Five-year study of quality of life in myotonic dystrophy

The myotonic dystrophy type 1 drug development pipeline: 2022 edition

The beginning of the 20th decade has witnessed an increase in drug development programs for myotonic dystrophy type 1 (DM1). We have collected nearly 20 candidate drugs with accomplished preclinical and clinical phases, updating our previous drug development pipeline review with new entries and relevant milestones for pre-existing candidates. Three interventional first-in-human clinical trials got underway with distinct drug classes, namely AOC 1001 and DYNE-101 nucleic acid-based therapies, and the small molecule pitolisant, which joins the race toward market authorization with other repurposed drugs, including tideglusib, metformin, or mexiletine, already in clinical evaluation. Furthermore, newly disclosed promising preclinical data for several additional nucleic-acid therapeutic candidates and a CRISPR-based approach, as well as the advent into the pipeline of novel therapeutic programs, increase the plausibility of success in the demanding task of providing valid treatments to patients with DM1.

Quality of life and subjective symptom impact in Japanese patients with myotonic dystrophy type 1

BACKGROUND

Although functional impairment in patients with myotonic dystrophy is an important determinant of the quality of life (QoL), patients' subjective evaluation of their symptoms may also affect their QoL. The aim of this study was to investigate the association between subjective symptom impact and the QoL of patients with myotonic dystrophy, after controlling for functional impairment.

METHODS

Eligible patients with myotonic dystrophy type 1 (DM1) were recruited from four hospitals in Japan. The subjective symptom impact of four symptoms (muscle weakness, fatigue, pain, and myotonia) and overall QoL were evaluated using the Individualized Neuromuscular Quality of Life (INQoL) questionnaire. Functional impairment was assessed using the modified Rankin Scale.

RESULTS

Seventy-seven patients with DM1 were included in this study. Overall QoL was significantly associated with subjective symptom impact of muscular weakness, fatigue, pain, myotonia, swallowing difficulty, and droopy eyelids. In the regression models, disease duration (beta = 0.11) and moderate to severe functional impairment (beta = 0.33) explained a significant part of the overall QoL. Furthermore, muscular weakness, fatigue, and myotonia significantly explained additional variance of the overall QoL (beta = 0.17-0.43).

CONCLUSIONS

Subjective symptom impact and functional impairment are independent features influencing the QoL of Japanese patients with DM1.

Molecular and Clinical Implications of Variant Repeats in Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 (DM1) is one of the most variable monogenic diseases at phenotypic, genetic, and epigenetic level. The disease is multi-systemic with the age at onset ranging from birth to late age. The underlying mutation is an unstable expansion of CTG repeats in the DMPK gene, varying in size from 50 to >1000 repeats. Generally, large expansions are associated with an earlier age at onset. Additionally, the most severe, congenital DM1 form is typically associated with local DNA methylation. Genetic variability of DM1 mutation is further increased by its structural variations due to presence of other repeats (e.g., CCG, CTC, CAG). These variant repeats or repeat interruptions seem to confer an additional level of epigenetic variability since local DNA methylation is frequently associated with variant CCG repeats independently of the expansion size. The effect of repeat interruptions on DM1 molecular pathogenesis is not investigated enough. Studies on patients indicate their stabilizing effect on DMPK expansions because no congenital cases were described in patients with repeat interruptions, and the age at onset is frequently later than expected. Here, we review the clinical relevance of repeat interruptions in DM1 and genetic and epigenetic characteristics of interrupted DMPK expansions based on patient studies.

Brain Pathogenesis and Potential Therapeutic Strategies in Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy that affects multiple systems including the muscle and heart. The mutant CTG expansion at the 3′-UTR of the DMPK gene causes the expression of toxic RNA that aggregate as nuclear foci. The foci then interfere with RNA-binding proteins, affecting hundreds of mis-spliced effector genes, leading to aberrant alternative splicing and loss of effector gene product functions, ultimately resulting in systemic disorders. In recent years, increasing clinical, imaging, and pathological evidence have indicated that DM1, though to a lesser extent, could also be recognized as true brain diseases, with more and more researchers dedicating to develop novel therapeutic tools dealing with it. In this review, we summarize the current advances in the pathogenesis and pathology of central nervous system (CNS) deficits in DM1, intervention measures currently being investigated are also highlighted, aiming to promote novel and cutting-edge therapeutic investigations.

Understanding Symptoms in RYR1-Related Myopathies: A Mixed-Methods Analysis Based on Participants' Experience

BACKGROUND

In rare diseases such as ryanodine receptor 1-related myopathies (RYR1-RM), health-related quality of life (HRQoL) measures are critically important so clinicians and researchers can better understand what symptoms are most important to participants, with the ultimate goal of finding tangible solutions for them.

OBJECTIVES

The main objective of this study was to characterize symptoms in individuals with RYR1-RM to inform future research. A secondary objective of this study was to analyze positive and negative sentiments regarding symptoms and treatment effects post N-acetylcysteine (NAC) administration in individuals with RYR1-RM.

METHODS

The study used a mixed-methods design applying methodological triangulation. Qualitative data were collected via semi-structured interviews at three visits to characterize symptoms in individuals with RYR1-RM and to analyze treatment effects. Qualitative data were then transformed into quantitative results to measure the frequency with which each symptom was mentioned by participants.

RESULTS

A total of 12 symptoms were identified as areas of interest to participants with RYR1-RM, highlighting fatigue and weakness as key symptoms. Data transformation categorized more than 1000 citations, reporting a greater number of positive comments for postintervention interviews than for baseline and preintervention visits and that NAC group participants stated more positive comments regarding treatment effect than did the placebo group.

CONCLUSIONS

We present a comprehensive characterization of symptoms in RYR1-RM and how those symptoms influence HRQoL. Furthermore, the introduction of mixed methods may be a valuable way to better understand patient-centered data in rare diseases to support affected individuals in coping with their symptoms.

Multisystemic Impairments in 93 Chinese Patients With Myotonic Dystrophy Type 1

Background: Myotonic dystrophy type 1 (DM1) is an autosomal dominant neuromuscular disease characterized by muscle weakness and multisystemic impairments, which significantly impact the quality of life. There is currently an increasing consensus on the necessity of a multidisciplinary assessment in patients with DM1, to improve the management of the disease.

Methods: To analyze the prevalence and pairwise relationships between various organs involved, we performed a retrospective study by reviewing demographic and clinical information of DM1 patients including age, disease duration, clinical history, muscular impairment rating scale score (MIRS), results of blood biochemistry, electrocardiogram, echocardiography, and ophthalmologic examination.

Results: Ninety three DM1 patients (60 males and 33 females), aged 34.7 ± 12.6 (mean ± standard deviation) years were recruited. Of which, two congenital cases were of maternal and paternal inheritance, respectively. In the other 91 patients, cataract was found in 44.1% of patients, followed by hypogonadism (40.8%), frontal balding (40.7%), and cardiac abnormalities (34.5%). Thyroid dysfunction and insulin insensitivity were relatively uncommon. Age (p < 0.001) is independently correlated with cataract, and MIRS correlates positively with cardiac abnormalities (p = 0.005) and frontal balding (p = 0.015). Male patients more frequently had frontal balding (Risk ratio, 3.98; 95% confidence interval, 1.493–10.611) compared with female patients. Male patients with cataract presented more frequent cardiac abnormalities (Risk ratio, 4.40; 95% confidence interval, 1.055–18.358) compared with non-cataract male patients. Hypogonadism in male patients was characterized as decreased testosterone level, accompanied by elevated levels of luteinizing hormone and follicle-stimulating hormone.

Conclusions: In Chinese patients with DM1, we conclude that (1) cataract, hypogonadism, frontal balding and cardiac abnormalities are frequently observed; (2) age is an independent indicator to cataract and MIRS is the only predictor for cardiac abnormalities and frontal balding; (3) a positive correlation between ophthalmologic and cardiac impairments in male patients is found; (4) endocrine abnormalities show diverse manifestations and hormone tests are recommended; (5) particular attention should be given to patients with older age and higher MIRS score.

Health-Related Quality of Life in Patients with Adult-Onset Myotonic Dystrophy Type 1: A Systematic Review

Background

Adult-onset myotonic dystrophy type 1 (DM1) is a chronic, multisystem disorder that leads to disability and premature death.

Objectives

The objective of our study was to conduct a systematic literature review of the health-related quality of life (HRQoL) of patients with DM1.

Methods

We searched Embase, Web of Science, and PubMed for English language full-text articles reporting results from studies of HRQoL in patients with adult-onset DM1 published between 1 January 2000 and 21 February 2018. We excluded reviews, editorials, and studies reporting results for a sample with fewer than five patients (to allow for meaningful inference).

Results

The search identified 266 unique publications. Of these, 231 were excluded following title and abstract screening and 16 after full-text review, leaving 19 articles for data synthesis. We found 15 articles measuring the HRQoL of patients with adult-onset DM1 using the 36-Item Short Form Health Survey (SF-36), six using the Individualized Neuromuscular Quality of Life Questionnaire (INQoL), and one using Cantril’s Ladder. Available evidence shows that patient HRQoL is impaired in DM1, mainly due to compromised physical health, but also reveals that substantial heterogeneity exists in estimates across studies.

Conclusions

HRQoL in adult-onset DM1 has been extensively studied using the SF-36 and the INQoL, but current estimates are inconclusive, and little is known of the impact of the disease as measured using other instruments. Our data synthesis should help characterize the patient burden of DM1 and inform future studies of HRQoL in this indication.

Electronic supplementary material

The online version of this article (10.1007/s40271-019-00357-y) contains supplementary material, which is available to authorized users.

Uncovering health and social care needs among myotonic dystrophy patients: Utility of the Needs and Provisions Complexity Scale

OBJECTIVES

Myotonic dystrophy type 1 (DM1) is a slowly progressive multisystem disorder. Guidelines recommend multidisciplinary follow-up. We aimed to investigate the presence of unmet health and social care needs among patients with DM1 and whether unmet needs correlated with motor function, cognitive impairments, or quality of life.

MATERIAL AND METHODS

Patients were 22 adults with DM1. "Needs and Provisions Complexity Scale" (NPCS) was applied to evaluate the individual's needs and provision of health and social services. The Muscular Impairment Rating Scale (MIRS) was used to measure motor function and disease stage. All patients underwent neuropsychological testing. The EQ-5D-3L questionnaire was used to evaluate the patients' health-related quality of life (HRQoL).

RESULTS

Median time from diagnosis was 11 years (range: 1-40). Twenty patients had developed needs related to social care, personal care, and rehabilitation that had not been met, whereas need for medical follow-up was largely met. The more pronounced the muscular impairment, the more unmet needs were experienced by DM1 patients (r = 0.50, P = 0.019). Degree of unmet needs did not correlate with full-scale IQ (r = -0.27, P = 0.23) or HRQoL (r = -0.14, P = 0.55).

CONCLUSION

Using NPCS, we discovered that patients with DM1 had unmet needs with respect to social care, personal care, and rehabilitation although their need for medical follow-up was met. Thus, the use of NPCS helped bring our practice in better accordance with guidelines. A higher MIRS grade should alert the clinician to the likelihood of unmet needs.

Disease burden of myotonic dystrophy type 1

OBJECTIVE

The objective of this cross-sectional, observational study was to investigate the disease burden of myotonic dystrophy type 1 (DM1), a disabling muscle disorder.

METHODS

Adults with DM1 were recruited as part of the PhenoDM1 study from Newcastle University (Newcastle upon Tyne, UK). Disease burden data were recorded through the Individualized Neuromuscular Quality of Life (INQoL) questionnaire. Results were examined by sex and clinical variables [e.g. the six-minute walk test (6MWT), the Mini Mental State Examination, and estimated progenitor and modal allele CTG repeat length].

RESULTS

Our sample consisted of 60 patients with DM1 (mean age: 45 years; 45% female). Muscle weakness and fatigue constituted the two most common disease manifestations, reported by 93% and 90% of patients, respectively, followed by muscle locking (73%). Most patients (> 55%) reported feeling anxious/worried, depressed, frustrated, and/or having low confidence/self-esteem, 23% and 33% indicated substantial impairment of daily and leisure activities, respectively, and 47% did not work as a consequence of the disease. Estimated progenitor CTG length corrected by age correlated surprisingly well with INQoL scores. Differences by sex were generally minor.

CONCLUSION

We show that DM1 is associated with a substantial disease burden resulting in impairment across many different domains of patients' lives, emphasizing the need for a holistic approach to medical management. Our results also show that the INQoL records relevant information about patients with DM1, but that further investigation of the psychometric properties of the scale is needed for meaningful interpretation of instrument scores.

Progressive Decline in Daily and Social Activities: A 9-year Longitudinal Study of Participation in Myotonic Dystrophy Type 1

OBJECTIVE

To describe and compare changes in participation over a 9-year period in women and men with myotonic dystrophy type 1 (DM1). To compare participation restrictions with available reference values from a typical aging population living in the community.

DESIGN

Descriptive longitudinal design comparing data from baseline (2002) with data from follow-up (2011).

SETTING

Neuromuscular clinic and participant's home.

PARTICIPANTS

Adults with DM1 participated in the follow-up study (N=115).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

The Assessment of Life Habits measured participation in 10 domains of daily and social activities. The minimal clinically important difference is 0.5 on a 10-point scale for participation accomplishment level.

RESULTS

A total of 62% of participants were women, and the mean age was 52.3±10.3 years. A decline (P<.01) was observed with increasing difficulty and assistance required in global participation (mean ± SD, -0.5±0.9), social activities subscore (-0.6±1.2), nutrition (-0.7±1.4), fitness (-1.0±1.6), personal care (-0.7±1.2), mobility (-0.5±1.9), community life (-0.8±1.9), and recreation (-1.5±3.0). More life areas are disrupted over time: 8 domains were below reference values from a population aged 55-64 years at follow-up compared with 2 domains at baseline. Satisfaction with participation remains high and stable over time.

CONCLUSION

As disease duration increases, global participation and more daily and social domains were restricted with increasing difficulty and assistance required. Adults with DM1 showed not only age-associated but disease-specific changes in participation. Description over time of participation could improve clinical assessment and guide interdisciplinary management of DM1, leading to higher rehabilitation success. Further investigation of the factors influencing changes in participation is required to support disease management and services planning.

Health-related quality of life and its correlates in Japanese patients with myotonic dystrophy type 1

PURPOSE

Myotonic dystrophy type 1 (DM1) is a common form of muscular dystrophy that presents with a variety of symptoms that can affect patients' quality of life (QoL). Despite the importance of clarifying patients' subjective experience in both physical and psychosocial aspects for improved symptom management, there is lack of evidence concerning QoL of patients with DM1 in Japan.

PATIENTS AND METHODS

A cross-sectional study was performed with 51 DM1 patients who completed questionnaires that measured health-related QoL (HRQoL), depression, and daytime sleepiness. Activities of daily living, body mass index (BMI), and genetic information were also collected, together with general demographic information. Correlation analyses using these variables were performed. Furthermore, regression analysis was utilized to assess the relationship that HRQoL, depression, and daytime sleepiness scores have with other variables.

RESULTS

Physical component summary (PCS) score was affected by the disease more than the mental component summary (MCS) score among study participants. Moderate correlation was observed between PCS and depression, PCS and Barthel index, and depression and daytime sleepiness. Regression analysis revealed that age, sex, cytosine-thymine-guanine repeats, and BMI did not predict the aforementioned dependent variables.

CONCLUSION

DM1 symptoms influenced physical component scores more than mental component scores, although the state of physical wellness seemed to affect patients' mood. Explaining the QoL of these patients only using biologic and genetic characteristics was not sufficient. We conclude that social and psychological aspects of these patients' lives and the nature of adjustments made by patients due to DM1 to require further examination in order to improve the standard of care.

Quality of life in adult patients with limb-girdle muscular dystrophies

Although limb-girdle muscular dystrophies (LGMD) can cause permanent disability, to date there are no studies that examined quality of life (QoL) in these patients. Our aim was to evaluate QoL in patients with LGMD, and to identify the most significant predictors of QoL. The study comprised 46 patients with diagnosis of limb-girdle muscular weakness. QoL in patients was evaluated using two scales-SF-36 questionnaire and the Individualized Neuromuscular Quality of Life questionnaire (INQoL). Following scales were also applied: Epworth Sleepiness Scale (ESS), Hamilton Scale for Depression (HamD), and Krupp's Fatigue Severity Scale (FSS). Mean SF-36 score was 52.4 ± 23.5, and physical composite score was worse than mental. Total INQoL score was 46.1 ± 20.4, with worst results obtained for weakness, fatigue and independence, while social relationships and emotions showed better results. Significant predictors of worse SF-36 score in LGMD patients were higher fatigue level (β = - 0.470, p < 0.01) and use of assistive device (β = - 0.245, p < 0.05). Significant predictors of worse INQoL score were higher fatigue level (β = 0.514, p < 0.01) and presence of cardiomyopathy (β = - 0.385, p < 0.01). It is of special interest that some of the identified factors that correlated with worse QoL in LGMD patients were amenable to treatment.

Validation of The Individualized Neuromuscular Quality of Life in Japanese patients with myotonic dystrophy

INTRODUCTION

The Individualized Neuromuscular Quality of Life (INQoL) is used to measure the quality of life (QoL) of patients with neuromuscular disease. We conducted this study to translate and validate the Japanese version of the INQoL in patients with myotonic dystrophy.

METHODS

Forward and backward translation, patient testing, and psychometric validation were performed. We used the 36-Item Short Form Health Survey (SF-36) and the modified Rankin scale for concurrent validation.

RESULTS

The Japanese INQoL was administered to 90 adult patients. The coefficients for internal consistency and test-retest reliability were adequately high in most domains (Cronbach α 0.88-0.96 and intraclass coefficient 0.64-0.99). INQoL domains were moderately to strongly associated with relevant SF-36 subscales (Spearman's ρ -0.23 to -0.74). Symptom severity, disease duration, employment status, and use of a ventilator influenced overall QoL.

DISCUSSION

The INQoL is a reliable and validated measure of QoL for Japanese patients with myotonic dystrophy. Muscle Nerve, 2018.

Myotonic dystrophy patient preferences in patient-reported outcome measures

INTRODUCTION

When preparing for clinical trials in myotonic dystrophy type-1 (DM1), it is important that researchers develop and identify patient-reported outcome measures with good measurement properties.

METHODS

Fifty-two DM1 patients enrolled in 2 clinical studies completed the Myotonic Dystrophy Health Index (MDHI), 36-Item Short Form Health Survey (version 2; SF-36v2), Individualized Neuromuscular Quality of Life questionnaire (INQoL), and a questionnaire comparing the relevance, usability, overall preference, and perceived responsiveness of each measure. The associations between instrument scores and physical function, genetic test results, and employment status were examined.

RESULTS

The MDHI was preferred over the INQoL in 13 of 13 areas and was preferred over the SF-36v2 in 9 of 13 areas. The MDHI was the only score that was associated with participant employment status, CTG repeat length, and the 3 measurements of clinical function.

DISCUSSION

The MDHI correlates well with physical function and is viewed favorably by participants in DM1 clinical studies. Muscle Nerve, 2018.

Prospective measurement of quality of life in myotonic dystrophy type 1

INTRODUCTION

Generic patient reported outcome measures have had varied success in tracking QoL in myotonic dystrophy type 1 (DM1).

AIM

To analyze changes of Individualized Neuromuscular Quality of Life questionnaire (INQoL) scores in clinic patients with DM1 over a 6-year period.

METHOD

Patients completed the INQoL at baseline and after a 6-year period through their attendance in a neurology outpatient clinic. Severity of muscular involvement in DM1 was analyzed using the Muscular Impairment Rating Scale (MIRS).

RESULTS

Ninety-nine DM1 patients completed a baseline visit. Sixty-seven of these patients were retested at an interval time. The overall INQoL score improved in our sample of patients (P<.05) as did the following subscales: myotonia (P<.05), pain (P<.05), activities (P<.01), social relationships (P<.01), and body image (P<.05). No changes were observed for the independence and emotions scales. There were no differences in mean change of INQoL scores between patients with worsened MIRS and those with no change in MIRS scale after follow-up (P>.05).

CONCLUSION

Individualized Neuromuscular Quality of Life questionnaire scores improved in our cohort of DM1 patients during a 6-year period. INQoL score did not correlate with progression of muscle weakness. This must be better understood before the selection of the instrument for use in trials to measure therapeutic benefit in DM1 patients.

Quality of life in patients with myotonic dystrophy type 2

AIM

To analyze quality of life (QoL) in a large cohort of myotonic dystrophy type 2 (DM2) patients in comparison to DM1 control group using both generic and disease specific questionnaires. In addition, we intended to identify different factors that might affect QoL of DM2 subjects.

PATIENTS AND METHOD

49 DM2 patients were compared with 42 adult-onset DM1 patients. Patients completed SF-36 questionnaire and individualized neuromuscular quality of life questionnaire (INQoL). Following measures were also included: Medical Research Council 0-5 point scale for muscle strength, Addenbrooke's cognitive examination revised for cognitive status, Hamilton rating scale for depression, Krupp's fatigue severity scale and daytime sleepiness scale (DSS) RESULTS: SF-36 total score and physical composite score did not differ between DM1 and DM2 patients (p>0.05). However, role emotional and mental composite score were better in DM2 (p<0.05). INQoL total score was similar in both groups (p>0.05), although DM2 patients showed less impairment in independence (p<0.05) and body image domains (p<0.01). Regarding symptoms assessed by INQoL, DM2 patients showed less severe complaint of myotonia (p<0.01). Multiple linear regression analysis showed that significant predictors of worse QoL in DM2 patients were older age, worse muscle strength and higher level of fatigue.

CONCLUSION

QoL reports of DM2 patients with the most severe form of the disease are comparable to those of DM1 patients. Special attention of clinicians should be paid to DM2 patients with older age, more severe muscle weakness and higher level of fatigue since they may be at higher risk to have worse QoL.