Safety, Tolerability and Efficacy Study of STX209 in Subjects With Fragile X Syndrome

Study Overview
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Brief Summary
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The study objective is to explore the efficacy, safety and tolerability of STX209 for treatment of irritability in subjects with FSX. We hypothesize that STX209 will improve irritability and other typical problem behaviors associated with fragile X syndrome. We also hypothesize that STX209 will be safe and well tolerated.

Official Title
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A Double-Blind, Placebo-Controlled, Crossover, Flexible-Dose Evaluation of the Efficacy, Safety and Tolerability of STX209 in the Treatment of Irritability in Subjects With Fragile X Syndrome

Conditions
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Fragile X Syndrome

Intervention / Treatment
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* Drug: STX209
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male or female subjects 12 to 40 years of age eventually expanding to 6 years of age Molecular documentation of the fragile X mutation. Clinical Global Impression - Severity (CGI-S) rating for problem behavior of moderate or higher at screening and at Visit 1 An Aberrant Behavior Checklist (ABC-C) Irritability Subscale score >12 and at least 3 items on the Irritability Subscale rated at least moderate or above. Current treatment with no more than three psychoactive medications, including anti-epileptics. Current pharmacological treatment regimen has been stable for at least 4 weeks. Exclusion Criteria: Subjects with a history of seizure disorder who are not currently receiving treatment with antiepileptics. 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. This includes, but is not limited to impairment of renal function, evidence or history of malignancy or any significant hematological, endocrine, cardiovascular, respiratory, hepatic, or gastrointestinal disease. Subjects who plan to initiate or change pharmacologic or non-pharmacologic interventions during the course of the study. Subjects who are currently receiving treatment with racemic baclofen. Subjects currently treated with vigabatrin or tiagabine. Subjects taking another investigational drug currently or within the last 30 days.

Ages Eligible for Study
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Minimum Age: 6 Years
Maximum Age: 40 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: Crossover Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: STX209<br>STX209 variable dose from 1mg bid to 10mg tid, capsule, oral, 4 weeks | Drug: STX209<br>* Variable dose from 1 mg bid to 10 mg tid, Capsule, Oral, 4 weeks<br>* Other names: arbaclofen;|
| Placebo Comparator: Placebo<br>variable dose (same flexible dose titration protocol), bid to tid, capsule, Oral, 4 weeks | Drug: Placebo<br>* variable dose (same flexible dose titration protocol), bid to tid, capsule, Oral, 4 weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Aberrant Behavior Checklist Irritability Subscore | The Aberrant Behavior Checklist-Community Edition (ABC-C) is a 58-item questionnaire composed of five different independent subscales. The questionnaire is completed by the parent/caregiver and lists aberrant behaviors and asks about the severity of the problem. ABC-Irritability is one of the subscales and comprises of 15 items. Minimum score is 0, maximum is 45. A decreased score indicates few aberrant behaviors and clinical improvement. The entire ABC-C assessment is administered at baseline and then at the end of each Intervention Period (4 weeks after Baseline). | After 4 weeks of treatment | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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fragile X syndrome, irritability, behavior problems