Cited by 183Genetics and Neurodevelopmental DisordersAutism Spectrum Disorder ResearchWilliams Syndrome Research

Arbaclofen in fragile X syndrome: results of phase 3 trials

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Berry-Kravis, Elizabeth, Hagerman, Randi, Visootsak, Jeannie, Budimirovic, Dejan, Kaufmann, Walter E., Cherubini, Maryann, Zarevics, Peter, Walton-Bowen, Karen +3 more·2017·Journal of Neurodevelopmental Disorders

Abstract

Arbaclofen improved multiple abnormal phenotypes in animal models of fragile X syndrome (FXS) and showed promising results in a phase 2 clinical study. The objective of the study is to determine safety and efficacy of arbaclofen for social avoidance in FXS. Two phase 3 placebo-controlled trials were conducted, a flexible dose trial in subjects age 12–50 (209FX301, adolescent/adult study) and a fixed dose trial in subjects age 5–11 (209FX302, child study). The primary endpoint for both trials was the Social Avoidance subscale of the Aberrant Behavior Checklist-Community Edition, FXS-specific (ABC-C FX ). Secondary outcomes included other ABC-C FX subscale scores, Clinical Global Impression-Improvement (CGI-I), Clinical Global Impression-Severity (CGI-S), and Vineland Adaptive Behavior Scales, Second Edition (Vineland-II) Socialization domain score. A total 119 of 125 randomized subjects completed the adolescent/adult study ( n = 57 arbaclofen, 62 placebo) and 159/172 completed the child study (arbaclofen 5 BID n = 38; 10 BID n = 39; 10 TID n = 38; placebo n = 44). There were no serious adverse events (AEs); the most common AEs included somatic (headache, vomiting, nausea), neurobehavioral (irritability/agitation, anxiety, hyperactivity), decreased appetite, and infectious conditions, many of which were also common on placebo. In the combined studies, there were 13 discontinuations ( n = 12 arbaclofen, 1 placebo) due to AEs (all neurobehavioral). The adolescent/adult study did not show benefit for arbaclofen over placebo for any measure. In the child study, the highest dose group showed benefit over placebo on the ABC-C FX Irritability subscale ( p = 0.03) and Parenting Stress Index (PSI, p = 0.03) and trends toward benefit on the ABC-C FX Social Avoidance and Hyperactivity subscales (both p < 0.1) and CGI-I ( p = 0.119). Effect size in the highest dose group was similar to effect sizes for FDA-approved serotonin reuptake inhibitors (SSRIs). Arbaclofen did not meet the primary outcome of improved social avoidance in FXS in either study. Data from secondary measures in the child study suggests younger patients may derive benefit, but additional studies with a larger cohort on higher doses would be required to confirm this finding. The reported studies illustrate the challenges but represent a significant step forward in translating targeted treatments from preclinical models to clinical trials in humans with FXS.

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Crossref · 10.1186/s11689-016-9181-6

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  • In the arbaclofen phase III study, children receiving the highest dose improved over placebo on the secondary ABC-CFX Irritability subscale and the Parenting Stress Index, both with P = 0.03.

    “In the phase III study, children receiving the highest dose of arbaclofen also showed improvement over placebo on the secondary end points of the ABC-CFX Irritability subscale (P = 0.03) and the Parenting Stress Index (P = 0.03).”
  • In the paediatric arbaclofen phase III study, the primary endpoint, ABC-CFX Social Avoidance, narrowly missed significant improvement with P = 0.08.

    “In the phase III study carried out in children, the primary end point (ABC-CFX Social Avoidance subscale) narrowly missed significant improvement (P = 0.08)72.”
  • The arbaclofen phase III trial was limited by incomplete enrolment due to sponsor financial issues, fixed rather than flexible dosing, and possible symptom inflation by families to meet inclusion criteria.

    “This trial was limited by a lack of full enrolment due to financial issues for the sponsor, the use of fixed rather than flexible dosing and possible inflation of symptoms by families in order to meet inclusion criteria72.”
  • Pediatric trials of arbaclofen in FXS did not reach significance for the primary outcome measure.

    “However, the adult studies of FXS did not demonstrate efficacy and the pediatric trials did not reach significance for the primary outcome measure, but did show limited improvements in secondary measures including the Parenting Stress Index because of lowered irritability in the children [132].”
  • Adult studies of FXS with arbaclofen did not demonstrate efficacy.

    “However, the adult studies of FXS did not demonstrate efficacy and the pediatric trials did not reach significance for the primary outcome measure, but did show limited improvements in secondary measures including the Parenting Stress Index because of lowered irritability in the children [132].”

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Research works printed but not linked: 5

  1. [17]Qin M, Huang T, Kader M, Krych L, Xia Z, Burlin T, Zeidler Z, Zhao T, Smith CB. R-Baclofen Reverses a Social Behavior Deficit and Elevated Protein Synthesis in a Mouse Model of Fragile X Syndrome. Int J Neuropsychopharmacol. 2015;18(9). PMC4576516 25820841
  2. [21]Sparrow S Cicchetti D Balla D Vineland adaptive behavior scales, second edition (Vineland II). Survey interview form/caregiver rating form 2005 Livonia Pearson Assessments
  3. [40]Sansone SM Berry-Kravis E Crestodina C McLennan Y Hagerman R Hessl D Sensitivity of an eye tracking paradigm as an outcome measure in a fragile X syndrome targeted treatment clinical trial 49th Annual Gatlinburg conference on research and theory in intellectual and developmental disabilities; San Diego 2016
  4. [42]De Sonia A Visootsak J Smith M Budimirovic D Tartaglia N Welnik N Analysis of arbaclofen responses in fragile X syndrome 14th International Fragile X Conference; Orange County, CA 2014
  5. [45]Berry-Kravis E, Erickson CA, Kolevzon A, N T, Hagerman R, Hatti S, Frazier J, Sanders K, Challman T, Needelman H, et al: The treatment of fragile X syndrome with Trofinetide (NNZ-2566). In Proceedings of the 15th international fragile X conference; San Antonio. 2016

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Authors
Berry-Kravis, E., Hagerman, R., Visootsak, J., Budimirovic, D., Kaufmann, W. E., Cherubini, M., Zarevics, P., Walton-Bowen, K., Wang, P., Bear, M. F., & Carpenter, R. L.
Affiliations
  • University of California Davis Medical Center (US)
  • Emory University (US)
  • Kennedy Krieger Institute (US)
  • Boston Children's Hospital (US)
  • Seaside Therapeutics (United States) (US)
  • Simons Foundation (US)
  • Autism Speaks (US)
  • Massachusetts Institute of Technology (US)
  • Rett Syndrome Research Trust (US)
Venue
Journal of Neurodevelopmental Disorders
Published
2017-06-12
Volume
9
Issue
1
Pages
3-3
ISSN
  • 1866-1947 (ISSN-L)
  • 1866-1955
OpenAlex
W2576165191
Cited by
183
References
39
Citations by year
2026: 11 · 2025: 16 · 2024: 16 · 2023: 13 · 2022: 22 · 2021: 21 · 2020: 24 · 2019: 23 · 2018: 17 · 2017: 11 · 2016: 6 · 2015: 3
FWCI
13.61
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • Journal of Neurodevelopmental Disorders (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, other-oa)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
  • DSpace@MIT (Massachusetts Institute of Technology) (submittedVersion, cc-by-nc)
  • eScholarship (California Digital Library) (submittedVersion)
  • eScholarship (California Digital Library) (submittedVersion, cc-by)
Funders
Seaside Therapeutics, Inc.
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetics and Neurodevelopmental Disorders
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Autism Spectrum Disorder Research
  • Life Sciences › Neuroscience › Developmental Neuroscience › Williams Syndrome Research
Keywords
fragile X syndrome, social avoidance, irritability, hyperactivity, parental stress, adaptive behavior, adverse events, dose-response relationship, children and adolescents, serotonin reuptake inhibitors, NMDA receptor antagonists, behavioral phenotypes, drug safety and efficacy

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