A Study of the Safety and Tolerability of GTX-102 in Children With Angelman Syndrome
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The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. |
ClinicalTrials.gov Identifier: NCT04259281 |
Recruitment Status :
Recruiting
First Posted : February 6, 2020
Last Update Posted : January 25, 2023
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Condition or disease | Intervention/treatment | Phase |
---|---|---|
Angelman Syndrome | Drug: GTX-102 | Phase 1 Phase 2 |
This is a Phase 1/2, open-label, multiple-dose, study to evaluate the safety, tolerability, and plasma and CSF concentrations of GTX-102 in pediatric patients with AS.
The study includes a monthly dosing period followed by a maintenance period. The duration of study for each patient in the monthly dosing period is anticipated to be approximately 5 months. Patients will then transition to a maintenance period of study where they may receive continued treatment until GTX-102 becomes commercially available in their respective country or the study is discontinued.
This study was previously posted by GeneTX Biotherapeutics, LLC and was transferred to Ultragenyx in July 2022.
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 83 participants |
Allocation: | Non-Randomized |
Intervention Model: | Parallel Assignment |
Masking: | None (Open Label) |
Primary Purpose: | Treatment |
Official Title: | A Phase 1/2 Open-label, Multiple-dose, Dose-escalating Clinical Trial of the Safety and Tolerability of GTX-102 in Pediatric Patients With Angelman Syndrome (AS) |
Actual Study Start Date : | February 24, 2020 |
Estimated Primary Completion Date : | December 2023 |
Estimated Study Completion Date : | December 2025 |

Arm | Intervention/treatment |
---|---|
Experimental: GTX-102 Cohort 4
3.3 mg for 3-4 monthly doses followed by a quarterly maintenance regimen (in participants 4 to < 8 years of age)
|
Drug: GTX-102
antisense oligonucleotide |
Experimental: GTX-102 Cohort 5
5 mg for 3-4 monthly doses followed by a quarterly maintenance regimen (in participants ≥ 8 to 17 years of age)
|
Drug: GTX-102
antisense oligonucleotide |
Experimental: GTX-102 Cohort 6
7.5 mg for 3-4 monthly doses followed by a quarterly maintenance regimen (in participants 4 to < 8 years of age)
|
Drug: GTX-102
antisense oligonucleotide |
Experimental: GTX-102 Cohort 7
10 mg for 3-4 monthly doses followed by a quarterly maintenance regimen (in participants ≥ 8 to 17 years of age)
|
Drug: GTX-102
antisense oligonucleotide |
Experimental: GTX-102 Cohort A
Sponsor selected dose for 3-4 monthly doses followed by a maintenance regimen (in participants 4 to < 8 years of age)
|
Drug: GTX-102
antisense oligonucleotide |
Experimental: GTX-102 Cohort B
Sponsor selected dose for 3-4 monthly doses followed by a maintenance regimen (in participants ≥ 8 to 17 years of age)
|
Drug: GTX-102
antisense oligonucleotide |
Experimental: GTX-102 US Cohort
2 mg for 4 monthly doses followed by a quarterly maintenance regimen
|
Drug: GTX-102
antisense oligonucleotide |
- Number of Participants with Treatment-Emergent Adverse Events (TEAEs), Serious TEAEs (SAEs), TEAEs Leading to Discontinuation and Severity of TEAEs [ Time Frame: Up to Day 128 ]
- Pharmacokinetics of GTX-102 [ Time Frame: Day 2, Day 3, Day 4, Day 30, Day 58, Day 86, Day 100/128 ]Maximum drug concentration (Cmax)

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Ages Eligible for Study: | 4 Years to 17 Years (Child) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Key Inclusion Criteria:
- Signed informed consent from parent(s) or legal guardian(s)
- Documented genetic confirmation of full maternal UBE3A gene deletion causing AS (e.g. DNA methylation testing with either a chromosomal microarray or FISH) in the region of 15q11.2-q13 including class I, II or III).
- Age ≥ 4 to ≤ 17 years at screening (in US Age ≥ 4 to < 8 years at screening)
- Stable seizure control (defined as clinically stable with no changes in antiepileptic medications over the prior 1 month before screening visit, other than weight associated dose adjustments)
- Platelet count, prothrombin time (PT) / international normalized ratio (INR) and partial thromboplastin time (PTT) within normal limits
- Normal renal function with serum creatinine and spot urine protein within normal limits
- Normal hepatic function with total bilirubin, aspartate aminotransferase (AST),alanine aminotransferase (ALT) and alkaline phosphatase within normal limits
- Willing and able to comply with scheduled visits, drug administration plan, laboratory tests, study restrictions, and all study procedures LP.
- Able to tolerate the anesthetic regimen required for LP procedure
Key Exclusion Criteria:
- Any change in medications (excluding antiepileptic drugs) or diet intended to treat symptoms of AS (e.g. sleeping aids, supplements, ketogenic or low-glycemic index diet, other) over the prior 1 month before screening.
- Inability to ambulate independently or with an assistive device or caregiver hand-hold
- Any bleeding or platelet disorder
- Any clinically significant cardiovascular, endocrine, hepatic, renal, pulmonary, gastrointestinal, neurologic, malignant, metabolic, psychiatric, or other condition that, in the judgment of the Investigator, will pose a safety risk, will make the patient unsuitable for participation in, and/or unable to complete the study procedures.
- Any laboratory abnormality, that, in the Investigator's opinion, could adversely affect the safety of the patient, make it unlikely that the course of treatment or follow up would be completed, or impair the assessment of study result
- Any active infection
- Bone, spine, bleeding, or other disorder that exposes the patient to risk of injury or unsuccessful lumbar puncture
- Drugs that increase the risk of bleeding (e.g. heparin, low molecular weight heparin, platelet inhibitors).
- Use of any investigational oligonucleotide in the past 6 months (with the exception of GTX-102)
- Any prior use of gene therapy
- Use of any investigational drugs in the past 6 months (with the exception of GTX-102)
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Any medical condition that would require intubation for the anesthesia procedure
- NOTE: Additional Inclusion/Exclusion Criteria may apply

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04259281
Contact: Patients Contact: Trial Recruitment | 1-888-756-8657 | trialrecruitment@ultragenyx.com | |
Contact: HCPs Contact: Medical Information | 1-888-756-8657 | medinfo@ultragenyx.com |
United States, Illinois | |
Rush University Medical Center | Active, not recruiting |
Chicago, Illinois, United States, 60612 | |
Canada, Alberta | |
MAGIC Clinic Ltd | Recruiting |
Calgary, Alberta, Canada, T2E 7Z4 | |
Contact: Aneal Khan, MD khaa@ucalgary.ca | |
Canada, Ontario | |
Children's Hospital of Western Ontario | Recruiting |
London, Ontario, Canada | |
Contact: Rhiannon Hicks rhiannon.hicks@lhsc.on.ca | |
Children's Hospital of Eastern Ontario | Recruiting |
Ottawa, Ontario, Canada, K1H 8L1 | |
Contact: Erick Sell, MD esell@cheo.on.ca | |
Canada, Quebec | |
McGill University Health Centre | Recruiting |
Montréal, Quebec, Canada | |
Contact: Freqerique Arnaud Frederique.Arnaud@MUHC.MCGILL.CA | |
United Kingdom | |
Cambridge University Hospitals | Recruiting |
Cambridge, United Kingdom | |
Contact: Kay Lilley kay.lilley@addenbrookes.nhs.uk | |
Great Ormond Street Hospital for Children | Recruiting |
London, United Kingdom | |
Contact: Helen Cross, MD Helen.Cross@gosh.nhs.uk | |
Oxford University Hospitals NHS Foundation Trust | Recruiting |
Oxford, United Kingdom, OX3 7LE | |
Contact: Laurent Servais, MD PhD laurent.servais@paediatrics.ox.ac.uk |
Study Director: | Medical Director | Ultragenyx Pharmaceutical Inc |
Responsible Party: | Ultragenyx Pharmaceutical Inc |
ClinicalTrials.gov Identifier: | NCT04259281 |
Other Study ID Numbers: |
GTX-102-001 |
First Posted: | February 6, 2020 Key Record Dates |
Last Update Posted: | January 25, 2023 |
Last Verified: | January 2023 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
Angelman Syndrome Syndrome Disease Pathologic Processes Movement Disorders Central Nervous System Diseases |
Nervous System Diseases Abnormalities, Multiple Congenital Abnormalities Chromosome Disorders Genetic Diseases, Inborn |