas each time.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-521353-16-00Protocol codeADX-324-302Estimated enrolment98 patientsSponsorAdarx Pharmaceuticals Inc.

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