A Long-term Follow-up Study of Patients With MPS IIIA Treated With ABO-102

Study Overview
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Brief Summary
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The main objective of this study is to evaluate the long-term safety and tolerability of ABO-102 in participants with MPS IIIA.

Detailed Description
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This is a multicenter, long-term follow-up study of patients with MPS IIIA who have completed a prior clinical trial involving the administration of ABO-102 (NCT02716246 and NCT04088734). No investigational product will be provided. At approved sites immunosuppression (IS) 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 IS therapy. Not all participants may receive IS therapy. This study was previously posted by Abeona Therapeutics, Inc and was transferred to Ultragenyx in August 2022.

Official Title
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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)

Conditions
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Mucopolysaccharidosis III-A

Intervention / Treatment
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* Other: No Investigational Product
* Drug: Adjuvant Immunosuppression (IS) Therapy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participants that have completed a prior clinical trial involving the administration of 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.
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Cohort 1<br>Participants who have completed a prior clinical trial involving the administration of ABO-102 and are able to comply with onsite scheduled visits and assessments. Select participants may receive adjuvant IS therapy. | Other: No Investigational Product<br>* No investigational product will be administered in this follow-up trial.<br>Drug: Adjuvant Immunosuppression (IS) Therapy<br>* The Principal Investigator and/or caregiver, in consultation with the medical monitor, will determine whether to initiate adjuvant IS therapy.<br>|
| Other: Cohort 2<br>Participants who have completed a prior clinical trial involving the administration of ABO-102 and who cannot participate in Cohort 1. Participants will partake in a reduced number of assessments, performed either onsite or at home via a combination of telehealth and home healthcare visits. | Other: No Investigational Product<br>* No investigational product will be administered in this follow-up trial.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Adverse Events | Long-term Product Safety as Defined by the Incidence, Type, and Severity of Adverse Events (AEs) and Serious Adverse Events (SAEs). | Up to Year 5 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change From Baseline (in Prior Trial) in Cerebrospinal Fluid Heparan Sulfate (CSF HS) |  | Up to Month 12 | 
| Change From Baseline (in Prior Trial) in the Cognitive Subtest of the Bayley Scales of Infant and Toddler Development -Third Edition (BSID-III) or the Kaufman Assessment Battery for Children - Second Edition (KABC-II), Based on Developmental Age |  | Baseline, Up to Year 5 | 
| Change From Baseline (in Prior Trial) in the Language Subtest of the Bayley Scales of Infant and Toddler Development -Third Edition (BSID-III) or the Kaufman Assessment Battery for Children - Second Edition (KABC-II), Based on Developmental Age |  | Baseline, Up to Year 5 | 
| Change From Baseline (in Prior Trial), as Assessed by the Parent Report Using the Vineland Adaptive Behavior Scale II - Survey Interview Form (VABS-II) |  | Baseline, Up to Year 5 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Sanfilippo A, MPS IIIA, Mucopolysaccharidosis IIIA