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Long-term safety study of rebisufligene etisparvovec gene therapy in patients previously treated for Mucopolysaccharidosis type IIIA

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What is this trial about?

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

This study focuses on patients with Mucopolysaccharidosis type IIIA, a rare genetic disorder that affects the body's ability to break down certain complex sugars. The study will evaluate a gene therapy treatment called ABO-102 (also known as rebisufligene etisparvovec), which is given as an injection into the bloodstream. This treatment is designed to help the body produce an important enzyme that is missing in patients with this condition.

The main purpose of this research is to assess the long-term safety and effectiveness of the treatment in patients who have previously received ABO-102 in earlier clinical trials. The treatment works by introducing a corrective gene into the patient's cells, which should then be able to produce the missing enzyme and help restore normal cellular function.

During the study, participants will be monitored through various tests and examinations to track their progress and any potential side effects. The research team will evaluate different aspects of the participants' health, including their cognitive development, communication abilities, and certain substances in their spinal fluid. The study will also track changes in brain volume and overall survival of the participants.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial treatment verification

    Confirmation of previous participation in a clinical trial where you received UX111 (also known as ABO-102)

    Review and signing of informed consent documents by you or your legal guardian

  2. Step 2

    Treatment monitoring

    Regular assessment of any side effects that may occur after the treatment

    Monitoring of cognitive development using specialized tests (Bayley Scales of Infant and Toddler Development)

    Evaluation of communication skills, including both understanding and expressing language

    Collection of spinal fluid samples to measure levels of a substance called heparan sulfate

    Brain imaging to measure changes in brain volume

  3. Step 3

    Long-term follow-up

    Continued monitoring until August 2027

    Regular medical check-ups to ensure safety and track progress

    Assessment of overall health status and survival outcomes

  4. Step 4

    Medical supervision

    The medication (rebisufligene etisparvovec) was previously administered through intravenous injection

    This study focuses on monitoring the long-term effects of that treatment

    Your participation helps understand how the treatment affects patients with Mucopolysaccharidosis type IIIA over time

Who can join the trial?

8 criteria

  • Must have previously participated in a clinical trial where they received UX111 (an investigational treatment)
  • Must be between 2-11 years old
  • Can be either male or female
  • Parents or legal guardians must be willing and able to:
    • Give informed consent (written permission to participate)
    • Follow all study procedures
    • Attend all scheduled study visits
    • Must have been diagnosed with Mucopolysaccharidosis type IIIA (a rare genetic condition affecting the body's ability to break down certain complex sugars)
    • Must be able to comply with all study requirements and procedures

Who cannot join the trial?

13 criteria

  • History of hematopoietic stem cell transplantation (a procedure where damaged blood-forming cells are replaced with healthy ones)
  • Participation in another clinical trial within 30 days before starting this study
  • Any serious medical condition or abnormal test result that could interfere with the study or put the participant at risk
  • Known allergies to the study medication or similar compounds
  • Presence of any contraindications (conditions that make a treatment inadvisable) to the required procedures
  • Inability to comply with study procedures and follow-up visits
  • Pregnancy or breastfeeding
  • Use of prohibited medications within 30 days before starting the study
  • Major surgery planned during the study period
  • Significant abnormal findings in laboratory tests or medical examinations
  • Mental conditions that could affect the ability to provide informed consent or follow study procedures
  • History of substance abuse within the past year
  • Any condition that, in the opinion of the study doctor, would make participation unsafe
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Investigated drugs

ABO-102 (also known as UX111) is a gene therapy product designed to treat patients with MPS IIIA (Mucopolysaccharidosis type IIIA), also known as Sanfilippo syndrome type A. This therapy uses a modified virus (AAV9) to deliver a working copy of the SGSH gene to cells. The therapy aims to help the body produce an enzyme that patients with MPS IIIA are missing, which is needed to break down certain complex sugars in the body.

What is already known about the treatment

ABO-102 (UX111) - A gene therapy medication administered through intravenous injection, designed to treat Mucopolysaccharidosis type IIIA (MPS IIIA), a rare genetic disorder. The treatment uses a modified adeno-associated virus (AAV9) vector to deliver a functional copy of the SGSH gene to cells, helping to produce the missing enzyme that causes the condition. This investigational therapy is currently being evaluated in clinical trials to assess its long-term safety and effectiveness in treating MPS IIIA patients, representing a potential breakthrough in treating this genetic disorder through targeted gene therapy.

Investigated diseases

Mucopolysaccharidosis type IIIA - A rare genetic disorder that affects the body's ability to break down complex sugar molecules called heparan sulfate. The condition is characterized by progressive deterioration of the central nervous system. Children with this disorder typically begin showing symptoms between ages 2 and 6, including developmental delays and behavioral problems. As the disease progresses, affected individuals experience a decline in cognitive abilities and language skills. The condition also causes mild physical changes and can affect motor skills over time. The disease is inherited in an autosomal recessive pattern, meaning both parents must pass on the altered gene for a child to be affected.
Trial detailsLast updated 2 Oct 2026
Age0-17PhasePhase IIITrial ID2023-510392-66-00Protocol codeLTFU-ABO-102Estimated enrolment41 patientsSponsorUltragenyx Pharmaceutical 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).