Clinical Utility and Diagnostic Yield of Genetic Testing for Inherited Neuromuscular Disorders in a Single, Large Neuromuscular Center.

Background and Objectives: Most published studies on the clinical utility of genetic testing for neuromuscular diseases (NMDs) focus on disease-specific cohorts and/or involve multiple centers. The aim of this study was to examine the clinical utility and diagnostic yield of genetic testing at a single, large neuromuscular center. Unlike previous studies, this study is unique in that it includes a broad array of patients at a single, large neuromuscular center, providing real-world data that may assist both neuromuscular specialists as well as general neurologists in decision-making regarding the need for genetic testing in patients with suspected NMDs. Methods: Genetic testing results were reviewed for all patients who underwent testing through a single genetic testing company for NMDs in this single laboratory at a large neuromuscular center from 2015 to 2020. Retrospective chart reviews were performed to determine whether genetic testing results conferred a specific NMD diagnosis, including cases where a variant of uncertain significance (VUS) was identified. Results: Genetic testing was pursued for 192 patients. A positive result, defined as a pathogenic mutation, a VUS, or both, was found in 77.1%. A definitive diagnosis was conferred in 35.9%. The most common testing indication was suspected neuropathy (53.3%), and the indication with the highest diagnostic yield was suspected myopathy (48.7%). Discussion: This study provides further evidence of the clinical utility of genetic testing for NMDs in a real-world setting with over one-third of patients tested receiving a definitive diagnosis. Over time, genetic testing will continue to become increasingly accessible, cost-effective, and sensitive, which will lead to even more utilization.

Identification and Management of Acute Neuromuscular Respiratory Failure in the ICU.

Respiratory failure is a common and potentially life-threatening complication of neuromuscular diseases. Prompt recognition and accurate diagnosis of new or worsening chronic neuromuscular disease have important clinical management and prognostic implications. In this article, we present an approach to the acute presentation of undifferentiated neuromuscular respiratory failure in the ICU and guidance for determination and respiratory management of the underlying disorder.

The amyotrophic lateral sclerosis-health index (ALS-HI): development and evaluation of a novel outcome measure.

Objective: The identification of effective therapeutics for ALS necessitates valid and responsive outcome measures to track disease progression and therapeutic gain in clinical trial settings. The Amyotrophic Lateral Sclerosis-Health Index (ALS-HI) is a multifaceted, disease-specific patient-reported outcome measure (PRO) designed to measure ALS symptomatic disease burden in adults with ALS. Methods: Through a national cross-sectional study of individuals with ALS, we identified the most important symptoms in ALS. These symptoms were incorporated into the ALS-HI, a measure that quantifies the multifaceted disease burden in ALS. We performed factor analysis, qualitative patient interviews, test-retest reliability assessment, and known groups analysis to evaluate and validate the ALS-HI. Results: The cross-sectional study included 497 participants with ALS who identified the most important symptoms to include in the ALS-HI. Fifteen participants beta tested the ALS-HI and found it to be clear, easy to use, and relevant. Twenty-one participants engaged in a test-retest reliability study, which indicated the reliability of the instrument (intraclass correlation coefficient = 0.952 for full instrument). The final ALS-HI and its subscales demonstrated a high internal consistency (Cronbach's α = 0.981 for full instrument) and an ability to differentiate between groups with dissimilar disease severity. Conclusions: This research supports use of the ALS-HI as a valid, sensitive, reliable, and relevant PRO to assess the multifactorial disease burden faced by adults with ALS. The ALS-HI has potential as a mechanism to track disease progression and treatment efficacy during therapeutic trials.

Patient reported impact of symptoms in amyotrophic lateral sclerosis (PRISM-ALS): A national, cross-sectional study.

Background: As novel therapeutic interventions are being developed and tested in the amyotrophic lateral sclerosis (ALS) population, there is a need to better understand the symptoms and issues that have the greatest impact on the lives of individuals with ALS. We aimed to determine the frequency and relative importance of symptoms experienced by adults in a national ALS sample and to identify factors that are associated with the greatest disease burden in this population. Methods: We conducted 15 qualitative interviews of individuals with varied ALS phenotypes and analyzed 732 quotes regarding the symptomatic disease burden of ALS between August 2018 and March 2019. We subsequently conducted a national, cross-sectional study of 497 participants with ALS and ALS variants through the Centers for Disease Control and Prevention's (CDC) National ALS Registry between July 2019 and December 2019. Participants reported on the prevalence and relative importance of 189 symptomatic questions representing 17 symptomatic themes that were previously identified through qualitative interviews. Analysis was performed to determine how age, sex, education, employment, time since onset of symptoms, location of symptom onset, feeding tube status, breathing status and speech status relate to symptom and symptomatic theme prevalence. Findings: Symptomatic themes with the highest prevalence in our sample were an inability to do activities (93.8%), fatigue (92.6%), problems with hands or fingers (87.7%), limitations with mobility or walking (86.7%), and a decreased performance in social situations (85.7%). Participants identified inability to do activities and limitations with mobility or walking as having the greatest overall effect on their lives. Interpretation: Individuals with ALS experience a variety of symptoms that affect their lives. The prevalence and importance of these symptoms differ among the ALS population. The most prevalent and important symptoms offer potential targets for improvements in future therapeutic interventions. Funding: Research funding was provided by ALS Association.

Effect of sodium phenylbutyrate/taurursodiol on tracheostomy/ventilation-free survival and hospitalisation in amyotrophic lateral sclerosis: long-term results from the CENTAUR trial.

BACKGROUND: Coformulated sodium phenylbutyrate/taurursodiol (PB/TURSO) was shown to prolong survival and slow functional decline in amyotrophic lateral sclerosis (ALS). OBJECTIVE: Determine whether PB/TURSO prolonged tracheostomy/ventilation-free survival and/or reduced first hospitalisation in participants with ALS in the CENTAUR trial. METHODS: Adults with El Escorial Definite ALS ≤18 months from symptom onset were randomised to PB/ TURSO or placebo for 6 months. Those completing randomised treatment could enrol in an open-label extension (OLE) phase and receive PB/TURSO for ≤30 months. Times to the following individual or combined key events were compared in the originally randomised treatment groups over a period spanning trial start through July 2020 (longest postrandomisation follow-up, 35 months): death, tracheostomy, permanent assisted ventilation (PAV) and first hospitalisation. RESULTS: Risk of any key event was 47% lower in those originally randomised to PB/TURSO (n=87) versus placebo (n=48, 71% of whom received delayed-start PB/TURSO in the OLE phase) (HR=0.53; 95% CI 0.35 to 0.81; p=0.003). Risks of death or tracheostomy/PAV (HR=0.51; 95% CI 0.32 to 0.84; p=0.007) and first hospitalisation (HR=0.56; 95% CI 0.34 to 0.95; p=0.03) were also decreased in those originally randomised to PB/TURSO. CONCLUSIONS: Early PB/TURSO prolonged tracheostomy/PAV-free survival and delayed first hospitalisation in ALS. TRIAL REGISTRATION NUMBER: NCT03127514; NCT03488524.

ALSUntangled #64: butyrates.

ALSUntangled reviews alternative and off-label treatments for people living with amyotrophic lateral sclerosis (PALS). Here we review butyrate and its different chemical forms (butyrates). Butyrates have plausible mechanisms for slowing ALS progression and positive pre-clinical studies. One trial suggests that sodium phenylbutyrate (NaPB) in combination with Tauroursodeoxycholic acid (TUDCA) can slow ALS progression and prolong survival, but the specific contribution of NaPB toward this effect is unclear. Butyrates appear reasonably safe for use in humans. Based on the above information, we support a trial of a butyrate in PALS, but we cannot yet recommend one as a treatment.

Harnessing the power of the electronic health record for ALS research and quality improvement: CReATe CAPTURE-ALS and the ALS Toolkit.

The electronic health record (EHR) is designed principally to support the provision and documentation of clinical care, as well as billing and insurance claims. Broad implementation of the EHR, however, also yields an opportunity to use EHR data for other purposes, including research and quality improvement. Indeed, effective use of clinical data for research purposes has been a long-standing goal of physicians who provide care for patients with ALS, but the quality and completeness of clinical data, as well as the burden of double data entry into the EHR and into a research database, have been persistent barriers. These factors provided motivation for the development of the ALS Toolkit, a set of interactive digital forms within the EHR that enable easy, consistent, and structured capture of information relevant to ALS patient care (as well as research and quality improvement) during clinical encounters. Routine use of the ALS Toolkit within the context of the CReATe Consortium's institutional review board-approved Clinical Procedures to Support Research in ALS (CAPTURE-ALS) study protocol, permits aggregation of structured ALS patient data, with the goals of empowering research and driving quality improvement. Widespread use of the ALS Toolkit through the CAPTURE-ALS protocol will help to ensure that ALS clinics become a driving force for collecting and aggregating clinical data in a way that reflects the true diversity of the populations affected by this disease, rather than the restricted subset of patients that currently participate in dedicated research studies.

Tocilizumab is safe and tolerable and reduces C-reactive protein concentrations in the plasma and cerebrospinal fluid of ALS patients.

INTRODUCTION/AIMS: We tested safety, tolerability, and target engagement of tocilizumab in amyotrophic lateral sclerosis (ALS) patients. METHODS: Twenty-two participants, whose peripheral blood mononuclear cell (PBMC) gene expression profile reflected high messenger ribonucleic acid (mRNA) expression of inflammatory markers, were randomized 2:1 to three tocilizumab or placebo treatments (weeks 0, 4, and 8; 8 mg/kg intravenous). Participants were followed every 4 wk in a double-blind fashion for 16 wk and assessed for safety, tolerability, plasma inflammatory markers, and clinical measures. Cerebrospinal fluid (CSF) was collected at baseline and after the third treatment. Participants were genotyped for Asp358 Ala polymorphism of the interleukin 6 receptor (IL-6R) gene. RESULTS: Baseline characteristics, safety, and tolerability were similar between treatment groups. One serious adverse event was reported in the placebo group; no deaths occurred. Mean plasma C-reactive protein (CRP) level decreased by 88% in the tocilizumab group and increased by 4% in the placebo group (-3.0-fold relative change, P < .001). CSF CRP reduction (-1.8-fold relative change, P = .01) was associated with IL-6R C allele count. No differences in PBMC gene expression or clinical measures were observed between groups. DISCUSSION: Tocilizumab treatment was safe and well tolerated. PBMC gene expression profile was inadequate as a predictive or pharmacodynamic biomarker. Treatment reduced CRP levels in plasma and CSF, with CSF effects potentially dependent on IL-6R Asp358 Ala genotype. IL-6 trans-signaling may mediate a distinct central nervous system response in individuals inheriting the IL-6R C allele. These results warrant further study in ALS patients where IL-6R genotype and CRP levels may be useful enrichment biomarkers.

Porphyric neuropathy.

Acute hepatic porphyrias are inherited metabolic disorders that may present with polyneuropathy, which if not diagnosed early can lead to quadriparesis, respiratory weakness, and death. Porphyric neuropathy is an acute to subacute motor predominant axonal neuropathy with a predilection for the upper extremities and usually preceded by a predominantly parasympathetic autonomic neuropathy. The rapid progression and associated dysautonomia mimic Guillain-Barré syndrome but are distinguished by the absence of cerebrospinal fluid albuminocytologic dissociation, progression beyond 4 wk, and associated abdominal pain. Spot urine test to assess the porphyrin precursors delta-aminolevulinic acid and porphobilinogen can provide a timely diagnosis during an acute attack. Timely treatment with intravenous heme, carbohydrate loading, and avoidance of porphyrinogenic medications can prevent further neurological morbidity and mortality.

ALSUntangled 59: Tamoxifen.

Here we use the ALSUntangled methodology to review Tamoxifen as an ALS treatment. We show that it has plausible mechanisms, a positive preclinical study, a case report and 2 small trials suggesting benefits. We show that it appears reasonably safe, though there is a small risk of developing cancer with long term use. While we cannot yet endorse this as an ALS treatment, there is enough evidence to warrant another larger ALS trial.

Machine learning suggests polygenic risk for cognitive dysfunction in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a multi-system disease characterized primarily by progressive muscle weakness. Cognitive dysfunction is commonly observed in patients; however, factors influencing risk for cognitive dysfunction remain elusive. Using sparse canonical correlation analysis (sCCA), an unsupervised machine-learning technique, we observed that single nucleotide polymorphisms collectively associate with baseline cognitive performance in a large ALS patient cohort (N = 327) from the multicenter Clinical Research in ALS and Related Disorders for Therapeutic Development (CReATe) Consortium. We demonstrate that a polygenic risk score derived using sCCA relates to longitudinal cognitive decline in the same cohort and also to in vivo cortical thinning in the orbital frontal cortex, anterior cingulate cortex, lateral temporal cortex, premotor cortex, and hippocampus (N = 90) as well as post-mortem motor cortical neuronal loss (N = 87) in independent ALS cohorts from the University of Pennsylvania Integrated Neurodegenerative Disease Biobank. Our findings suggest that common genetic polymorphisms may exert a polygenic contribution to the risk of cortical disease vulnerability and cognitive dysfunction in ALS.

Interleukin 6 (IL6) level is a biomarker for functional disease progression within IL6R358Ala variant groups in amyotrophic lateral sclerosis patients.

Interleukin-6 (IL6) expression increases in atrophying muscles and lung tissue during compromised function. Considering ALS patients undergo these same pathological changes, IL6 levels may be relevant for prognostication and treatment. The amount of soluble IL6 receptor, dictated by the IL6R358Ala variant, and local tissue environment in which IL6 signaling occurs is known to influence the ultimate effects of IL6 in multiple diseases. In this longitudinal study, we show that serum IL6 levels negatively correlate both with the patient's functional status as measured by the overall ALSFRS-R and subscores, and with respiratory function as measured by the percent predicted FVC (ppFVC). The correlations are only present in the two-thirds of patients who carry the IL6R358Ala variant that mediates pro-inflammatory transsignaling in the cases of ALSFRS-R limb and respiratory subscores and ppFVC. These results suggest that some observed associations between IL6 and ALS are driven by the subset of patients carrying the IL6R358Ala variant and thus that any IL6-targeted therapeutic approaches may be more advantageous when aimed at this group. Specifically, with relation to respiratory decline, these patients may benefit from closer respiratory follow-up and early initiation of noninvasive ventilation.

Long-term survival of participants in the CENTAUR trial of sodium phenylbutyrate-taurursodiol in amyotrophic lateral sclerosis.

An orally administered, fixed-dose coformulation of sodium phenylbutyrate-taurursodiol (PB-TURSO) significantly slowed functional decline in a randomized, placebo-controlled, phase 2 trial in ALS (CENTAUR). Herein we report results of a long-term survival analysis of participants in CENTAUR. In CENTAUR, adults with ALS were randomized 2:1 to PB-TURSO or placebo. Participants completing the 6-month (24-week) randomized phase were eligible to receive PB-TURSO in the open-label extension. An all-cause mortality analysis (35-month maximum follow-up post-randomization) incorporated all randomized participants. Participants and site investigators were blinded to treatment assignments through the duration of follow-up of this analysis. Vital status was obtained for 135 of 137 participants originally randomized in CENTAUR. Median overall survival was 25.0 months among participants originally randomized to PB-TURSO and 18.5 months among those originally randomized to placebo (hazard ratio, 0.56; 95% confidence interval, 0.34-0.92; P = .023). Initiation of PB-TURSO treatment at baseline resulted in a 6.5-month longer median survival as compared with placebo. Combined with results from CENTAUR, these results suggest that PB-TURSO has both functional and survival benefits in ALS.