SLC6A1-NDD Prospective Longitudinal Natural History Study (SPIRIT)

The overall objective of this prospective longitudinal natural history study is to collect clinical data to characterize and evaluate the natural course of SLC6A1-NDD and assess the feasibility of certain assessments for the purpose of conducting future clinical studies in patients with this disease.

Study Overview

• Status: Not yet recruiting
• Conditions: Developmental and Epileptic Encephalopathies; SLC6A1 Neurodevelopmental Disorder (NDD)

Detailed Description

GTEP01 is a noninterventional, multicenter, multinational, prospective longitudinal natural history study that will be conducted in different countries/languages to prepare for future international clinical studies.

The aim of this study is to characterize the natural course of SLC6A1-NDD through collecting clinical data longitudinally.

Approximately 60 patients with SLC6A1-NDD are planned to be enrolled within 2 age groups, a minimum of approximately 20 patients in each of the 2 age groups. The study consists of Enrollment and Baseline visits followed by 5 study visits over a 2-year Observational Period.

• Study Type: Observational
• Enrollment (Estimated): 60

Contacts and Locations

• Study Contact: Name: UCB Cares; Phone Number: +18445992273; Email: ucbcares@ucb.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population comprises pediatric patients with a diagnosis of SLC6A1-NDD.

Description

Inclusion Criteria:

• Patient with a diagnosis of SLC6A1-NDD characterized by epilepsy, global developmental delay, autism spectrum disorder, or intellectual disability, with a documented history of an SLC6A1 mutation, defined as pathogenic or likely pathogenic by the Investigator.
• Patients should not be older than 17 years at time of assent/consent.
• Patients under the age of 18 years with legal guardians providing informed consent. Assent will be obtained from any patients judged to have sufficient capacity to provide assent at the discretion of the Investigator.
• Patient and patient's caregiver are willing and able to comply with study requirements (including diary completion and visit schedule).

Exclusion Criteria:

• Patients and their caregivers are unable to complete follow-up visits.
• Patients with a history of an alternate diagnosis for disease, including a genetic cause, which is known to contribute to epilepsy or NDD.
• Patient is currently receiving an investigational product(s) other than 4-phenylbutyrate or has received an investigational product within 30 days or within <5 times the half-life of the investigational product, whichever is longer, prior to the Enrollment Visit.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Age group 1 (< 6 years); This age group consists of patients which are < 6 years at the time of study enrollment.
Age group 2 (6 to 17 years); This age group consists of patients which are between 6 and 17 years at the time of study enrollment.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Seizure frequency by type (countable seizures per 28 days) by visit as compared to Baseline	2 years
Seizure free days per 28 days by visit as compared to Baseline	2 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number and proportion of tests completed by visit	Number and proportion of scheduled assessments completed by participants at each study visit for domains relevant to the natural history of SLC6A1 NDD, including epileptic seizures, neurodevelopment, behavioral, communication, sleep, and overall symptom severity.	2 years
Patient retention (dropout by visit and reason for dropout)		2 years
EEG over time: Number/proportion of tests completed by study patients by visit		2 years

Collaborators and Investigators

• Sponsor: UCB Biopharma SRL
• Investigators: Study Director: UCB Cares, 001 844 599 2273 (UCB)

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): May 25, 2029
• Study Completion (Estimated): May 25, 2029

Study Registration Dates

• First Submitted: April 8, 2026
• First Submitted That Met QC Criteria: April 8, 2026
• First Posted (Actual): April 15, 2026

Study Record Updates

• Last Update Posted (Actual): April 15, 2026
• Last Update Submitted That Met QC Criteria: April 8, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Natural history study; SLC6A1- NDD
• Other Study ID Numbers: GTEP01; EUPAS1000000861 (Registry Identifier: HMA-EMA Catalogue of RWD studies)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Not yet confirmed

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No