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

This study has been completed.
Information provided by (Responsible Party):
Seaside Therapeutics, Inc. Identifier:
First received: March 28, 2011
Last updated: July 30, 2013
Last verified: July 2013
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

Condition Intervention Phase
Fragile X Syndrome
Drug: arbaclofen
Drug: Placebo
Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: 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

Resource links provided by NLM:

Further study details as provided by Seaside Therapeutics, Inc.:

Primary Outcome Measures:
  • Aberrant Behavior Checklist-Lethargy Social Withdrawal subscale [ Time Frame: at 8 weeks of treatment ]
    This is a single subscale of the aberrant behavior checklist entitiled Lethargy Social Withdrawal

Enrollment: 172
Study Start Date: June 2011
Primary Completion Date: June 2013 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: STX209 5 mg BID Drug: arbaclofen
5 mg bid
Other Name: R-baclofen, STX209
Active Comparator: STX209 10 mg BID Drug: arbaclofen
10 mg bid
Other Name: R-baclofen, STX209
Active Comparator: STX209 10 mg TID Drug: arbaclofen
10 mg tid
Other Name: R-baclofen, STX209
Placebo Comparator: Placebo Drug: Placebo


Ages Eligible for Study:   5 Years to 11 Years   (Child)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

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
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01325220

  Hide Study Locations
United States, Arizona
Southwest Autism Research & Resource Center
Phoenix, Arizona, United States, 85006
United States, California
Miller Children's Hospital
Long Beach, California, United States, 90806
University of California-Davis, M.I.N.D. Institute
Sacramento, California, United States, 95817
Psychiatric Centers at San Diego
San Diego, California, United States, 92108
United States, Colorado
University of Colorado Denver, Children's Hospital
Aurora, Colorado, United States, 80045
United States, Florida
University of Miami, Mailman Center for Child Development
Miami, Florida, United States, 33136
Lake Mary Pediatrics
Orange City, Florida, United States, 32763
United States, Georgia
Emory University School of Medicine
Decatur, Georgia, United States, 30033
United States, Illinois
Rush University Medical Center
Chicago, Illinois, United States, 60612
United States, Kansas
Kansas University Clinical Research Center
Fairway, Kansas, United States, 66205
United States, Maryland
Kennedy Krieger Institute
Baltimore, Maryland, United States, 21205
United States, Massachusetts
University of Massachusetts
Worcester, Massachusetts, United States, 01605
United States, Michigan
Children's Hospital of Michigan
Detriot, Michigan, United States, 48201
United States, Missouri
University of Missouri, Thompson Research Center for Autism & Neurodevelopmental Disorders
Columbia, Missouri, United States, 65211
United States, New York
Seaver Autism Center, Mount Sinai Medical Center
New York, New York, United States, 10029
New York State Institute for Basic Research in Developmental Disabilities
Staten Island, New York, United States, 10314
United States, North Carolina
Duke Clinical Research Unit
Durham, North Carolina, United States, 27710
United States, Ohio
Akron Children's Hospital
Akron, Ohio, United States, 44308
Cincinnati Children's Hospital
Cincinnati, Ohio, United States, 45229
United States, Oklahoma
University of Oklahoma, Physician's Child Study Center
Oklahoma City, Oklahoma, United States, 73117
United States, Pennsylvania
Suburban Research Associates/Elwyn Genetics
Media, Pennsylvania, United States, 19063
United States, South Carolina
Greenwood Genetics Center
Greenwood, South Carolina, United States, 29646
United States, Tennessee
Vanderbilt Kennedy Center
Nashville, Tennessee, United States, 37203
United States, Texas
Childrens Medical Center Dallas
Dallas, Texas, United States, 75235
Texas Children's Hospital
Houston, Texas, United States, 77030
Red Oaks Psychiatry Associates, P.A.
Houston, Texas, United States, 77090
Road Runner Research
San Antonio, Texas, United States, 78258
United States, Washington
Seattle Children's Hospital
Seattle, Washington, United States, 98101
Sponsors and Collaborators
Seaside Therapeutics, Inc.
Study Director: Paul Wang, M.D. Seaside Therapeutics, Inc.
  More Information

Responsible Party: Seaside Therapeutics, Inc. Identifier: NCT01325220     History of Changes
Other Study ID Numbers: 209FX302
Study First Received: March 28, 2011
Last Updated: July 30, 2013

Additional relevant MeSH terms:
Fragile X Syndrome
Pathologic Processes
Mental Retardation, X-Linked
Intellectual Disability
Neurobehavioral Manifestations
Neurologic Manifestations
Nervous System Diseases
Sex Chromosome Disorders
Chromosome Disorders
Congenital Abnormalities
Genetic Diseases, Inborn
Genetic Diseases, X-Linked
Heredodegenerative Disorders, Nervous System processed this record on April 24, 2017