Patient-identified impact of symptoms in spinal and bulbar muscular atrophy

A phenotypically robust model of spinal and bulbar muscular atrophy in Drosophila

Spinal and bulbar muscular atrophy (SBMA) is an X-linked disorder that affects males who inherit the androgen receptor (AR) gene with an abnormal CAG triplet repeat expansion. The resulting protein contains an elongated polyglutamine (polyQ) tract and causes motor neuron degeneration in an androgen-dependent manner. The precise molecular sequelae of SBMA are unclear. To assist with its investigation and the identification of therapeutic options, we report here a new model of SBMA in Drosophila melanogaster. We generated transgenic flies that express the full-length, human AR with a wild-type or pathogenic polyQ repeat. Each transgene is inserted into the same safe harbor site on the third chromosome of the fly as a single copy and in the same orientation. Expression of pathogenic AR, but not of its wild-type variant, in neurons or muscles leads to consistent, progressive defects in longevity and motility that are concomitant with polyQ-expanded AR protein aggregation and reduced complexity in neuromuscular junctions. Additional assays show adult fly eye abnormalities associated with the pathogenic AR species. The detrimental effects of pathogenic AR are accentuated by feeding flies the androgen, dihydrotestosterone. This new, robust SBMA model can be a valuable tool toward future investigations of this incurable disease.

Patient-Reported Impact of Symptoms in Spinal and Bulbar Muscular Atrophy

Background and Objectives

The aim of this study was to determine the frequency and relative importance of symptoms experienced by patients with spinal and bulbar muscular atrophy (SBMA).

Methods

We conducted a cross-sectional study of 232 participants with SBMA. Participants provided input regarding 18 themes and 208 symptoms that affect patients with SBMA. Participants were asked about the relative importance of each symptom, and analysis was conducted to determine how age, education, disease duration, CAG repeat length, and ambulation status relate to symptom prevalence.

Results

Hip, thigh, or knee weakness (96.5%), fatigue (96.5%), problems with hands and fingers (95.7%), and limitations with walking (95.7%) were the themes with the highest prevalence in the study population. Ambulatory status was associated with the prevalence of 9 of the 14 themes, and CAG repeat length and education were each associated with 4 of 14 themes. The prevalence of fatigue was reduced in those with a lower CAG repeat length and increased with a longer disease duration. Younger patients reported a higher prevalence of emotional issues.

Discussion

There are a diversity of themes that are important to patients with SBMA. These themes have a variable level of importance to the population with SBMA and represent clinically meaningful outcome measures for future therapeutic interventions.

Patient-reported impact of symptoms in lung cancer (PRISM-LC)

Background

Individuals with lung cancer (LC) face a variety of symptoms that significantly impact their lives. We use extensive patient input to determine the relative importance and prevalence of these symptoms and identify which demographic features are associated with a higher level of disease burden.

Methods

We performed semi-structured qualitative interviews with participants with LC to identify potentially important symptoms. We then conducted a cross-sectional study, in which participants rated the relative importance of 162 individual symptoms covering 14 symptomatic themes. Participant responses were analyzed by age, sex, disability status, disease duration, LC stage, type of treatment received, and smoking history, among other categories.

Results

Our cross-sectional study had 139 participants with LC. The most prevalent symptomatic themes reported by this population were fatigue (85.5%), impaired sleep and daytime sleepiness (73.5%), and emotional issues (73.0%). The symptomatic themes that had the greatest average impact (on a scale of 0 to 4, with 4 being the most impactful) were social role dissatisfaction (1.67), inability to do activities (1.64), and fatigue (1.60). Disability status had the strongest association with symptomatic theme prevalence. LC stage (stage IV), receipt of therapy, and smoking experience were also associated with higher frequency of symptomatic themes.

Conclusions

Individuals with LC face diverse and disease-specific symptoms that affect their daily lives. Patient insight on the prevalence and relative importance of these symptoms is invaluable to advance meaningful therapeutic interventions.

Respiratory features of centronuclear myopathy in the Netherlands

Centronuclear myopathy (CNM) is a heterogeneous group of muscle disorders primarily characterized by muscle weakness and variable degrees of respiratory dysfunction caused by mutations in MTM1, DNM2, RYR1, TTN and BIN1. X-linked myotubular myopathy has been the focus of recent natural history studies and clinical trials. Data on respiratory function for other genotypes is limited. To better understand the respiratory properties of the CNM spectrum, we performed a retrospective study in a non-selective Dutch CNM cohort. Respiratory dysfunction was defined as an FVC below 70% of predicted and/or a daytime pCO2 higher than 6 kPa. We collected results of other pulmonary function values (FEV1/FVC ratio) and treatment data from the home mechanical ventilation centres. Sixty-one CNM patients were included. Symptoms of respiratory weakness were reported by 15/47 (32%) patients. Thirty-three individuals (54%) with different genotypes except autosomal dominant (AD)-BIN1-related CNM showed respiratory dysfunction. Spirometry showed decreased FVC, FEV1 & PEF values in all but two patients. Sixteen patients were using HMV (26%), thirteen of them only during night-time. In conclusion, this study provides insight into the prevalence of respiratory symptoms in four genetic forms of CNM in the Netherlands and offers the basis for future natural history studies.

Patient-Reported Impact of Symptoms in Crohn's Disease

INTRODUCTION

Patients with Crohn's disease (CD) experience a variety of symptoms that significantly affect their lives. In this study, we (i) ascertain the most prevalent and impactful symptoms in CD and (ii) identify modifying factors that are associated with a higher disease burden in CD.

METHODS

We conducted semistructured interviews with adult participants with CD to determine what issues have the greatest impact on their lives. Next, we conducted a large cross-sectional study of individuals with CD to determine the prevalence and relative importance of those symptoms and themes and to identify the demographic features that are associated with a higher disease burden.

RESULTS

Sixteen individuals with CD provided 792 direct quotes regarding their symptomatic burden. Four hundred three people with CD participated in our cross-sectional study. The symptomatic themes with the highest prevalence in CD were gastrointestinal issues (93.0%), fatigue (86.4%), dietary restrictions (77.9%), and impaired sleep or daytime sleepiness (75.6%). The symptomatic themes that had the greatest impact on patients' lives (0-4 scale) related to fatigue (1.82), impaired sleep or daytime sleepiness (1.71), gastrointestinal issues (1.66), and dietary restrictions (1.61). Symptomatic theme prevalence was strongly associated with a higher number of soft stools per day, greater number of bowel movements per day, missed work, employment and disability status, and having perianal disease.

DISCUSSION

Patients with CD experience numerous symptoms that affect their daily life. These symptoms, some underrecognized, vary based on disease and demographic characteristics and represent potential targets for future therapeutic interventions.

The role of ubiquitination in spinal and bulbar muscular atrophy

Spinal and bulbar muscular atrophy (SBMA) is a neurodegenerative and neuromuscular genetic disease caused by the expansion of a polyglutamine-encoding CAG tract in the androgen receptor (AR) gene. The AR is an important transcriptional regulator of the nuclear hormone receptor superfamily; its levels are regulated in many ways including by ubiquitin-dependent degradation. Ubiquitination is a post-translational modification (PTM) which plays a key role in both AR transcriptional activity and its degradation. Moreover, the ubiquitin-proteasome system (UPS) is a fundamental component of cellular functioning and has been implicated in diseases of protein misfolding and aggregation, including polyglutamine (polyQ) repeat expansion diseases such as Huntington's disease and SBMA. In this review, we discuss the details of the UPS system, its functions and regulation, and the role of AR ubiquitination and UPS components in SBMA. We also discuss aspects of the UPS that may be manipulated for therapeutic effect in SBMA.

Patient-reported disease burden in oculopharyngeal muscular dystrophy

INTRODUCTION

There is currently little evidence regarding oculopharyngeal muscular dystrophy (OPMD) disease burden reported by patients. In this study we aim to elicit direct patient input regarding OPMD disease burden.

METHODS

We conducted semistructured interviews with 25 participants with genetically confirmed OPMD and a wide range of disease duration (15 ± 8 years). Using the Framework Technique, themes and categories were then extracted.

RESULTS

Analyses revealed 7 themes (physical impact, mental impact, social impact, perception of progression, treatment perceptions, coping strategies, and access to disease information), encompassing 27 categories of OPMD disease burden. The most frequent categories were related to dysphagia, coping strategies for dysphagia, and impaired mobility.

DISCUSSION

This study demonstrates the importance of considering, when providing clinical care, the broad range of coping strategies patients use to deal with OPMD symptoms, especially dysphagia, to properly assess limitations and monitor real disease progression.

Safety, tolerability, and preliminary efficacy of an IGF-1 mimetic in patients with spinal and bulbar muscular atrophy: a randomised, placebo-controlled trial

BACKGROUND

Spinal and bulbar muscular atrophy is an X-linked neuromuscular disease caused by CAG repeat expansion in the androgen receptor gene. Patients with this disease have low concentrations of insulin-like growth factor-1 (IGF-1), and studies of overexpression and administration of IGF-1 showed benefit in a transgenic model; thus the IGF-1 pathway presents as a potential treatment target. We assessed safety, tolerability, and preliminary efficacy of BVS857, an IGF-1 mimetic, in patients with spinal and bulbar muscular atrophy.

METHODS

In this randomised, double-blind, placebo-controlled trial, we recruited patients from neuromuscular centres in Denmark (Copenhagen), Germany (Ulm), Italy (Padova), and three sites within the USA (Bethesda, MD; Irvine, CA; and Columbus, OH). Eligible patients were 18 years or older with a confirmed genetic diagnosis of spinal and bulbar muscular atrophy, were ambulatory, had symptomatic weakness, and had serum IGF-1 concentrations of 170 ng/mL or lower. Patients were randomly assigned (2:1) to study drug or placebo by a number scheme. Patients, investigators, and study personnel were masked to treatment assignment. After a safety and tolerability assessment with eight patients, BVS857 was administered once a week (0·06 mg/kg intravenously) for 12 weeks. Primary outcome measures were safety, tolerability, and the effects of BVS857 on thigh muscle volume (TMV) measured by MRI. The ratio of TMV at day 85 to baseline was analysed with ANCOVA per protocol. Secondary outcomes of muscle strength and function were measured with the Adult Myopathy Assessment Tool, lean body mass through dual energy x-ray absorptiometry, and BVS857 pharmacokinetics. This trial was registered with ClinicalTrials.gov, NCT02024932.

FINDINGS

31 patients were assessed for eligibility, 27 of whom were randomly assigned to either BVS857 treatment (n=18) or placebo (n=9), and 24 were included in the preliminary efficacy analysis (BVS857 group, n=15; placebo group, n=9). BVS857 was generally safe with no serious adverse events. No significant differences were found in adverse events between the BVS857 and placebo groups. Immunogenicity was detected in 13 (72%) of 18 patients in the BVS857 group, including crossreacting antibodies with neutralising capacity to endogenous IGF-1 in five patients. TMV decreased from baseline to day 85 in the placebo group (-3·4% [-110 cm³]) but not in the BVS857 group (0% [2 cm³]). A significant difference in change in TMV was observed in the BVS857 group versus the placebo group (geometric-mean ratio 1·04 [90% CI 1·01-1·07]; p=0·02). There were no differences between groups in measures of muscle strength and function.

INTERPRETATION

TMV remained stable in patients with spinal and bulbar muscular atrophy after being given BVS857 for 12 weeks. The intervention was associated with high incidence of immunogenicity and did not improve muscle strength or function. Additional studies might be needed to assess the efficacy of activating the IGF-1 pathway in this disease.

FUNDING

Novartis Pharmaceuticals and the US National Institutes of Health.

Biomarkers of Spinal and Bulbar Muscle Atrophy (SBMA): A Comprehensive Review

Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy's disease, is a rare, X-linked, late onset neuromuscular disorder. The disease is caused by a CAG trinucleotide repeat expansion in the first exon of the androgen receptor gene. It is characterized by slowly progressive lower motor neurons degeneration, primary myopathy and widespread multisystem involvement. Respiratory involvement is rare, and the condition is associated with a normal life expectancy. Despite a plethora of therapeutic studies in mouse models, no effective disease-modifying therapy has been licensed for clinical use to date. The development of sensitive monitoring markers for the particularly slowly progressing pathology of SBMA is urgently required to aid future clinical trials. A small number of outcome measures have been proposed recently, including promising biochemical markers, which show correlation with clinical disability and disease-stage and progression. Nevertheless, a paucity of SBMA-specific biomarker studies persists, delaying the development of monitoring markers for pharmaceutical trials. Collaborative efforts through international consortia and multicenter registries are likely to contribute to the characterization of the natural history of the condition, the establishment of disease-specific biomarker panels and ultimately contribute to the development of disease-modifying drugs.