Gene Transfer Study of ABO-102 in Patients With Middle and Advanced Phases of MPS IIIA Disease

Open-label, clinical trial of scAAV9.U1a.hSGSH injected intravenously through a peripheral limb vein

This is an open-label, single dose clinical trial. All participants will receive 3 X 10\^13 vg/kg of ABO-102 delivered one time through a venous catheter inserted into a peripheral limb vein. The target population includes MPS IIIA participants with a DQ lower than 60 in middle and advanced phases of the disease. Similar numbers of MPS IIIA participants with age equivalent above and below 18 months of age will be enrolled to ensure a representation of middle and advanced phases of the disease.

This study was previously posted by Abeona Therapeutics, Inc and was transferred to Ultragenyx in August 2022.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of MPS IIIA confirmed by the following methods:

  1. No detectable or significantly reduced SGSH enzyme activity by leukocyte assay and
  2. Genomic DNA analysis demonstrating homozygous or compound heterozygous mutations in the SGSH gene
* Cognitive Development Quotient (DQ) lower than 60 (calculated by Bayley Scales of Infant and Toddler Development - Third Edition)
* Must be ambulatory, though may receive assistance with ambulation
* Age range of 2 years up to 18 years (excluded)

Exclusion Criteria:

* Inability to participate in the clinical evaluation as determined by Principal Investigator
* Identification of two nonsense or null variants on genetic testing of the SGSH gene
* At least one S298P mutation in the SGSH gene
* Has evidence of an attenuated phenotype of MPS IIIA
* Presence of a concomitant medical condition that precludes lumbar puncture or use of anesthetics
* Active viral infection based on clinical observations
* Concomitant illness or requirement for chronic drug treatment that in the opinion of the PI creates unnecessary risks for gene transfer, or precludes the child from participating in the protocol assessments and follow up
* Participants with total anti-AAV9 antibody titers greater than or equal to 1:100 as determined by ELISA binding immunoassay
* Participants with a positive response for the ELISPOT for T-cell responses to AAV9
* Serology consistent with exposure to HIV, or serology consistent with active hepatitis B or C infection
* Bleeding disorder or any other medical condition or circumstance in which a lumbar puncture (for collection of CSF) is contraindicated according to local institutional policy
* Visual or hearing impairment sufficient to preclude cooperation with neurodevelopmental testing
* Any item (braces, etc.) which would exclude the participant from being able to undergo MRI according to local institutional policy
* Any other situation that precludes the participant from undergoing procedures required in this study
* Participants with cardiomyopathy or significant congenital heart abnormalities
* The presence of significant non-MPS IlIA related CNS impairment or behavioral disturbances that would confound the scientific rigor or interpretation of results of the study
* Abnormal laboratory values Grade 2 or higher as defined in CTCAE v4.03 for GGT, total bilirubin (except in subjects diagnosed with Gilbert's syndrome), creatinine, hemoglobin, WBC count, platelet count, PT and aPTT
* Female participant who is pregnant or demonstrates a positive urine or beta-hCG result at screening assessment (if applicable)
* Any vaccination with viral attenuated vaccines less than 30 days prior to the scheduled date of treatment (and use of prednisolone)
* Previous treatment by Haematopoietic Stem Cell transplantation
* Previous participation in a gene/cell therapy or ERT clinical trial
* Participants who are anticipated to undergo a procedure involving anesthesia within 6 months post- drug administration
* Dysphagia present at Grade 3 or higher, as defined in CTCAE v4.03