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Can a One-Time gene therapy change the future of MPS II?

NCT ID NCT04597385

Knowledge-focused Sponsor: REGENXBIO 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
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 This study
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 Results may not be published yet.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This status has not been confirmed recently, so it may be out of date.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 Aug 19, 2026 · Last updated Aug 20, 2026 · Updated 1 time

Summary

This study follows people who previously received RGX-121, a gene therapy designed to deliver a working copy of the IDS gene to the brain, as a treatment for Mucopolysaccharidosis II (MPS II). The goal is to see how safe the therapy is over the long term and whether it helps with cognitive, motor, and behavioral development. Participants are observed without receiving any new treatment, and their health and development are tracked over time.

What this could mean

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

Active substance
RGX-121 gene therapy (delivers a functional copy of the IDS gene to the central nervous system)
What this could lead to
If successful, this could show that a one-time gene therapy provides lasting benefits for people with MPS II, potentially slowing or preventing developmental decline.
What could go wrong
This is a small, observational follow-up study, not a new treatment test. It cannot prove the therapy works, and long-term safety or effectiveness may still be uncertain.

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.

Participants

27 people

The number who actually took part.

Started

Mar 2021

Expected to finish

Oct 2028

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.

Who is studied

Up to 54 subjects who have received RGX-121 in a previous parent study.

Ages

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

Sex

Male participants only

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: * To be eligible, a participant must have previously received RGX-121 in a separate parent trial. * Participant or participant's legal guardian(s) is/(are) willing and able to provide written, signed informed consent Exclusion Criteria: * Participant has not received RGX-121 previously in a separate parent trial.

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Conditions

The condition(s) this trial relates to.

mucopolysaccharidosis type 2 Sudden Infant Death

As listed by the trial registrant

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

Mucopolysaccharidosis ii

Contacts and locations

Locations

  • Hospital de Clinicas de Porto Alegre

    Porto Alegre, 90035-903, Brazil

  • Saint Peter's Healthcare System

    New Brunswich, New Jersey, 08901, United States

  • The Children's Hospital of Philadelphia (CHOP)

    Philadelphia, Pennsylvania, 19104, United States

  • University of California, San Francisco (UCSF)- Benioff Children's Hospital

    San Francisco, California, 94158, United States

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