RecruitingPhase 2

A Safety and Efficacy Study of GTX-102 in Subjects With Deletion- or Nondeletion-type Angelman Syndrome (AS)

United States, Argentina, Brazil60 participantsStarted 2025-10-13

Plain-language summary

The main goal of the study is to evaluate the safety and efficacy of GTX-102 in participants with Angelman syndrome.

Who can participate

Age range

1 Year – 64 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion criteria

. 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
. 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

Exclusion criteria

. 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)

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

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

Timeframe: Up to Day 506

Subprotocol A Only: Bayley-4 Cognitive Without Caregiver Input Raw Score Change from Baseline at Day 338

Timeframe: Baseline, Day 338

Subprotocol B/D Only: Multidomain Responder Index (MDRI) Net Response at Day 338

Timeframe: Baseline, Day 338

Subprotocol C Only: MDRI Net Response at Day 338

Timeframe: Baseline, Day 338

Trial details

NCT IDNCT07157254

SponsorUltragenyx Pharmaceutical Inc

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2030-01

Contact for this trial

Patients Contact Trial Recruitment

1-888-756-8657 Trialrecruitment@ultragenyx.com

View on ClinicalTrials.gov More Angelman Syndrome trials

Who can participate

Age range

1 Year – 64 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion criteria

. 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
. 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

Exclusion criteria

. 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)

What they're measuring

Timeframe: Up to Day 506

Subprotocol A Only: Bayley-4 Cognitive Without Caregiver Input Raw Score Change from Baseline at Day 338

Timeframe: Baseline, Day 338

Subprotocol B/D Only: Multidomain Responder Index (MDRI) Net Response at Day 338

Timeframe: Baseline, Day 338

Subprotocol C Only: MDRI Net Response at Day 338

Timeframe: Baseline, Day 338