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A Phase 3 study to evaluate the efficacy and safety of ION582 in children and adults with Angelman syndrome

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What is this trial about?

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

This study aims to evaluate the efficacy and safety of ION582 in children and adults with Angelman syndrome. This condition is a rare genetic disorder typically caused by a deletion, which is a missing piece of genetic material, or a mutation, which is a change in the DNA sequence, of the UBE3A gene. The study focuses on how this specific genetic change affects the body and brain.

The treatment being investigated is ION582, which is a type of antisense oligonucleotide. This is a specialized substance designed to target and interact with specific parts of genetic instructions to help manage the effects of the disease. The medication will be delivered through an intrathecal injection, which is a method where the medicine is injected into the fluid surrounding the brain and spinal cord.

During the study, participants will receive the medication and undergo regular follow-up periods to monitor how they are doing. The duration of the observation for participants is approximately 52 weeks. This process allows for the monitoring of various aspects of health and development over time.

The research process

The trial runs in 3 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Participation in the study

    After joining the study, the treatment phase begins to evaluate the effects of the study medication ION582.

    The medication ION582 is an injection administered via intrathecal use, which means it is delivered directly into the spinal fluid.

  2. Step 2

    Medication administration

    The dose of ION582 is 80 mg.

  3. Step 3

    Monitoring and evaluation

    Assessments are conducted at baseline, which is the starting point before treatment, and continue through week 52.

    Evaluations include measuring changes in communication abilities, thinking skills, fine motor skills, and daily living skills.

    The progress of angelman syndrome symptoms, including sleep problems, is monitored by a clinician.

    Medical safety is tracked by checking vital signs (such as pulse and blood pressure), clinical laboratory results, and any adverse events (side effects) that may occur up to week 52.

Who can join the trial?

6 criteria

  • The person looking after the patient or their legally-authorized representative (someone allowed by law to make medical decisions for the patient) must provide written permission to join the study and follow all study rules.
  • The patient must be medically stable, meaning their health condition is steady and not changing rapidly, and they must be able to undergo sedation (medicine used to make a person sleepy or relaxed) or general anesthesia (medicine that puts a person into a deep sleep for a procedure) without needing a breathing tube placed down their throat, which is called intubation.
  • The participant can be male or female and must be between 2 and 50 years of age at the time of the first screening visit.
  • The participant must have a confirmed medical diagnosis of Angelman syndrome, which must be proven through molecular confirmation (testing the body's genetic material) showing a deletion (a missing piece) or a mutation (a change) in the UBE3A gene.
  • The participant must have been taking their usual, steady doses of concomitant medications (other medicines being taken at the same time) for at least 8 weeks before the study begins. These may include anti-epileptic medications (medicine used to prevent seizures), medicines for behavior, sleep medicines, gabapentin, cannabidiol, or specific diets and nutritional supplements.
  • The caregiver or representative must agree not to share any of the participant's private medical information or study details on any social media websites or platforms.

Who cannot join the trial?

6 criteria

  • You cannot participate if you have had major surgery within the last 3 months or if you have other health issues that would make it unsafe to use an antisense oligonucleotide (ASO), which is a type of medicine designed to change how certain genes work.
  • You cannot participate if you have a known disease of the brain or spine that would make a lumbar puncture (LP) unsafe; a lumbar puncture is a medical procedure where a needle is used to collect fluid from the area around the spinal cord.
  • You cannot participate if the study doctor believes you have any other health conditions that would make it difficult or unsafe for you to take part in or finish the study.
  • You cannot participate if your laboratory results (such as blood tests) or physical exams show health problems that the doctor believes make it unsuitable for you to join the study.
  • You cannot participate if you have previously received gene editing or treatments involving oligonucleotides, which are small pieces of genetic material used to affect gene activity; however, this does not include approved mRNA vaccines.
  • You cannot participate if your Angelman syndrome is caused by specific genetic patterns such as paternal uniparental disomy (where a child inherits two copies of a chromosome from the father and none from the mother), imprinting defects (problems with how genes are turned on or off), or mosaic findings (where some cells in the body have a different genetic makeup than others).
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Investigated drugs

ION582 is an experimental injection given directly into the fluid surrounding the spinal cord. This medication is designed to work with the body's genetic instructions to help increase the activity of a specific protein that is missing or not working correctly in people with Angelman syndrome.

What is already known about the treatment

ION582 - This medication is an experimental injection administered directly into the fluid surrounding the spinal cord to treat Angelman syndrome. Currently being studied in clinical trials, it belongs to a class of drugs known as antisense oligonucleotides. It works by targeting and blocking a specific piece of genetic material that prevents a necessary protein from being produced in the brain. By stopping this interference, the drug aims to help the body produce more of the protein needed for normal nerve cell function.

Investigated diseases

Angelman syndrome - This condition is a genetic disorder caused by a loss of function in a specific gene called UBE3A. It typically affects the development of the brain and nervous system. People with this condition often experience delays in reaching developmental milestones, such as sitting, walking, or talking. It is frequently characterized by significant challenges with communication and movement. Over time, the symptoms can impact various aspects of daily living and cognitive functions.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-519711-33-01Protocol codeION582-CS2Estimated enrolment158 patientsSponsorIonis Pharmaceuticals Inc.

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