Population-Based Evidence for the Use of Serum Neurofilaments as Individual Diagnostic and Prognostic Biomarkers in Amyotrophic Lateral Sclerosis

OBJECTIVE

Neurofilament light chains (NfL) and phosphorylated neurofilament heavy chains (pNfH), established as diagnostic and prognostic biomarkers in hospital-based amyotrophic lateral sclerosis (ALS) cohorts, are now surrogate markers in clinical trials. This study extends their evaluation to a population level, with the aim of advancing their full establishment and assessing the transferability of biomarker findings from controlled cohorts to real-world ALS populations.

METHODS

We measured serum NfL and pNfH levels in all ALS patients (n = 790) and general population controls (n = 570) with available baseline samples participating in the epidemiological ALS Registry Swabia, providing platform-specific (ELLA™) reference data and Z-scores for controls, as well as reference data, disease-specific Z-scores and longitudinal data in ALS. We evaluated the diagnostic and prognostic utility of neurofilaments and quantified the impact of ALS-related factors and non-ALS confounders.

RESULTS

Neurofilaments showed high diagnostic and prognostic utility at the population level, with NfL superior to pNfH. The novel concept of a population-based ALS Z-score significantly improved the prognostic utility compared to absolute raw values. Both biomarkers increased more strongly with age in controls than in ALS, and age adjustment improved diagnostic accuracy. Our data show that disease progression rates, ALS phenotype, body mass index (BMI), and renal function need to be considered when interpreting neurofilament levels; longitudinal neurofilament levels were generally stable in individual patients, especially when adjusted for age and baseline levels.

INTERPRETATION

Population-based assessment enhances the utility of particularly serum NfL as a diagnostic and prognostic biomarker in ALS and improves the translation of findings from controlled cohorts to real-world populations. ANN NEUROL 2024.

Categorization of the amyotrophic lateral sclerosis population via the clinical determinant of post-onset ΔFS for study design and medical practice

The amyotrophic lateral sclerosis (ALS) functional rating scale-revised (ALSFRS-R) has become the most widely utilized measure of disease severity in patients with ALS, with change in ALSFRS-R from baseline being a trusted primary outcome measure in ALS clinical trials. This is despite the scale having several established limitations, and although alternative scales have been proposed, it is unlikely that these will displace ALSFRS-R in the foreseeable future. Here, we discuss the merits of delta FS (ΔFS), the slope or rate of ALSFRS-R decline over time, as a relevant tool for innovative ALS study design, with an as yet untapped potential for optimization of drug effectiveness and patient management. In our view, categorization of the ALS population via the clinical determinant of post-onset ΔFS is an important study design consideration. It serves not only as a critical stratification factor and basis for patient enrichment but also as a tool to explore differences in treatment response across the overall population; thereby, facilitating identification of responder subgroups. Moreover, because post-onset ΔFS is derived from information routinely collected as part of standard patient care and monitoring, it provides a suitable patient selection tool for treating physicians. Overall, post-onset ΔFS is a very attractive enrichment tool that is, can and should be regularly incorporated into ALS trial design.

ALSFRS-R decline rate prior to baseline is not useful for stratifying subsequent progression of functional decline

OBJECTIVE

One of the difficulties in developing a novel drug for patients with amyotrophic lateral sclerosis (ALS) is the significant variation in the clinical course. To control this variation, a 12-week run-in period is used in some clinical trials. Based on the Amyotrophic Lateral Sclerosis Functional Rating Scale Revised (ALSFRS-R) change during the run-in period, only moderate progressors are selected in some clinical trials. Some reports showed that the ALSFRS-R progression rate was associated with survival. However, it is unclear whether the ALSFRS-R change in the run-in period is a useful prognostic factor of the ALSFRS-R change from baseline. In addition, we explore the inclusion criteria that could control the variability in ALS-function progression without setting a run-in period.

METHODS

We utilized the Japanese and US ALS registry databases (JaCALS and PRO-ACT). Patients were classified into three populations (rapid, moderate, and slow progressors) based on the ALSFRS-R change prior to baseline. We also classified patients into three prognostic populations based on the ALSFRS-R change from baseline. We confirmed whether each of the three populations were matched with their respective three prognostic populations.

RESULTS

Our data showed that the three groups classified by the ALSFRS-R change during the 12 weeks prior to baseline or by the rate of progression from onset to baseline did not accord with the three prognostic groups.

CONCLUSIONS

Our results showed that the ALSFRS-R change in the run-in period or from onset to baseline is not useful for stratifying subsequent progression of functional decline in clinical trials.

Improving the measurement properties of the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R): deriving a valid measurement total for the calculation of change

BACKGROUND

The Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) total score is a widely used measure of functional status in Amyotrophic Lateral Sclerosis/Motor Neuron Disease (ALS), but recent evidence has raised doubts about its validity. The objective was to examine the measurement properties of the ALSFRS-R, aiming to produce valid measurement from all 12 scale items.

METHOD

Longitudinal ALSFRS-R data were collected between 2013-2020 from 1120 people with ALS recruited from 35 centers, together with other scales in the Trajectories of Outcomes in Neurological Conditions-ALS (TONiC-ALS) study. The ALSFRS-R was analyzed by confirmatory factor analysis (CFA), Rasch Analysis (RA) and Mokken scaling.

RESULTS

No definite factor structure of the ALSFRS-R was confirmed by CFA. RA revealed the raw score total to be invalid even at the ordinal level because of multidimensionality; valid interval level subscale measures could be found for the Bulbar, Fine-Motor and Gross-Motor domains but the Respiratory domain was only valid at an ordinal level. All four domains resolved into a single valid, interval level measure by using a bifactor RA. The smallest detectable difference was 10.4% of the range of the interval scale.

CONCLUSION

A total ALSFRS-R ordinal raw score can lead to inferential bias in clinical trial results due to its non-linear nature. On the interval level transformation, more than 5 points difference is required before a statistically significant detectable difference can be observed. Transformation to interval level data should be mandatory in clinical trials.

Relationship between quantitative strength and functional outcomes in the phase 2 FORTITUDE-ALS trial

OBJECTIVE

To assess the relationship among measurements of strength, function, and quality of life in an amyotrophic lateral sclerosis (ALS) clinical trial.

METHODS

In the FORTITUDE-ALS clinical trial (NCT03160898), 456 participants in the full-analysis set were treated with either reldesemtiv or placebo for 12 weeks; this post hoc analysis included all participants regardless of treatment assignments. Assessments included slow vital capacity (SVC), the ALS Functional Rating Scale-Revised (ALSFRS-R), and the 5-item ALS Assessment Questionnaire (ALSAQ-5). Muscle strength was measured quantitatively with hand-held dynamometry, and grip strength with a dedicated dynamometer. The relationship between strength and ALSFRS-R fine and gross motor domain scores, or responses to ALSAQ-5 questions on hand function and walking, was assessed with Spearman's rank correlation. The relationship between mean upper- or lower-extremity muscle strength and specific ALSFRS-R domains was modeled using principal-components analysis.

RESULTS

Upper-extremity muscle strength and hand grip were highly correlated with ALSFRS-R fine motor scores and the ALSAQ-5 hand function question. Similarly, lower-extremity strength correlated well with ALSFRS-R gross motor domain and the ALSAQ-5 walking question. For SVC, correlation was poor with the ALSFRS-R respiratory domain, but stronger with the total score, potentially reflecting the insensitivity of the respiratory questions in the scale. Upper- and lower-extremity strength were both strong predictors of ALSFRS-R domain scores.

CONCLUSIONS

In this analysis of data from an ALS clinical trial, muscle strength quantified by dynamometry was strongly correlated with functional capacity. These results suggest that muscle strength directly relates to specific functions of importance to people with ALS.

Use of hip- versus wrist-based actigraphy for assessing functional decline and disease progression in patients with motor neuron disease

BACKGROUND

Actigraphy has been proposed as a measure for tracking functional decline and disease progression in patients with Motor Neuron Disease (MND). There is, however, little evidence to show that wrist-based actigraphy measures correlate with functional decline, and no consensus on how best to implement actigraphy. We report on the use of wrist actigraphy to show decreased activity in patients compared to controls, and compared the utility of wrist- and hip-based actigraphy for assessing functional decline in patients with MND.

METHODS

In this multi-cohort, multi-centre, natural history study, wrist- and hip-based actigraphy were assessed in 139 patients with MND (wrist, n = 97; hip, n = 42) and 56 non-neurological control participants (wrist, n = 56). For patients with MND, longitudinal measures were contrasted with clinical outcomes commonly used to define functional decline.

RESULTS

Patients with MND have reduced wrist-based actigraphy scores when compared to controls (median differences: prop. active = - 0.053 [- 0.075, - 0.026], variation axis 1 = - 0.073 [- 0.112, - 0.021]). When comparing wrist- and hip-based measures, hip-based accelerometery had stronger correlations with disease progression (prop. active: τ = 0.20 vs 0.12; variation axis 1: τ = 0.33 vs 0.23), whereas baseline wrist-based accelerometery was better related with future decline in fine-motor function (τ = 0.14-0.23 vs 0.06-0.16).

CONCLUSIONS

Actigraphy outcomes measured from the wrist are more variable than from the hip and present differing sensitivity to specific functional outcomes. Outcomes and analysis should be carefully constructed to maximise benefit, should wrist-worn devices be used for at-home monitoring of disease progression in patients with MND.

An Exploratory Trial of EPI-589 in Amyotrophic Lateral Sclerosis (EPIC-ALS): Protocol for a Multicenter, Open-Labeled, 24-Week, Single-Group Study

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder, with its currently approved drugs, including riluzole and edaravone, showing limited therapeutic effects. Therefore, safe and effective drugs are urgently necessary. EPI-589 is an orally available, small-molecule, novel redox-active agent characterized by highly potent protective effects against oxidative stress with high blood-brain barrier permeability. Given the apparent oxidative stress and mitochondrial dysfunction involvement in the pathogenesis of ALS, EPI-589 may hold promise as a therapeutic agent.

OBJECTIVE

This protocol aims to describe the design and rationale for the EPI-589 Early Phase 2 Investigator-Initiated Clinical Trial for ALS (EPIC-ALS).

METHODS

EPIC-ALS is an explorative, open-labeled, single-arm trial that evaluates the safety and tolerability of EPI-589 in patients with ALS. This trial consists of 12-week run-in, 24-week treatment, and 4-week follow-up periods. Patients will receive 500 mg of EPI-589 3 times daily over the 24-week treatment period. Clinical assessments include the mean monthly change of Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised total score. The biomarkers are selected to analyze the effect on oxidative stress and neuronal damage. The plasma biomarkers are 8-hydroxy-2'-deoxyguanosine (8-OHdG), 3-nitrotyrosine (3-NT), neurofilament light chain (NfL), phosphorylated neurofilament heavy chain (pNfH), homocysteine, and creatinine. The cerebrospinal fluid biomarkers are 8-OHdG, 3-NT, NfL, pNfH, and ornithine. The magnetic resonance biomarkers are fractional anisotropy in the corticospinal tract and N-acetylaspartate in the primary motor area.

RESULTS

This trial began data collection in September 2021 and is expected to be completed in October 2023.

CONCLUSIONS

This study can provide useful data to understand the characteristics of EPI-589.

TRIAL REGISTRATION

Japan Primary Registries Network jRCT2061210031; tinyurl.com/2p84emu6.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/42032.

Motor unit number index (MUNIX) in the D50 disease progression model reflects disease accumulation independently of disease aggressiveness in ALS

The neurophysiological technique motor unit number index (MUNIX) is increasingly used in clinical trials to measure loss of motor units. However, the heterogeneous disease course in amyotrophic lateral sclerosis (ALS) obfuscates robust correlations between clinical status and electrophysiological assessments. To address this heterogeneity, MUNIX was applied in the D50 disease progression model by analyzing disease aggressiveness (D50) and accumulation (rD50 phase) in ALS separately. 237 ALS patients, 45 controls and 22 ALS-Mimics received MUNIX of abductor pollicis brevis (APB), abductor digiti minimi (ADM) and tibialis anterior (TA) muscles. MUNIX significantly differed between controls and ALS patients and between ALS-Mimics and controls. Within the ALS cohort, significant differences between Phase I and II revealed in MUNIX, compound muscle action potential (CMAP) and motor unit size index (MUSIX) of APB as well as in MUNIX and CMAP of TA. For the ADM, significant differences occurred later in CMAP and MUNIX between Phase II and III/IV. In contrast, there was no significant association between disease aggressiveness and MUNIX. In application of the D50 disease progression model, MUNIX can demonstrate disease accumulation already in early Phase I and evaluate effects of therapeutic interventions in future therapeutic trials independent of individual disease aggressiveness.

Identifying patterns in amyotrophic lateral sclerosis progression from sparse longitudinal data

The clinical presentation of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease, varies widely across patients, making it challenging to determine if potential therapeutics slow progression. We sought to determine whether there were common patterns of disease progression that could aid in the design and analysis of clinical trials. We developed an approach based on a mixture of Gaussian processes to identify clusters of patients sharing similar disease progression patterns, modeling their average trajectories and the variability in each cluster. We show that ALS progression is frequently nonlinear, with periods of stable disease preceded or followed by rapid decline. We also show that our approach can be extended to Alzheimer's and Parkinson's diseases. Our results advance the characterization of disease progression of ALS and provide a flexible modeling approach that can be applied to other progressive diseases.

Cortical and subcortical grey matter atrophy in Amyotrophic Lateral Sclerosis correlates with measures of disease accumulation independent of disease aggressiveness

There is a growing demand for reliable biomarkers to monitor disease progression in Amyotrophic Lateral Sclerosis (ALS) that also take the heterogeneity of ALS into account. In this study, we explored the association between Magnetic Resonance Imaging (MRI)-derived measures of cortical thickness (CT) and subcortical grey matter (GM) volume with D50 model parameters. T1-weighted MRI images of 72 Healthy Controls (HC) and 100 patients with ALS were analyzed using Surface-based Morphometry for cortical structures and Voxel-based Morphometry for subcortical Region-Of-Interest analyses using the Computational Anatomy Toolbox (CAT12). In Inter-group contrasts, these parameters were compared between patients and HC. Further, the D50 model was used to conduct subgroup-analyses, dividing patients by a) Phase of disease covered at the time of MRI-scan and b) individual overall disease aggressiveness. Finally, correlations between GM and D50 model-derived parameters were examined. Inter-group analyses revealed ALS-related cortical thinning compared to HC located mainly in frontotemporal regions and a decrease in GM volume in the left hippocampus and amygdala. A comparison of patients in different phases showed further cortical and subcortical GM atrophy along with disease progression. Correspondingly, regression analyses identified negative correlations between cortical thickness and individual disease covered. However, there were no differences in CT and subcortical GM between patients with low and high disease aggressiveness. By application of the D50 model, we identified correlations between cortical and subcortical GM atrophy and ALS-related functional disability, but not with disease aggressiveness. This qualifies CT and subcortical GM volume as biomarkers representing individual disease covered to monitor therapeutic interventions in ALS.

Exploring the association between outcome measures to guide clinical management in patients with amyotrophic lateral sclerosis

[Purpose] The usefulness and limitations of outcome measures changes throughout functional decline of patients with Amyotrophic Lateral Sclerosis (ALS). This study aims to describe associations between outcome measures in patients with ALS over time. [Participants and Methods] Participant data was collected at a multidisciplinary ALS clinic during regular clinic visits, including gait velocity, Timed Up and Go, the ALS Functional Rating Scale-Revised, and it’s Gross Motor Subscale. [Results] All gait velocity measures were <1.2 m/sec; average Timed Up and Go was >13.5 sec. There was strong internal consistency between ALS Functional Rating Scale-Revised and its functional mobility components and a strong, significant correlation between the Timed Up and Go and the Gross Motor Subscale. [Conclusion] Patients with ALS are not community ambulators and demonstrate risk for falls. We found concurrent validity between objective and self-reported measures. The strong association between the Gross Motor Subscale and the Timed Up and Go may allow PTs to utilize the self-reported Gross Motor Subscale to predict fall risk. Clinically, when the Timed Up and Go and gait velocity are no longer appropriate due to disease progression, the Gross Motor Subscale can provide insight into functional decline.

Neurofilament light and heterogeneity of disease progression in amyotrophic lateral sclerosis: development and validation of a prediction model to improve interventional trials

Background

Interventional trials in amyotrophic lateral sclerosis (ALS) suffer from the heterogeneity of the disease as it considerably reduces statistical power. We asked if blood neurofilament light chains (NfL) could be used to anticipate disease progression and increase trial power.

Methods

In 125 patients with ALS from three independent prospective studies—one observational study and two interventional trials—we developed and externally validated a multivariate linear model for predicting disease progression, measured by the monthly decrease of the ALS Functional Rating Scale Revised (ALSFRS-R) score. We trained the prediction model in the observational study and tested the predictive value of the following parameters assessed at diagnosis: NfL levels, sex, age, site of onset, body mass index, disease duration, ALSFRS-R score, and monthly ALSFRS-R score decrease since disease onset. We then applied the resulting model in the other two study cohorts to assess the actual utility for interventional trials. We analyzed the impact on trial power in mixed-effects models and compared the performance of the NfL model with two currently used predictive approaches, which anticipate disease progression using the ALSFRS-R decrease during a three-month observational period (lead-in) or since disease onset (ΔFRS).

Results

Among the parameters provided, the NfL levels (P < 0.001) and the interaction with site of onset (P < 0.01) contributed significantly to the prediction, forming a robust NfL prediction model (R = 0.67). Model application in the trial cohorts confirmed its applicability and revealed superiority over lead-in and ΔFRS-based approaches. The NfL model improved statistical power by 61% and 22% (95% confidence intervals: 54%–66%, 7%–29%).

Conclusion

The use of the NfL-based prediction model to compensate for clinical heterogeneity in ALS could significantly increase the trial power.

NCT00868166, registered March 23, 2009; NCT02306590, registered December 2, 2014.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40035-021-00257-y.

Mapping of critical events in disease progression through binary classification: Application to amyotrophic lateral sclerosis

BACKGROUND

The progression of many degenerative diseases is tracked periodically using scales evaluating functionality in daily activities. Although estimating the timing of critical events (i.e., disease tollgates) during degenerative disease progression is desirable, the necessary data may not be readily available in scale records. Further, analysis of disease progression poses data challenges, such as censoring and misclassification errors, which need to be addressed to provide meaningful research findings and inform patients.

METHODS

We developed a novel binary classification approach to map scale scores into disease tollgates to describe disease progression leveraging standard/modified Kaplan-Meier analyses. The approach is demonstrated by estimating progression pathways in amyotrophic lateral sclerosis (ALS). Tollgate-based ALS Staging System (TASS) specifies the critical events (i.e., tollgates) in ALS progression. We first developed a binary classification predicting whether each TASS tollgate was passed given the itemized ALSFRS-R scores using 514 ALS patients' data from Mayo Clinic-Rochester. Then, we utilized the binary classification to translate/map the ALSFRS-R data of 3,264 patients from the PRO-ACT database into TASS. We derived the time trajectories of ALS progression through tollgates from the augmented PRO-ACT data using Kaplan-Meier analyses. The effects of misclassification errors, condition-dependent dropouts, and censored data in trajectory estimations were evaluated with Interval Censored Kaplan Meier Analysis and Multistate Model for Panel Data.

RESULTS

The approach using Mayo Clinic data accurately estimated tollgate-passed states of patients given their itemized ALSFRS-R scores (AUCs > 0.90). The tollgate time trajectories derived from the augmented PRO-ACT dataset provide valuable insights; we predicted that the majority of the ALS patients would have modified arm function (67%) and require assistive devices for walking (53%) by the second year after ALS onset. By the third year, most (74%) ALS patients would occasionally use a wheelchair, while 48% of the ALS patients would be wheelchair-dependent by the fourth year. Assistive speech devices and feeding tubes were needed in 49% and 30% of the patients by the third year after ALS onset, respectively. The onset body region alters some tollgate passage time estimations by 1-2 years.

CONCLUSIONS

The estimated tollgate-based time trajectories inform patients and clinicians about prospective assistive device needs and life changes. More research is needed to personalize these estimations according to prognostic factors. Further, the approach can be leveraged in the progression of other diseases.

A model incorporating ultrasound to predict the probability of fast disease progression in amyotrophic lateral sclerosis

OBJECTIVE

We aimed to develop a model to predict amyotrophic lateral sclerosis (ALS) disease progression based on clinical and neuromuscular ultrasound (NMUS) parameters.

METHODS

ALS patients were prospectively recruited. Muscle fasciculation (≥2 over 30-seconds, examined in biceps brachii-brachialis (BB), brachioradialis, tibialis anterior and vastus medialis) and nerve cross-sectional area (CSA) (median, ulnar, tibial, fibular nerve) were evaluated through NMUS. Ultrasound parameters were correlated with clinical data, including revised ALS Functional Rating Scale (ALSFRS-R) progression at one year. A predictive model was constructed to differentiate fast progressors (ALSFRS-R decline ≥ 1/month) from non-fast progressors.

RESULTS

40 ALS patients were recruited. Three parameters emerged as strong predictors of fast progressors: (i) ALSFRS-R slope at time of NMUS (p = 0.041), (ii) BB fasciculation count (p = 0.027) and (iii) proximal to distal median nerve CSA ratio < 1.22 (p = 0.026). A predictive model (scores 0-5) was built with excellent discrimination (area under curve: 0.915). Using a score of ≥ 3, the model demonstrated good sensitivity (81.3%) and specificity (91.0%) in differentiating fast from non-fast progressors.

CONCLUSION

The current model is simple and can predict the probability of fast disease progression.

SIGNIFICANCE

This model has potential as a surrogate biomarker of ALS disease progression.

An old friend who has overstayed their welcome: the ALSFRS-R total score as primary endpoint for ALS clinical trials

Objective: The ALSFRS-R is limited by multidimensionality, which originates from the summation of various subscales. This prevents a direct comparison between patients with identical total scores. We aim to evaluate how multidimensionality affects the performance of the ALSFRS-R in clinical trials. Methods: We simulated clinical trial data with different treatment effects for the ALSFRS-R total score and its subscales (i.e. bulbar, fine motor, gross motor and respiratory). We considered scenarios where treatment reduced the rate of ALSFRS-R subscale decline either uniformly (i.e. all subscales respond identically to treatment) or non-uniformly (i.e. subscales respond differently to treatment). Two main analytical strategies were compared: (1) analyzing only the total score or (2) utilizing a subscale-based test (i.e. alternative strategy). For each analytical strategy, we calculated the empirical power and required sample size. Results: Both strategies are valid when there is no treatment benefit and provide adequate control of type 1 error. If all subscales respond identically to treatment, using the total score is the most powerful approach. As the differences in treatment responses between subscales increase, the more the total score becomes affected. For example, to detect a 40% reduction in the bulbar rate of decline with 80% power, the total score requires 1380 patients, whereas this is 336 when using the alternative strategy. Conclusions: Ignoring the multidimensional structure of the ALSFRS-R total score could have negative consequences for ALS clinical trials. We propose determining treatment benefit on a subscale level, prior to stating whether a treatment is generally effective.

Prediction of survival in amyotrophic lateral sclerosis: a nationwide, Danish cohort study

Introduction

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease with great heterogeneity. Biological prognostic markers are needed for the patients to plan future supportive treatment, palliative treatment, and end-of-life decisions. In addition, prognostic markers are greatly needed for the randomization in clinical trials.

Objective

This study aimed to test the ALS Functional Rating Scale-Revised (ALSFRS-R) progression rate (ΔFS) as a prognostic marker of survival in a Danish ALS cohort.

Methods

The ALSFRS-R score at test date in association with duration of symptoms, from the onset of symptoms until test date, (defined as ΔFS’) was calculated for 90 Danish patients diagnosed with either probable or definite sporadic ALS. Median survival time was then estimated from the onset of symptoms until primary endpoint (either death or tracheostomy). ΔFS’ was subjected to survival analysis using Cox proportional hazards modelling, log-rank test, and Kaplan-Meier survival analysis.

Results and conclusions

Both ΔFS’ and age was found to be strong predictors of survival of the Danish ALS cohort. Both variables are easily obtained at the time of diagnosis and could be used by clinicians and ALS patients to plan future supportive and palliative treatment. Furthermore, ΔFS’, is a simple, prognostic marker that predicts survival in the early phase of disease as well as at later stages of the disease.

A Cost-Effectiveness Framework for Amyotrophic Lateral Sclerosis, Applied to Riluzole

OBJECTIVES

Reexamine cost-effectiveness of riluzole in the treatment of amyotrophic lateral sclerosis (ALS) in light of recent advances in disease staging and understanding of stage-specific drug effect.

METHODS

ALS was staged according to the "fine'til 9" (FT9) staging method. Stage-specific health utilities (EQ-5D, US valuation) were estimated from an institutional cohort, whereas literature informed costs and transition probabilities. Costs at 2018 prices were disaggregated into recurring costs (RCs) and "one-off" transition/"tollgate" costs (TCs). Five- and 10-year horizons starting in stage 1 disease were examined from healthcare sector and societal perspectives using Markov models to evaluate riluzole use, at a threshold of $100 000/quality-adjusted life year (QALY). Probabilistic and deterministic sensitivity analyses were conducted.

RESULTS

Mean EQ-5D utilities for stages 0 to 4 were 0.79, 0.74, 0.63, 0.54, and 0.46, respectively. From the healthcare sector perspective at the 5-year horizon, riluzole use contributed to 0.182 QALY gained at the cost difference of $12 348 ($5403 riluzole cost, $8870 RC and -$1925 TC differences), translating to an incremental cost-effectiveness ratio (ICER) of $67 658/QALY. Transition probability variation contributed considerably to ICER uncertainty (-30.2% to +90.0%). ICER was sensitive to drug price and RCs, whereas higher TCs modestly reduced ICER due to delayed tollgates.

CONCLUSION

This study provides a framework for health economic studies of ALS treatments using FT9 staging. Prospective stage-specific and disaggregated cost measurement is warranted for accurate future cost-effectiveness analyses. Appropriate separation of TCs from RCs substantially mitigates the high burden of background cost of care on the ICER.

A Phase 2, Double-Blind, Randomized, Dose-Ranging Trial Of Reldesemtiv In Patients With ALS

Objective:

To evaluate safety, dose response, and preliminary efficacy of reldesemtiv over 12 weeks in patients with amyotrophic lateral sclerosis (ALS).

Methods:

Patients (≤2 years since diagnosis) with slow upright vital capacity (SVC) of ≥60% were randomized 1:1:1:1 to reldesemtiv 150, 300, or 450 mg twice daily (bid) or placebo; active treatment was 12 weeks with 4-week follow-up. Primary endpoint was change in percent predicted SVC at 12 weeks; secondary measures included ALS Functional Rating Scale-Revised (ALSFRS-R) and muscle strength mega-score.

Results:

Patients (N = 458) were enrolled; 85% completed 12-week treatment. The primary analysis failed to reach statistical significance (p = 0.11); secondary endpoints showed no statistically significant effects (ALSFRS-R, p = 0.09; muscle strength megascore, p = 0.31). Post hoc analyses pooling all active reldesemtiv-treated patients compared against placebo showed trends toward benefit in all endpoints (progression rate for SVC, ALSFRS-R, and muscle strength mega-score (nominal p values of 0.10, 0.01 and 0.20 respectively)). Reldesemtiv was well tolerated, with nausea and fatigue being the most common side effects. A dose-dependent decrease in estimated glomerular filtration rate was noted, and transaminase elevations were seen in approximately 5% of patients. Both hepatic and renal abnormalities trended toward resolution after study drug discontinuation.

Conclusions:

Although the primary efficacy analysis did not demonstrate statistical significance, there were trends favoring reldesemtiv for all three endpoints, with effect sizes generally regarded as clinically important. Tolerability was good; modest hepatic and renal abnormalities were reversible. The impact of reldesemtiv on patients with ALS should be assessed in a pivotal Phase 3 trial. (ClinicalTrials.gov Identifier: NCT03160898)

Addressing heterogeneity in amyotrophic lateral sclerosis CLINICAL TRIALS

Amyotrophic lateral sclerosis (ALS) is a debilitating neurodegenerative disorder with complex biology and significant clinical heterogeneity. Many preclinical and early phase ALS clinical trials have yielded promising results that could not be replicated in larger phase 3 confirmatory trials. One reason for the lack of reproducibility may be ALS biological and clinical heterogeneity. Therefore, in this review, we explore sources of ALS heterogeneity that may reduce statistical power to evaluate efficacy in ALS trials. We also review efforts to manage clinical heterogeneity, including use of validated disease outcome measures, predictive biomarkers of disease progression, and individual clinical risk stratification. We propose that personalized prognostic models with use of predictive biomarkers may identify patients with ALS for whom a specific therapeutic strategy may be expected to be more successful. Finally, the rapid application of emerging clinical and biomarker strategies may reduce heterogeneity, increase trial efficiency, and, in turn, accelerate ALS drug development.

Modelling disease course in amyotrophic lateral Sclerosis: pseudo-longitudinal insights from cross-sectional health-related quality of life data

BACKGROUND

Amyotrophic Lateral Sclerosis (ALS) is a rapidly progressive neurodegenerative disorder with limited robust disease-modifying therapies presently available. While several treatments are aimed at improving health-related quality of life (HRQoL), longitudinal data on how QoL changes across the disease course are rare.

OBJECTIVES

To explore longitudinal changes in emotional well-being and HRQoL in ALS.

METHODS

Of the 161 subjects initially recruited, 39 received 2 subsequent follow-up assessments at 6 and 12 months after baseline. The ALS Functional Rating Scale-Revised (ALSFRS-R) was used to assess physical impairment. HRQoL was assessed using the ALS Assessment Questionnaire (ALSAQ-40). The D50 disease progression model was applied to explore longitudinal changes in HRQoL.

RESULTS

Patients were primarily in the early semi-stable and early progressive model-derived disease phases. Non-linear correlation analyses showed that the ALSAQ-40 summary index and emotional well-being subdomain behaved differently across disease phases, indicating that the response shift occurs early in disease. Both the ALSFRS-R and ALSAQ-40 significantly declined at 6- and 12-monthly follow-ups.

CONCLUSION

ALSAQ-40 summary index and emotional well-being change comparably over both actual time and model-derived phases, indicating that the D50 model enables pseudo-longitudinal interpretations of cross-sectional data in ALS.

The rise and fall of fasciculations in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a devastating neurodegenerative disease with a median survival of 3 years from symptom onset. Accessible and reliable biomarkers of motor neuron decline are urgently needed to quicken the pace of drug discovery. Fasciculations represent an early pathophysiological hallmark of amyotrophic lateral sclerosis and can be reliably detected by high-density surface electromyography. We set out to quantify fasciculation potentials prospectively over 14 months, seeking comparisons with established markers of disease progression. Twenty patients with amyotrophic lateral sclerosis and five patients with benign fasciculation syndrome underwent up to seven assessments each. At each assessment, we performed the amyotrophic lateral sclerosis-functional rating scale, sum power score, slow vital capacity, 30-min high-density surface electromyography recordings from biceps and gastrocnemius and the motor unit number index. We employed the Surface Potential Quantification Engine, which is an automated analytical tool to detect and characterize fasciculations. Linear mixed-effect models were employed to account for the pseudoreplication of serial measurements. The amyotrophic lateral sclerosis-functional rating scale declined by 0.65 points per month (P < 0.0001), 35% slower than average. A total of 526 recordings were analysed. Compared with benign fasciculation syndrome, biceps fasciculation frequency in amyotrophic lateral sclerosis was 10 times greater in strong muscles and 40 times greater in weak muscles. This was coupled with a decline in fasciculation frequency among weak muscles of -7.6/min per month (P = 0.003), demonstrating the rise and fall of fasciculation frequency in biceps muscles. Gastrocnemius behaved differently, whereby strong muscles in amyotrophic lateral sclerosis had fasciculation frequencies five times greater than patients with benign fasciculation syndrome while weak muscles were increased by only 1.5 times. Gastrocnemius demonstrated a significant decline in fasciculation frequency in strong muscles (2.4/min per month, P < 0.0001), which levelled off in weak muscles. Fasciculation amplitude, an easily quantifiable surrogate of the reinnervation process, was highest in the biceps muscles that transitioned from strong to weak during the study. Pooled analysis of >900 000 fasciculations revealed inter-fasciculation intervals <100 ms in the biceps of patients with amyotrophic lateral sclerosis, particularly in strong muscles, consistent with the occurrence of doublets. We hereby present the most comprehensive longitudinal quantification of fasciculation parameters in amyotrophic lateral sclerosis, proposing a unifying model of the interactions between motor unit loss, muscle power and fasciculation frequency. The latter showed promise as a disease biomarker with linear rates of decline in strong gastrocnemius and weak biceps muscles, reflecting the motor unit loss that drives clinical progression.

Long-term edaravone efficacy in amyotrophic lateral sclerosis: Post-hoc analyses of Study 19 (MCI186-19)

Background

In a Phase 3 study, amyotrophic lateral sclerosis (ALS) patients experienced significantly less physical functional decline with 24‐week edaravone vs placebo, followed by open‐label treatment for an additional 24 weeks.

Methods

Outcome (the change in ALS Functional Rating Scale–Revised, ALSFRS‐R, from baseline) was projected for placebo patients through 48 weeks and compared with 48‐week edaravone or 24‐week edaravone after switching from placebo.

Results

A total of 123 patients received open‐label treatment (65 edaravone‐edaravone; 58 placebo‐edaravone). The projected ALSFRS‐R decline for placebo from baseline through week 48 was greater than for 48‐week edaravone (P < .0001). For patients switching from placebo to edaravone, ALSFRS‐R slope approached that of continued edaravone for 48 weeks. ALSFRS‐R decline did not differ between actual and projected edaravone through week 48.

Conclusions

Compared with placebo, these analyses suggest that edaravone is beneficial in ALS patients even after 6 mo of receiving placebo, and efficacy is maintained for up to 1 year.

https://doi.org/10.1002/mus.26770.

IL6 receptor358Ala variant and trans-signaling are disease modifiers in amyotrophic lateral sclerosis

Objective

To test the hypothesis that patients with amyotrophic lateral sclerosis (ALS) inheriting the common interleukin 6 receptor (IL6R) coding variant (Asp³⁵⁸Ala, rs2228145, C allele) have associated increases in interleukin 6 (IL6) and IL6R levels in serum and CSF and faster disease progression than noncarriers.

Methods

An observational, case-control study of paired serum and CSF of 47 patients with ALS, 46 healthy, and 23 neurologic disease controls from the Northeastern ALS Consortium Biofluid Repository (cohort 1) was performed to determine serum levels of IL6, sIL6R, and soluble glycoprotein 130 and compared across groups and IL6R genotype. Clinical data regarding disease progression from a separate cohort of 35 patients with ALS from the Wake Forest ALS Center (cohort 2) were used to determine change in ALSFRS-R scores by genotype.

Results

Patients with ALS had increased CSF IL6 levels compared with healthy (p < 0.001) and neurologic (p = 0.021) controls. Patients with ALS also had increased serum IL6 compared with healthy (p = 0.040) but not neurologic controls. Additive allelic increases in serum IL6R were observed in all groups (average increase of 52% with the presence of the IL6R C allele; p < 0.001). However, only subjects with ALS had significantly increased CSF sIL6R levels compared with controls (p < 0.001). When compared across genotypes, only patients with ALS inheriting the IL6R C allele exhibit increased CSF IL6. ALSFRS-R scores decreased more in patients with ALS with the IL6R C allele than in those without (p = 0.019).

Conclusions

Theses results suggest that for individuals inheriting the IL6R C allele, the cytokine exerts a disease- and location-specific role in ALS. Follow-up, prospective studies are necessary, as this subgroup of patients may be identified as ideally responsive to IL6 receptor–blocking therapies.

Variation in noninvasive ventilation use in amyotrophic lateral sclerosis

Objective

We sought to examine prevalence and predictors of noninvasive ventilation (NIV) in a composite cohort of patients with amyotrophic lateral sclerosis (ALS) followed in a clinical trials setting (Pooled Resource Open-Access ALS Clinical Trials database).

Methods

NIV initiation and status were ascertained from response to question 12 of the revised ALS Functional Rating Scale (ALSFRS-R). Factors affecting NIV use in patients with forced vital capacity (FVC) ≤50% of predicted were examined. Predictors of NIV were evaluated by Cox proportional hazard models and generalized linear mixed models.

Results

Among 1,784 patients with 8,417 simultaneous ALSFRS-R and FVC% measures, NIV was used by 604 (33.9%). Of 918 encounters when FVC% ≤50%, NIV was reported in 482 (52.5%). Independent predictors of NIV initiation were lower FVC% (hazard ratio [HR] 1.27, 95% confidence interval [CI] 1.17–1.37 for 10% drop), dyspnea (HR 2.62, 95% CI 1.87–3.69), orthopnea (HR 4.09, 95% CI 3.02–5.55), lower bulbar and gross motor subscores of ALSFRS-R (HRs 1.09 [95% CI 1.03–1.14] and 1.13 [95% CI 1.07–1.20], respectively, per point), and male sex (HR 1.73, 95% CI 1.31–2.28). Adjusted for other variables, bulbar onset did not significantly influence time to NIV (HR 0.72, 95% CI 0.47–1.08). Considerable unexplained variability in NIV use was found.

Conclusion

NIV use was lower than expected in this ALS cohort that was likely to be optimally managed. Absence of respiratory symptoms and female sex may be barriers to NIV use. Prospective exploration of factors affecting adoption of NIV may help bridge this gap and improve care in ALS.

Tracking a Fast-Moving Disease: Longitudinal Markers, Monitoring, and Clinical Trial Endpoints in ALS

Amyotrophic lateral sclerosis (ALS) encompasses a heterogeneous group of phenotypes with different progression rates, varying degree of extra-motor involvement and divergent progression patterns. The natural history of ALS is increasingly evaluated by large, multi-time point longitudinal studies, many of which now incorporate presymptomatic and post-mortem assessments. These studies not only have the potential to characterize patterns of anatomical propagation, molecular mechanisms of disease spread, but also to identify pragmatic monitoring markers. Sensitive markers of progressive neurodegenerative change are indispensable for clinical trials and individualized patient care. Biofluid markers, neuroimaging indices, electrophysiological markers, rating scales, questionnaires, and other disease-specific instruments have divergent sensitivity profiles. The discussion of candidate monitoring markers in ALS has a dual academic and clinical relevance, and is particularly timely given the increasing number of pharmacological trials. The objective of this paper is to provide a comprehensive and critical review of longitudinal studies in ALS, focusing on the sensitivity profile of established and emerging monitoring markers.

Is edaravone harmful? (A placebo is not a control)

Edaravone is delivered by long-term daily intravenous infusions, yet the risk of infusion was not considered in the design or analysis of studies examining the efficacy of edaravone in ALS. A reappraisal of the pivotal edaravone study (Study 19) on which claims of efficacy are based suggests that this risk cannot be dismissed, that the efficacy of edaravone may be over-estimated, and that some differences between edaravone and placebo may not implicate the ALS disease process. When trial conditions may be harmful to both arms of a placebo-controlled trial, not only is it necessary that treatment prove superior to placebo, but also that treatment is better than no intervention. In Study 19, edaravone performed better than placebo, but both placebo and edaravone likely did worse than no intervention, an interpretation more in keeping with previous trial experience of drugs with similar mechanisms of action, and with previous trial experience with edaravone. Edaravone, as presently delivered, may be both ineffective and harmful.

Deconstructing progression of amyotrophic lateral sclerosis in stages: a Markov modeling approach

OBJECTIVES

Propose an empirical amyotrophic lateral sclerosis (ALS) staging approach called Fine'til 9 (FT9) based on how many of the patient's ALS functional rating scale (ALSFRS-R) subscores are 9 or less (of normal 12). Gain insights into progression of ALS by applying Markov models to ALS stages by multiple systems (King's, Milan-Torino system (MITOS) and FT9).

METHODS

Patients from the Pooled Resource Open-Access ALS Clinical Trials (PRO-ACT) dataset were staged using ALSFRS-R responses. Risks of progression through stages and death were estimated, as were effects of prognostic variables on these risks.

RESULTS

A total of 29,947 time points in 3199 patients from the PRO-ACT dataset were assigned stages. Although the three systems were moderately correlated, MITOS stages were heavily skewed toward advanced disease, whereas King's and FT9 stages were more balanced. Non-sequential progression was observed with King's system. Markov models adequately described transitions from stage to stage in the first year of observation, but underestimated risks beyond that point. Regardless of staging method, initial rate of ALSFRS-R decline had a powerful effect on rate of progression through sequential stages, whereas age predominantly influenced stage-specific mortality.

CONCLUSION

King's and FT9 are more sensitive to observed progression of disease in clinical trials than MITOS. FT9 can partition the course similar to King's, and may have advantages of sequential progression and easy applicability to retrospective data. Markov transition intensity estimates may be of value for counseling, health economic studies, and research design. In particular, this framework permits estimation of multidimensional effects of variables (including treatment) on outcome.