Top caregiver concerns in Rett syndrome and related disorders: data from the US natural history study

Assessing Communication Impairments in a Rare Neurodevelopmental Disorder: The SCN2A Clinical Trials Readiness Study

Background and Objectives

SCN2A-related disorders (SCN2A-RDs) entail severe impairments in multiple domains that could serve as nonseizure outcomes in clinical trials. This study evaluated the fitness for purpose of several clinical instruments with both standardized and alternative scoring and with some measures used out of their intended age range for assessing communication in SCN2A-affected participants.

Methods

Parents of SCN2A-affected children were recruited through FamilieSCN2A Foundation outreach for a combined cross-sectional and longitudinal study. They completed assessments of their children at study entry and 6 and 12 months later. Assessments included the Vineland Adaptive Behavior Scale (VABS-3), Adaptive Behavior Assessment System (ABAS), Communication Matrix, and Communication and Symbolic Behavior Scale (CSBS). Analyses examined floor and ceiling effects, inter-rater and test-retest reliability, discrimination among different levels of functional impairment, and sensitivity to clinical aspects of SCN2A-RDs.

Results

Of 65 participants (28 females, median age 6.4 years, IQR 4.1-10.5), 56 (86%) had epilepsy. Eleven (17%) used speech as their primary communication mode; 84% were considered ineffective communicators. The mean Vineland composite standardized score (SS) was 34 (IQR 26-46). Cross-sectionally, standardized scores decreased with increasing age. There were substantial floor effects for receptive (75%) and expressive (83%) communication. SSs discriminated poorly between verbal vs nonverbal and communicative vs noncommunicative participants and were not sensitive to features reflecting epilepsy severity (e.g., epileptic spasms and number of current medications). By contrast, Vineland growth scale value (GSV) and ABAS, Matrix, and CSBS raw scores had minimal floor effects; most increased with age. These alternative scores distinguished clearly between participants with different levels of communication and were sensitive to aspects of epilepsy severity. Longitudinally, SSs decreased, but other scores remained relatively stable over a year.

Discussion

SCN2A-RD is characterized by severe-to-profound impairment with a SS <4 SDs of the norm-referenced mean. Owing to severe floor effects and their insensitivity to markers of communication function, age-standardized scores (e.g., Vineland SS) are not fit for purpose in clinical trials or other settings for evaluating nonseizure outcomes such as communication. GSVs and alternative scoring and assessments have much better measurement profiles in all these regards and should be considered in future precision medicine trials for SCN2A-RDs and other similar rare diseases.

Gastrointestinal manifestations of Rett syndrome: An updated analysis using the Gastrointestinal Health Questionnaire

OBJECTIVE

We conducted a nationwide survey using a validated Gastrointestinal Health Questionnaire (GHQ) for Rett syndrome (RTT) to provide an updated and accurate baseline assessment of the prevalence of common gastrointestinal (GI) issues in RTT, based on parental reporting.

METHODS

Parents and caregivers of females with RTT or normally developing, unaffected, age-matched controls completed the GHQ survey. The prevalence of GI symptoms and personality and mood symptoms due to stomach or intestinal problems, as well as GI medication usage and surgical interventions, were assessed in females with RTT and unaffected controls. The relation between GI symptoms and medication usage, surgical status, age, and genetic mutation were analyzed.

RESULTS

Parents of 118 females with RTT and 27 unaffected females completed the GHQ. GI symptoms were common in females with RTT, including constipation (81%), gas and bloating (70%), issues with eating, chewing and swallowing (73%), and irritability because of stomach or intestinal problems (53%). Females with RTT commonly used proton pump inhibitors (52%) and laxatives (64%). Medication usage was associated with significantly higher GHQ symptom scores. Parents of individuals with RTT reported a significantly higher prevalence of GI symptoms affecting their daughters in all symptom categories compared with unaffected females.

CONCLUSIONS

GI problems are common in RTT and pose a significant medical burden to caregivers. The GHQ is a useful tool to assess GI issues in individuals with RTT. Improved recognition of these issues may allow for improved treatment and enhanced quality of life for girls and women affected by RTT.

International workshop: what is needed to ensure outcome measures for Rett syndrome are fit-for-purpose for clinical trials? June 7, 2023, Nashville, USA

INTRODUCTION

The clinical, research and advocacy communities for Rett syndrome are striving to achieve clinical trial readiness, including having fit-for-purpose clinical outcome assessments. This study aimed to (1) describe psychometric properties of clinical outcome assessment for Rett syndrome and (2) identify what is needed to ensure that fit-for-purpose clinical outcome assessments are available for clinical trials.

METHODS

Clinical outcome assessments for the top 10 priority domains identified in the Voice of the Patient Report for Rett syndrome were compiled and available psychometric data were extracted. The clinical outcome assessments measured clinical severity, functional abilities, comorbidities and quality of life, and electrophysiological biomarkers. An international and multidisciplinary panel of 29 experts with clinical, research, psychometric, biostatistical, industry and lived experience was identified through International Rett Syndrome Foundation networks, to discuss validation of the clinical outcome assessments, gaps and next steps, during a workshop and in a follow-up questionnaire. The identified gaps and limitations were coded using inductive content analysis.

RESULTS

Variable validation profiles across 26 clinical outcome assessments of clinical severity, functional abilities, and comorbidities were discussed. Reliability, validity, and responsiveness profiles were mostly incomplete; there were limited content validation data, particularly parent-informed relevance, comprehensiveness and comprehensibility of items; and no data on meaningful change or cross-cultural validity. The panel identified needs for standardised administration protocols and systematic validation programmes.

CONCLUSION

A pipeline of collaborative clinical outcome assessment development and validation research in Rett syndrome can now be designed, aiming to have fit-for-purpose measures that can evaluate meaningful change, to serve future clinical trials and clinical practice.

Review of a specialist Rett syndrome clinic from 2003 to the COVID pandemic: clinic experience and carer perspectives

BACKGROUND

We have held a 'trouble-shooting' clinic for Rett syndrome patients from 2003 until the COVID pandemic in 2020. The clinic was multidisciplinary, including clinical genetics, paediatric neurology, adult learning disability psychiatry and physiotherapy. Access to specialist communication support and eye-gaze equipment was also often available. We have reviewed the files of patients seen in the clinic and conducted a survey of parents' and carers' satisfaction with the clinic and their experiences during COVID.

RESULTS

Of the 117 patients seen in the clinic, records were reviewed of 103 (97 female, six male) who attended a total of 123 appointments. The records were unavailable for 14 patients. The most common reasons for referral were assessment of 'episodes' of uncertain nature (possibly epileptic, possibly autonomic), the wish for a general review by an experienced team, and questions about the diagnosis. We discuss the nature of the advice we were able to provide and offer some brief case vignettes. We wrote to the parents or carers of all patients seen and 63 respondents were willing to be interviewed about the clinic and their experiences during COVID. Respondents were generally complimentary about the clinic team, emphasising the value of a specialist clinic for those affected by a rare condition. Respondents gave insight into the range of problems experienced during COVID, especially the isolation resulting from the withdrawal of services, demonstrating the value of community support. Some respondents mentioned the shift to remote consultations, which they hoped would continue after COVID for its convenience. However, others talked about how difficult it is in a remote consultation to explain the problems of the affected family member to professionals who do not know the patient or know about Rett syndrome.

CONCLUSIONS

Our findings demonstrate the value of a disease-specific clinic provided by staff experienced with the particular rare condition. Meeting the needs of patients with ultra-rare conditions presents additional challenges. We have also found that the shift to holding a virtual clinic during COVID brought the benefit of convenience but was unsatisfactory in other ways, as it makes clinical assessment more difficult and fails to overcome the sense of isolation during a pandemic.

Modification of a parent-report sleep scale for individuals with CDKL5 deficiency disorder: a psychometric study

STUDY OBJECTIVES

Sleep difficulties are common in CDKL5 deficiency disorder, a developmental and epileptic encephalopathy. This study evaluated the factor structure of the Disorders of Initiating and Maintaining Sleep (DIMS), Disorders of Excessive Somnolence (DOES), and Sleep Breathing Disorders domains of the Sleep Disturbance Scale for Children for CDKL5 deficiency disorder.

METHODS

A cross-sectional psychometric study design was used. Data were collected for 125 individuals aged 3 years or older who attended a United States Centers of Excellence clinic or registered with the International CDKL5 Disorder Database.

RESULTS

The median age was 10.3 years (range 3.2-40.7 years) and 105 (84%) were female. Two of the 3 Sleep Breathing Disorders items were not observed by most respondents and analysis was restricted to the DIMS and DOES domains. Using all items in the initial confirmatory factor analysis, 2 items in the DIMS domain and 1 item in the DOES domain loaded poorly. After deleting these items and repeating the analysis, item loading (.524-.814) and internal consistency (DIMS: .78, DOES: .76) statistics were good. The square of the interdomain correlation coefficient was .17, less than average variance extracted values for both domains and indicating good discriminant validity. The Tucker-Lewis and Comparative Fit indices were slightly lower than the threshold of > .9 for establishing goodness of fit.

CONCLUSIONS

The modified DIMS and DOES domains from the Sleep Disturbance Scale for Children could be suitable clinical outcome assessments of insomnia and related impairments in CDKL5 deficiency disorder and potentially other developmental and epileptic encephalopathy conditions.

CITATION

Saldaris JM, Demarest S, Jacoby P, et al. Modification of a parent-report sleep scale for individuals with CDKL5 deficiency disorder: a psychometric study. J Clin Sleep Med. 2024;20 (12):1887-1893.

Rett syndrome

Rett syndrome (RTT) is a severe, progressive, neurodevelopmental disorder, which affects predominantly females. In most cases, RTT is associated with pathogenic variants in MECP2. MeCP2, the protein product of MECP2, is known to regulate gene expression and is highly expressed in the brain. RTT is characterized by developmental regression of spoken language and hand use that, with hand stereotypies and impaired ambulation, constitute the four core diagnostic features. Affected individuals may present multiple other neurological impairments and comorbidities, such as seizures, breathing irregularities, anxiety and constipation. Studies employing neuroimaging, neuropathology, neurochemistry and animal models show reductions in brain size and global decreases in neuronal size, as well as alterations in multiple neurotransmitter systems. Management of RTT is mainly focused on preventing the progression of symptoms, currently improved by guidelines based on natural history studies. Animal and cellular models of MeCP2 deficiency have helped in understanding the pathophysiology of RTT and guided the development of trofinetide, an IGF1-related compound, which is an approved drug for RTT, as well as of other drugs and gene therapies currently under investigation.

Parent-reported outcome measures evaluating communication in individuals with rare neurodevelopmental disorders: A systematic review

BACKGROUND

Communication impairments are a leading concern for parent caregivers of individuals with rare neurodevelopmental disorders (RNDDs). Clinical trials of disease modifying therapies require valid and responsive outcome measures that are relevant to individuals with RNDDs. Identifying and evaluating current psychometric properties for communication measures is a critical step towards the selection and use of appropriate instruments.

AIMS

This systematic review offers (1) a description of parent-reported communication measures and (2) evidence for their psychometric properties, in RNDDs.

METHODS

The systematic review protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42022334649). MEDLINE (Ovid), Embase, PsychINFO, Web of Science, CINAHL Plus, Cochrane Library, ClinicalTrials.gov, the Australian New Zealand Clinical Trials Registry were searched from inception to August 2023. Methodological assessment of quality was completed using the COnsensus-based Standards for the selection of health status Measurement INstruments (COSMIN) checklist. Parent-reported measures used in observational studies and clinical trials were identified. Data on utility, reliability and validity for RNDDs were extracted.

MAIN CONTRIBUTION

Sixteen parent-reported communication measures were used in RNDD research, the Vineland Adaptive Behavior Scales being most commonly used. Validation data in RNDDs were identified for six of these measures. Limitations related to sample size or the scope of psychometric testing.

CONCLUSIONS

Many communication measures have been used for RNDDs but there are few data validating their use. Valid and reliable methods of measuring communication in persons with RNDDs is a priority for future high-quality clinical trials.

WHAT THIS PAPER ADDS

What is already known on the subject Communication is a critical domain for families with a child with a rare neurodevelopmental disorder (RNDD). Validated outcome measures are essential for accurate evaluation and interpretation of responses to treatments in clinical trials. What this paper adds to existing knowledge We identified 16 parent-reported communication measures that have been used with RNDDs, but only six measures had validation data for at least one RNDD. High quality evidence is accumulating, with all validation studies in this review published between 2020 to 2023. Modifications of existing measures may be required to assess communication for RNDDs. What are the clinical implications of this work? This systematic review catalogues the available psychometric data for communication measures and indicates an ongoing need for new validation studies to ensure they are fit-for-purpose for upcoming clinical trials in RNDDs. This review will inform the selection of communication measures for clinical trials and research studies.

Rett Syndrome: The Emerging Landscape of Treatment Strategies

Rett syndrome (RTT) has enjoyed remarkable progress in achieving specific therapies. RTT, a unique neurodevelopmental disorder first described in 1966, progressed slowly until the landmark paper of Hagberg and colleagues in 1983. Thereafter, rapid advances were achieved including the development of specific diagnostic criteria and the active search for a genetic etiology, resulting 16 years later in identification of variants in the methyl-CpG-binding protein (MECP2) gene located at Xq28. Shortly thereafter, the NIH Office of Rare Diseases funded the RTT Natural History Study (NHS) in 2003, initiating the acquisition of natural history data on clinical features from a large population of individuals with RTT. This information was essential for advancement of clinical trials to provide specific therapies for this disorder. In the process, the International Rett Syndrome Association (IRSA) was formed (now the International Rett Syndrome Foundation-IRSF), which participated directly in encouraging and expanding enrollment in the NHS and, subsequently, in developing the SCOUT program to facilitate testing of potential therapeutic agents in a mouse model of RTT. The overall objective was to review clinical characteristics developed from the NHS and to discuss the status of specific therapies for this progressive neurodevelopmental disorder. The NHS study provided critical information on RTT: growth, anthropometrics, longevity, key comorbidities including epilepsy, breath abnormalities, gastroesophageal dysfunction, scoliosis and other orthopedic issues, puberty, behavior and anxiety, and progressive motor deterioration including the appearance of parkinsonian features. Phenotype-genotype correlations were noted including the role of X chromosome inactivation. Development of clinical severity and quality of life measures also proved critical for subsequent clinical trials. Further, development of biochemical and neurophysiologic biomarkers offered further endpoints for clinical trials. Initial clinical trials prior to the NHS were ineffective, but advances resulting from the NHS and other studies worldwide promoted significant interest from pharmaceutical firms resulting in several clinical trials. While some of these have been unrewarding such as sarizotan, others have been quite promising including the approval of trofinetide by the FDA in 2023 as the first agent available for specific treatment of RTT. Blarcamesine has been trialed in phase 3 trials, 14 agents have been studied in phase 2 trials, and 7 agents are being evaluated in preclinical/translational studies. A landmark study in 2007 by Guy et al. demonstrated that activation of a normal MECP2 gene in a null mouse model resulted in significant improvement. Gene replacement therapy has advanced through translational studies to two current phase 1/2 clinical trials (Taysha102 and Neurogene-401). Additional genetic therapies are also under study including gene editing, RNA editing, and X-chromosome reactivation. Taken together, progress in understanding and treating RTT over the past 40 years has been remarkable. This suggests that further advances can be expected.

Associations between genotype, phenotype and behaviours measured by the Rett syndrome behaviour questionnaire in Rett syndrome

INTRODUCTION

Rett syndrome (RTT) is a rare neurodevelopmental disorder with developmental impairments, comorbidities, and abnormal behaviours such as hand stereotypies and emotional features. The Rett Syndrome Behaviour Questionnaire (RSBQ) was developed to describe the behavioural and emotional features of RTT. Little is known how RSBQ scores are associated with genetic and clinical characteristics in RTT. This study investigated relationships between genotype, age, walking, hand function, sleep, and RSBQ total and subscale scores in RTT.

METHODS

This is a cross-sectional analysis of data collected in the Australian Rett Syndrome Database and the International Rett Syndrome Phenotype Database. Parent caregivers completed the RSBQ and Sleep Disturbance Scale for Children [subscales for disorders of initiating and maintaining sleep (DIMS), disorders of excessive somnolence (DOES)], and provided information on age, variant type, functional abilities (mobility, hand function), seizure frequency and gastrointestinal problems. Associations between the RSBQ scores and the independent variables were modelled using linear regression.

RESULTS

Data were available for 365 individuals with RTT [median (range) age 17.8 (2.9-51.9) years, 2 males]. Compared to adults, 2- to 12-year-old children had higher mean Total, Night-time Behaviour and Fear/Anxiety scores. Compared to individuals with a C-terminal deletion, individuals with the p.Arg255* variant had higher mean Total and Night-time Behaviours scores, whereas the p.Arg294* variant had higher mean Mood scores. Individuals with intermediate mobility and hand function abilities had a higher mean Total score. Total RSBQ and subscale scores were similar across categories for seizures, constipation, and reflux, but were higher with abnormal DIMS and abnormal DOES scores.

CONCLUSION

Except for associations with sleep, the RSBQ measures the behavioural phenotype rather than clinical severity in RTT, as traditionally conceptualised in terms of functional abilities and comorbidities. When designing clinical trials, the RSBQ needs to be complemented by other outcome measures to assess specific core functions and associated comorbidities in RTT.

Trofinetide for the treatment of Rett syndrome: Long-term safety and efficacy results of the 32-month, open-label LILAC-2 study

BACKGROUND

Trofinetide was approved for the treatment of Rett syndrome (RTT) in patients aged ≥2 years based on the results of the 12-week, randomized, phase 3 LAVENDER study. In LILAC, a 40-week, open-label extension study of LAVENDER, trofinetide continued to improve the symptoms of RTT, with a similar safety profile as LAVENDER. Here, we report long-term safety and efficacy results of LILAC-2, a 32-month, open-label extension study.

METHODS

Females aged 5-22 years who completed LILAC were eligible to enter LILAC-2. Safety and tolerability were assessed with the incidence of adverse events (AEs). Efficacy was assessed with Rett Syndrome Behaviour Questionnaire (RSBQ) and Clinical Global Impression-Improvement (CGI-I) scores. Caregiver interviews explored the patient's experience with RTT and the efficacy of trofinetide during study participation.

FINDINGS

In total, 77 participants were enrolled in LILAC-2. The most common AEs were diarrhea (53.2%), COVID-19 (27.3%), and vomiting (19.5%). The mean (standard error [SE]) change in RSBQ score from LAVENDER baseline to week 104 of LILAC-2 was -11.8 (2.45). The mean (SE) CGI-I score from LILAC baseline to week 12 of LILAC-2 was 3.1 (0.10). Most caregivers (96%; n = 24/25) were satisfied or very satisfied with the benefits of trofinetide.

CONCLUSIONS

Long-term treatment with trofinetide continued to improve RTT symptoms, without new safety concerns. Caregivers reported satisfaction with trofinetide related to improvements that were meaningful for their child and themselves.

FUNDING

The study was supported by Acadia Pharmaceuticals (San Diego, CA, USA). This study was registered at ClinicalTrials.gov: NCT04776746.

Research Priorities of Individuals and Families with Sex Chromosome Aneuploidies

Sex chromosome aneuploidies (SCAs) are chromosomal variations that result from an atypical number of X and/or Y chromosomes. Combined, SCAs affect ~1/400 live births, including individuals with Klinefelter syndrome (47,XXY), Turner syndrome (45,X and variants), Double Y syndrome (47,XYY), Trisomy X (47,XXX), and rarer tetrasomies and pentasomies. Individuals with SCAs experience a wide variety of physical health, mental health, and healthcare experiences that differ from the standard population. To understand the priorities of the SCA community we surveyed participants in two large SCA registries, the Inspiring New Science in Guiding Healthcare in Turner Syndrome (INSIGHTS) Registry and the Generating Advancements in Longitudinal Analysis in X and Y Variations (GALAXY) Registry. 303/629 (48.1% response rate) individuals from 13 sites across the United States responded to the survey, including 251 caregivers and 52 self-advocates, with a range of ages from 3 weeks to 73 years old and represented SCAs including Turner syndrome, XXX, XXY, XYY, XXYY, and combined rare tetrasomies and pentasomies. Results demonstrate the priorities for physical health and emotional/behavioral health identified by the SCA community, as well as preferred types of research. All SCA subtypes indicated intervention studies as the top priority, emphasizing the need for researchers to focus on clinical treatments in response to priorities of the SCA community.

Burden of illness in Rett syndrome: initial evaluation of a disorder-specific caregiver survey

BACKGROUND

Rett syndrome (RTT) is a severe X-linked neurodevelopmental disorder associated with multiple neurologic impairments. Previous studies have shown challenges to the quality of life of individuals with RTT and their caregivers. However, instruments applied to quantify disease burden have not adequately captured the impact of these impairments on affected individuals and their families. Consequently, an international collaboration of stakeholders aimed at evaluating Burden of Illness (BOI) in RTT was organized.

METHODS

Based on literature reviews and qualitative interviews with parents of children and adults with RTT, a caregiver questionnaire was constructed to evaluate 22 problems (inclusive of core characteristics, functional impairments, and comorbidities) often experienced with RTT, rated mainly with a 5-level Likert scale. The questionnaire was administered anonymously online to an international sample of 756 caregivers (predominantly parents) of girls and women with RTT. Descriptive statistics were used to identify problems of high frequency and impact on affected individuals and caregivers. Chi-square tests characterized the relationship between problem severity and impact responses, while nonparametric ANOVAs of raw and z-score adjusted scores identified agreement between severity and impact on individual and caregiver. Secondary inferential tests were used to determine the roles of age, clinical type, and country of residence on BOI in RTT.

RESULTS

There was variability in reported frequency of problems, with the most prevalent, severe and impactful being those related to the core features of RTT (i.e., communication and fine and gross motor impairments). Chi-square analyses demonstrated interdependence between severity and impact responses, while ANOVAs showed that many problems had disproportionately greater impact than severity, either on affected individuals (e.g., hand stereotypies) or their caregivers (e.g., sleep difficulties, seizures, pain, and behavioral abnormalities). With certain exceptions (e.g., breath-holding, seizures), age, clinical type, or country of residence did not influence these BOI profiles.

CONCLUSIONS

Our data demonstrate that core features and related impairments are particularly impactful in RTT. However, problems with mild severity can also have disproportionate impact on affected individuals and, particularly, on their caregivers. Future analyses will examine the role of factors such as treatment outcomes, healthcare services, and healthcare provider's perspectives, in these BOI profiles.

Recommendations for the management of gastrointestinal comorbidities with or without trofinetide use in Rett syndrome

INTRODUCTION

Although gastrointestinal (GI) comorbidities are experienced by over 90% of individuals with Rett syndrome (RTT), a neurodevelopmental disorder associated with mutations in the MECP2 gene, many neurologists and pediatricians do not rank the management of these comorbidities among the most important treatment goals for RTT. Trofinetide, the first approved pharmacologic treatment for RTT, confers improvements in RTT symptoms but is associated with adverse GI events, primarily diarrhea and vomiting. Treatment strategies for GI comorbidities and drug-associated symptoms in RTT represent an unmet clinical need.

AREAS COVERED

This perspective covers GI comorbidities experienced by those with RTT, either with or without trofinetide treatment. PubMed literature searches were undertaken on treatment recommendations for the following conditions: constipation, diarrhea, vomiting, aspiration, dysphagia, gastroesophageal reflux, nausea, gastroparesis, gastritis, and abdominal bloating.

EXPERT OPINION

The authors recommend a proactive approach to management of symptomatic GI comorbidities and drug-associated symptoms in RTT to enhance drug tolerance and improve the quality of life of affected individuals. Management strategies for common GI comorbidities associated with RTT are reviewed based on authors' clinical experience and augmented by recommendations from the literature.

Exposure-Response Efficacy Modeling to Support Trofinetide Dosing in Individuals with Rett Syndrome

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.

Psychometric Assessment of the Rett Syndrome Caregiver Assessment of Symptom Severity (RCASS)

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.

Trofinetide Treatment Demonstrates a Benefit Over Placebo for the Ability to Communicate in Rett Syndrome

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.

Rett Syndrome and the Role of MECP2: Signaling to Clinical Trials

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.

The small steps that lead to big impact: translating therapeutics from idea to reality for the CDKL5 deficiency disorder community

Despite the unmet needs of patients living with cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) and the challenges facing a rare population with small patient numbers, now is a time of unprecedented opportunities to turn scientific breakthroughs into safe and effective treatments for families of CDD patients. New data collected for over a decade and an evolution in genetics technologies have resulted in transformational new treatments currently in development for CDD. This progress is in great part due to the patient advocacy efforts early on to drive development of stakeholder research tools necessary to de-risk industry entry into the CDD space, family participation in longitudinal natural history studies, and a robust caregiver-reported database. Cumulatively, these efforts offered new insights into CDD, specifically patterns in disease progression, helped identify the most burdensome symptoms to patients and caregivers, improved clinical trial design, and reduced financial barriers for therapeutic development for potential industry partners. This paper documents the growth of a small patient community through relationship building and collaboration. The International Foundation for CDKL5 Research is mindful of ongoing challenges namely the long research timelines, high development and production costs, and inequitable access to approved therapies. Therefore, sustaining strong early resources while recognizing opportunities that engagement, advocacy, and funding can accelerate progress remains at the heart of the agile foundation strategy.