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Percy AK, Neul JL, Benke TA, Berry-Kravis EM, Glaze DG, Marsh ED, An D, Bishop KM, Youakim JM. Trofinetide for the treatment of Rett syndrome: Results from the open-label extension LILAC study. MED 2024:S2666-6340(24)00222-8. [PMID: 38917793 DOI: 10.1016/j.medj.2024.05.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 04/04/2024] [Accepted: 05/30/2024] [Indexed: 06/27/2024]
Abstract
BACKGROUND Trofinetide was approved for the treatment of Rett syndrome based on the results of the phase 3, randomized, placebo-controlled, 12-week LAVENDER study. Rett syndrome is a chronic disorder requiring long-term treatment. We report the efficacy and safety results of LILAC, a 40-week, open-label extension study of LAVENDER. METHODS Females with Rett syndrome aged 5-21 years received open-label treatment with trofinetide for 40 weeks. The primary endpoint was long-term safety of trofinetide; secondary endpoints included the change from baseline at week 40 in the Rett Syndrome Behaviour Questionnaire score and the Clinical Global Impression-Improvement score at week 40. FINDINGS Overall, 154 participants were enrolled and treated with trofinetide in LILAC. The most common adverse events in LILAC were diarrhea (74.7%), vomiting (28.6%), and COVID-19 (11.0%). Diarrhea was the most common adverse event leading to treatment withdrawal (21.4%). The Rett Syndrome Behaviour Questionnaire mean score (standard error) improvement from the LAVENDER baseline to week 40 in LILAC was -7.3 (1.62) and -7.0 (1.61) for participants treated with trofinetide and placebo in LAVENDER, respectively. Mean Clinical Global Impression-Improvement scores (standard error) at week 40 rated from the LILAC baseline were 3.1 (0.11) and 3.2 (0.14) for participants treated with trofinetide and placebo in LAVENDER, respectively. CONCLUSIONS Treatment with trofinetide for ≤40 weeks continued to improve symptoms of Rett syndrome. Trofinetide had a similar safety profile in LILAC as in LAVENDER. FUNDING The study was supported by Acadia Pharmaceuticals Inc. (San Diego, CA, USA). This trial was registered at ClinicalTrials.gov (NCT04279314).
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Affiliation(s)
- Alan K Percy
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Jeffrey L Neul
- Department of Pediatrics, Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Timothy A Benke
- Department of Pediatrics, Children's Hospital of Colorado/University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Elizabeth M Berry-Kravis
- Departments of Pediatrics, Neurological Sciences and Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA
| | - Daniel G Glaze
- Department of Pediatrics and Neurology, Texas Children's Hospital/Baylor College of Medicine, Houston, TX 77030, USA
| | - Eric D Marsh
- Division of Child Neurology, Children's Hospital of Philadelphia, Departments of Neurology and Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Di An
- Acadia Pharmaceuticals Inc., San Diego, CA 92130, USA
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Lebeda D, Fierenz A, Werfel L, Rosin-Arbesfeld R, Hofhuis J, Thoms S. Systematic and quantitative analysis of stop codon readthrough in Rett syndrome nonsense mutations. J Mol Med (Berl) 2024; 102:641-653. [PMID: 38430393 PMCID: PMC11055764 DOI: 10.1007/s00109-024-02436-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 01/16/2024] [Accepted: 02/20/2024] [Indexed: 03/03/2024]
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder resulting from genetic mutations in the methyl CpG binding protein 2 (MeCP2) gene. Specifically, around 35% of RTT patients harbor premature termination codons (PTCs) within the MeCP2 gene due to nonsense mutations. A promising therapeutic avenue for these individuals involves the use of aminoglycosides, which stimulate translational readthrough (TR) by causing stop codons to be interpreted as sense codons. However, the effectiveness of this treatment depends on several factors, including the type of stop codon and the surrounding nucleotides, collectively referred to as the stop codon context (SCC). Here, we develop a high-content reporter system to precisely measure TR efficiency at different SCCs, assess the recovery of the full-length MeCP2 protein, and evaluate its subcellular localization. We have conducted a comprehensive investigation into the intricate relationship between SCC characteristics and TR induction, examining a total of 14 pathogenic MeCP2 nonsense mutations with the aim to advance the prospects of personalized therapy for individuals with RTT. Our results demonstrate that TR induction can successfully restore full-length MeCP2 protein, albeit to varying degrees, contingent upon the SCC and the specific position of the PTC within the MeCP2 mRNA. TR induction can lead to the re-establishment of nuclear localization of MeCP2, indicating the potential restoration of protein functionality. In summary, our findings underscore the significance of SCC-specific approaches in the development of tailored therapies for RTT. By unraveling the relationship between SCC and TR therapy, we pave the way for personalized, individualized treatment strategies that hold promise for improving the lives of individuals affected by this debilitating neurodevelopmental disorder. KEY MESSAGES: The efficiency of readthrough induction at MeCP2 premature termination codons strongly depends on the stop codon context. The position of the premature termination codon on the transcript influences the readthrough inducibility. A new high-content dual reporter assay facilitates the measurement and prediction of readthrough efficiency of specific nucleotide stop contexts. Readthrough induction results in the recovery of full-length MeCP2 and its re-localization to the nucleus. MeCP2 requires only one of its annotated nuclear localization signals.
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Affiliation(s)
- Dennis Lebeda
- Department for Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany
| | - Adrian Fierenz
- Department of Child and Adolescent Health, University Medical Center Göttingen, Göttingen, Germany
| | - Lina Werfel
- Department of Child and Adolescent Health, University Medical Center Göttingen, Göttingen, Germany
- Present Address: Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| | - Rina Rosin-Arbesfeld
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Julia Hofhuis
- Department for Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany
| | - Sven Thoms
- Department for Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany.
- Department of Child and Adolescent Health, University Medical Center Göttingen, Göttingen, Germany.
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Darwish M, Passarell J, Youakim JM, Bradley H, Bishop KM. Exposure-Response Efficacy Modeling to Support Trofinetide Dosing in Individuals with Rett Syndrome. Adv Ther 2024; 41:1462-1480. [PMID: 38363467 PMCID: PMC10960884 DOI: 10.1007/s12325-024-02796-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/19/2024] [Indexed: 02/17/2024]
Abstract
INTRODUCTION Trofinetide was recently approved for the treatment of Rett syndrome (RTT) on the basis of the efficacy and safety findings of the phase 3 LAVENDER study, which used a body weight-based dosing regimen. Exposure-response (E-R) efficacy modeling was used to characterize relationships between trofinetide exposure measures (maximum drug concentration and area under the concentration-time curve for the dosing interval of 0-12 h [AUC0-12]) and efficacy endpoints in RTT clinical studies to support the trofinetide dosing regimen. METHODS Efficacy endpoints were modeled using trofinetide exposure measures predicted from the population pharmacokinetic model and Bayesian estimates. The analysis population for each E-R model comprised individuals receiving placebo or trofinetide who had available trofinetide exposure measures. Efficacy endpoints were scores from the Rett Syndrome Behaviour Questionnaire (RSBQ), the Clinical Global Impression-Improvement, the Communication and Symbolic Behavior Scales Developmental Profile™ Infant-Toddler Checklist (CSBS-DP-IT) Social Composite, and the Rett Syndrome Clinician Rating of Ability to Communicate Choices (RTT-COMC). RESULTS Higher trofinetide exposure was associated with improvements in RSBQ, CSBS-DP-IT Social Composite, and RTT-COMC scores. Assuming target trofinetide AUC0-12 values of 800-1200 μg·h/mL, the reductions in RSBQ total scores at week 12 were approximately five- to seven-fold greater with trofinetide (range 3.55-4.94) versus placebo (0.76). Significant E-R relationships were also found for the CSBS-DP-IT Social Composite and RTT-COMC scores. CONCLUSION E-R efficacy modeling demonstrated significant relationships between trofinetide exposure and RSBQ, CSBS-DP-IT Social Composite, and RTT-COMC scores. Trofinetide is efficacious within the target exposure range, supporting the approved dosing regimen for trofinetide. TRIAL REGISTRATION NCT01703533, NCT02715115, NCT04181723.
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Affiliation(s)
- Mona Darwish
- Acadia Pharmaceuticals Inc., 12830 El Camino Real, Suite 400, San Diego, CA, 92130, USA.
| | - Julie Passarell
- Cognigen Corporation (a Simulations Plus Company), Buffalo, NY, USA
| | - James M Youakim
- Acadia Pharmaceuticals Inc., 12830 El Camino Real, Suite 400, San Diego, CA, 92130, USA
| | - Heather Bradley
- Acadia Pharmaceuticals Inc., 12830 El Camino Real, Suite 400, San Diego, CA, 92130, USA
| | - Kathie M Bishop
- Acadia Pharmaceuticals Inc., 12830 El Camino Real, Suite 400, San Diego, CA, 92130, USA
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Brito F, Lagos C, Cubillos J, Orellana J, Gajardo M, Böhme D, Encina G, Repetto GM. Genomic analysis in Chilean patients with suspected Rett syndrome: keep a broad differential diagnosis. Front Genet 2024; 15:1278198. [PMID: 38566815 PMCID: PMC10986174 DOI: 10.3389/fgene.2024.1278198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 02/12/2024] [Indexed: 04/04/2024] Open
Abstract
Introduction: Rett syndrome (RTT, MIM #312750) is a rare genetic disorder that leads to developmental regression and severe disability and is caused by pathogenic variants in the MECP2 gene. The diagnosis of RTT is based on clinical features and, depending on resources and access, on molecular confirmation. There is scarce information on molecular diagnosis from patients in Latin America, mostly due to limited availability and coverage of genomic testing. This pilot study aimed to implement genomic testing and characterize clinical and molecular findings in a group of Chilean patients with a clinical diagnosis of RTT. Methods: Twenty-eight patients with suspected RTT underwent characterization of phenotypic manifestations and molecular testing using Clinical Exome SolutionTM CES_V2 by SOPHiA Genetics. Data was analyzed using the commercial bioinformatics platform, SOPHiA DDMTM. A virtual panel of 34 genes, including MECP2 and other genes that are in the differential diagnosis of RTT, was used to prioritize initial analyses, followed by evaluation of the complete exome sequence data. Results: Twelve patients (42.8% of participants) had variants in MECP2, of which 11 (39.2%) were interpreted as pathogenic/likely pathogenic (P/LP), thus confirming the diagnosis of RTT in them. Eight additional patients (28.5%) harbored ten variants in nine other genes. Four of these variants were interpreted as P/LP (14.2%) (GRIN2B, MADD, TRPM3 and ZEB2) resulting in alternative neurodevelopmental diagnoses, and six were considered of uncertain significance. No evident candidate variant was found for eight patients. Discussion: This study allowed to reach a diagnosis in half of the participants. The diagnosis of RTT was confirmed in over a third of them, while others were found to have alternative neurodevelopmental disorders. Further evaluation is needed to identify the cause in those with negative or uncertain results. This information is useful for the patients, families, and clinicians to guide clinical management, even more so since the development of novel therapies for RTT. We also show the feasibility of implementing a step-wide approach to genomic testing in a setting with limited resources.
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Affiliation(s)
- Florencia Brito
- Rare Diseases Program, Center for Genetics and Genomics, Institute of Sciences and Innovation in Medicine, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Catalina Lagos
- Rare Diseases Program, Center for Genetics and Genomics, Institute of Sciences and Innovation in Medicine, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | | | - Joan Orellana
- Rare Diseases Program, Center for Genetics and Genomics, Institute of Sciences and Innovation in Medicine, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Mallen Gajardo
- Escuela de Ingeniería, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile
| | - Daniela Böhme
- Rare Diseases Program, Center for Genetics and Genomics, Institute of Sciences and Innovation in Medicine, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
- Biosoluciones-UDD, Santiago, Chile
| | | | - Gabriela M. Repetto
- Rare Diseases Program, Center for Genetics and Genomics, Institute of Sciences and Innovation in Medicine, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
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Raspa M, Gwaltney A, Bann C, von Hehn J, Benke TA, Marsh ED, Peters SU, Ananth A, Percy AK, Neul JL. Psychometric Assessment of the Rett Syndrome Caregiver Assessment of Symptom Severity (RCASS). J Autism Dev Disord 2024:10.1007/s10803-024-06238-0. [PMID: 38438817 DOI: 10.1007/s10803-024-06238-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2024] [Indexed: 03/06/2024]
Abstract
Rett syndrome is a severe neurodevelopmental disorder that affects about 1 in 10,000 females. Clinical trials of disease modifying therapies are on the rise, but there are few psychometrically sound caregiver-reported outcome measures available to assess treatment benefit. We report on a new caregiver-reported outcome measure, the Rett Caregiver Assessment of Symptom Severity (RCASS). Using data from the Rett Natural History Study (n = 649), we examined the factor structure, using both exploratory and confirmatory factor analysis, and the reliability and validity of the RCASS. The four-factor model had the best overall fit, which covered movement, communication, behavior, and Rett-specific symptoms. The RCASS had moderate internal consistency. Strong face validity was found with age and mutation type, and convergent validity was established with other similar measures, including the Revised Motor-Behavior Assessment Scale, Clinical Severity Scale, Clinical Global Impression Scale, and the Child Health Questionnaire. These data provide initial evidence that the RCASS is a viable caregiver-outcome measure for use in clinical trials in Rett syndrome. Future work to assess sensitivity to change and other measures of reliability, such as test-retest and inter-rater agreement, are needed.
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Affiliation(s)
- Melissa Raspa
- RTI International, 3040 East Cornwallis Road, Research Triangle Park, NC, 27708, USA.
| | - Angela Gwaltney
- RTI International, 3040 East Cornwallis Road, Research Triangle Park, NC, 27708, USA
| | - Carla Bann
- RTI International, 3040 East Cornwallis Road, Research Triangle Park, NC, 27708, USA
| | | | - Timothy A Benke
- Children's Hospital Colorado and University of Colorado School of Medicine, Aurora, USA
| | - Eric D Marsh
- Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
| | - Sarika U Peters
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, USA
| | - Amitha Ananth
- University of Alabama at Birmingham, Birmingham, USA
| | - Alan K Percy
- University of Alabama at Birmingham, Birmingham, USA
| | - Jeffrey L Neul
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, USA.
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Neul JL, Percy AK, Benke TA, Berry-Kravis EM, Glaze DG, Peters SU, Marsh ED, An D, Bishop KM, Youakim JM. Trofinetide Treatment Demonstrates a Benefit Over Placebo for the Ability to Communicate in Rett Syndrome. Pediatr Neurol 2024; 152:63-72. [PMID: 38232652 DOI: 10.1016/j.pediatrneurol.2023.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 10/27/2023] [Accepted: 11/18/2023] [Indexed: 01/19/2024]
Abstract
BACKGROUND Trofinetide was approved by the US Food and Drug Administration for the treatment of Rett syndrome (RTT) in March 2023. Benefiting the ability to communicate in RTT is often identified as the most important caregiver goal for new therapies. This analysis reports the communication-related end points from the phase 3 LAVENDER study of trofinetide in RTT. METHODS Females with RTT, aged five to 20 years, were randomized 1:1 to trofinetide or placebo for 12 weeks. Secondary efficacy end points related to communication were based on change from baseline to week 12 and included the caregiver-rated Communication and Symbolic Behavior Scales Developmental Profile™ Infant-Toddler Checklist (CSBS-DP-IT) Social Composite score (key secondary end point; scores ranged from 0 to 26 [higher scores indicated better communication]) and novel clinician rating scales (0 [normal] to 7 [severe impairment]) measuring the ability to communicate choices nonverbally (RTT-COMC) and verbally (RTT-VCOM). RESULTS Trofinetide demonstrated a statistically significant difference versus placebo for the CSBS-DP-IT Social Composite score (least squares mean [LSM] difference = 1.0; 95% confidence interval [CI], 0.3 to 1.7; P = 0.0064; Cohen's d effect size = 0.43) and a nominally significant difference for the RTT-COMC (LSM difference: -0.3; 95% CI, -0.6 to -0.0; P = 0.0257; Cohen's d effect size = 0.36). As expected, there was no difference for the RTT-VCOM. CONCLUSIONS Significant treatment benefit for trofinetide versus placebo was observed in scales measuring the ability to communicate. These scales may be appropriate for future clinical studies in RTT and other neurodevelopmental disorders.
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Affiliation(s)
- Jeffrey L Neul
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Alan K Percy
- University of Alabama at Birmingham, Birmingham, Alabama
| | - Timothy A Benke
- Children's Hospital of Colorado, University of Colorado School of Medicine, Aurora, Colorado
| | | | - Daniel G Glaze
- Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Sarika U Peters
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Eric D Marsh
- Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Di An
- Acadia Pharmaceuticals Inc, San Diego, California
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7
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Wang YT, Yang PC, Zhang YF, Sun JF. Synthesis and clinical application of new drugs approved by FDA in 2023. Eur J Med Chem 2024; 265:116124. [PMID: 38183778 DOI: 10.1016/j.ejmech.2024.116124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/02/2024] [Accepted: 01/02/2024] [Indexed: 01/08/2024]
Abstract
In 2023, the U.S. Food and Drug Administration (FDA) granted approval to a total of 55 new drugs, comprising 29 new chemical entities (NCEs) and 25 new biological entities (NBEs). These drugs primarily focus on oncology, the central nervous system, anti-infection, hematology, cardiovascular, ophthalmology, immunomodulatory and other therapeutic areas. Out of the 55 drugs, 33 (60 %) underwent an accelerated review process and received approval, while 25 (45 %) were specifically approved for the treatment of rare diseases. The purpose of this review is to provide an overview of the clinical uses and production techniques of 29 newly FDA-approved NCEs in 2023. Our intention is to offer a comprehensive understanding of the synthetic approaches employed in the creation of these drug molecules, with the aim of inspiring the development of novel, efficient, and applicable synthetic methodologies.
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Affiliation(s)
- Ya-Tao Wang
- First People's Hospital of Shangqiu, Henan Province, Shangqiu, 476100, China.
| | - Peng-Cheng Yang
- Key Laboratory of Natural Medicines of the Changbai Mountain, Ministry of Education, Yanbian University, College of Pharmacy, Yanji, Jilin, 133002, China
| | - Yan-Feng Zhang
- Shangqiu Municipal Hospital, Henan Province, Shangqiu, 476100, China.
| | - Jin-Feng Sun
- Key Laboratory of Natural Medicines of the Changbai Mountain, Ministry of Education, Yanbian University, College of Pharmacy, Yanji, Jilin, 133002, China; Rega Institute for Medical Research, Medicinal Chemistry, KU Leuven, Herestraat 49-Box 1041, 3000, Leuven, Belgium.
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8
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Bhowal A, Cooper F, Donner E. Inconsolability in a Nonverbal Adolescent. Clin Pediatr (Phila) 2024; 63:282-286. [PMID: 37119013 DOI: 10.1177/00099228231168473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Affiliation(s)
- Anushka Bhowal
- Department of Pediatrics, Nemours Children's Health, Orlando, FL, USA
| | - Felicia Cooper
- Department of Pediatrics, Nemours Children's Health, Orlando, FL, USA
| | - Elizabeth Donner
- Department of Pediatrics, Nemours Children's Health, Orlando, FL, USA
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Lopes AG, Loganathan SK, Caliaperumal J. Rett Syndrome and the Role of MECP2: Signaling to Clinical Trials. Brain Sci 2024; 14:120. [PMID: 38391695 PMCID: PMC10886956 DOI: 10.3390/brainsci14020120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/11/2024] [Accepted: 01/17/2024] [Indexed: 02/24/2024] Open
Abstract
Rett syndrome (RTT) is a neurological disorder that mostly affects females, with a frequency of 1 in 10,000 to 20,000 live birth cases. Symptoms include stereotyped hand movements; impaired learning, language, and communication skills; sudden loss of speech; reduced lifespan; retarded growth; disturbance of sleep and breathing; seizures; autism; and gait apraxia. Pneumonia is the most common cause of death for patients with Rett syndrome, with a survival rate of 77.8% at 25 years of age. Survival into the fifth decade is typical in Rett syndrome, and the leading cause of death is cardiorespiratory compromise. Rett syndrome progression has multiple stages; however, most phenotypes are associated with the nervous system and brain. In total, 95% of Rett syndrome cases are due to mutations in the MECP2 gene, an X-linked gene that encodes for the methyl CpG binding protein, a regulator of gene expression. In this review, we summarize the recent developments in the field of Rett syndrome and therapeutics targeting MECP2.
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Affiliation(s)
- Adele Gaspar Lopes
- Department of Pharmacology, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3G 2M1, Canada
- Cancer Research Program, Research Institute of the McGill University Health Centre, Montreal, QC H4A 3J1, Canada
| | - Sampath Kumar Loganathan
- Cancer Research Program, Research Institute of the McGill University Health Centre, Montreal, QC H4A 3J1, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
- Department of Otolaryngology, Head & Neck Surgery, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
- Departments of Experimental Surgery and Experimental Medicine, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
| | - Jayalakshmi Caliaperumal
- Ingram School of Nursing, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3A 2M7, Canada
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Kennedy M, Glass L, Glaze DG, Kaminsky S, Percy AK, Neul JL, Jones NE, Tropea D, Horrigan JP, Nues P, Bishop KM, Youakim JM. Development of trofinetide for the treatment of Rett syndrome: from bench to bedside. Front Pharmacol 2024; 14:1341746. [PMID: 38318312 PMCID: PMC10839050 DOI: 10.3389/fphar.2023.1341746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 12/18/2023] [Indexed: 02/07/2024] Open
Abstract
Rett syndrome (RTT) is rare neurodevelopmental disorder caused by mutations in the MECP2 gene that encodes methyl-CpG-binding protein 2 (MeCP2), a DNA-binding protein with roles in epigenetic regulation of gene expression. Functional loss of MeCP2 results in abnormal neuronal maturation and plasticity, characterized by loss of verbal communication and loss of fine and gross motor function, among others. Trofinetide, a synthetic analog of glycine-proline-glutamate, was approved by the US Food and Drug Administration for the treatment of RTT in adult and pediatric patients aged 2 years and older. Here, we present the development of trofinetide from bench research to clinical studies and emphasize how the collaboration between academia, the pharmaceutical industry, and patient advocacy led to the recent approval. The bench-to-bedside development of trofinetide underscores the value of collaboration between these groups in the development and approval of treatments for rare diseases.
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Affiliation(s)
- Melissa Kennedy
- International Rett Syndrome Foundation, Cincinnati, OH, United States
| | - Larry Glass
- Neuren Pharmaceuticals Ltd., Melbourne, VIC, Australia
| | - Daniel G. Glaze
- Texas Children’s Hospital, Baylor College of Medicine, Houston, TX, United States
| | - Steve Kaminsky
- International Rett Syndrome Foundation, Cincinnati, OH, United States
| | - Alan K. Percy
- Division of Pediatric Neurology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jeffrey L. Neul
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, United States
| | | | - Daniela Tropea
- Institute of Neuroscience, Trinity College, Dublin, Ireland
| | - Joseph P. Horrigan
- Department of Psychiatry and Behavioral Sciences, Duke University, Durham, NC, United States
| | - Paige Nues
- International Rett Syndrome Foundation, Cincinnati, OH, United States
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Li L, Liang Y, Liu Y, Sun Z, Liu Y, Yuan Z, Fu C. Transcriptome analyses reveal photosynthesis-related genes involved in photosynthetic regulation under low temperature stress in Lavandula angustifolia Mill. FRONTIERS IN PLANT SCIENCE 2023; 14:1268666. [PMID: 38107014 PMCID: PMC10722586 DOI: 10.3389/fpls.2023.1268666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 11/01/2023] [Indexed: 12/19/2023]
Abstract
In order to reveal the mechanisms of photosynthetic regulation of Lavandula angustifolia Mill. under low temperature stress, photosynthesis-related genes were screened and the molecular mechanism were analyzed for this species growing in Harbin, northeast of China. RNA-seq technique and photosynthetic physiology measurement were performed under 20°C, 10°C, and 0°C in this study. The results showed that the observing modified rectangular hyperbola mode could accurately reflect the light-response processes under low temperature stress and the low temperature reduced the light energy utilization of L. angustifolia. The stomatal conductance decreased with the temperature dropping, which was associated with the up-regulation of LaBAM1s, LaMPK4-1 and LaMMK2. The up-regulation of LaMPK4-1 and LaMMK2 was beneficial for ROS scavenging. The improvement of cold resistance in L. angustifolia was related to the up-regulated expression of LaFBA and LaOMTs and down-regulated expression of LaGAPAs, LaGOX, and LaTKL1s with the temperature decreasing. The up-expression of LaPSY at 10°C than it at 20°C could protect the photosynthetic organs from oxidative damage. Moreover, the photosynthetic rates at 10°C and 0°C were close to the measured values, which was related to the interactions of RCA with SBPase and Rubisco with SBPase. These findings could provide a theoretical reference for further exploring the cold tolerance mechanism of L. angustifolia, as an important aromatic plant resource, and promoting its cultivation and distribution in the northeast of China.
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Affiliation(s)
- Ling Li
- Key Laboratory of Aquatic Biodiversity Research in Hei Longjiang Province, Harbin Normal University, Harbin, China
- Heilongjiang Provincial Key Laboratory of Plant Biology in Ordinary Colleges and Universities, Harbin Normal University, Harbin, China
| | - Yuchen Liang
- Key Laboratory of Aquatic Biodiversity Research in Hei Longjiang Province, Harbin Normal University, Harbin, China
- Heilongjiang Provincial Key Laboratory of Plant Biology in Ordinary Colleges and Universities, Harbin Normal University, Harbin, China
| | - Yinan Liu
- Key Laboratory of Aquatic Biodiversity Research in Hei Longjiang Province, Harbin Normal University, Harbin, China
- Heilongjiang Provincial Key Laboratory of Plant Biology in Ordinary Colleges and Universities, Harbin Normal University, Harbin, China
| | - Zeyi Sun
- Heilongjiang Provincial Key Laboratory of Plant Biology in Ordinary Colleges and Universities, Harbin Normal University, Harbin, China
| | - Yuning Liu
- College of Science and Technology, Harbin Normal University, Harbin, China
| | - Zening Yuan
- Key Laboratory of Aquatic Biodiversity Research in Hei Longjiang Province, Harbin Normal University, Harbin, China
- Heilongjiang Provincial Key Laboratory of Plant Biology in Ordinary Colleges and Universities, Harbin Normal University, Harbin, China
| | - Chang Fu
- College of Science and Technology, Harbin Normal University, Harbin, China
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12
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Furqan M. Trofinetide-a new chapter in rett syndrome's treatment. Front Pharmacol 2023; 14:1284035. [PMID: 38035006 PMCID: PMC10687465 DOI: 10.3389/fphar.2023.1284035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 11/09/2023] [Indexed: 12/02/2023] Open
Abstract
Trofinetide is the first drug approved by the FDA to treat Rett Syndrome in children aged 2 years or above. The drug significantly improved Rett syndrome behavioral scores Rett syndrome behavioral questionnaire in clinical studies. Although further research is needed to assess potential adverse events, Trofinetide's notable efficacy signifies a significant advancement in Rett syndrome treatment, offering a new therapeutic avenue with the potential to ameliorate the condition.
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Affiliation(s)
- Muhammad Furqan
- Department of Medicine, Mayo Hospital, King Edward Medical University, Lahore, Punjab, Pakistan
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13
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Neul JL, Benke TA, Marsh ED, Suter B, Silveira L, Fu C, Peters SU, Percy AK. Top caregiver concerns in Rett syndrome and related disorders: data from the US natural history study. J Neurodev Disord 2023; 15:33. [PMID: 37833681 PMCID: PMC10571464 DOI: 10.1186/s11689-023-09502-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 09/20/2023] [Indexed: 10/15/2023] Open
Abstract
OBJECTIVE Recent advances in the understanding of neurodevelopmental disorders such as Rett syndrome (RTT) have enabled the discovery of novel therapeutic approaches that require formal clinical evaluation of efficacy. Clinical trial success depends on outcome measures that assess clinical features that are most impactful for affected individuals. To determine the top concerns in RTT and RTT-related disorders we asked caregivers to list the top caregiver concerns to guide the development and selection of appropriate clinical trial outcome measures for these disorders. METHODS Caregivers of participants enrolled in the US Natural History Study of RTT and RTT-related disorders (n = 925) were asked to identify the top 3 concerning problems impacting the affected participant. We generated a weighted list of top caregiver concerns for each of the diagnostic categories and compared results between the disorders. Further, for classic RTT, caregiver concerns were analyzed by age, clinical severity, and common RTT-causing mutations in MECP2. RESULTS The top caregiver concerns for classic RTT were effective communication, seizures, walking/balance issues, lack of hand use, and constipation. The frequency of the top caregiver concerns for classic RTT varied by age, clinical severity, and specific mutations, consistent with known variation in the frequency of clinical features across these domains. Caregivers of participants with increased seizure severity often ranked seizures as the first concern, whereas caregivers of participants without active seizures often ranked hand use or communication as the top concern. Comparison across disorders found commonalities in the top caregiver concerns between classic RTT, atypical RTT, MECP2 duplication syndrome, CDKL5 deficiency disorder, and FOXG1 syndrome; however, distinct differences in caregiver concerns between these disorders are consistent with the relative prevalence and impact of specific clinical features. CONCLUSION The top caregiver concerns for individuals with RTT and RTT-related disorders reflect the impact of the primary clinical symptoms of these disorders. This work is critical in the development of meaningful therapies, as optimal therapy should address these concerns. Further, outcome measures to be utilized in clinical trials should assess these clinical issues identified as most concerning by caregivers.
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Affiliation(s)
- Jeffrey L Neul
- Department of Pediatrics, Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Timothy A Benke
- University of Colorado School of Medicine/Children's Hospital Colorado, Aurora, CO, USA
| | - Eric D Marsh
- Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | | | - Lori Silveira
- University of Colorado School of Medicine/Children's Hospital Colorado, Aurora, CO, USA
| | - Cary Fu
- Department of Pediatrics, Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sarika U Peters
- Department of Pediatrics, Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alan K Percy
- University of Alabama at Birmingham, Birmingham, AL, USA
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Hudu SA, Elmigdadi F, Qtaitat AA, Almehmadi M, Alsaiari AA, Allahyani M, Aljuaid A, Salih M, Alghamdi A, Alrofaidi MA, Abida, Imran M. Trofinetide for Rett Syndrome: Highlights on the Development and Related Inventions of the First USFDA-Approved Treatment for Rare Pediatric Unmet Medical Need. J Clin Med 2023; 12:5114. [PMID: 37568516 PMCID: PMC10420089 DOI: 10.3390/jcm12155114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/29/2023] [Accepted: 07/04/2023] [Indexed: 08/13/2023] Open
Abstract
Rett syndrome (RTT) is a rare disability causing female-oriented pediatric neurodevelopmental unmet medical need. RTT was recognized in 1966. However, over the past 56 years, the United States Food and Drug Administration (USFDA) has authorized no effective treatment for RTT. Recently, Trofinetide was approved by the USFDA on 10 March 2023 as the first RTT treatment. This article underlines the pharmaceutical advancement, patent literature, and prospects of Trofinetide. The data for this study were gathered from the PubMed database, authentic websites (Acadia Pharmaceuticals, Neuren Pharmaceuticals, and USFDA), and free patent databases. Trofinetide was first disclosed by Neuren Pharmaceuticals in 2000 as a methyl group containing analog of the naturally occurring neuroprotective tripeptide called glycine-proline-glutamate (GPE). The joint efforts of Acadia Pharmaceuticals and Neuren Pharmaceuticals have developed Trofinetide. The mechanism of action of Trofinetide is not yet well established. However, it is supposed to improve neuronal morphology and synaptic functioning. The patent literature revealed a handful of inventions related to Trofinetide, providing excellent and unexplored broad research possibilities with Trofinetide. The development of innovative Trofinetide-based molecules, combinations of Trofinetide, patient-compliant drug formulations, and precise MECP2-mutation-related personalized medicines are foreseeable. Trofinetide is in clinical trials for some neurodevelopmental disorders (NDDs), including treating Fragile X syndrome (FXS). It is expected that Trofinetide may be approved for treating FXS in the future. The USFDA-approval of Trofinetide is one of the important milestones for RTT therapy and is the beginning of a new era for the therapy of RTT, FXS, autism spectrum disorder (ASD), brain injury, stroke, and other NDDs.
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Affiliation(s)
- Shuaibu A. Hudu
- Department of Basic Medical and Dental Sciences, Faculty of Dentistry, Zarqa University, Zarqa 13110, Jordan
| | - Fayig Elmigdadi
- Department of Basic Medical and Dental Sciences, Faculty of Dentistry, Zarqa University, Zarqa 13110, Jordan
| | - Aiman Al Qtaitat
- Department of Basic Medical and Dental Sciences, Faculty of Dentistry, Zarqa University, Zarqa 13110, Jordan
- Department of Anatomy and Histology, Faculty of Medicine, Mutah University, Karak 61710, Jordan
| | - Mazen Almehmadi
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Ahad Amer Alsaiari
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Mamdouh Allahyani
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Abdulelah Aljuaid
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Magdi Salih
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Adel Alghamdi
- Department of Pharmaceutical Chemistry, Faculty of Clinical Pharmacy, Al-Baha University, P.O. Box 1988, Al-Baha 65779, Saudi Arabia
| | - Mohammad A. Alrofaidi
- Department of Pharmaceutical Chemistry, Faculty of Clinical Pharmacy, Al-Baha University, P.O. Box 1988, Al-Baha 65779, Saudi Arabia
| | - Abida
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Northern Border University, Rafha 91911, Saudi Arabia;
| | - Mohd Imran
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Northern Border University, Rafha 91911, Saudi Arabia;
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15
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Percy AK, Neul JL, Benke TA, Marsh ED, Glaze DG. A review of the Rett Syndrome Behaviour Questionnaire and its utilization in the assessment of symptoms associated with Rett syndrome. Front Pediatr 2023; 11:1229553. [PMID: 37635789 PMCID: PMC10450502 DOI: 10.3389/fped.2023.1229553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 07/03/2023] [Indexed: 08/29/2023] Open
Abstract
The Rett Syndrome Behaviour Questionnaire (RSBQ), which is completed by the caregiver, is one of the most widely used efficacy measures in clinical studies of Rett syndrome (RTT) due to its specificity to the core features of RTT. As healthcare providers participate in routine healthcare assessments of individuals with RTT in clinical practice, there is a need for these providers to understand the psychometric properties of the RSBQ and how it relates to the core clinical features of RTT. Here, we describe the characteristics of the RSBQ, review the literature on its validity and reliability as well as its performance in a phase 2 study and the recent phase 3 LAVENDER study. The RSBQ was first shown to discriminate RTT from other intellectual disorders with good inter-rater and test-retest reliability scores. It was subsequently validated as an appropriate instrument for measuring behavior in females with RTT and adopted as a clinical trial outcome. In LAVENDER, the FDA-approved drug trofinetide significantly improved the RSBQ total score over placebo in girls and women with RTT and change from baseline for all RSBQ subscores were directionally in favor of trofinetide. The change in RSBQ was aligned with the Clinical Global Impression-Improvement scale, suggesting that improvement in behavioral components may be related to overall clinical status. Given its validity and ubiquity in RTT clinical studies, it is important that the interplay of the domains and the psychometric profile of the RSBQ are understood.
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Affiliation(s)
- Alan K. Percy
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jeffrey L. Neul
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Timothy A. Benke
- Children’s Hospital of Colorado/University of Colorado School of Medicine, Aurora, CO, United States
| | - Eric D. Marsh
- Department of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, United States
| | - Daniel G. Glaze
- Texas Children’s Hospital/Baylor College of Medicine, Houston, TX, United States
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16
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Oluigbo DC. Rett Syndrome: A Tale of Altered Genetics, Synaptic Plasticity, and Neurodevelopmental Dynamics. Cureus 2023; 15:e41555. [PMID: 37554594 PMCID: PMC10405636 DOI: 10.7759/cureus.41555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2023] [Indexed: 08/10/2023] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder that is a leading cause of severe cognitive and physical impairment. RTT typically occurs in females, although rare cases of males with the disease exist. Its genetic cause, symptoms, and clinical progression timeline have also become well-documented since its initial discovery. However, a relatively late diagnosis and lack of an available cure signify that our understanding of the disease is incomplete. Innovative research methods and tools are thereby helping to fill gaps in our knowledge of RTT. Specifically, mouse models of RTT, video analysis, and retrospective parental analysis are well-established tools that provide valuable insights into RTT. Moreover, current and anticipated treatment options are improving the quality of life of the RTT patient population. Collectively, these developments are creating optimistic future perspectives for RTT.
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Affiliation(s)
- David C Oluigbo
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, USA
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17
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Neul JL, Percy AK, Benke TA, Berry-Kravis EM, Glaze DG, Marsh ED, Lin T, Stankovic S, Bishop KM, Youakim JM. Trofinetide for the treatment of Rett syndrome: a randomized phase 3 study. Nat Med 2023; 29:1468-1475. [PMID: 37291210 PMCID: PMC10287558 DOI: 10.1038/s41591-023-02398-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 05/12/2023] [Indexed: 06/10/2023]
Abstract
Rett syndrome is a rare, genetic neurodevelopmental disorder. Trofinetide is a synthetic analog of glycine-proline-glutamate, the N-terminal tripeptide of the insulin-like growth factor 1 protein, and has demonstrated clinical benefit in phase 2 studies in Rett syndrome. In this phase 3 study ( https://clinicaltrials.gov identifier NCT04181723 ), females with Rett syndrome received twice-daily oral trofinetide (n = 93) or placebo (n = 94) for 12 weeks. For the coprimary efficacy endpoints, least squares mean (LSM) change from baseline to week 12 in the Rett Syndrome Behaviour Questionnaire for trofinetide versus placebo was -4.9 versus -1.7 (P = 0.0175; Cohen's d effect size, 0.37), and LSM Clinical Global Impression-Improvement at week 12 was 3.5 versus 3.8 (P = 0.0030; effect size, 0.47). For the key secondary efficacy endpoint, LSM change from baseline to week 12 in the Communication and Symbolic Behavior Scales Developmental Profile Infant-Toddler Checklist Social Composite score was -0.1 versus -1.1 (P = 0.0064; effect size, 0.43). Common treatment-emergent adverse events included diarrhea (80.6% for trofinetide versus 19.1% for placebo), which was mostly mild to moderate in severity. Significant improvement for trofinetide compared with placebo was observed for the coprimary efficacy endpoints, suggesting that trofinetide provides benefit in treating the core symptoms of Rett syndrome.
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Affiliation(s)
- Jeffrey L Neul
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alan K Percy
- University of Alabama at Birmingham, Birmingham, AL, USA
| | - Timothy A Benke
- Children's Hospital of Colorado and University of Colorado School of Medicine, Aurora, CO, USA
| | | | - Daniel G Glaze
- Texas Children's Hospital and Baylor College of Medicine, Houston, TX, USA
| | - Eric D Marsh
- Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Tim Lin
- Acadia Pharmaceuticals Inc., San Diego, CA, USA
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Singh J, Goodman-Vincent E, Santosh P. Evidence Synthesis of Gene Therapy and Gene Editing from Different Disorders-Implications for Individuals with Rett Syndrome: A Systematic Review. Int J Mol Sci 2023; 24:ijms24109023. [PMID: 37240368 DOI: 10.3390/ijms24109023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 05/06/2023] [Accepted: 05/12/2023] [Indexed: 05/28/2023] Open
Abstract
This systematic review and thematic analysis critically evaluated gene therapy trials in amyotrophic lateral sclerosis, haemoglobinopathies, immunodeficiencies, leukodystrophies, lysosomal storage disorders and retinal dystrophies and extrapolated the key clinical findings to individuals with Rett syndrome (RTT). The PRISMA guidelines were used to search six databases during the last decade, followed by a thematic analysis to identify the emerging themes. Thematic analysis across the different disorders revealed four themes: (I) Therapeutic time window of gene therapy; (II) Administration and dosing strategies for gene therapy; (III) Methods of gene therapeutics and (IV) Future areas of clinical interest. Our synthesis of information has further enriched the current clinical evidence base and can assist in optimising gene therapy and gene editing studies in individuals with RTT, but it would also benefit when applied to other disorders. The findings suggest that gene therapies have better outcomes when the brain is not the primary target. Across different disorders, early intervention appears to be more critical, and targeting the pre-symptomatic stage might prevent symptom pathology. Intervention at later stages of disease progression may benefit by helping to clinically stabilise patients and preventing disease-related symptoms from worsening. If gene therapy or editing has the desired outcome, older patients would need concerted rehabilitation efforts to reverse their impairments. The timing of intervention and the administration route would be critical parameters for successful outcomes of gene therapy/editing trials in individuals with RTT. Current approaches also need to overcome the challenges of MeCP2 dosing, genotoxicity, transduction efficiencies and biodistribution.
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Affiliation(s)
- Jatinder Singh
- Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK
- Centre for Interventional Paediatric Psychopharmacology and Rare Diseases (CIPPRD), South London and Maudsley NHS Foundation Trust, London SE5 8AZ, UK
- Centre for Interventional Paediatric Psychopharmacology (CIPP) Rett Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London and South London and Maudsley NHS Foundation Trust, London SE5 8AZ, UK
| | - Ella Goodman-Vincent
- Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK
- Centre for Interventional Paediatric Psychopharmacology and Rare Diseases (CIPPRD), South London and Maudsley NHS Foundation Trust, London SE5 8AZ, UK
- Centre for Interventional Paediatric Psychopharmacology (CIPP) Rett Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London and South London and Maudsley NHS Foundation Trust, London SE5 8AZ, UK
| | - Paramala Santosh
- Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK
- Centre for Interventional Paediatric Psychopharmacology and Rare Diseases (CIPPRD), South London and Maudsley NHS Foundation Trust, London SE5 8AZ, UK
- Centre for Interventional Paediatric Psychopharmacology (CIPP) Rett Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London and South London and Maudsley NHS Foundation Trust, London SE5 8AZ, UK
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19
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Abstract
Trofinetide (DAYBUE™), an oral, small molecule, synthetic analog of glycine-proline-glutamate [GPE; the N-terminal tripeptide derivative of insulin like growth factor-1 (IGF-1)], is being developed by Neuren Pharmaceuticals and Acadia Pharmaceuticals for the treatment of rare childhood neurodevelopmental disorders. Trofinetide was approved in March 2023 in the USA for the treatment of Rett syndrome in adult and pediatric patients 2 years of age and older. This article summarizes the milestones in the development of trofinetide leading to this first approval for Rett syndrome.
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Affiliation(s)
- Susan J Keam
- Springer Nature, Private Bag 65901, Mairangi Bay, Auckland, 0754, New Zealand.
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20
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Saldaris J, Leonard H, Wong K, Jacoby P, Spence M, Marsh ED, Benke TA, Demarest S, Downs J. Validating the Communication and Symbolic Behavior Scales-Developmental Profile Infant-Toddler Checklist (CSBS-DP ITC) Beyond Infancy in the CDKL5 Deficiency Disorder. J Autism Dev Disord 2023:10.1007/s10803-023-06002-w. [PMID: 37184758 PMCID: PMC10699574 DOI: 10.1007/s10803-023-06002-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2023] [Indexed: 05/16/2023]
Abstract
CDKL5 deficiency disorder (CDD) results in early-onset epilepsy and lifelong cognitive and motor impairments. With no validated measure for communication in CDD, this study evaluated the psychometric properties of the Communication and Symbolic Behavior Scales-Developmental Profile Infant Toddler Checklist (CSBS-DP ITC). Caregivers (n = 150; affected individuals aged 1-29 years) completed the CSBS-DP ITC. Distribution of scores indicated a floor effect. There was poor divergent validity for the three-factor model but goodness of fit and convergent validity data were satisfactory for the one-factor model. Individuals with poorer overall functional abilities scored lower on the CSBS-DP ITC. Test-retest reliability was excellent. The floor effect could explain the very high reliability, suggesting problems as a sensitive outcome measure in clinical trials for CDD.
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Affiliation(s)
- Jacinta Saldaris
- Telethon Kids Institute, Centre for Child Health Research, The University of Western Australia, PO Box 855, West Perth, WA, 6872, Australia
| | - Helen Leonard
- Telethon Kids Institute, Centre for Child Health Research, The University of Western Australia, PO Box 855, West Perth, WA, 6872, Australia
| | - Kingsley Wong
- Telethon Kids Institute, Centre for Child Health Research, The University of Western Australia, PO Box 855, West Perth, WA, 6872, Australia
| | - Peter Jacoby
- Telethon Kids Institute, Centre for Child Health Research, The University of Western Australia, PO Box 855, West Perth, WA, 6872, Australia
| | - Mary Spence
- Children's Hospital Colorado Therapy Care, Highlands Ranch, CO, USA
| | - Eric D Marsh
- Division of Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Tim A Benke
- Children's Hospital Colorado, Paediatric Neurology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Scott Demarest
- Children's Hospital Colorado, Paediatric Neurology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Jenny Downs
- Telethon Kids Institute, Centre for Child Health Research, The University of Western Australia, PO Box 855, West Perth, WA, 6872, Australia.
- School of Physiotherapy and Exercise Science, Curtin University, Perth, WA, Australia.
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Lotan M, Downs J, Stahlhut M, Romano A. Evaluation Tools Developed for Rett Syndrome. Diagnostics (Basel) 2023; 13:diagnostics13101708. [PMID: 37238191 DOI: 10.3390/diagnostics13101708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 05/08/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
Rett syndrome (RTT) is a complex neurodevelopmental X-linked disorder associated with severe functional impairments and multiple comorbidities. There is wide variation in the clinical presentation, and because of its unique characteristics, several evaluation tools of clinical severity, behavior, and functional motor abilities have been proposed specifically for it. This opinion paper aims to present up-to date evaluation tools which have specifically been adapted for individuals with RTT often used by the authors in their clinical and research practice and to provide the reader with essential considerations and suggestions regarding their use. Due to the rarity of Rett syndrome, we found it important to present these scales in order to improve and professionalize their clinical work. The current article will review the following evaluation tools: (a) the Rett Assessment Rating Scale; (b) the Rett Syndrome Gross Motor Scale; (c) the Rett Syndrome Functional Scale; (d) the Functional Mobility Scale-Rett Syndrome; (e) the Two-Minute Walking Test modified for Rett syndrome; (f) the Rett Syndrome Hand Function Scale; (g) the StepWatch Activity Monitor; (h) the activPALTM; (i) the Modified Bouchard Activity Record; (j) the Rett Syndrome Behavioral Questionnaire; and (k) the Rett Syndrome Fear of Movement Scale. The authors recommend that service providers consider evaluation tools validated for RTT for evaluation and monitoring to guide their clinical recommendations and management. In this article, the authors suggest factors that should be considered when using these evaluation tools to assist in interpreting scores.
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Affiliation(s)
- Meir Lotan
- Department of Physiotherapy, Ariel University, Ariel 4070000, Israel
- Israeli Rett Syndrome National Evaluation Team, Ramat Gan 5211401, Israel
| | - Jenny Downs
- Telethon Kids Institute, Centre for Child Health Research, The University of Western Australia, Nedlands, WA 6009, Australia
- School of Allied Health, Curtin University, Perth, WA 6102, Australia
| | - Michelle Stahlhut
- Department of Paediatrics and Adolescent Medicine, Center for Rett Syndrome, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Alberto Romano
- Department of Health System Management, Ariel University, Ariel 4070000, Israel
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22
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Neul JL, Benke TA, Marsh ED, Suter B, Silveira L, Fu C, Peters SU, Percy AK. Top Caregiver Concerns in Rett syndrome and related disorders: data from the US Natural History Study. RESEARCH SQUARE 2023:rs.3.rs-2566253. [PMID: 36993737 PMCID: PMC10055548 DOI: 10.21203/rs.3.rs-2566253/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Objective Recent advances in the understanding of neurodevelopmental disorders such as Rett syndrome (RTT) has enabled development of novel therapeutic approaches that are currently undergoing clinical evaluation or are proposed to move into clinical development. Clinical trial success depends on outcome measures that assess clinical features that are most impactful for affected individuals. To determine the top concerns in RTT and RTT-related disorders we asked caregivers to list the top clinical concerns in order to gain information to guide the development and selection of outcome measures for future clinical trials. Methods Caregivers of participants enrolled in the US Natural History Study of RTT and related disorders were asked to identify the top 3 concerning problems impacting the affected participant. We generated a weighted list of top caregiver concerns for each of the diagnostic categories and compared results between the disorders. Further, for Classic RTT, caregiver concerns were analyzed by age, clinical severity, and common RTT-causing mutations in MECP2. Results The top caregiver concerns for Classic RTT were effective communication, seizures, walking/balance issues, lack of hand use, and constipation. The rank order of the frequency of the top caregiver concerns for Classic RTT varied by age, clinical severity, and specific mutations, consistent with known variation in the frequency of clinical features across these domains. The frequency of caregiver concern for seizures, hand use, and spoken language increased in relation to clinician assessed severity in these clinical domains, showing consistency between clinician assessments and caregiver concerns. Comparison across disorders found commonalities in the top caregiver concerns between Classic RTT, Atypical RTT, MECP2 Duplication Syndrome, CDKL5 Deficiency Disorder, and FOXG1 Syndrome; however, distinct differences in caregiver concerns between these disorders are consistent with the relative prevalence and impact of specific clinical features. Conclusion The top caregiver concerns for individuals with RTT and the RTT-related disorders reflect the impact of the primary clinical symptoms of these disorders. This work is critical in the development of meaningful therapies, as optimal therapy should address these concerns. Further, outcome measures to be utilized in clinical trials should assess these clinical issues identified as most concerning by caregivers.
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Affiliation(s)
| | - Timothy A Benke
- University of Colorado School of Medicine: University of Colorado Anschutz Medical Campus School of Medicine
| | | | | | - Lori Silveira
- University of Colorado School of Medicine: University of Colorado Anschutz Medical Campus School of Medicine
| | - Cary Fu
- Vanderbilt University Medical Center
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23
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Transition from Animal-Based to Human Induced Pluripotent Stem Cells (iPSCs)-Based Models of Neurodevelopmental Disorders: Opportunities and Challenges. Cells 2023; 12:cells12040538. [PMID: 36831205 PMCID: PMC9954744 DOI: 10.3390/cells12040538] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/25/2023] [Accepted: 02/02/2023] [Indexed: 02/11/2023] Open
Abstract
Neurodevelopmental disorders (NDDs) arise from the disruption of highly coordinated mechanisms underlying brain development, which results in impaired sensory, motor and/or cognitive functions. Although rodent models have offered very relevant insights to the field, the translation of findings to clinics, particularly regarding therapeutic approaches for these diseases, remains challenging. Part of the explanation for this failure may be the genetic differences-some targets not being conserved between species-and, most importantly, the differences in regulation of gene expression. This prompts the use of human-derived models to study NDDS. The generation of human induced pluripotent stem cells (hIPSCs) added a new suitable alternative to overcome species limitations, allowing for the study of human neuronal development while maintaining the genetic background of the donor patient. Several hIPSC models of NDDs already proved their worth by mimicking several pathological phenotypes found in humans. In this review, we highlight the utility of hIPSCs to pave new paths for NDD research and development of new therapeutic tools, summarize the challenges and advances of hIPSC-culture and neuronal differentiation protocols and discuss the best way to take advantage of these models, illustrating this with examples of success for some NDDs.
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Silva-Reis SC, Sampaio-Dias IE, Costa VM, Correia XC, Costa-Almeida HF, García-Mera X, Rodríguez-Borges JE. Concise Overview of Glypromate Neuropeptide Research: From Chemistry to Pharmacological Applications in Neurosciences. ACS Chem Neurosci 2023; 14:554-572. [PMID: 36735764 PMCID: PMC9936549 DOI: 10.1021/acschemneuro.2c00675] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Neurodegenerative diseases of the central nervous system (CNS) pose a serious health concern worldwide, with a particular incidence in developed countries as a result of life expectancy increase and the absence of restorative treatments. Presently, treatments for these neurological conditions are focused on managing the symptoms and/or slowing down their progression. As so, the research on novel neuroprotective drugs is of high interest. Glypromate (glycyl-l-prolyl-l-glutamic acid, also known as GPE), an endogenous small peptide widespread in the brain, holds great promise to tackle neurodegenerative diseases such as Parkinson's, Alzheimer's, and Huntington's, s well as other CNS-related disorders like Rett and Down's syndromes. However, the limited pharmacokinetic properties of Glypromate hinder its clinical application. As such, intense research has been devoted to leveraging the pharmacokinetic profile of this neuropeptide. This review aims to offer an updated perspective on Glypromate research by exploring the vast array of chemical derivatizations of more than 100 analogs described in the literature over the past two decades. The collection and discussion of the most relevant structure-activity relationships will hopefully guide the discovery of new Glypromate-based neuroprotective drugs.
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Affiliation(s)
- Sara C. Silva-Reis
- LAQV/REQUIMTE,
Department of Chemistry and Biochemistry, Faculty of Sciences, University
of Porto, 4169-007 Porto, Portugal,UCIBIO/REQUIMTE,
Laboratory of Toxicology, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Ivo E. Sampaio-Dias
- LAQV/REQUIMTE,
Department of Chemistry and Biochemistry, Faculty of Sciences, University
of Porto, 4169-007 Porto, Portugal,
| | - Vera M. Costa
- UCIBIO/REQUIMTE,
Laboratory of Toxicology, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal,Associate
Laboratory i4HB, Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Xavier Cruz Correia
- LAQV/REQUIMTE,
Department of Chemistry and Biochemistry, Faculty of Sciences, University
of Porto, 4169-007 Porto, Portugal
| | - Hugo F. Costa-Almeida
- LAQV/REQUIMTE,
Department of Chemistry and Biochemistry, Faculty of Sciences, University
of Porto, 4169-007 Porto, Portugal
| | - Xerardo García-Mera
- Department
of Organic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - José E. Rodríguez-Borges
- LAQV/REQUIMTE,
Department of Chemistry and Biochemistry, Faculty of Sciences, University
of Porto, 4169-007 Porto, Portugal
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Guan J, Li F, Kang D, Anderson T, Pitcher T, Dalrymple-Alford J, Shorten P, Singh-Mallah G. Cyclic Glycine-Proline (cGP) Normalises Insulin-Like Growth Factor-1 (IGF-1) Function: Clinical Significance in the Ageing Brain and in Age-Related Neurological Conditions. Molecules 2023; 28:molecules28031021. [PMID: 36770687 PMCID: PMC9919809 DOI: 10.3390/molecules28031021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/16/2023] [Accepted: 01/17/2023] [Indexed: 01/20/2023] Open
Abstract
Insulin-like growth factor-1 (IGF-1) function declines with age and is associated with brain ageing and the progression of age-related neurological conditions. The reversible binding of IGF-1 to IGF binding protein (IGFBP)-3 regulates the amount of bioavailable, functional IGF-1 in circulation. Cyclic glycine-proline (cGP), a metabolite from the binding site of IGF-1, retains its affinity for IGFBP-3 and competes against IGF-1 for IGFBP-3 binding. Thus, cGP and IGFBP-3 collectively regulate the bioavailability of IGF-1. The molar ratio of cGP/IGF-1 represents the amount of bioavailable and functional IGF-1 in circulation. The cGP/IGF-1 molar ratio is low in patients with age-related conditions, including hypertension, stroke, and neurological disorders with cognitive impairment. Stroke patients with a higher cGP/IGF-1 molar ratio have more favourable clinical outcomes. The elderly with more cGP have better memory retention. An increase in the cGP/IGF-1 molar ratio with age is associated with normal cognition, whereas a decrease in this ratio with age is associated with dementia in Parkinson disease. In addition, cGP administration reduces systolic blood pressure, improves memory, and aids in stroke recovery. These clinical and experimental observations demonstrate the role of cGP in regulating IGF-1 function and its potential clinical applications in age-related brain diseases as a plasma biomarker for-and an intervention to improve-IGF-1 function.
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Affiliation(s)
- Jian Guan
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine and Health Sciences, School of Biomedical Sciences, The University of Auckland, Auckland 1142, New Zealand
- Centre for Brain Research, Faculty of Medicine and Health Sciences, School of Biomedical Sciences, The University of Auckland, Auckland 1142, New Zealand
- Brain Research New Zealand, The Centre for Research Excellent, Dunedin 9016, New Zealand
- The cGP Lab Limited New Zealand, Auckland 1021, New Zealand
- Correspondence: ; Tel.: +64-9-923-6134
| | - Fengxia Li
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine and Health Sciences, School of Biomedical Sciences, The University of Auckland, Auckland 1142, New Zealand
- Centre for Brain Research, Faculty of Medicine and Health Sciences, School of Biomedical Sciences, The University of Auckland, Auckland 1142, New Zealand
- Guangdong Pharmaceutical University, Guangzhou Higher Education Mega Center, Guangzhou 510075, China
- The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen 518107, China
| | - Dali Kang
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine and Health Sciences, School of Biomedical Sciences, The University of Auckland, Auckland 1142, New Zealand
- Centre for Brain Research, Faculty of Medicine and Health Sciences, School of Biomedical Sciences, The University of Auckland, Auckland 1142, New Zealand
- Brain Research New Zealand, The Centre for Research Excellent, Dunedin 9016, New Zealand
- Shenyang Medical College, Shenyang 110034, China
| | - Tim Anderson
- New Zealand Brain Research Institute, Christchurch 4710, New Zealand
- Department of Medicine, University of Otago, Dunedin 9016, New Zealand
- Department of Neurology, Canterbury District Health Board, Christchurch 4710, New Zealand
| | - Toni Pitcher
- New Zealand Brain Research Institute, Christchurch 4710, New Zealand
- Department of Medicine, University of Otago, Dunedin 9016, New Zealand
- Department of Neurology, Canterbury District Health Board, Christchurch 4710, New Zealand
| | - John Dalrymple-Alford
- Department of Neurology, Canterbury District Health Board, Christchurch 4710, New Zealand
- Department of Psychology, University of Canterbury, Christchurch 4710, New Zealand
| | - Paul Shorten
- AgResearch Ltd., Ruakura Research Centre, Hamilton 3214, New Zealand
- Riddet Institute, Massey University, Palmerston North 4474, New Zealand
| | - Gagandeep Singh-Mallah
- Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
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Lumsden JM, Urv TK. The Rare Diseases Clinical Research Network: a model for clinical trial readiness. THERAPEUTIC ADVANCES IN RARE DISEASE 2023; 4:26330040231219272. [PMID: 38152157 PMCID: PMC10752072 DOI: 10.1177/26330040231219272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 11/15/2023] [Indexed: 12/29/2023]
Abstract
Background The current road to developing treatments for rare diseases is often slow, expensive, and riddled with risk. Change is needed to improve the process, both in how we think about rare disease treatment development and the infrastructure we build to support ongoing science. The National Institutes of Health (NIH)-supported Rare Diseases Clinical Research Network (RDCRN) was established to advance the diagnosis, management, and treatment of rare diseases and to promote highly collaborative, multi-site, patient-centric, translational, and clinical research. The current iteration of the RDCRN intends to build upon and enhance successful approaches within the network while identifying innovative methods to fill gaps and address needs in the approach to the rare disease treatment development process through innovation, collaboration, and clinical trial readiness. Objective The objective of this paper is to provide an overview of the productivity and influence of the RDCRN since it was first established 20 years ago. Design and methods Using a suite of tools available to NIH staff that provides access to a comprehensive, curated, extensively linked data set of global grants, patents, publications, clinical trials, and FDA-approved drugs, a series of queries were executed that conducted bibliometric, co-author, and co-occurrence analysis. Results The results demonstrate that the entire RDCRN consortia and network has been highly productive since its inception. They have produced 2763 high-quality publications that have been cited more than 100,000 times, expanded international networks, and contributed scientifically to eight FDA-approved treatments for rare diseases. Conclusion The RDCRN program has successfully addressed some significant challenges while developing treatments for rare diseases. However, looking to the future and being agile in facing new challenges that arise as science progresses is important.
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Affiliation(s)
- Joanne M. Lumsden
- Division of Rare Diseases Research Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, 6801 Democracy Boulevard, Bethesda, MD 20892-0001, USA
| | - Tiina K. Urv
- Division of Rare Diseases Research Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, USA
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Ramirez JM, Karlen-Amarante M, Wang JDJ, Huff A, Burgraff N. Breathing disturbances in Rett syndrome. HANDBOOK OF CLINICAL NEUROLOGY 2022; 189:139-151. [PMID: 36031301 PMCID: PMC10029146 DOI: 10.1016/b978-0-323-91532-8.00018-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Rett Syndrome is an X-linked neurological disorder characterized by behavioral and neurological regression, seizures, motor deficits, and dysautonomia. A particularly prominent presentation includes breathing abnormalities characterized by breathing irregularities, hyperventilation, repetitive breathholding during wakefulness, obstructive and central apneas during sleep, and abnormal responses to hypoxia and hypercapnia. The condition and pathology of the respiratory system is further complicated by dysfunctions of breathing-motor coordination, which is reflected in dysphagia. The discovery of the X-linked mutations in the MECP2 gene has transformed our understanding of the cellular and molecular mechanisms that are at the root of various clinical phenotypes. However, the genotype-phenotype relationship is complicated by various factors which include not only X-inactivation but also consequences of the intermittent hypoxia and oxidative stress associated with the breathing abnormalities.
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Affiliation(s)
- Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States; Department of Neurological Surgery, University of Washington School of Medicine, Seattle, WA, United States.
| | - Marlusa Karlen-Amarante
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Jia-Der Ju Wang
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Alyssa Huff
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Nicholas Burgraff
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
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