Angelman SyndromePhase 3NCT06415344
Long-term Extension of GTX-102 in Angelman Syndrome
A Phase 3 study testing GTX-102 in people with Angelman Syndrome, run by Ultragenyx Pharmaceutical Inc at 23 sites in 8 countries.
Trial summary
The primary objective of the study is to evaluate the long-term safety profile of GTX-102 in participants with Angelman Syndrome (AS) Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Angelman Syndrome
- What is being tested?
- GTX-102
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 66 participants
- Where
- 23 sitesin 8 countries
- Study dates
- 31 Jul 2024to 30 Oct 2026
- Phase
- Phase 3
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Signed informed consent from parent(s) or legal guardian(s).
- Completed a final study visit in a prior clinical trial with GTX-102. If the subject has an ongoing adverse event, medical monitor approval is required to rollover. The Screening visit must occur within 6 months of the last visit in the prior GTX-102 trial.
- From the time of informed consent through the end of the study and for at least 6 months after the final dose of GTX-102, females of childbearing potential who are sexually active must use highly effective contraception or abstinence. Males are able to participate if they agree to remain abstinent (refrain from heterosexual intercourse) or use acceptable contraceptive methods during the study and for at least 3 months after the final dose of GTX-102.
Who cannot join
- Discontinued from study or withdrew from study treatment in a prior GTX-102 trial.
- History or evidence of any other medical, neurological, or psychological condition that would expose the subject to an undue risk of a significant AE or interfere with study assessments during the course of the trial as determined by the clinical judgment of the Investigator.
- Known hypersensitivity to GTX-102 or its excipients that, in the judgment of the Investigator, places the subject at increased risk for adverse effects.
- Pregnant or breastfeeding or planning to become pregnant (self or partner) at any time during the study
Trial locations and contacts
23 sites in 8 countries.
23 sites in 8 countries
United States6 sites
Rare Disease Research, LLC
Atlanta, Georgia, 30329
Boston Children's Hospital
Boston, Massachusetts, 02115
Rush University Medical Center
Chicago, Illinois, 60612
University of California, Los Angeles (UCLA)
Los Angeles, California, 90095
Weill Cornell Medicine
New York, New York, 10021
University of California, San Diego - Rady Children's Hospital
San Diego, California, 92123
Canada5 sites
MAGIC Clinic Ltd
Calgary, Alberta, T2E 7Z4
Childrens Hospital London Health Sciences Centre
London, Ontario, N6A 5W9
The Research Institute of the McGill University Health Centre
Montreal, Quebec, H3G 1A4
Childrens Hospital of Eastern Ontario
Ottawa, Ontario, K1H 8L1
British Columbia Children's Hospital
Vancouver, British Columbia, V6H 3V4
United Kingdom3 sites
University of Cambridge
Cambridge, CB2 0QQ
Great Ormond Street Hospital for Children
London, WC1N 3JH
Oxford University Hospitals NHS Foundation Trust
Oxford, OX3 9DU
Australia2 sites
The Royal Children's Hospital
Melbourne, Victoria, 3052
Queensland Children's Hospital
South Brisbane, Queensland, 4101
France2 sites
AP-HM - Hopital de la Timone
Marseille, 13385
AP-HP Hopital Necker-Enfants Malades
Paris, 75015
Germany2 sites
Universitaetsklinikum Hamburg-Eppendorf
Hamburg, 20246
Universitaetsklinikum Leipzig
Leipzig, 04103
Spain2 sites
Hospital Universitario Puerta de Hierro
Majadahonda, 28222
Corporacio Sanitaria Parc Tauli - Hospital de Sabadell
Sabadell, 08208
About this study
Official title: A Long-term Extension Trial Investigating the Safety and Efficacy of GTX-102 in Patients With Angelman Syndrome
The primary objective of the study is to evaluate the long-term safety profile of GTX-102 in participants with Angelman Syndrome (AS)
Read the detailed description
This study is a phase 3, long term extension (LTE) which is open to participants rolling over from a prior GTX-102 clinical study. The LTE study will evaluate the long-term safety and efficacy of GTX-102 in participants with AS.
- Conditions
- Angelman Syndrome
- Being tested
- GTX-102
- Medical subject headings
- Angelman Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
GTX-102Drug
Also called apazunersen
Antisense Oligonucleotide
| Study group | Role | What they receive |
|---|---|---|
| GTX-102 | Experimental | Participants will receive GTX-102 via intrathecal lumbar puncture (IT LP) on a intrapatient flexible dosing schedule. Receives: Drug: GTX-102 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Incidence of Treatment Emergent Adverse Events (TEAEs)
Measured: Up to 5 Years
Secondary outcomes (2)
Change from Baseline in the Bayley-4 Raw Score
Measured: Baseline, Up to 5 Years
Net Response in Multidomain Responder Index (MDRI)
Measured: Month 12, Month 24
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 May 2024
- Study start31 Jul 2024
- Primary completion30 Oct 2026
- Study completion30 Oct 2026
Why it stopped: Lack of efficacy
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Angelman SyndromeStudies of the same condition, open and under way.
- More trials run by Ultragenyx Pharmaceutical IncThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 66 participants (actual)
Sponsor and investigators
- Lead sponsor
- Ultragenyx Pharmaceutical Inc
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Medical Director, Study director, Ultragenyx Pharmaceuticals Inc.
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06415344
- Sponsor's protocol ID
- GTX-102-CL302
- Other IDs
- 2024-510917-14-00
- Status last verified
- Oct 2026
- First submitted
- 10 May 2024
- Last updated
- 3 Nov 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 3 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Long-term Extension Trial Investigating the Safety and Efficacy of GTX-102 in Patients With Angelman Syndrome
- ClinicalTrials.gov ID
- NCT06415344
- Acronym / sponsor ID
- GTX-102-CL302
- Conditions
- Angelman Syndrome
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Lack of efficacy
- Enrolment
- 66 participants (actual)
- Lead sponsor
- Ultragenyx Pharmaceutical IncIndustry (pharma, biotech, devices)
- Study start
- 31 Jul 2024 (actual)
- Primary completion
- 30 Oct 2026 (actual)
- Study completion
- 30 Oct 2026 (actual)
- First posted
- 16 May 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The primary objective of the study is to evaluate the long-term safety profile of GTX-102 in participants with Angelman Syndrome (AS)
Detailed description
This study is a phase 3, long term extension (LTE) which is open to participants rolling over from a prior GTX-102 clinical study. The LTE study will evaluate the long-term safety and efficacy of GTX-102 in participants with AS.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| GTX-102 | Experimental | Drug: GTX-102Participants will receive GTX-102 via intrathecal lumbar puncture (IT LP) on a intrapatient flexible dosing schedule. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (3 listed)
- Signed informed consent from parent(s) or legal guardian(s).
- Completed a final study visit in a prior clinical trial with GTX-102. If the subject has an ongoing adverse event, medical monitor approval is required to rollover. The Screening visit must occur within 6 months of the last visit in the prior GTX-102 trial.
- From the time of informed consent through the end of the study and for at least 6 months after the final dose of GTX-102, females of childbearing potential who are sexually active must use highly effective contraception or abstinence. Males are able to participate if they agree to remain abstinent (refrain from heterosexual intercourse) or use acceptable contraceptive methods during the study and for at least 3 months after the final dose of GTX-102.
Key exclusion criteria (4 listed)
- Discontinued from study or withdrew from study treatment in a prior GTX-102 trial.
- History or evidence of any other medical, neurological, or psychological condition that would expose the subject to an undue risk of a significant AE or interfere with study assessments during the course of the trial as determined by the clinical judgment of the Investigator.
- Known hypersensitivity to GTX-102 or its excipients that, in the judgment of the Investigator, places the subject at increased risk for adverse effects.
- Pregnant or breastfeeding or planning to become pregnant (self or partner) at any time during the study
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| GTX-102Also: apazunersenAntisense Oligonucleotide | Drug | GTX-102 |
Primary outcome
Incidence of Treatment Emergent Adverse Events (TEAEs)
Time frame: Up to 5 Years
2 secondary outcomes
Change from Baseline in the Bayley-4 Raw Score
Time frame: Baseline, Up to 5 Years
Net Response in Multidomain Responder Index (MDRI)
Time frame: Month 12, Month 24
Results and safety
The study was stopped early (reason given: Lack of efficacy). Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Nov 2026.
- Ultragenyx Patient Advocacy WebsiteLink provided by the sponsor.
- Ultragenyx Transparency CommitmentLink provided by the sponsor.
- Ultragenyx Angelman Syndrome (AS) Research Study OpportunityLink provided by the sponsor.
- Individual participant dataSharing planned: No
Related trials for Angelman Syndrome
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BEACON - Phase III Clinical Study of Rugonersen in Angelman Syndrome.
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CHAMPION: A Study to Evaluate the Efficacy and Safety of Obudanersen (ION582) in Children and Adults With Angelman Syndrome (AS)
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A Natural History Study of Angelman Syndrome
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REVEAL: A Phase 3 Study of Obudanersen (ION582) in Angelman Syndrome
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Medical Director study director
Ultragenyx Pharmaceuticals Inc.
23 sites in 8 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing GTX-102 in people with Angelman Syndrome, run by Ultragenyx Pharmaceutical Inc at 23 sites in 8 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 3 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 23 sites in United States, Canada, United Kingdom, Australia, France and 3 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study was stopped early (reason given: Lack of efficacy). Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Incidence of Treatment Emergent Adverse Events (TEAEs) (time frame: Up to 5 Years). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Nov 2026.