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Erickson CA, Davenport MH, Schaefer TL, Wink LK, Pedapati EV, Sweeney JA, Fitzpatrick SE, Brown WT, Budimirovic D, Hagerman RJ, Hessl D, Kaufmann WE, Berry-Kravis E. Fragile X targeted pharmacotherapy: lessons learned and future directions. J Neurodev Disord 2017; 9:7. [PMID: 28616096 PMCID: PMC5467059 DOI: 10.1186/s11689-017-9186-9] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 01/18/2017] [Indexed: 01/04/2023] Open
Abstract
Our understanding of fragile X syndrome (FXS) pathophysiology continues to improve and numerous potential drug targets have been identified. Yet, current prescribing practices are only symptom-based in order to manage difficult behaviors, as no drug to date is approved for the treatment of FXS. Drugs impacting a diversity of targets in the brain have been studied in recent FXS-specific clinical trials. While many drugs have focused on regulation of enhanced glutamatergic or deficient GABAergic neurotransmission, compounds studied have not been limited to these mechanisms. As a single-gene disorder, it was thought that FXS would have consistent drug targets that could be modulated with pharmacotherapy and lead to significant improvement. Unfortunately, despite promising results in FXS animal models, translational drug treatment development in FXS has largely failed. Future success in this field will depend on learning from past challenges to improve clinical trial design, choose appropriate outcome measures and age range choices, and find readily modulated drug targets. Even with many negative placebo-controlled study results, the field continues to move forward exploring both the new mechanistic drug approaches combined with ways to improve trial execution. This review summarizes the known phenotype and pathophysiology of FXS and past clinical trial rationale and results, and discusses current challenges facing the field and lessons from which to learn for future treatment development efforts.
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Affiliation(s)
- Craig A Erickson
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Department of Psychiatry, College of Medicine, University of Cincinnati, Cincinnati, OH USA
| | - Matthew H Davenport
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Department of Biomedical Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH USA
| | - Tori L Schaefer
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Logan K Wink
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Department of Psychiatry, College of Medicine, University of Cincinnati, Cincinnati, OH USA
| | - Ernest V Pedapati
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Department of Psychiatry, College of Medicine, University of Cincinnati, Cincinnati, OH USA
| | - John A Sweeney
- Department of Psychiatry, College of Medicine, University of Cincinnati, Cincinnati, OH USA
| | - Sarah E Fitzpatrick
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - W Ted Brown
- Institute for Basic Research in Developmental Disabilities, New York, NY USA
| | - Dejan Budimirovic
- Clinical Research Center, Clinical Trials Unit, Fragile X Clinic, Kennedy Krieger Institute, The Johns Hopkins Medical Institutions, Baltimore, MD USA.,Departments of Psychiatry & Behavioral Sciences, Child Psychiatry, The Johns Hopkins Medical Institutions, Baltimore, MD USA
| | - Randi J Hagerman
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, Davis Medical Center, University of California, Sacramento, CA USA.,Department of Pediatrics, Davis Medical Center, University of California, Sacramento, California USA
| | - David Hessl
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, Davis Medical Center, University of California, Sacramento, CA USA.,Department of Psychiatry and Behavioral Sciences, Davis Medical Center, University of California, Sacramento, California USA
| | - Walter E Kaufmann
- Greenwood Genetic Center, Greenwood, SC USA.,Boston Children's Hospital, Boston, Massachusetts USA
| | - Elizabeth Berry-Kravis
- Departments of Pediatrics, Neurological Sciences, Biochemistry, Rush University Medical Center, Chicago, Illinois USA
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Schaefer TL, Davenport MH, Grainger LM, Robinson CK, Earnheart AT, Stegman MS, Lang AL, Ashworth AA, Molinaro G, Huber KM, Erickson CA. Acamprosate in a mouse model of fragile X syndrome: modulation of spontaneous cortical activity, ERK1/2 activation, locomotor behavior, and anxiety. J Neurodev Disord 2017; 9:6. [PMID: 28616095 PMCID: PMC5467053 DOI: 10.1186/s11689-017-9184-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 01/13/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Fragile X Syndrome (FXS) occurs as a result of a silenced fragile X mental retardation 1 gene (FMR1) and subsequent loss of fragile X mental retardation protein (FMRP) expression. Loss of FMRP alters excitatory/inhibitory signaling balance, leading to increased neuronal hyperexcitability and altered behavior. Acamprosate (the calcium salt of N-acetylhomotaurinate), a drug FDA-approved for relapse prevention in the treatment of alcohol dependence in adults, is a novel agent with multiple mechanisms that may be beneficial for people with FXS. There are questions regarding the neuroactive effects of acamprosate and the significance of the molecule's calcium moiety. Therefore, the electrophysiological, cellular, molecular, and behavioral effects of acamprosate were assessed in the Fmr1-/y (knock out; KO) mouse model of FXS controlling for the calcium salt in several experiments. METHODS Fmr1 KO mice and their wild-type (WT) littermates were utilized to assess acamprosate treatment on cortical UP state parameters, dendritic spine density, and seizure susceptibility. Brain extracellular-signal regulated kinase 1/2 (ERK1/2) activation was used to investigate this signaling molecule as a potential biomarker for treatment response. Additional adult mice were used to assess chronic acamprosate treatment and any potential effects of the calcium moiety using CaCl2 treatment on behavior and nuclear ERK1/2 activation. RESULTS Acamprosate attenuated prolonged cortical UP state duration, decreased elevated ERK1/2 activation in brain tissue, and reduced nuclear ERK1/2 activation in the dentate gyrus in KO mice. Acamprosate treatment modified behavior in anxiety and locomotor tests in Fmr1 KO mice in which control-treated KO mice were shown to deviate from control-treated WT mice. Mice treated with CaCl2 were not different from saline-treated mice in the adult behavior battery or nuclear ERK1/2 activation. CONCLUSIONS These data indicate that acamprosate, and not calcium, improves function reminiscent of reduced anxiety-like behavior and hyperactivity in Fmr1 KO mice and that acamprosate attenuates select electrophysiological and molecular dysregulation that may play a role in the pathophysiology of FXS. Differences between control-treated KO and WT mice were not evident in a recognition memory test or in examination of acoustic startle response/prepulse inhibition which impeded conclusions from being made about the treatment effects of acamprosate in these instances.
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Affiliation(s)
- Tori L Schaefer
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Matthew H Davenport
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Lindsay M Grainger
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Chandler K Robinson
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Anthony T Earnheart
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Melinda S Stegman
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Present address: Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229 USA
| | - Anna L Lang
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Present address: Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202 USA
| | - Amy A Ashworth
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Present address: BlackbookHR, Cincinnati, OH 45202 USA
| | - Gemma Molinaro
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Kimberly M Huber
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Craig A Erickson
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
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Davenport MH, Schaefer TL, Friedmann KJ, Fitzpatrick SE, Erickson CA. Pharmacotherapy for Fragile X Syndrome: Progress to Date. Drugs 2016; 76:431-45. [PMID: 26858239 DOI: 10.1007/s40265-016-0542-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
To date, no drug is approved for the treatment of Fragile X Syndrome (FXS) although many drugs are used to manage challenging behaviors from a symptomatic perspective in this population. While our understanding of FXS pathophysiology is expanding, efforts to devise targeted FXS-specific treatments have had limited success in placebo-controlled trials. Compounds aimed at rectifying excessive glutamate and deficient gamma-aminobutyric acid (GABA) neurotransmission, as well as other signaling pathways known to be affected by Fragile X Mental Retardation Protein (FMRP) are under various phases of development in FXS. With the failure of several metabotropic glutamate receptor subtype 5 (mGlur5) selective antagonists under clinical investigation, no clear single treatment appears to be greatly effective. These recent challenges call into question various aspects of clinical study design in FXS. More objective outcome measures are under development and validation. Future trials will likely be aimed at correcting multiple pathways known to be disrupted by the loss of FMRP. This review offers a brief summary of the prevalence, phenotypic characteristics, genetic causes and molecular functions of FMRP in the brain (as these have been extensively reviewed elsewhere), discusses the most recent finding in FXS drug development, and summarizes FXS trials utilizing symptomatic treatment.
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Affiliation(s)
- Matthew H Davenport
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229-3039, USA
- Department of Biomedical Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Tori L Schaefer
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229-3039, USA
| | - Katherine J Friedmann
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229-3039, USA
| | | | - Craig A Erickson
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229-3039, USA.
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Schaefer TL, Davenport MH, Erickson CA. Emerging pharmacologic treatment options for fragile X syndrome. APPLICATION OF CLINICAL GENETICS 2015; 8:75-93. [PMID: 25897255 PMCID: PMC4396424 DOI: 10.2147/tacg.s35673] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Fragile X syndrome (FXS) is the most common single gene cause of intellectual disability and autism spectrum disorder. Caused by a silenced fragile X mental retardation 1 gene and the subsequent deficiency in fragile X mental retardation protein, patients with FXS experience a range of physical, behavioral, and intellectual debilitations. The FXS field, as a whole, has recently met with some challenges, as several targeted clinical trials with high expectations of success have failed to elucidate significant improvements in a variety of symptom domains. As new clinical trials in FXS are planned, there has been much discussion about the use of the commonly used clinical outcome measures, as well as study design considerations, patient stratification, and optimal age range for treatment. The evidence that modification of these drug targets and use of these failed compounds would prove to be efficacious in human clinical study were rooted in years of basic and translational research. There are questions arising as to the use of the mouse models for studying FXS treatment development. This issue is twofold: many of the symptom domains and molecular and biochemical changes assessed and indicative of efficacy in mouse model study are not easily amenable to clinical trials in people with FXS because of the intolerability of the testing paradigm or a lack of noninvasive techniques (prepulse inhibition, sensory hypersensitivity, startle reactivity, or electrophysiologic, biochemical, or structural changes in the brain); and capturing subtle yet meaningful changes in symptom domains such as sociability, anxiety, and hyperactivity in human FXS clinical trials is challenging with the currently used measures (typically parent/caregiver rating scales). Clinicians, researchers, and the pharmaceutical industry have all had to take a step back and critically evaluate the way we think about how to best optimize future investigations into pharmacologic FXS treatments. As new clinical trials are coming down the drug discovery pipeline, it is clear that the field is moving in a direction that values the development of molecular biomarkers, less subjective quantitative measures of symptom improvement, and rating scales developed specifically for use in FXS in conjunction with drug safety. While summarizing preclinical evidence, where applicable, and discussing challenges in FXS treatment development, this review details both completed clinical trials for the targeted and symptomatic treatment of FXS and introduces novel projects on the cusp of clinical trial investigation.
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Affiliation(s)
- Tori L Schaefer
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Matthew H Davenport
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Craig A Erickson
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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Erickson CA, Wink LK, Ray B, Early MC, Stiegelmeyer E, Mathieu-Frasier L, Patrick V, Lahiri DK, McDougle CJ. Impact of acamprosate on behavior and brain-derived neurotrophic factor: an open-label study in youth with fragile X syndrome. Psychopharmacology (Berl) 2013; 228:75-84. [PMID: 23436129 DOI: 10.1007/s00213-013-3022-z] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 01/29/2013] [Indexed: 12/13/2022]
Abstract
RATIONALE Fragile X syndrome (FXS) is an inherited form of developmental disability and a single gene cause of autism. As a disorder with increasingly understood pathophysiology, FXS is a model form of developmental disability for targeted drug development efforts. Preclinical animal model findings have focused targeted drug treatment development in FXS on an imbalance between excessive glutamate and deficient gamma-aminobutyric acid (GABA) neurotransmission. METHODS We conducted a prospective open-label 10-week trial of acamprosate in 12 youth aged 6-17 years (mean age: 11.9 years) with FXS. RESULTS Acamprosate use (mean dose: 1,054 ± 422 mg/day) was associated with treatment response (defined by a Clinical Global Impressions Improvement (CGI-I) scale score of "very much improved" or "much improved") in nine of 12 (75 %) subjects. Improvement was noted in social behavior and inattention/hyperactivity using multiple standard behavioral outcome measures. No significant adverse effects or changes in vital signs, including weight or laboratory measures, occurred during treatment with acamprosate. Additionally, pre- and post-treatment blood biomarker analyses looking at brain-derived neurotrophic factor (BDNF) levels found a significant increase in BDNF with treatment. In our pilot sample, treatment response did not correlate with change in BDNF with treatment. CONCLUSIONS Acamprosate was generally safe and well tolerated and was associated with a significant improvement in social behavior and a reduction in inattention/hyperactivity. The increase in BDNF that occurred with treatment may be a useful pharmacodynamic marker in future acamprosate studies. Given these findings, a double-blind, placebo-controlled study of acamprosate in youth with FXS is warranted.
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Affiliation(s)
- Craig A Erickson
- Department of Psychiatry, Indiana University School of Medicine, and James Whitcomb Riley Hospital for Children, Indianapolis, IN, USA.
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Cuttitta CM, Guariglia SR, Idrissi AE, L’Amoreaux WJ. Taurine’s Effects on the Neuroendocrine Functions of Pancreatic β Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 775:299-310. [DOI: 10.1007/978-1-4614-6130-2_25] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Cellular Mechanisms for the Biogenesis and Transport of Synaptic and Dense-Core Vesicles. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 299:27-115. [DOI: 10.1016/b978-0-12-394310-1.00002-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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