ClinicalTrials.gov record NCT04360265

Follow-up Study of AAV-Mediated Gene Transfer (UX111; Previously Known as ABO-102) for MPS Type IIIA

Record copied from ClinicalTrials.gov: Oct 10, 2026AI summaries generated: Jul 27, 2026

A Long-term Follow-up Study of Patients With MPS IIIA From Gene Therapy Clinical Trials Involving the Administration of ABO-102 (scAAV9.U1a.hSGSH)

About this page. This page shows the study's official ClinicalTrials.gov record ↗, with added help to make it easier to understand. We explain medical terms, highlight key details in plain language, and suggest questions you may want to ask the study team.

The record is periodically copied from ClinicalTrials.gov and may lag behind changes. AI summaries are checked by software, not a clinician.Read moreShow less

The official record is written by the study sponsor and published on ClinicalTrials.gov. It may not always reflect the latest changes. Before making any decisions, please confirm important information with the study team and your own healthcare team.

Where you see "AI summary", AI was used to create a plain-language explanation and software checked it against the source. It has not been reviewed by a clinician, so it may contain mistakes or leave out important details.

StatusEnrolling by invitationThe study enrols only people the study team invites, for example patients already at a particular clinic. It is not open to the public.

Study typeInterventionalA study in which researchers assign participants to one or more interventions, such as a drug, procedure, device, behavioural programme or other approach, to measure their effects.

PhasePhase 3A later-stage study, usually with more participants, designed to give stronger evidence about how well a treatment works and how safe it is. It often compares the treatment with standard care or a placebo, and results may support an application for approval.

SexAll

LocationAustralia, Spain, United States

AI summaryWhat this study is about, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

This study follows people with MPS IIIA who previously received UX111 (also called ABO-102) in earlier clinical trials. No investigational product will be given in this follow-up; at some sites selected participants may receive adjuvant immunomodulatory (IM) therapy based on investigator and caregiver decision. The study monitors safety, tolerability, and clinical measures over time.

What it is studying. The study is testing the long-term safety, tolerability, and clinical outcomes after prior administration of UX111 gene therapy in people with MPS IIIA. It collects data on treatment-emergent adverse events and serious adverse events, cognitive development scores, cerebrospinal fluid heparan sulfate, brain cortical volume, and survival over follow-up.

What the researchers hope to learn. Collect long-term safety and tolerability data (treatment-emergent adverse events and serious adverse events) up to five years; measure cognitive outcomes over time; assess cerebrospinal fluid heparan sulfate and changes in cortical brain volume; record survival. These data aim to improve understanding of long-term outcomes after UX111 administration.

What this study is about

The study's own summary, as published on ClinicalTrials.gov. Underlined terms have a short explanation.

The main objective of this study is to evaluate the safety/tolerability and efficacy of UX111 (previously known as ABO-102) in participants with Mucopolysaccharidosis IIIA (MPS IIIA).

Interventions being studied

Being studied in this trial does not mean the treatment or procedure is approved or available for this condition.

Drug: Adjuvant Immunomodulatory (IM) Therapy
Other: No Investigational Product

Eligibility

The criteria exactly as listed on ClinicalTrials.gov. Only the study team can say whether they apply to you.

Inclusion criteria

Participants that have participated in a prior clinical trial in which they received UX111
Parent(s)/legal guardian(s) of participant willing and able to complete the informed consent process and comply with study procedures and visit schedule

Exclusion criteria

Planned or current participation in another clinical trial that may confound the safety or efficacy evaluation of UX111 during this study
Any other situation or medical condition that precludes the participant from undergoing procedures required in this study

Study description and what participation involves

The study's detailed description, as published on ClinicalTrials.gov.

Detailed description from the registry

This is a multicenter, long-term follow-up study of patients with MPS IIIA who have participated in a prior clinical trial involving the administration of UX111 (NCT02716246 and NCT04088734). No investigational product will be provided. At approved sites adjuvant immunomodulatory (IM) therapy may be administered to selected participants. The Principal Investigator and/or caregiver, in consultation with the medical monitor, will determine whether to initiate adjuvant IM therapy. Not all participants may receive IM therapy. This study was previously posted by Abeona Therapeutics, Inc and was transferred to Ultragenyx in August 2022.

AI summaryWhat participation may involve, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

This is a long-term follow-up with periodic assessments over multiple years (some outcomes tracked up to 5 years, others up to 36 months). No investigational product will be given in this study; at some approved sites selected participants may receive adjuvant immunomodulatory (IM) therapy if the investigator and caregiver agree with the medical monitor. Assessments may include developmental testing (e.g., Bayley Scales), collection of cerebrospinal fluid (CSF) for heparan sulfate measurement, measurements of brain cortical volume, and safety monitoring for adverse events. Participants who cannot attend full onsite visits may have a reduced set of assessments done by telehealth or home healthcare visits.

How the study is structured. Interventional (Phase 3) long-term follow-up. Non-randomized, parallel groups, with no masking. Participants who previously received UX111 enter either Cohort A (onsite, fuller assessments; selected participants at some sites may receive adjuvant IM therapy) or Cohort B (reduced assessments done onsite or via telehealth/home healthcare). No investigational product will be administered as part of this follow-up study.

Questions you could ask

These questions are suggestions for a conversation with the study team or your own clinician, not advice.

The registry says participants are enrolled by invitation. Who decides who is invited, and how?
The listed sites are in Australia, Spain, United States. Is any of them reachable for me, and does the study help with travel?
Which of the eligibility criteria would need to be checked with tests before I could join?

More on Sanfilippo syndrome

Clinical trials12 trials listed for Sanfilippo syndromeEvery trial the registry lists for Sanfilippo syndrome, with recruitment status, phase and sites, updated from ClinicalTrials.gov.See all trials →Research updatesWhat changed in Sanfilippo syndrome researchLatest monthly update: September 2026. Includes: Approved drug shortlist. New research summarized each month in plain language, with links to every source paper.Read the latest update →

Important dates

Study start: Sep 28, 2020
Primary completion: August 2027 (estimated)
Study completion: August 2027 (estimated)
Target enrollment: 41 participants (estimated)
Last updated on registry: Jul 17, 2026
Data verified: Oct 10, 2026

Sponsor and research team

The lead sponsor funds and oversees the trial. A pharmaceutical or biotech company sponsor typically means the study is testing that company's drug or device; a hospital, university, or government agency usually indicates investigator-initiated or publicly funded research.

Lead sponsor: Ultragenyx Pharmaceutical Inc

Participating sites (4)

Filter by country:

Nationwide Children's Hospital
Columbus, Ohio, 43205 · United States
Women's and Children's Hospital
North Adelaide, South Australia · Australia
Vall d'Hebron Barcelona Campus
Barcelona, 08035 · Spain
Hospital Clínico Universitario de Santiago
Santiago de Compostela · Spain

Terms used on this page · explanations by MedicalUpdates.ai

legal guardian: A person who is legally allowed to make decisions, including consent to research, on behalf of someone who cannot consent for themselves.
informed consent: The process of explaining a study, including its risks and what participation involves, so that a person can decide freely whether to take part. Consent is usually documented in writing, and a participant can choose to leave the study later.
Inclusion Criteria: The conditions a person must meet to be considered for the study, for example a confirmed diagnosis, an age range or a test result.
Exclusion Criteria: The conditions that rule a person out even if they meet the inclusion criteria, for example other illnesses, certain medicines or pregnancy.
long-term follow-up: Observation that continues for years after the study treatment, often required for gene and cell therapies.
investigational product: A treatment that is being tested and has not been approved for this use. It may be approved for a different condition. Being studied does not mean it works or is available outside the study.
Principal Investigator: The doctor or scientist responsible for running the study at a site or overall.

The study record on this page is reproduced from ClinicalTrials.gov, a database of the U.S. National Library of Medicine, where it was submitted by the study sponsor. MedicalUpdates.ai does not own this content, is not affiliated with or endorsed by ClinicalTrials.gov, NIH, or the U.S. Government, and does not verify the record. Plain-language notes, the glossary and the questions above are added by this site; text in the boxes marked "AI summary" was written by an AI model and may contain errors. Registry records change over time. Check the original record for the current version and discuss eligibility or participation with a qualified healthcare professional.

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