Fragile X SyndromePhase 2NCT06334419
Placebo-Controlled, Single-Dose Challenge Study of Gaboxadol in Adult Males With Fragile X Syndrome (FXS)
A Phase 2 study testing Gaboxadol in people with Fragile X Syndrome, run by Craig Erickson at 1 site in United States.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 40 years, men only
- Conditions the study is for
- Fragile X Syndrome
- What is being tested?
- Gaboxadol
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 10 participants
- Where
- 1 siteUnited States
- Study dates
- 29 Jan 2024to 24 Jun 2025
- Phase
- Phase 2
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 18 to 40 years
- Men only
- No healthy volunteers
- Adult
Who may be able to join
- 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
Who cannot join
- 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
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- 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
Trial locations and contacts
1 site in 1 country.
United States1 site
Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, 45229
About this study
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
- Being tested
- Gaboxadol, Placebo
- Keywords
- Fragile X, Fragile X Syndrome, FXS
- Medical subject headings
- Fragile X Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
GaboxadolDrug
Drug: Gaboxadol 10 mg as a single dose (two 5mg capsules)
PlaceboDrug
Two placebo capsules
| Study group | Role | What they receive |
|---|---|---|
| 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. Receives: 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. Receives: 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. Receives: 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. Receives: Drug: Gaboxadol; Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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.
Measured: 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
Quality and test-retest reliability of assessments performed at home compared with the hospital setting. This includes blood testing for Fragile X messenger ribonucleoprotein (FMRP: range of 0-40 picomolar) and eye-tracking of eye gaze to eye regions when viewing faces (range of value from 0 percent to 100 percent; higher values are associated with a neurotypical phenotype).
Measured: Pre-dose, 60 minutes post-dose
To Investigate the Feasibility of High Density EEG Recording at Home in Adult Males With FXS
This endpoint examined the reliability of pre-dose resting-state EEG absolute power estimates between in-lab and in-home assessments using intraclass correlation (ICC). ICCs were calculated separately for 129 electrodes using absolute power estimates (μV²/Hz). The reported ICC represents the mean ICC across electrodes, with the standard deviation reflecting variability in ICC values across electrodes. whole-head, pre-dose resting state EEG power estimates from data collected in-lab vs in-home using intraclass correlation (ICC).
Measured: 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
PK profile (the level of gaboxadol in human plasma) will be obtained at 60 +/- 10 minutes post-dose only).
Measured: Sixty minutes post-dose on 4 study visits, up to day 42
To Investigate the Effect of Gaboxadol Treatment on Neuropsychological Assessments
Changes in cognitive and neuropsychological assessment measures with gaboxadol treatment (RBANS List Learning). During the RBANS List Learning subtests, participants listen to a list of 10 words and repeat back as many as they can remember four times, for a maximum score of 40. Change scores were calculated by subtracting pre-dose words remembered from post-dose words remembered, with positive scores meaning an improvement in memory.
Measured: 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
Change in eye tracking outcomes (60-90 minutes post-dose compared to pre-dose on percent viewing of social versus geometric scene
Measured: Baseline compared to 60 minutes post-dose on 4 study visits, up to day 42
To Investigate the Effect of Gaboxadol Treatment on Clinician-rated Measures
Score on the Clinical Global Impressions - Improvement (CGI-I) scale, a clinician rating scale with "1" anchored to "very much improved" and "7" anchored to "very much worse."
Measured: Post-dose on 4 study visits, up to day 42
To Determine Whether FMRP Levels Predict Treatment Response
Relationship between FMRP (Fragile X messenger ribonucleoprotein) level and degree of change (baseline/screen to post-dose) across measures
Measured: Baseline compared to 60 minutes post-dose on 4 study visits, up to day 42
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Mar 2024
- Study start29 Jan 2024
- Primary completion13 May 2025
- Study completion24 Jun 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Fragile X SyndromeStudies of the same condition, open and under way.
- 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
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- 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.
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 10 participants (actual)
Sponsor and investigators
- Lead sponsor
- Craig Erickson
- Sponsor type
- University, hospital or other
- Collaborators
- Healx Limited
- Responsible party
- Sponsor-investigator, Craig Erickson, Children's Hospital Medical Center, Cincinnati
- Investigators
- Cragi A Erickson, MD, Principal investigator, Children's Hospital Medical Center, Cincinnati
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06334419
- Sponsor's protocol ID
- 2023-0795
- Status last verified
- Jul 2026
- First submitted
- 8 Mar 2024
- Last updated
- 30 Sep 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Publications
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.
PubMed 42104256
Study at a glance
From the registry record, last updated by the sponsor on 30 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Placebo-Controlled, Single-Dose Challenge Study of Gaboxadol in Adult Males With Fragile X Syndrome (FXS)
- ClinicalTrials.gov ID
- NCT06334419
- Acronym / sponsor ID
- 2023-0795
- Conditions
- Fragile X Syndrome
- Keywords
- Fragile X, Fragile X Syndrome, FXS
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 10 participants (actual)
- Lead sponsor
- Craig EricksonUniversity, hospital or other
- Collaborators
- Healx Limited
- Study start
- 29 Jan 2024 (actual)
- Primary completion
- 13 May 2025 (actual)
- Study completion
- 24 Jun 2025 (actual)
- First posted
- 28 Mar 2024 (actual)
- Results
- Posted 30 Sep 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 4
- Model description
- 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.
| Arm | Type | Receives |
|---|---|---|
| Placebo in lab, Gaboxadol in home, Gaboxadol in lab, Placebo in home | Experimental | Drug: Gaboxadol, Drug: PlaceboIndividuals in this condition received Placebo in lab, Gaboxadol in home, Gaboxadol in lab, then Placebo in home. |
| Gaboxadol in lab, Gaboxadol in home, Placebo in lab, Placebo in home | Experimental | Drug: Gaboxadol, Drug: PlaceboIndividuals in this condition received Gaboxadol in lab, Gaboxadol in home, Placebo in lab, then Placebo in home. |
| Placebo in lab, Placebo in home, Gaboxadol in lab, Gaboxadol in home | Experimental | Drug: Gaboxadol, Drug: PlaceboIndividuals in this condition received Placebo in lab, Placebo in home, Gaboxadol in lab, then Gaboxadol in home. |
| Gaboxadol in lab, Placebo in home, Placebo in lab, Gaboxadol in home | Experimental | Drug: Gaboxadol, Drug: PlaceboIndividuals in this condition received Gaboxadol in lab, Placebo in home, Placebo in lab, then Gaboxadol in home. |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- Male only
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (8 listed)
- 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
Key exclusion criteria (11 listed)
- 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
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 |
|---|---|---|
| GaboxadolDrug: Gaboxadol 10 mg as a single dose (two 5mg capsules) | Drug | 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 |
| PlaceboTwo placebo capsules | Drug | 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 |
Primary outcome
Target Engagement of Gaboxadol Treatment on EEG Power
Time frame: Pre-dose compared to 60 minutes post-dose on 4 study visits, up to day 42
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.
Target Engagement of Gaboxadol Treatment on Auditory Chirp
Time frame: Pre-dose compared to 60 minutes post-dose on 4 study visits, up to day 42
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.
7 secondary outcomes
To Investigate the Feasibility of Home Research Visits and Procedures in Adult Males With FXS
Time frame: Pre-dose, 60 minutes post-dose
To Investigate the Feasibility of High Density EEG Recording at Home in Adult Males With FXS
Time frame: 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
Time frame: Sixty minutes post-dose on 4 study visits, up to day 42
To Investigate the Effect of Gaboxadol Treatment on Neuropsychological Assessments
Time frame: 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
Time frame: Baseline compared to 60 minutes post-dose on 4 study visits, up to day 42
To Investigate the Effect of Gaboxadol Treatment on Clinician-rated Measures
Time frame: Post-dose on 4 study visits, up to day 42
To Determine Whether FMRP Levels Predict Treatment Response
Time frame: Baseline compared to 60 minutes post-dose on 4 study visits, up to day 42
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Sep 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 42104256De 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.
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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.
Cragi A Erickson, MD principal investigator
Children's Hospital Medical Center, Cincinnati
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Gaboxadol in people with Fragile X Syndrome, run by Craig Erickson at 1 site in United States.
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 8 inclusion and 11 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: finished, as of the sponsor's last update on 30 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. 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?
Yes. Results are posted in the registry (first posted 30 Sep 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
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?
Target Engagement of Gaboxadol Treatment on EEG Power (time frame: Pre-dose compared to 60 minutes post-dose on 4 study visits, up to day 42). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06334419, which also lists 1 linked publication.
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 30 Sep 2026; AzTrials last refreshed its copy on 8 Nov 2026.