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Gene therapy for sanfilippo a: does it last?

NCT ID NCT04360265

Disease control Sponsor: Ultragenyx Pharmaceutical Inc Source: ClinicalTrials.gov ↗

What the study statuses mean

This study's is highlighted.

Recruitment status, easiest to join first

Recruiting now
This trial is taking on new participants right now.
Not yet recruiting
Registered, but not yet taking participants.
By invitation only This study
Not open to general applications. Only people the study team invites can take part.
Paused
Paused for now. It may or may not start again.
Ongoing
Running, but no longer taking on new participants.
Completed
The trial has finished. Results may not be published yet.
Stopped early
Stopped early, before it reached the end. That can be for many reasons, including safety.
Cancelled
Cancelled before anyone took part.

Expanded access (not trials)

Expanded access
Not a trial. This treatment can be requested outside a study, case by case, for people who qualify.
Expanded access (paused)
Not a trial. The treatment can normally be requested outside a study, but is unavailable right now.
Expanded access (ended)
Not a trial. The treatment could once be requested outside a study, but no longer can.
Approved
The treatment has been approved, so it is available normally rather than through this programme.

When the status isn't known

Details not published
The full record has not been published yet, so there is little to show here.
Status unknown
This status has not been confirmed recently, so it may be out of date.

First seen Jun 26, 2026 · Last updated Jul 17, 2026 · Updated 2 times

Summary

This study follows 41 children with Sanfilippo A (MPS IIIA) who previously received UX111 gene therapy in earlier trials. Researchers will monitor safety and how well the therapy controls the disease over time, using tests like the Bayley cognitive scale. No new gene therapy is given in this follow-up; some children may receive immune-suppressing drugs if needed.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance
UX111 (gene therapy)
What this could lead to
If successful, this could show that a single gene therapy treatment safely controls Sanfilippo A symptoms for years, offering a long-term management option.
What could go wrong
This is a follow-up study with no new treatment given, so it only measures past effects. The number of participants is small (41), and results may not apply to all patients. Some children may need additional immune-suppressing drugs.
Why investors are watching

Ultragenyx is running a long-term follow-up study of 41 patients with MPS IIIA, a rare and fatal genetic disease, who previously received its gene therapy UX111 in earlier trials. For a small company, this readout matters because it tests whether the therapy remains safe and controls the disease over time, which could determine the product's future value.

If it works: If the follow-up data show lasting safety and disease control, Ultragenyx could have stronger evidence to support regulatory approval and commercial launch of UX111, a major step for a company of its size.

If it fails: A failure or delay in this study could set back the program, hurt the company's prospects, and reduce investor confidence. Trials often fail or produce unclear results, so the outcome is uncertain.

AI-written from the trial record. Speculative, and not investment advice.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Phase 3

Large-scale testing in a bigger group. Usually the last step before a treatment can be approved.

Participants

About 41 people

The number the study aims to enrol. It can still change while the study runs.

Started

Sep 2020

Expected to finish

Aug 2027

An estimate. End dates often move.

Lead sponsor

A company

The lead sponsor is a pharmaceutical, biotech, or medical-device company.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

Children (under 18), adults (18 to 64) and older adults (65 and over)

Sex

Anyone

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

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

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Conditions

The condition(s) this trial relates to.

Mucopolysaccharidosis III mucopolysaccharidosis type 3 mucopolysaccharidosis type 3A

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

MPS iiia Mucopolysaccharidosis iiia Sanfilippo A Sanfilippo syndrome

How to take part

Only the study team decides who joins. These are the ways to reach them.

  1. The places running it

    4 sites in 3 countries. The list below names each one and where it is.

  2. The official record

    The full official record for this study. This one lists no contact details, but it is the first place any would appear.

    Open the record ↗

  3. A doctor treating you

    A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.

Contacts and locations

Locations

  • Hospital Clínico Universitario de Santiago

    Santiago de Compostela, Spain

  • Nationwide Children's Hospital

    Columbus, Ohio, 43205, United States

  • Vall d'Hebron Barcelona Campus

    Barcelona, 08035, Spain

  • Women's and Children's Hospital

    North Adelaide, South Australia, Australia

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