Efficacy and Safety Study of STX209 (Arbaclofen) for the Treatment of Social Withdrawal in Children With Fragile X Syndrome

Study Overview
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Brief Summary
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There will be four study periods: Screening (up to 14 days in length), the Treatment Period (8 weeks), the Withdrawal Period (22 days), and Follow-up Period (up to 31 days). Subjects will be randomized to receive either STX209 (5 mg twice daily [BID], 10 mg BID or 10 mg three times daily [TID]) or placebo. Efficacy,safety and tolerability assessments will be performed periodically

Official Title
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A Randomized, Double-Blind, Placebo-Controlled, Fixed-Dose Study of the Efficacy, Safety, and Tolerability of STX209 (Arbaclofen) Administered for the Treatment of Social Function in Children With Fragile X Syndrome

Conditions
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Fragile X Syndrome

Intervention / Treatment
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* Drug: arbaclofen
* Drug: arbaclofen
* Drug: arbaclofen
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Molecular documentation of the full FMR1 mutation Current pharmacological treatment regimen has been stable for at least 4 weeks prior to Screening. Subjects with a history of seizure disorder must currently be receiving treatment with antiepileptics and must have been seizure free for 6 months, or must be seizure free for 3 years if not currently receiving antiepileptics. If the subject is already receiving stable non-pharmacologic educational, behavioral, and/or dietary interventions, participation in these programs must have been continuous during the 2 months prior to Screening Exclusion Criteria: Subjects with any condition, including alcohol and drug abuse, which might interfere with the conduct of the study, confound interpretation of the study results, or endanger their own well-being. Subjects who plan to initiate or change pharmacologic or non-pharmacologic interventions during the course of the study. Subjects who have taken another investigational drug within the last 30 days. Subjects who are not able to take oral medications

Ages Eligible for Study
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Minimum Age: 5 Years
Maximum Age: 11 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: STX209 5 mg BID<br> | Drug: arbaclofen<br>* 5 mg bid<br>* Other names: R-baclofen, STX209;|
| Active Comparator: STX209 10 mg BID<br> | Drug: arbaclofen<br>* 10 mg bid<br>* Other names: R-baclofen, STX209;|
| Active Comparator: STX209 10 mg TID<br> | Drug: arbaclofen<br>* 10 mg tid<br>* Other names: R-baclofen, STX209;|
| Placebo Comparator: Placebo<br> | Drug: Placebo<br>* tid<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Aberrant Behavior Checklist-Lethargy Social Withdrawal subscale | This is a single subscale of the aberrant behavior checklist entitiled Lethargy Social Withdrawal | at 8 weeks of treatment |