Development of trofinetide for the treatment of Rett syndrome: from bench to bedside.

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.

Design and outcome measures of LAVENDER, a phase 3 study of trofinetide for Rett syndrome.

INTRODUCTION: Rett syndrome (RTT) is a debilitating neurodevelopmental disorder with no approved treatments. Trofinetide is a synthetic analog of glycine-proline-glutamate, the N-terminal tripeptide of insulin-like growth factor 1. In a phase 2, placebo-controlled trial in 82 females with RTT aged 5-15 years, a significant (p ≤ 0.042) improvement over placebo was observed with the highest trofinetide dose (200 mg/kg twice daily [BID]) on three measures: Rett Syndrome Behaviour Questionnaire (RSBQ), Clinical Global Impression-Improvement (CGI-I), and RTT-Clinician Domain Specific Concerns-Visual Analog Scale (RTT-DSC-VAS). Trofinetide was well tolerated at all doses (50, 100, and 200 mg/kg BID). A phase 3 trial utilizing disease-specific and novel scales was designed to investigate the efficacy and safety of trofinetide in girls and women with RTT. METHODS: This 12-week, double-blind, randomized, placebo-controlled study (LAVENDER; NCT04181723) will evaluate trofinetide in 187 females, aged 5-20 years, with RTT. Co-primary endpoints are the RSBQ and CGI-I scales. Clinical domains of the CGI-I include communication, ambulation, hand use, seizures, attentiveness, and social (eye contact) and autonomic (breathing) aspects. Secondary endpoints will leverage four novel RTT-specific clinician ratings (derived from the RTT-DSC-VAS) of hand function, ambulation, ability to communicate, and verbal communication, and existing scales, to evaluate other core symptoms of RTT, quality of life and caregiver burden. A 40-week, open-label extension study will follow. DISCUSSION: This study was designed using disease-specific scales optimized to demonstrate changes in core symptoms of RTT and may provide the first phase 3 data demonstrating drug efficacy in individuals with RTT. TRIAL REGISTRATION: Clinicaltrials.govNCT04181723.

A Double-Blind, Randomized, Placebo-Controlled Clinical Study of Trofinetide in the Treatment of Fragile X Syndrome.

BACKGROUND: We analyze the safety and tolerability of trofinetide and provide a preliminary evaluation of its efficacy in adolescent and adult males with fragile X syndrome. METHODS: This study was an exploratory, phase 2, multicenter, double-blind, placebo-controlled, parallel group study of the safety and tolerability of orally administered trofinetide in 72 adolescent and adult males with fragile X syndrome. Subjects were randomly assigned in a 1:1:1 ratio to 35 or 70 mg/kg twice daily trofinetide or placebo for 28 days. Safety assessments included adverse events, clinical laboratory tests, vital signs, electrocardiograms, physical examinations, and concomitant medications. Efficacy measurements were categorized into four efficacy domains, which related to clinically relevant phenotypic dimensions of impairment associated with fragile X syndrome. RESULTS: Both 35 and 70 mg/kg dose levels of trofinetide were well tolerated and appeared to be generally safe. Trofinetide at the 70 mg/kg dose level demonstrated efficacy compared with placebo based on prespecified criteria. On the basis of a permutation test, the probability of a false-positive outcome for the achieved prespecified success was 0.045. In the group analysis, improvement from treatment baseline was demonstrated on three fragile X syndrome-specific outcome measures. CONCLUSIONS: Trofinetide was well tolerated in adolescent and adult males with fragile X syndrome. Despite the relatively short duration of the study, a consistent signal of efficacy at the higher dose was observed in both caregiver and clinician assessments, based on a novel analytical model incorporating evaluation of multiple key symptom areas of fragile X syndrome. This finding suggests a potential for trofinetide treatment to provide clinically meaningful improvement in core fragile X syndrome symptoms.

Double-blind, randomized, placebo-controlled study of trofinetide in pediatric Rett syndrome.

OBJECTIVE: To determine safety, tolerability, and pharmacokinetics of trofinetide and evaluate its efficacy in female children/adolescents with Rett syndrome (RTT), a debilitating neurodevelopmental condition for which no pharmacotherapies directed at core features are available. METHODS: This was a phase 2, multicenter, double-blind, placebo-controlled, parallel-group study, in which safety/tolerability, pharmacokinetics, and clinical response to trofinetide were characterized in 82 children/adolescents with RTT, aged 5 to 15 years. Sixty-two participants were randomized 1:1:1:1 to receive placebo twice a day (bid) for 14 days, followed by placebo, 50, 100, or 200 mg/kg bid of trofinetide for 42 days. Following blinded safety data review, 20 additional participants were randomized 1:1 to the 200 mg/kg or placebo bid groups. Safety assessments included adverse events, clinical laboratory tests, physical examinations, and concomitant medications. Clinician- and caregiver-based efficacy measurements assessed clinically relevant, phenotypic dimensions of impairment of RTT. RESULTS: All dose levels were well tolerated and generally safe. Trofinetide at 200 mg/kg bid showed statistically significant and clinically relevant improvements relative to placebo on the Rett Syndrome Behaviour Questionnaire, RTT-Clinician Domain Specific Concerns-Visual Analog Scale, and Clinical Global Impression Scale-Improvement. Exploratory analyses suggested that observed changes correlated with trofinetide exposure. CONCLUSION: These results, together with those from a previous adolescent/adult trial, indicate trofinetide's potential for treating core RTT symptoms and support further trials. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that for children/adolescents with RTT, trofinetide was safe, well-tolerated, and demonstrated improvement over placebo at 200 mg/kg bid in functionally important dimensions of RTT.

A Double-Blind, Randomized, Placebo-Controlled Clinical Study of Trofinetide in the Treatment of Rett Syndrome.

BACKGROUND: This study aimed to determine the safety and tolerability of trofinetide and to evaluate efficacy measures in adolescent and adult females with Rett syndrome, a serious and debilitating neurodevelopmental condition for which no therapies are available for its core features. METHODS: This was an exploratory, phase 2, multicenter, double-blind, placebo-controlled, dose-escalation study of the safety and tolerability of trofinetide in 56 adolescent and adult females with Rett syndrome. Subjects were randomly assigned in a 2:1 ratio to 35 mg/kg twice daily of trofinetide or placebo for 14 days; 35 mg/kg twice daily or placebo for 28 days; or 70 mg/kg twice daily or placebo for 28 days. Safety assessments included adverse events, clinical laboratory tests, vital signs, electrocardiograms, physical examinations, and concomitant medications. Efficacy measurements were categorized into four efficacy domains, which related to clinically relevant, phenotypic dimensions of impairment associated with Rett syndrome. RESULTS: Both 35 mg/kg and 70 mg/kg dose levels of trofinetide were well tolerated and generally safe. Trofinetide at 70 mg/kg demonstrated efficacy compared with placebo based on prespecified criteria. CONCLUSION: Trofinetide was well tolerated in adolescent and adult females with Rett syndrome. Although this study had a relatively short duration in a small number of subjects with an advanced stage of disease, consistent efficacy trends at the higher dose were observed in several outcome measures that assess important dimensions of Rett syndrome. These results represented clinically meaningful improvement from the perspective of the clinicians as well as the caregivers.

Assessment of Caregiver Inventory for Rett Syndrome.

Rett syndrome (RTT) requires total caregiver attention and leads to potential difficulties throughout life. The Caregiver Burden Inventory, designed for Alzheimer disease, was modified to a RTT Caregiver Inventory Assessment (RTT CIA). Reliability and face, construct, and concurrent validity were assessed in caregivers of individuals with RTT. Chi square or Fisher's exact test for categorical variables and t tests or Wilcoxon two-sample tests for continuous variables were utilized. Survey completed by 198 caregivers; 70 caregivers completed follow-up assessment. Exploratory factor analysis revealed good agreement for physical burden, emotional burden, and social burden. Internal reliability was high (Cronbach's alpha 0.898). RTT CIA represents a reliable and valid measure, providing a needed metric of caregiver burden in this disorder.

Improving Treatment Trial Outcomes for Rett Syndrome: The Development of Rett-specific Anchors for the Clinical Global Impression Scale.

Rett syndrome is a genetically based neurodevelopmental disorder. Although the clinical consequences of Rett syndrome are profound and lifelong, currently no approved drug treatments are available specifically targeted to Rett symptoms. High quality outcome measures, specific to the core symptoms of a disorder are a critical component of well-designed clinical trials for individuals with neurodevelopmental disorders. The Clinical Global Impression Scale is a measure of global clinical change with strong face validity that has been widely used as an outcome measure in clinical trials of central nervous system disorders. Despite its favorable assay sensitivity in clinical trials, as a global measure, the Clinical Global Impression Scale is not specific to the signs and symptoms of the disorder under study. Development of key anchors for the scale, specific to the disorder being assessed, holds promise for enhancing the validity and reliability of the measure for disorders such as Rett syndrome.

Measuring anxiety as a treatment endpoint in youth with autism spectrum disorder.

Despite the high rate of anxiety in individuals with autism spectrum disorder (ASD), measuring anxiety in ASD is fraught with uncertainty. This is due, in part, to incomplete consensus on the manifestations of anxiety in this population. Autism Speaks assembled a panel of experts to conduct a systematic review of available measures for anxiety in youth with ASD. To complete the review, the panel held monthly conference calls and two face-to-face meetings over a fourteen-month period. Thirty eight published studies were reviewed and ten assessment measures were examined: four were deemed appropriate for use in clinical trials, although with conditions; three were judged to be potentially appropriate, while three were considered not useful for clinical trials assessing anxiety. Despite recent advances, additional relevant, reliable and valid outcome measures are needed to evaluate treatments for anxiety in ASD.

Healthcare for children with autism: the Autism Treatment Network.

PURPOSE OF REVIEW: Autism spectrum disorders (ASDs) are a group of a neurodevelopmental disorders affecting social, communicative, and behavioral functioning. ASD is a heterogeneous group of disorders, often accompanied by associated medical issues. Thus, the development of effective treatments is a complex task requiring consideration of diverse etiologic and phenotypic characteristics. Recent attention to the diagnosis and treatment of medical conditions in ASD children has led to the formation of a new international collaboration to improve autism care, the Autism Treatment Network (ATN). RECENT FINDINGS: Numerous studies have highlighted the high prevalence of gastrointestinal and sleep disorders among ASD children. Problems in communication - including being nonverbal - make the diagnosis and treatment of these conditions more difficult. Although a number of studies suggest links between neurologic impairments and gastrointestinal dysfunction and disordered sleep, these relationships remain unproven. Recent work by the ATN has begun the development of clinical guidelines in these areas, based on clinical consensus, adapting the model developed by the Cystic Fibrosis Foundation. New funding has also supported the network's development of a robust clinical research program focused on improving the physical health and care of children with ASD. These efforts promise more systematic and consistent approaches to diagnosis and treatment of these conditions. SUMMARY: Improved understanding of the underlying pathology of ASD and associated conditions, and the development of a common purpose across multiple treating sites, can improve the consistent and coordinated healthcare of children with autism.