Angelman SyndromePhase 2AuroraNCT07157254
A Safety and Efficacy Study of GTX-102 in Subjects With Deletion- or Nondeletion-type Angelman Syndrome (AS)
A Phase 2 study testing GTX-102 in people with Angelman Syndrome, run by Ultragenyx Pharmaceutical Inc at 21 sites in 8 countries.
Trial summary
The main goal of the study is to evaluate the safety and efficacy of GTX-102 in participants with Angelman syndrome. Read more about this study
- Who is it for?
- Ages 1 year to 64 years
- Conditions the study is for
- Angelman Syndrome
- What is being tested?
- GTX-102
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 55 participants
- Where
- 21 sitesin 8 countries
- Study dates
- 13 Oct 2025to 30 Oct 2026
- Phase
- Phase 2
- 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 1 year to 64 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- Signed informed consent from parent(s) or legal guardian(s)
- Males and females of the following ages and genotypes at time of informed consent:
- Subprotocol A: ≥ 1 to < 4 years of age with a genetically confirmed diagnosis of deletion-type Angelman syndrome
- Subprotocol B: ≥ 4 to < 18 years of age with a genetically confirmed diagnosis of UPD/ICD Angelman syndrome
- Subprotocol C: ≥ 18 to < 65 years of age with a genetically confirmed diagnosis of Angelman syndrome, any genotype
- Subprotocol D: ≥ 4 to < 18 years of age with a genetically confirmed diagnosis of mutation-type Angelman syndrome
Show all 10Show fewer
- Weight ≥ 8 kg at Screening Visit
- Platelet count, prothrombin time / international normalized ratio, and partial thromboplastin time < 1.5x the upper limit of normal and platelets > 75,000 cells/mm3 at the Screening Visit
- Willing and able to comply with scheduled visits, drug administration plan, laboratory tests, and all study procedures, including lumbar puncture (LP) procedure, magnetic resonance imaging (MRI) and tolerating anesthesia without intubation
- From the time of informed consent through to 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
- Any change in medications or diet/supplements intended to treat symptoms of Angelman Syndrome (eg, sleeping aids, antiseizure medications, supplements, dietary change including ketogenic or low-glycemic index diet, other) within the month prior to the Screening Visit (excluding weight-based adjustments)
- Any condition that creates an increased risk of unsuccessful lumbar puncture
- Current or expected concomitant use of drugs that increase the risk of bleeding (eg, heparin, low molecular weight heparin, platelet inhibitors)
- Known hypersensitivity to GTX-102 or its excipients or required premedication that, in the judgment of the Investigator, places the subject at increased risk for adverse effects
- Presence or history of any condition, lab abnormality, or infection that, in the judgment of the Investigator, would interfere with study participation, pose undue safety risk, or would confound interpretation of results
- Pregnant or breastfeeding or planning to become pregnant (self or partner) at any time during the study
- Use of any investigational product or investigational medical device within 6 months or 5 half-lives prior to the Screening Visit, or any prior use of gene therapy or an ASO regardless of length of time since last use
- Concurrent participation in any interventional study
Trial locations and contacts
21 sites in 8 countries.
21 sites in 8 countries
United States8 sites
Akron Children's Hospital
Akron, Ohio, 44308
UT Health Austin
Austin, Texas, 78723
Kennedy Kreiger Institute
Baltimore, Maryland, 21205
Rush University Medical Center
Chicago, Illinois, 60612
Carum Research Inc.
Dallas, Texas, 75243
Rare Disease Research
Hillsborough, North Carolina, 27278
Clinical Trial Site
Kansas City, Missouri, 64108
Cedars Sinai Medical Center
Los Angeles, California, 90048
Italy3 sites
Azienda Ospedaliera Universitaria Meyer IRCCS
Florence
Fondazione IRCCS Istituto Neurologico C. Besta
Milan
Clinical Trial Site
Rome
Brazil2 sites
Hospital de Crianças César Pernetta e Hospital Pequeno Príncipe
Curitiba, Paraná
Casa dos Raros
Santa Cecília, Porto Alegre
France2 sites
Hopital de la Timone
Marseille
Necker-Enfants Malades Hospital
Paris
United Kingdom2 sites
Clinical Trial Site
London
University of Oxford
Oxford
About this study
Official title: A Phase 2, Open-label, Basket Study Investigating the Safety and Efficacy of GTX-102 in Adult and Pediatric Subjects With Deletion- or Nondeletion-type Angelman Syndrome
The main goal of the study is to evaluate the safety and efficacy of GTX-102 in participants with Angelman syndrome.
Read the detailed description
This basket study is designed to evaluate safety and efficacy of GTX-102 in participants with Angelman syndrome across genotypes and age groups. The study consists of subprotocols A, B, C and D. All subprotocols are open-label and follow the same design which includes a Screening, Loading and Maintenance period. Subprotocols A, B and C are single arm only. In subprotocol D, participants are randomized 2:1 to a GTX-102 group or a No Treatment group. The No Treatment group follows the same schedule of events as all other groups after completion of the No Treatment period. Participants from all the subprotocols have the option to continue treatment in a long-term extension study following their end of study visit.
- Conditions
- Angelman Syndrome
- Being tested
- No intervention, GTX-102
- Keywords
- Angelman Syndrome
- Medical subject headings
- Angelman Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
No interventionOther
During the no treatment period participants do not receive any study drug
GTX-102Drug
Also called apazunersen
antisense oligonucleotide
| Study group | Role | What they receive |
|---|---|---|
| Subprotocol A GTX-102 | Experimental | Participants with deletion-type Angelman syndrome, ≥1 to <4 years of age will receive increasing doses of GTX-102 via intrathecal (IT) injection until the target dose is achieved. Dosing occurs every 3 months (Q3M) thereafter. Receives: Drug: GTX-102 |
| Subprotocol B GTX-102 | Experimental | Participants with paternal uniparental disomy (UPD)/imprinting center defect (ICD) Angelman syndrome, ≥4 to <18 years of age will receive increasing doses of GTX-102 via IT injection until the target dose is achieved. Dosing occurs Q3M thereafter. Receives: Drug: GTX-102 |
| Subprotocol C GTX-102 | Experimental | Participants with all genotypes of Angelman syndrome, ≥18 to <65 years of age will receive increasing doses of GTX-102 via IT injection until the target dose is achieved. Dosing occurs Q3M thereafter. Receives: Drug: GTX-102 |
| Subprotocol D GTX-102 | Experimental | Participants with mutation-type Angelman syndrome, ≥4 to <18 years of age will receive increasing doses of GTX-102 via IT injection until the target dose is achieved. Dosing occurs Q3M thereafter. Receives: Drug: GTX-102 |
| Subprotocol D No Intervention then GTX-102 | Experimental | Participants with mutation-type Angelman syndrome, ≥4 to <18 years of age will receive no treatment during the initial period. At the end of the no treatment period, participants will receive increasing doses of GTX-102 via IT injection until the target dose is achieved. Dosing occurs Q3M thereafter. Receives: Other: No intervention; Drug: GTX-102 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Subprotocol A/B/C/D: Number of Participants with Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs), Severe Events, and Events Related to Investigational Product, Procedure, and Premedication
Measured: Up to Day 506
Subprotocol A Only: Bayley-4 Cognitive Without Caregiver Input Raw Score Change from Baseline at Day 338
Measured: Baseline, Day 338
Subprotocol B/D Only: Multidomain Responder Index (MDRI) Net Response at Day 338
The following assessments will be included to calculate the MDRI net response: Bayley-4 Cognitive and Receptive Communication, Aberrant Behavior Checklist- Community (ABC-C) Hyperactivity/Noncompliance (H/N), Angelman Severity Assessment (ASA) Sleep, ASA Gross Motor. For each assessment a meaningful score difference (MSD) is defined. A single net response score per participant will be derived accordingly, and a summary measure of net response will then be calculated across all participants.
Measured: Baseline, Day 338
Subprotocol C Only: MDRI Net Response at Day 338
The following assessments will be included to calculate the MDRI net response: Vineland-3 Expressive and Receptive Communication, ABC-C Irritability, ASA Gross Motor. For each assessment a meaningful score difference (MSD) is defined. A single net response score per participant will be derived accordingly, and a summary measure of net response will then be calculated across all participants.
Measured: Baseline, Day 338
Secondary outcomes (9)
Subprotocol A/B/D Only: Change From Baseline at Day 338 in Bayley-4 Receptive Communication Raw Score
Measured: Baseline, Day 338
Subprotocol A/B/D Only: Change From Baseline at Day 338 in Bayley-4 Gross Motor Raw Score
Measured: Baseline, Day 338
Subprotocol B/D Only: Change From Baseline at Day 338 in Bayley-4 Cognitive Raw Score
Measured: Baseline, Day 338
Subprotocol B/C/D Only: Change From Baseline at Day 338 in Vineland-3 Receptive Communication Raw Score
Measured: Baseline, Day 338
Subprotocol B/C/D Only: Change From Baseline at Day 338 in Vineland-3 Expressive Communication Raw Score
Measured: Baseline, Day 338
Subprotocol B/D: Change From Baseline at Day 338 in Aberrant Behavior Checklist-Community (ABC-C) Hyperactivity/Noncompliance Raw Score
Measured: Baseline, Day 338
Subprotocol B/D Only: Change From Baseline at Day 338 in Angelman Severity Assessment (ASA) Sleep Rating
Measured: Baseline, Day 338
Subprotocol B/C/D Only: Change From Baseline at Day 338 in ASA Gross Motor Rating
Measured: Baseline, Day 338
Subprotocol C Only: Change From Baseline at Day 338 in ABC-C Irritability Raw Score
Measured: Baseline, Day 338
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Sep 2025
- Study start13 Oct 2025
- 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 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 55 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 Pharmaceutical Inc
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07157254
- Sponsor's protocol ID
- GTX-102-CL210
- Other IDs
- 2024-519393-39-00
- Acronym
- Aurora
- Status last verified
- Oct 2026
- First submitted
- 21 Aug 2025
- 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 Phase 2, Open-label, Basket Study Investigating the Safety and Efficacy of GTX-102 in Adult and Pediatric Subjects With Deletion- or Nondeletion-type Angelman Syndrome
- ClinicalTrials.gov ID
- NCT07157254
- Acronym / sponsor ID
- Aurora / GTX-102-CL210
- Conditions
- Angelman Syndrome
- Keywords
- Angelman Syndrome
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Lack of efficacy
- Enrolment
- 55 participants (actual)
- Lead sponsor
- Ultragenyx Pharmaceutical IncIndustry (pharma, biotech, devices)
- Study start
- 13 Oct 2025 (actual)
- Primary completion
- 30 Oct 2026 (actual)
- Study completion
- 30 Oct 2026 (actual)
- First posted
- 5 Sep 2025 (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 main goal of the study is to evaluate the safety and efficacy of GTX-102 in participants with Angelman syndrome.
Detailed description
This basket study is designed to evaluate safety and efficacy of GTX-102 in participants with Angelman syndrome across genotypes and age groups. The study consists of subprotocols A, B, C and D. All subprotocols are open-label and follow the same design which includes a Screening, Loading and Maintenance period. Subprotocols A, B and C are single arm only. In subprotocol D, participants are randomized 2:1 to a GTX-102 group or a No Treatment group. The No Treatment group follows the same schedule of events as all other groups after completion of the No Treatment period. Participants from all the subprotocols have the option to continue treatment in a long-term extension study following their end of study visit.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 5
| Arm | Type | Receives |
|---|---|---|
| Subprotocol A GTX-102 | Experimental | Drug: GTX-102Participants with deletion-type Angelman syndrome, ≥1 to <4 years of age will receive increasing doses of GTX-102 via intrathecal (IT) injection until the target dose is achieved. Dosing occurs every 3 months (Q3M) thereafter. |
| Subprotocol B GTX-102 | Experimental | Drug: GTX-102Participants with paternal uniparental disomy (UPD)/imprinting center defect (ICD) Angelman syndrome, ≥4 to <18 years of age will receive increasing doses of GTX-102 via IT injection until the target dose is achieved. Dosing occurs Q3M thereafter. |
| Subprotocol C GTX-102 | Experimental | Drug: GTX-102Participants with all genotypes of Angelman syndrome, ≥18 to <65 years of age will receive increasing doses of GTX-102 via IT injection until the target dose is achieved. Dosing occurs Q3M thereafter. |
| Subprotocol D GTX-102 | Experimental | Drug: GTX-102Participants with mutation-type Angelman syndrome, ≥4 to <18 years of age will receive increasing doses of GTX-102 via IT injection until the target dose is achieved. Dosing occurs Q3M thereafter. |
| Subprotocol D No Intervention then GTX-102 | Experimental | Other: No intervention, Drug: GTX-102Participants with mutation-type Angelman syndrome, ≥4 to <18 years of age will receive no treatment during the initial period. At the end of the no treatment period, participants will receive increasing doses of GTX-102 via IT injection until the target dose is achieved. Dosing occurs Q3M thereafter. |
Who may qualify
- Ages
- 1 year to 64 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult
Key inclusion criteria (10 listed)
- Signed informed consent from parent(s) or legal guardian(s)
- Males and females of the following ages and genotypes at time of informed consent:
- Weight ≥ 8 kg at Screening Visit
- Platelet count, prothrombin time / international normalized ratio, and partial thromboplastin time < 1.5x the upper limit of normal and platelets > 75,000 cells/mm3 at the Screening Visit
- Willing and able to comply with scheduled visits, drug administration plan, laboratory tests, and all study procedures, including lumbar puncture (LP) procedure, magnetic resonance imaging (MRI) and tolerating anesthesia without intubation
Key exclusion criteria (8 listed)
- Any change in medications or diet/supplements intended to treat symptoms of Angelman Syndrome (eg, sleeping aids, antiseizure medications, supplements, dietary change including ketogenic or low-glycemic index diet, other) within the month prior to the Screening Visit (excluding weight-based adjustments)
- Any condition that creates an increased risk of unsuccessful lumbar puncture
- Current or expected concomitant use of drugs that increase the risk of bleeding (eg, heparin, low molecular weight heparin, platelet inhibitors)
- Known hypersensitivity to GTX-102 or its excipients or required premedication that, in the judgment of the Investigator, places the subject at increased risk for adverse effects
- Presence or history of any condition, lab abnormality, or infection that, in the judgment of the Investigator, would interfere with study participation, pose undue safety risk, or would confound interpretation of results
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 |
|---|---|---|
| No interventionDuring the no treatment period participants do not receive any study drug | Other | Subprotocol D No Intervention then GTX-102 |
| GTX-102Also: apazunersenantisense oligonucleotide | Drug | Subprotocol A GTX-102, Subprotocol B GTX-102, Subprotocol C GTX-102, Subprotocol D GTX-102, Subprotocol D No Intervention then GTX-102 |
Primary outcome
Subprotocol A/B/C/D: Number of Participants with Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs), Severe Events, and Events Related to Investigational Product, Procedure, and Premedication
Time frame: Up to Day 506
Subprotocol A Only: Bayley-4 Cognitive Without Caregiver Input Raw Score Change from Baseline at Day 338
Time frame: Baseline, Day 338
Subprotocol B/D Only: Multidomain Responder Index (MDRI) Net Response at Day 338
Time frame: Baseline, Day 338
The following assessments will be included to calculate the MDRI net response: Bayley-4 Cognitive and Receptive Communication, Aberrant Behavior Checklist- Community (ABC-C) Hyperactivity/Noncompliance (H/N), Angelman Severity Assessment (ASA) Sleep, ASA Gross Motor. For each assessment a meaningful score difference (MSD) is defined. A single net response score per participant will be derived accordingly, and a summary measure of net response will then be calculated across all participants.
Subprotocol C Only: MDRI Net Response at Day 338
Time frame: Baseline, Day 338
The following assessments will be included to calculate the MDRI net response: Vineland-3 Expressive and Receptive Communication, ABC-C Irritability, ASA Gross Motor. For each assessment a meaningful score difference (MSD) is defined. A single net response score per participant will be derived accordingly, and a summary measure of net response will then be calculated across all participants.
9 secondary outcomes
Subprotocol A/B/D Only: Change From Baseline at Day 338 in Bayley-4 Receptive Communication Raw Score
Time frame: Baseline, Day 338
Subprotocol A/B/D Only: Change From Baseline at Day 338 in Bayley-4 Gross Motor Raw Score
Time frame: Baseline, Day 338
Subprotocol B/D Only: Change From Baseline at Day 338 in Bayley-4 Cognitive Raw Score
Time frame: Baseline, Day 338
Subprotocol B/C/D Only: Change From Baseline at Day 338 in Vineland-3 Receptive Communication Raw Score
Time frame: Baseline, Day 338
Subprotocol B/C/D Only: Change From Baseline at Day 338 in Vineland-3 Expressive Communication Raw Score
Time frame: Baseline, Day 338
Subprotocol B/D: Change From Baseline at Day 338 in Aberrant Behavior Checklist-Community (ABC-C) Hyperactivity/Noncompliance Raw Score
Time frame: Baseline, Day 338
Subprotocol B/D Only: Change From Baseline at Day 338 in Angelman Severity Assessment (ASA) Sleep Rating
Time frame: Baseline, Day 338
Subprotocol B/C/D Only: Change From Baseline at Day 338 in ASA Gross Motor Rating
Time frame: Baseline, Day 338
Subprotocol C Only: Change From Baseline at Day 338 in ABC-C Irritability Raw Score
Time frame: Baseline, Day 338
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.
- Individual participant dataSharing planned: No
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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 Pharmaceutical Inc
21 sites in 8 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing GTX-102 in people with Angelman Syndrome, run by Ultragenyx Pharmaceutical Inc at 21 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 10 inclusion and 8 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 21 sites in United States, Italy, Brazil, France, Portugal 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 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
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?
Subprotocol A/B/C/D: Number of Participants with Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs), Severe Events, and Events Related to Investigational Product, Procedure, and Premedication (time frame: Up to Day 506). The study lists 4 primary outcomes in all. 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.