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Study of the safety and efficacy of intrathecal rugonersen sodium in children and adults with Angelman syndrome

Verified siteInvestigationalNo placebo
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What is this trial about?

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

The study focuses on Angelman syndrome, a rare genetic disorder that causes severe developmental delay, speech problems, and frequent seizures. The investigational medicine is rugonersen, given as an injection into the fluid that surrounds the spinal cord (intrathecal). The medication is being tested in both children and adults who have the condition.

The purpose of the study is to see whether rugonersen improves developmental abilities compared with a sham procedure. Participants receive a series of intrathecal injections over several months and attend regular visits where their brain activity is recorded with an EEG, and their skills are measured with standardized tests such as Bayley-4 (which looks at thinking, language and movement) and Vineland-3 (which looks at daily living abilities). Safety is monitored throughout the trial, and any serious adverse events or side effects are recorded using the NCI CTCAE grading system. The study runs for about a year, ending with a final assessment at week 56.

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

    Enrollment and Baseline Evaluation

    After agreeing to take part, you will complete the enrollment paperwork and give informed consent.

    The study team will record your medical history, perform a physical exam, and collect baseline measurements, including cognitive and communication scores using the Bayley‑4 test and an electroencephalogram (EEG) to measure brain activity.

  2. Step 2

    Randomization and First Dose

    You will be randomly assigned to receive either rugonersen or a sham (placebo) procedure, without knowing which one you receive.

    If assigned to the active group, you will receive a single intrathecal injection of rugonersen sodium at a dose of 120 mg. The injection is given directly into the fluid surrounding the spinal cord.

  3. Step 3

    Regular Follow‑up Visits

    You will attend scheduled clinic visits throughout the study period. During each visit, the study staff will check for side effects, record any health changes, and perform safety tests such as blood work and neurological examinations.

    These visits occur at intervals defined by the study protocol, leading up to the final evaluation at Week 56.

  4. Step 4

    Week 56 Final Assessment

    At the end of the 56‑week period, you will undergo the same assessments that were performed at baseline, including the Bayley‑4 cognition and expressive communication tests, fine motor and receptive communication tests, and an EEG.

    The results will be used to determine any changes in your condition compared with the start of the study.

  5. Step 5

    Study Completion

    After the final assessment, the study will be concluded for you. The study team will provide a summary of your participation and discuss any follow‑up care that may be needed.

Who can join the trial?

13 criteria

  • Be at least 1 year old and no older than 50 years when signing the study consent form.
  • Have a reliable caregiver (parent, legal guardian, or similar) who is at least 18 years old, can give consent for the participant, attend clinic visits, stay in contact with the study team, and complete required questionnaires.
  • Have a doctor’s diagnosis of Angelman syndrome.
  • Have medical records that confirm the diagnosis with a genetic test showing either a mutation (a change) in the UBE3A gene or a deletion (missing piece) on the mother’s chromosome 15q11‑q13 that includes the UBE3A gene.
  • Be able to follow all study procedures and instructions.
  • Be able to have blood drawn safely.
  • Be able to undergo a lumbar puncture (LP) and an intrathecal (IT) injection, using sedation or anesthesia that does not require a breathing tube (intubation).
  • Have a stable medical condition for at least 4 weeks before screening and at the time of enrollment.
  • Weigh more than 7.5 kilograms (about 16.5 pounds).
  • The caregiver must agree not to share any personal medical data or study information on websites or social media (such as Facebook, Instagram, Twitter, YouTube, TikTok, etc.) from enrollment until the study is finished.
  • Take epilepsy medicines (including cannabidiol or CBD) that have been stable for at least 12 weeks before screening, with only allowed changes for age, weight, or blood‑level safety checks.
  • Take any psychotropic medicines (medications that affect mood or behavior) that have been stable for at least 4 weeks before screening, with no dose changes.
  • Follow the study’s contraception rules, with confirmation from the caregiver that this requirement is understood and accepted.

Who cannot join the trial?

22 criteria

  • If genetic testing shows a type of Angelman syndrome called uniparental paternal disomy (UPD), an imprinting center defect (ICD), or a partial diagnosis that cannot rule out these types, you cannot join the study.
  • If your blood tests show abnormal clotting numbers, such as a low platelet count (below 140 × 10⁹/L) or abnormal INR, PT, or aPTT results, you cannot join the study.
  • If an electrocardiogram (ECG) shows a dangerously long heart rhythm interval (QTcF greater than 460 ms) or you have a personal or family history of congenital long QT syndrome, you cannot join the study.
  • If you have serious blood, liver, heart, or kidney disease that could put you at risk, you cannot join the study.
  • If you have another medical condition that could affect how the study measures Angelman syndrome, you cannot join the study.
  • If you have a known history of HIV or any form of hepatitis (B, C, or E), you cannot join the study.
  • If you have a condition that increases your risk of meningitis (infection of the membranes around the brain and spinal cord), you cannot join the study.
  • If you have a tendency to bleed easily or a disorder that affects blood clotting, you cannot join the study.
  • If you have certain brain or spinal problems—such as tumors, bleeding in the brain, high pressure inside the skull, narrowed spinal canal, structural malformations like Chiari malformation or hydrocephalus, or connective‑tissue disorders such as Ehlers‑Danlos or Marfan syndrome—you cannot join the study.
  • If you have a ventriculoperitoneal (VP) shunt (a device that drains fluid from the brain) or any implanted central nervous system catheter, you cannot join the study.
  • If you have a history of brain or spinal injury (traumatic, bleeding, or other) that could affect Angelman syndrome symptoms, you cannot join the study.
  • If you previously had a serious headache after a lumbar puncture (spinal tap) that required a blood patch, you cannot join the study.
  • If you have been diagnosed with cancer (any malignancy) within the past five years, you cannot join the study.
  • If you need major surgery with general anesthesia during the study period, or had such surgery within four weeks before screening, you cannot join the study.
  • If you are taking antiplatelet or anticoagulant medicines (blood thinners) within two weeks before screening, you cannot join the study.
  • If you have any other health issue that makes participation unsafe or would prevent you from completing the study, including a reason you cannot receive the study’s intrathecal (into the spinal fluid) therapy, you cannot join the study.
  • If you were born extremely premature and have related complications that could affect the study’s results, you cannot join the study.
  • If you experienced lack of oxygen (asphyxia) around the time of birth, you cannot join the study.
  • If you are known or suspected to be allergic (hypersensitive) to the study drug or any of its inactive ingredients, you cannot join the study.
  • If you participated in another drug trial or used an experimental device within the past 90 days (or longer, based on how long the drug stays in your body), you cannot join the study.
  • If you are currently enrolled in another clinical study or plan to join one without a proper data‑sharing agreement between the studies, you cannot join the study.
  • If you have previously taken part in gene therapy, cell therapy, gene editing, or any other treatment that changes gene expression (such as an antisense oligonucleotide treatment), you cannot join the study.
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Investigated drugs

Rugonersen is an experimental medicine being tested in this study. It is given as an injection directly into the spinal fluid (intrathecal injection) so it can reach the brain. The drug is designed to target a specific genetic pathway that is involved in Angelman syndrome, a condition that affects brain development and causes severe developmental delays, speech problems, and movement difficulties. By acting on this pathway, Rugonersen aims to improve the neurological symptoms of the disorder. Participants in the trial receive the medication through a small procedure that places the drug into the fluid surrounding the spinal cord, and the study monitors how well it works and whether it is safe for both children and adults with Angelman syndrome.

What is already known about the treatment

Rugonersen - Rugonersen is given as an injection into the spinal fluid (intrathecal injection), allowing the drug to reach the brain directly. It is an experimental therapy that is currently being studied in clinical trials and is not yet approved for general medical use. The drug is being tested for Angelman syndrome, a rare genetic disorder that causes severe developmental delay and motor problems. Rugonersen works by binding to a specific RNA that blocks the UBE3A gene, helping the gene work more normally, and it is classified as an antisense oligonucleotide.

Investigated diseases

Angelman syndrome - Angelman syndrome is a genetic neurodevelopmental disorder caused by loss of function of the maternal UBE3A gene. Children are born with normal size and appearance but soon show delayed development, especially in speech and motor skills. As they grow, they often display frequent laughter, a happy demeanor, and difficulty with balance and coordination. Cognitive abilities remain limited, and communication challenges persist throughout life.
Trial detailsLast updated 25 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-523729-16-00Protocol codeOHB-724-301Estimated enrolment143 patients

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