Long-term Follow-up After ABO-102 Treatment for Sanfilippo Syndrome

Enrolling by invitation at 4 trial locations

Overseen By Medical Affairs

Age: Any Age

Sex: Any

Trial Phase: Phase 3

Sponsor: Ultragenyx Pharmaceutical Inc

Disqualifiers: Other trials, Medical conditions, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Pivotal Trial (Near Approval) This treatment is in the last trial phase before FDA approval

Prior Safety Data This treatment has passed at least one previous human trial

Compensation: Varies

Number of Visits: Unknown

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial examines the safety and effectiveness of ABO-102, a gene therapy for Sanfilippo Syndrome, a rare genetic disorder affecting the brain and body. Participants must have previously participated in an earlier trial with ABO-102. The study divides participants into two groups: those who can visit the clinic regularly and those with fewer visits, possibly conducted from home. The trial aims to better understand the treatment's long-term effects. As a Phase 3 trial, it represents the final step before potential FDA approval, offering participants a chance to contribute to a treatment nearing widespread availability.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications. It is best to discuss this with the trial coordinators or your doctor.

Is there any evidence suggesting that ABO-102 is likely to be safe for humans?

Research has shown that UX111 (also known as ABO-102) is generally safe for people. Studies with children who have Mucopolysaccharidosis IIIA (MPS IIIA) indicate that the treatment is well-tolerated. Reports have noted lower levels of a harmful substance in the spinal fluid, called CSF HS, which is a positive sign. Additionally, improvements in thinking and memory have been observed, further supporting the treatment's safety. While this gene therapy is still under review, positive results from previous studies suggest it could be a safe option for those considering joining a clinical trial. ^{1 2 3 4 5}

Why do researchers think this study treatment might be promising?

Most treatments for Sanfilippo Syndrome focus on managing symptoms rather than addressing the root cause. Unlike these options, ABO-102 is a gene therapy treatment that targets the genetic defect responsible for the condition. By delivering a functional copy of the missing or faulty gene directly to the brain and central nervous system, ABO-102 aims to correct the underlying genetic issue. This approach has the potential to significantly slow or halt the progression of the disease, which is why researchers are optimistic about its impact.

What evidence suggests that ABO-102 might be an effective treatment for MPS IIIA?

Research has shown that UX111 (formerly known as ABO-102) could be a promising treatment for Sanfilippo syndrome (MPS IIIA). This gene therapy significantly reduces heparan sulfate, a harmful substance that accumulates in the brain and causes damage in individuals with MPS IIIA. Studies also indicate that this treatment can quickly lower heparan sulfate levels in the fluid around the brain and spine and maintain these reduced levels over time. This suggests that UX111 could effectively manage the disease by addressing one of its main causes. The aim is for this one-time therapy to treat, and possibly cure, MPS IIIA.

In this trial, participants are divided into two cohorts. Cohort A includes those who can comply with onsite visits and assessments, with select participants potentially receiving adjuvant IM therapy. Cohort B includes those who cannot participate in Cohort A and will undergo a reduced number of assessments, conducted either onsite or at home via telehealth and home healthcare visits. ^{2 3 6 7 8}

Who Is on the Research Team?

Medical Director

Principal Investigator

Ultragenyx Pharmaceutical Inc

Are You a Good Fit for This Trial?

This trial is for patients with MPS IIIA who have already received ABO-102 in a previous study. Their parents or guardians must consent and be able to follow the study's procedures and schedule. Those currently in another trial or with conditions that interfere with this study can't participate.

Inclusion Criteria

You have participated in a previous study where you were given ABO-102.

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 and efficacy evaluation of ABO-102 during this study

Any other situation or medical condition that precludes the participant from undergoing procedures required in this study.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Long-term Follow-up

Participants are monitored for safety/tolerability and efficacy of UX111 after previous gene therapy trials

Long-term

Onsite scheduled visits and assessments; telehealth and home healthcare visits for some participants

Adjuvant Immunomodulatory Therapy

Selected participants may receive adjuvant immunomodulatory therapy based on consultation with the medical monitor

What Are the Treatments Tested in This Trial?

Interventions

• ABO-102

Trial Overview The focus of this trial is on the long-term safety and effects of ABO-102, a treatment previously given to participants. It also looks at whether additional immune system suppression therapy is needed alongside it.

How Is the Trial Designed?

Group I: Cohort B Experimental Treatment 1 Intervention

Participants who have participated in a prior clinical trial involving the administration of UX111 (rebisufligene etisparvovec) and who cannot participate in Cohort A. Participants will partake in a reduced number of assessments, performed either onsite or at home via a combination of telehealth and home healthcare visits.

Group II: Cohort A Experimental Treatment 2 Interventions

Participants who have participated in a prior clinical trial involving the administration of UX111 (rebisufligene etisparvovec) and are able to comply with onsite scheduled visits and assessments. Select participants may receive adjuvant IM therapy.

Who Is Running the Clinical Trial?

Ultragenyx Pharmaceutical Inc

Lead Sponsor

Trials

94

Recruited

104,000+

Dr. Emil D. Kakkis

Ultragenyx Pharmaceutical Inc

Chief Executive Officer since 2010

MD/PhD in Biological Chemistry from UCLA

Dr. Eric Crombez

Ultragenyx Pharmaceutical Inc

Chief Medical Officer since 2023

MD from Wayne State University School of Medicine

Abeona Therapeutics, Inc

Industry Sponsor

Trials

12

Recruited

1,100+

Citations

1. clinicaltrials.gov clinicaltrials.gov/study/NCT04360265

Follow-up Study of AAV-Mediated Gene Transfer (UX111; ... The main objective of this study is to evaluate the safety/tolerability and efficacy of UX111 (previously known as ABO-102) in participants with ...

2. ultragenyx.com ultragenyx.com/our-research/pipeline/ux111-for-mps-iiia/

UX111 for Sanfilippo syndrome type A (MPS IIIA) UX111 (rebisufligene etisparvovec and formerly ABO-102) gene therapy for the potential treatment of Sanfilippo syndrome (MPS IIIA). Program overview.

3. primetherapeutics.com primetherapeutics.com/high-cost-therapy-profile-july-2025

High-Cost Therapy Profile: July 2025 Ultragenyx announces data demonstrating treatment with UX111 results in significant reduction in heparan sulfate exposure in cerebrospinal fluid ...

4. horizonscandb.pcori.org horizonscandb.pcori.org/report/topics/124

Rebisufligene etisparvovec (UX111) to treat ... Rebisufligene etisparvovec is intended as a one-time gene therapy to treat, and potentially cure, MPS IIIA. It is composed of a recombinant, adeno-associated ...

5. ir.ultragenyx.com ir.ultragenyx.com/news-releases/news-release-details/ultragenyx-announces-data-demonstrating-treatment-ux111-results

Release details (NASDAQ: RARE) today announced data demonstrating treatment with UX111 (ABO-102) AAV gene therapy resulted in rapid and sustained decreased ...

6. ir.ultragenyx.com ir.ultragenyx.com/news-releases/news-release-details/ultragenyx-receives-complete-response-letter-fda-ux111-aav-gene

Ultragenyx Receives Complete Response Letter from FDA ... Ultragenyx Receives Complete Response Letter from FDA for UX111 AAV Gene Therapy to Treat Sanfilippo Syndrome Type A (MPS IIIA). July 11, 2025.

7. scge.mcw.edu scge.mcw.edu/platform/data/clinicalTrials/report/NCT02716246

Phase I/II/III Gene Transfer Clinical Trial of scAAV9.U1a. ... The main objective of this study is to evaluate the efficacy and safety of UX111 for the treatment of MPS IIIA. (Show More). Development Status, Active.

8. delta.larvol.com delta.larvol.com/Products/?ProductId=0727bd01-ba12-454f-987a-b23142467627

rebisufligene etisparvovec (UX111) / Abeona Therap, ... UX111 appears safe and effective in children with MPS IIIA leading to reduced CSF HS exposure and improved cognitive function.