Placebo-Controlled, Single-Dose Challenge Study of Gaboxadol in Adult Males With Fragile X Syndrome (FXS)

NCT06334419 | Completed Phase 2 Results DMC FDA Drug

• 1 other identifier: 2023-0795
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

This is a single dose, placebo-controlled study. Male subjects aged 18 to 40 years (inclusive) with a diagnosis of FXS. Eligible subjects may enroll in this study comprised of two in home and two in clinic visits each 14 days apart, for a total of four visits. Subjects will be given single dose gaboxadol (10 mg) or matched placebo at each of these visits to take orally. Thus, all enrolled subjects will receive placebo at home and in clinic and receive gaboxadol at home and in clinic in a blinded fashion.

Conditions

Fragile X Syndrome

Keywords

Fragile X; Fragile X Syndrome; FXS

Outcome Measures

Primary Outcomes (2)

• Target Engagement of Gaboxadol Treatment on EEG Power

  Changes in EEG recordings with gaboxadol treatment (assessed at pre-dose, 60 minutes post-dose, average response across home and lab reported). compared with pre-dose on resting theta, alpha and gamma band absolute power. Absolute power measures reflect the median power averaged across 129 electrodes in μV²/Hz. Means are presented using the average of home and lab values.

  Pre-dose compared to 60 minutes post-dose on 4 study visits, up to day 42

• Target Engagement of Gaboxadol Treatment on Auditory Chirp

  Changes in EEG recordings with gaboxadol treatment (60-90 minutes post-dose compared with pre-dose on brain response to auditory chirp stimuli), as measured by intertrial phase coherence (ITC). Means are presented using the average of home and lab values.

  Pre-dose compared to 60 minutes post-dose on 4 study visits, up to day 42

Secondary Outcomes (7)

• To Investigate the Feasibility of Home Research Visits and Procedures in Adult Males With FXS

  Pre-dose, 60 minutes post-dose

• To Investigate the Feasibility of High Density EEG Recording at Home in Adult Males With FXS

  Pre-dose, across four sessions (2 in-lab, 2 in-home), up to day 42

• To Potentially Explore the Pharmacokinetics of Gaboxadol Treatment in Single-dose Trial Design

  Sixty minutes post-dose on 4 study visits, up to day 42

• To Investigate the Effect of Gaboxadol Treatment on Neuropsychological Assessments

  Pre-dose compared to 60 minutes post-dose on 4 study visits, up to day 42

• To Investigate the Effect of Gaboxadol Treatment on Eye Tracking Assessments

  Baseline compared to 60 minutes post-dose on 4 study visits, up to day 42

Study Arms (4)

Placebo in lab, Gaboxadol in home, Gaboxadol in lab, Placebo in home

EXPERIMENTAL

Individuals in this condition received Placebo in lab, Gaboxadol in home, Gaboxadol in lab, then Placebo in home.

Drug: Gaboxadol; Drug: Placebo

Gaboxadol in lab, Gaboxadol in home, Placebo in lab, Placebo in home

EXPERIMENTAL

Individuals in this condition received Gaboxadol in lab, Gaboxadol in home, Placebo in lab, then Placebo in home.

Drug: Gaboxadol; Drug: Placebo

Placebo in lab, Placebo in home, Gaboxadol in lab, Gaboxadol in home

EXPERIMENTAL

Individuals in this condition received Placebo in lab, Placebo in home, Gaboxadol in lab, then Gaboxadol in home.

Drug: Gaboxadol; Drug: Placebo

Gaboxadol in lab, Placebo in home, Placebo in lab, Gaboxadol in home

EXPERIMENTAL

Individuals in this condition received Gaboxadol in lab, Placebo in home, Placebo in lab, then Gaboxadol in home.

Drug: Gaboxadol; Drug: Placebo

Interventions

Gaboxadol DRUG

Drug: Gaboxadol 10 mg as a single dose (two 5mg capsules)

Gaboxadol in lab, Gaboxadol in home, Placebo in lab, Placebo in home; Gaboxadol in lab, Placebo in home, Placebo in lab, Gaboxadol in home; Placebo in lab, Gaboxadol in home, Gaboxadol in lab, Placebo in home; Placebo in lab, Placebo in home, Gaboxadol in lab, Gaboxadol in home

Placebo DRUG

Two placebo capsules

Gaboxadol in lab, Gaboxadol in home, Placebo in lab, Placebo in home; Gaboxadol in lab, Placebo in home, Placebo in lab, Gaboxadol in home; Placebo in lab, Gaboxadol in home, Gaboxadol in lab, Placebo in home; Placebo in lab, Placebo in home, Gaboxadol in lab, Gaboxadol in home

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: male
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Subject consents to participate, or if they are not their own legal guardian, offers assent supported by legally authorized representative consent
• Subject is willing and able to comply with the study procedures as specified in the protocol and to comply with the study drug administration. Caregiver also commits to the study requirements prior to any study-related procedures
• Subject and caregiver are both able to understand the spoken national language clearly and caregiver can read and write to complete study assessments
• Males age 18 to 40 years (inclusive)
• Has FXS with molecular genetic confirmation of the full FMR1 mutation (\>200 cysteine-guanine-guanine \[CGG\] repeats). May have been confirmed historically or at Screening
• Is in general good health as deemed by the Investigator, determined by physical examination, medical history, and laboratory tests
• If receiving serotonin-selective reuptake inhibitor (SSRI), serotonin-norepinephrine reuptake inhibitor (SNRI), or serotonin antagonist and reuptake inhibitor (SARI), is on a stable, well-tolerated dose for the previous 3 months with no further changes anticipated
• Is not sexually active or can confirm at least one form of contraceptive

You may not qualify if:

• Any chronic major medical comorbid condition deemed by the Investigator as presenting added risk to the subject, including but not limited to, refractory hypertension, kidney disease, or liver disease
• Diagnosed with diabetes (Type 1 or II) or receiving any anti-diabetic medication
• Unstable seizure disorder, defined by any seizure within 6 months prior to baseline visit and/or a change in any anti-convulsant drug dosing in the 60 days prior to study consent
• Changes in psychotropic or anti-convulsant (where taken for reasons other than seizure control) drug treatment within 30 days prior to Screening
• Significant changes in any educational, behavioral, and/or dietary interventions the month prior to Screening
• Planned initiation of new, or modification of ongoing, interventions during the study
• Unable or unwilling to take oral medication (whole capsule, despite assistance with a spoonful of applesauce, yoghurt, or equivalent liquid food)
• Consumption of liver enzyme inducers or inhibitors including and not limited to foods, medicines, herbal remedies and supplements three days prior to any Visit. Foods or beverages containing CYP3A4/5 inhibitors (e.g., grapefruit, pomegranate, pomelo, and star fruit) should be avoided before taking study medication and for up to 1 hour post dose throughout the study
• Has abnormal baseline laboratory assessments including, but not limited to, alanine aminotransferase (ALT) or aspartate aminotransferase (AST) or total bilirubin \>1.5 × the upper limit of normal (ULN), serum creatinine \>1.5 x ULN or other clinically relevant laboratory abnormality
• Has a clinically significant heart rate or blood pressure (BP) at Screening as judged by the Investigator
• Has received an investigational drug in any prior clinical study within 30 days or 5 half-lives (whichever is longer) prior to Screening

Sponsors & Collaborators

• Craig Erickson: lead
• Healx Limited: collaborator

Study Sites (1)

Cincinnati Children's Hospital Medical Center

Cincinnati, Ohio, 45229, United States

Location

Related Publications (1)

• De Stefano LA, Kim H, Erickson CA, Schmitt LM, Dominick KC, Pedapati EV, Huckle R, Wilson R, McKinney WS, Reisinger DL, Nelson MN, Dapore AE, Horn PS, Miyakoshi M. Gaboxadol increases resting theta and alpha power without affecting evoked responses in fragile X syndrome in a home-based setting. J Neurodev Disord. 2026 May 8;18(1):36. doi: 10.1186/s11689-026-09700-5.

  PMID: 42104256 DERIVED

MeSH Terms

Conditions

Fragile X Syndrome

Interventions

gaboxadol

Condition Hierarchy (Ancestors)

X-Linked Intellectual Disability; Intellectual Disability; Neurobehavioral Manifestations; Neurologic Manifestations; Nervous System Diseases; Sex Chromosome Disorders; Chromosome Disorders; Congenital Abnormalities; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Genetic Diseases, Inborn; Genetic Diseases, X-Linked; Heredodegenerative Disorders, Nervous System

Results Point of Contact

• Title: Craig Erickson
• Organization: Cincinnati Children's Hospital Medical Center

FragileX@cchmc.org

5136366553

Study Officials

• Cragi A Erickson, MD

  Children's Hospital Medical Center, Cincinnati

  PRINCIPAL INVESTIGATOR

Publication Agreements

• PI is Sponsor Employee: No
• Restrictive Agreement: No

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Research Director and Research Endowed Professor

Model Details: This study was designed as a 2-intervention crossover, with all study participants receiving all possible interventions. These are placebo and Gaboxadol. Participants received a single dose of gaboxadol and a single dose of placebo in each of two locations (in-lab and in-home), for a total of four dosing occasions, with the first visit always occurring in-lab.

Study Record Dates

• First Submitted: March 8, 2024
• First Posted: March 28, 2024
• Study Start: January 29, 2024
• Primary Completion: May 13, 2025
• Study Completion: June 24, 2025
• Last Updated: September 30, 2026
• Results First Posted: September 30, 2026

Record last verified: 2026-07

Locations

US (1)