Development of an adapted Clinical Global Impression scale for use in Angelman syndrome

Precision Medicine in Angelman Syndrome

Angelman syndrome (AS) is a rare neurogenetic disorder caused by a loss of function of UBE3A on the maternal allele. Clinical features include severe neurodevelopmental delay, epilepsy, sleep disturbances, and behavioral disorders. Therapy currently evolves from conventional symptomatic, supportive, and antiseizure treatments toward alteration of mRNA expression, which is subject of several ongoing clinical trials.This article will provide an overview of clinical research and therapeutic approaches on AS.

A clinical-translational review of sleep problems in neurodevelopmental disabilities

Sleep disorders are very common across neurodevelopmental disorders and place a large burden on affected children, adolescents, and their families. Sleep disturbances seem to involve a complex interplay of genetic, neurobiological, and medical/environmental factors in neurodevelopmental disorders. In this review, we discuss animal models of sleep problems and characterize their presence in two single gene disorders, Rett Syndrome, and Angelman Syndrome and two more commonly occurring neurodevelopmental disorders, Down Syndrome, and autism spectrum disorders. We then discuss strategies for novel methods of assessment using wearable sensors more broadly for neurodevelopmental disorders in general, including the importance of analytical validation. An increased understanding of the mechanistic contributions and potential biomarkers of disordered sleep may offer quantifiable targets for interventions that improve overall quality of life for affected individuals and their families.

An adapted clinical global Impression of improvement for use in Angelman syndrome: Validation analyses utilizing data from the NEPTUNE study

PURPOSE

Angelman Syndrome (AS) is a rare, severe neurogenetic disorder that causes symptoms such as intellectual disability and motor impairments and is typically diagnosed in early childhood. The complexity and heterogeneity of AS confound characterization of disease severity and pose unique challenges when determining an individual's response to treatment. There is therefore a substantial unmet need for rating scales specifically designed for complex conditions such as AS. To address this, the Clinical Global Impressions (CGI) scale, which has components for both symptom severity (CGI-S) and improvement (CGI-I) was specifically adapted to measure severity (CGI-S-AS) and improvement (CGI-I-AS) in AS.

METHODS

The modified CGI-S/I-AS was used in the NEPTUNE trial of gaboxadol for the treatment of AS. Here we report on the validation of the CGI-I-AS using data from NEPTUNE and discuss insights for its potential use in future trials.

RESULTS

Improvements in the CGI-I-AS rating tended to be consistent with changes on other relevant rating scales. Sleep-related symptoms were particularly well represented, while communication-related symptoms were not.

CONCLUSIONS

Our validation analysis of the CGI-I-AS demonstrates its usefulness along with possible areas of improvement. The CGI-I-AS is a potential tool for use in other trials of AS drug candidates, and the process for its development can serve as a road map for the development of assessment tools for other neuropsychiatric disorders with similar complexities and heterogeneity.

Gaboxadol in angelman syndrome: A double-blind, parallel-group, randomized placebo-controlled phase 3 study

PURPOSE

To evaluate efficacy and safety of gaboxadol for treatment of children with Angelman syndrome (AS).

METHOD

In this international, double-blind, phase 3 trial, we randomized children 4-12 years old with a molecular diagnosis of AS and a Clinical Global Impression (CGI)-severity score ≥3 to either daily administration of weight-based gaboxadol or matching placebo for 12 weeks. The primary endpoint was the CGI-Improvement-AS (CGI-I-AS) score at week 12. Secondary endpoints included the proportion of participants with CGI-I-AS response of ≤3 (i.e., at least "minimal improvement") and ≤2 (i.e., at least "much improvement") at week 12. Safety and tolerability were monitored throughout the study. Weight based dosing of study drug ranged from 0.125 mg/kg to 0.24 mg/kg depending on weight range.

RESULTS

Between August 2019 and November 2020, 104 participants were enrolled: participants 4-12 years old were randomly (1:1) assigned to gaboxadol (n = 47) or placebo (n = 50), and 7 other participants 2─3 years old who received gaboxadol and were assessed for safety only. All gaboxadol-treated participants and 48 of 50 placebo-treated participants completed treatment. There was no significant difference in CGI-I-AS between groups: at week 12, mean CGI-I-AS score was 3.3 (SD, 1.00) and 3.2 (SD, 1.05) in the gaboxadol and placebo groups, respectively, yielding a least squares mean difference of zero (p = 0.83). There were no between-group significant differences with respect to CGI-I-AS responses. Gaboxadol was well tolerated in all age groups of this study.

CONCLUSIONS

There was no significant difference in CGI-I-AS between gaboxadol and placebo after 12 weeks of study treatment in pediatric AS participants.

CLINICALTRIALS

GOV: NCT04106557.

Understanding the impact of tuberous sclerosis complex: development and validation of the TSC-PROM

BACKGROUND

Tuberous sclerosis complex (TSC) is a rare and complex genetic disorder, associated with tumor growth in various organ systems, epilepsy, and a range of neuropsychiatric manifestations including intellectual disability. With improving patient-centered care and targeted therapies, patient-reported outcome measures (PROMs) are needed to measure the impact of TSC manifestations on daily functioning. The aim of this study was to develop a TSC-specific PROM for adults that captures the impact of TSC on physical functions, mental functions, activity and participation, and the social support individuals with TSC receive, called the TSC-PROM.

METHODS

COSMIN methodology was used to develop a self-reported and proxy-reported version. Development and validation consisted of the following studies: PROM development, content validity, structural validity, internal consistency, and construct validity. The International Classification of Functioning and Disability was used as a framework. Content validity was examined by a multidisciplinary expert group and cognitive interview study. Structural and construct validity, and internal consistency were examined in a large cohort, using confirmatory factor analysis, hypotheses testing, and Cronbach's alpha.

RESULTS

The study resulted in an 82-item self version and 75-item proxy version of the TSC-PROM with four subscales (physical functions 18 and 19 items, mental functions 37 and 28 items, activities and participation 13 and 14 items, social support 13 items, for self version and proxy version respectively). Sufficient results were found for structural validity with sufficient unidimensionality for each subscale. With regard to construct validity, 82% of the hypotheses were met for the self version and 59% for the proxy version. The PROM showed good internal consistency (Cronbach's alpha 0.78-0.97).

CONCLUSIONS

We developed a PROM for adults with TSC, named TSC-PROM, showing sufficient evidence for reliability and validity that can be used in clinical and research settings to systematically gain insight into their experiences. It is the first PROM in TSC that addresses the impact of specific TSC manifestations on functioning, providing a valuable, patient-centered addition to the current clinical outcomes.

Etomidate versus Propofol for Electroconvulsive Therapy in Patients with Major Depressive Disorders in Terms of Clinical Responses to Treatment: A Retrospective Analysis

General anesthetic agents may be associated with the clinical efficacy of electroconvulsive therapy (ECT), as they may influence seizure quality and duration. Hence, a retrospective study was conducted to compare the clinical effects and seizure variables of etomidate and propofol during ECT. Patients treated with ECT under anesthesia with etomidate (n = 43) or propofol (n = 12) were retrospectively analyzed. Seizure variables (seizure duration, intensity, and threshold) and hemodynamic changes during ECT were assessed and recorded. Clinical responses to treatment were evaluated using the Clinical Global Impression scale and mood at discharge after the course of ECT. Adverse effects were also recorded. The demographic characteristics were similar between the two groups. There were no significant differences in the Clinical Global Impression scale scores, mood at discharge, and adverse effects between the two groups (p > 0.05); however, etomidate was associated with a significantly longer motor (42.0 vs. 23.65 s, p < 0.001) and electroencephalogram (51.8 vs. 33.5 s, p < 0.001) seizure duration than propofol. In conclusion, etomidate showed more favorable seizure profiles than propofol during ECT; however, both agents (etomidate and propofol) were associated with similar clinical efficacy profiles at discharge.

Quantitative measures of motor development in Angelman syndrome

Angelman Syndrome is a rare neurodevelopmental disorder characterized by developmental delay, lack of speech, seizures, intellectual disability, characteristic behavior, and movement disorders. Clinical gait analysis provides the opportunity for movement quantification to investigate an observed maladaptive change in gait pattern and offers an objective outcome of change. Pressure-sensor-based technology, inertial and activity monitoring, and instrumented gait analysis (IGA) were employed to define motor abnormalities in Angelman syndrome. Temporal-spatial gait parameters of persons with Angelman Syndrome (pwAS) show deficiencies in gait performance through walking speed, step length, step width, and walk ratio. pwAS walk with reduced step lengths, increased step width, and greater variability. Three-dimensional motion kinematics showed increased anterior pelvic tilt, hip flexion, and knee flexion. PwAS have a walk ratio more than two standard deviations below controls. Dynamic electromyography showed prolonged activation of knee extensors, which was associated with a decreased range of motion and the presence of hip flexion contractures. Use of multiple gait tracking modalities revealed that pwAS exhibit a change in gait pattern to a flexed knee gait pattern.  Cross-sectional studies of individuals with AS show a regression toward this maladaptive gait pattern over development in pwAS ages 4-11. PwAS unexpectedly did not have spasticity associated with change in gait pattern. Multiple quantitative measures of motor patterning may offer early biomarkers of gait decline consistent with critical periods of intervention, insight into appropriate management strategies, objective primary outcomes, and early indicators of adverse events.

Developing Angelman syndrome-specific clinician-reported and caregiver-reported measures to support holistic, patient-centered drug development

BACKGROUND

Angelman syndrome (AS) is a rare, heterogenous neurogenetic condition, which significantly impacts the lives of people with AS and their families. Valid and reliable measures reporting key symptoms and functional impairments of AS are required to support development of patient-centered therapies. We describe the development of clinician- and caregiver-reported, AS-specific Global Impression scales for incorporation into clinical trials. Best practice US Food and Drug Administration guidance for measure development was followed with input from expert clinicians, patient advocates, and caregivers during content generation and refinement.

RESULTS

Initial measurement domains for the Symptoms of AS-Clinician Global Impression (SAS-CGI) and the Caregiver-reported AS Scale (CASS) were identified from a conceptual disease model of AS symptoms and impacts, derived from interviews with caregivers and clinicians. Two rounds of cognitive debriefing (CD) interviews were performed; clinicians debriefed the SAS-CGI, with patient advocates and caregivers debriefing the CASS to ensure relevance and comprehension. Feedback was used to refine items and ensure wording was age-appropriate and captured AS-specific symptoms, as well as associated impacts and functional impairments. The SAS-CGI and CASS capture global assessments of seizures, sleep, maladaptive behaviors, expressive communication, fine and gross motor skills, cognition, and self-care, which were determined by clinicians, patient advocates, and caregivers to be the most challenging aspects of AS. Additionally, the measures include items for assessing overall AS symptoms and the meaningfulness of any change. In addition to ratings for severity, impact, and change, a notes field was included in the SAS-CGI to provide the rationale for the chosen rating. CD interviews confirmed the measures covered key concepts of AS from the perspective of clinicians and caregivers, and demonstrated that the measures' instructions, items, and response options were clear and appropriate. Interview feedback informed adjustments to the wording of the instructions and the items.

CONCLUSIONS

The SAS-CGI and CASS were designed to capture multiple AS symptoms, reflecting the heterogeneity and complexity of AS in children 1 to 12 years old. These clinical outcome assessments have been incorporated into AS clinical studies, which will allow for the evaluation of their psychometric properties and inform further refinements if needed.

Development of the Clinical Gestalt Assessment: a visual clinical global impression scale for Proteus syndrome

BACKGROUND

Clinical outcome assessments are important tools for measuring the natural history of disease and efficacy of an intervention. The heterogenous phenotype and difficult to quantity features of Proteus syndrome present challenges to measuring clinical outcomes. To address these, we designed a global clinical assessment for Proteus syndrome, a rare mosaic overgrowth disorder. The Clinical Gestalt Assessment (CGA) aims to evaluate change over time in this phenotypically diverse disorder.

RESULTS

We gathered paired serial photographs and radiographs obtained at 12-to-36-month intervals from our natural history study of Proteus syndrome. The chronologic order of each set was blinded and presented to clinicians familiar with overgrowth disorders. They were asked to determine the chronologic order and, based on that response, rate global clinical change using a seven-point scale (Much Worse, Worse, Minimally Worse, No Change, Minimally Improved, Improved, Much Improved). Following a pilot, we tested the inter-rater reliability of the CGA using eight cases rated by eight clinicians. Raters identified the correct chronologic order in 53 of 64 (83%) of responses. There was low inter-rater variance and poor to moderate reliability with an intraclass correlation coefficient of 0.46 (95% CI 0.24-0.75). The overall estimate of global change was Minimally Worse over time, which is an accurate reflection of the natural history of Proteus syndrome.

CONCLUSIONS

The CGA is a tool to evaluate clinical change over time in Proteus syndrome and may be a useful adjunct to measure clinical outcomes in prospective therapeutic trials.

The Road to Personalized Therapies: Lessons Learned From Angelman Syndrome

Angelman syndrome (AS) is a neurogenetic disorder characterized by delays including a severe expressive language delay, motor concerns, ataxia, epilepsy, sleep disturbances, gastrointestinal problems, and characteristic behaviors, including a happy demeanor, hyperactivity, and excitability. The syndrome is one of the first neurodevelopmental disorders with a clear trajectory towards meaningful treatment with approximately 20 companies actively developing targeted therapeutics for AS. Herein, we highlight the historical context of the road to therapeutics and some of the challenges in the field with the potential to impact the success of clinical trials for Angelman syndrome and also have relevance of other neurogenetic developmental disabilities.

Clinician- and Patient-reported Endpoints in CNS Orphan Drug Clinical Trials: ISCTM Position Paper on Best Practices for Endpoint Selection, Validation, Training, and Standardization

OBJECTIVE

The International Society of CNS Clinical Trials Methodology (ISCTM) Working Group on Rare Disease/Orphan Drug Development is dedicated to improving and streamlining trials to best develop new treatments for rare diseases. The rarity of these disorders requires a drug development strategy that differs from those of nonrare conditions. Rare disease drug development programs are challenged with small sample sizes, heterogeneous clinical presentations, and few, if any, off-the-shelf endpoints. When disease-specific clinical endpoints exist, they might not be validated and are typically not well known or broadly used in clinical practice. This paper aims to provide an overview of the special issues surrounding endpoints in rare disease drug development, with guidance, practical applications, and discussion.

DISCUSSION

The paper covers regulatory considerations in endpoint selection; identification of relevant measurement domains; methods of quantifying clinical meaningfulness; incorporation of patient- and clinician-reported outcomes; considerations for global clinician- and patient-rated clinical assessments; cognition assessment challenges in rare diseases; translation considerations; training, standardization, and calibration of assessors; and endpoint quality assurance. Additionally, it provides guidance and resources for those involved in drug development for rare diseases.

CONCLUSION

In keeping with the mission of ISCTM and the rare disease/orphan drug development working group, this article is designed to encourage thoughtful consideration and provide insight and guidance to promote and further efforts in in central nervous system (CNS) rare disease drug development efforts.