Remote feasibility test of phenylbutyrate for SLC6A1-related disorders

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This phase 2 trial will evaluate the feasibility of conducting a fully remote clinical study in families affected by SLC6A1-related disorders. Participants will receive glycerol phenylbutyrate, have regular EEG monitoring and lab tests, and caregivers will report seizures and side effects. Participants are randomized to immediate treatment or a 6-week observation period before starting therapy, with treatment lasting up to 18 weeks and optional extension up to 3 years. Follow-up assessments occur at 18 weeks and, if extended, at 6 months, 1 year, and annually thereafter. The study aims to gather preliminary data on safety, tolerability, and potential seizure-related effects in a remote-trial format.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* Confirmed diagnosis of SLC6A1-related disorder based on a pathogenic or likely pathogenic variant in the SLC6A1 gene
* Age 2-60 years at time of consent
* Active clinical seizures, defined as ≥4 seizures in the 4 weeks prior to enrollment
* Seizures persisting despite an adequate trial of ≥2 prior antiseizure medications at therapeutic doses
* Stable antiseizure medication regimen for ≥4 weeks prior to enrollment
* Parent, legal guardian, or legally authorized representative (LAR) able to provide informed consent and participate in digital follow-up assessments
* Local licensed physician identified for ordering laboratory testing, EEG, and clinical evaluation as needed
* English-speaking caregiver for consent and study communication

Exclusion Criteria:

* Larger 3p25 chromosomal deletion extending beyond SLC6A1 and SLC6A11 to encompass additional genes
* Early-infantile developmental and epileptic encephalopathy (DEE) phenotype
* Epileptic spasms within the 6 months prior to enrollment
* Hepatic impairment (AST or ALT \>2× the upper limit of normal)
* Renal impairment (eGFR \<60 mL/min/1.73m²)
* Thrombocytopenia (platelet count \<150 × 10³/μL)
* Inborn errors of beta-oxidation
* Pancreatic insufficiency or intestinal malabsorption
* Known hypersensitivity to phenylbutyrate or any of its components
* Participation in another interventional investigational study within 30 days or 5 half-lives of the investigational product, whichever is longer
* Current use of alfentanil, quinidine, cyclosporine, or probenecid due to clinically significant interactions with phenylbutyrate based on CYP3A4 modulation
* Pregnancy or breastfeeding
* Any condition that in the investigator's judgment would interfere with study participation or safety monitoring

This is a fully remote study. Participants may enroll from any U.S. state. No facility visit is required.

Where it's running

• Scripps Research Translational Institute
  San Diego, California, United States Recruiting

Study contacts

• Principal investigator: Kristen Barbour, MD — This is a fully remote study. Participants may enroll from any U.S. state. No facility visit is required.
• Study coordinator: Kristen Barbour, MD
• Email: kbarbour@scripps.edu
• Phone: 619-613-0693

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.