OUP accepted manuscript

Debamestrocel multimodal effects on biomarker pathways in amyotrophic lateral sclerosis are linked to clinical outcomes

INTRODUCTION/AIMS

Biomarkers have shown promise in amyotrophic lateral sclerosis (ALS) research, but the quest for reliable biomarkers remains active. This study evaluates the effect of debamestrocel on cerebrospinal fluid (CSF) biomarkers, an exploratory endpoint.

METHODS

A total of 196 participants randomly received debamestrocel or placebo. Seven CSF samples were to be collected from all participants. Forty-five biomarkers were analyzed in the overall study and by two subgroups characterized by the ALS Functional Rating Scale-Revised (ALSFRS-R). A prespecified model was employed to predict clinical outcomes leveraging biomarkers and disease characteristics. Causal inference was used to analyze relationships between neurofilament light chain (NfL) and ALSFRS-R.

RESULTS

We observed significant changes with debamestrocel in 64% of the biomarkers studied, spanning pathways implicated in ALS pathology (63% neuroinflammation, 50% neurodegeneration, and 89% neuroprotection). Biomarker changes with debamestrocel show biological activity in trial participants, including those with advanced ALS. CSF biomarkers were predictive of clinical outcomes in debamestrocel-treated participants (baseline NfL, baseline latency-associated peptide/transforming growth factor beta1 [LAP/TGFβ1], change galectin-1, all p < .01), with baseline NfL and LAP/TGFβ1 remaining (p < .05) when disease characteristics (p < .005) were incorporated. Change from baseline to the last measurement showed debamestrocel-driven reductions in NfL were associated with less decline in ALSFRS-R. Debamestrocel significantly reduced NfL from baseline compared with placebo (11% vs. 1.6%, p = .037).

DISCUSSION

Following debamestrocel treatment, many biomarkers showed increases (anti-inflammatory/neuroprotective) or decreases (inflammatory/neurodegenerative) suggesting a possible treatment effect. Neuroinflammatory and neuroprotective biomarkers were predictive of clinical response, suggesting a potential multimodal mechanism of action. These results offer preliminary insights that need to be confirmed.

The Miami Framework for ALS and related neurodegenerative disorders: an integrated view of phenotype and biology

Increasing appreciation of the phenotypic and biological overlap between amyotrophic lateral sclerosis (ALS) and frontotemporal dementia, alongside evolving biomarker evidence for a pre-symptomatic stage of disease and observations that this stage of disease might not always be clinically silent, is challenging traditional views of these disorders. These advances have highlighted the need to adapt ingrained notions of these clinical syndromes to include both the full phenotypic continuum - from clinically silent, to prodromal, to clinically manifest - and the expanded phenotypic spectrum that includes ALS, frontotemporal dementia and some movement disorders. The updated clinical paradigms should also align with our understanding of the biology of these disorders, reflected in measurable biomarkers. The Miami Framework, emerging from discussions at the Second International Pre-Symptomatic ALS Workshop in Miami (February 2023; a full list of attendees and their affiliations appears in the Supplementary Information) proposes a classification system built on: first, three parallel phenotypic axes - motor neuron, frontotemporal and extrapyramidal - rather than the unitary approach of combining all phenotypic elements into a single clinical entity; and second, biomarkers that reflect different aspects of the underlying pathology and biology of neurodegeneration. This framework decouples clinical syndromes from biomarker evidence of disease and builds on experiences from other neurodegenerative diseases to offer a unified approach to specifying the pleiotropic clinical manifestations of disease and describing the trajectory of emergent biomarkers.

Current neuroprotective therapies and future prospects for motor neuron disease

Four medications with neuroprotective disease-modifying effects are now in use for motor neuron disease (MND). With FDA approvals for tofersen, relyvrio and edaravone in just the past year, 2022 ended a quarter of a century when riluzole was the sole such drug to offer to patients. The acceleration of approvals may mean we are witnessing the beginning of a step-change in how MND can be treated. Improvements in understanding underlying disease biology has led to more therapies being developed to target specific and multiple disease mechanisms. Consideration for how the pipeline of new therapeutic agents coming through in clinical and preclinical development can be more effectively evaluated with biomarkers, advances in patient stratification and clinical trial design pave the way for more successful translation for this archetypal complex neurodegenerative disease. While it must be cautioned that only slowed rates of progression have so far been demonstrated, pre-empting rapid neurodegeneration by using neurofilament biomarkers to signal when to treat, as is currently being trialled with tofersen, may be more effective for patients with known genetic predisposition to MND. Early intervention with personalized medicines could mean that for some patients at least, in future we may be able to substantially treat what is considered by many to be one of the most distressing diseases in medicine.

Neurofilaments as biomarkers in neurological disorders - towards clinical application

Neurofilament proteins have been validated as specific body fluid biomarkers of neuro-axonal injury. The advent of highly sensitive analytical platforms that enable reliable quantification of neurofilaments in blood samples and simplify longitudinal follow-up has paved the way for the development of neurofilaments as a biomarker in clinical practice. Potential applications include assessment of disease activity, monitoring of treatment responses, and determining prognosis in many acute and chronic neurological disorders as well as their use as an outcome measure in trials of novel therapies. Progress has now moved the measurement of neurofilaments to the doorstep of routine clinical practice for the evaluation of individuals. In this Review, we first outline current knowledge on the structure and function of neurofilaments. We then discuss analytical and statistical approaches and challenges in determining neurofilament levels in different clinical contexts and assess the implications of neurofilament light chain (NfL) levels in normal ageing and the confounding factors that need to be considered when interpreting NfL measures. In addition, we summarize the current value and potential clinical applications of neurofilaments as a biomarker of neuro-axonal damage in a range of neurological disorders, including multiple sclerosis, Alzheimer disease, frontotemporal dementia, amyotrophic lateral sclerosis, stroke and cerebrovascular disease, traumatic brain injury, and Parkinson disease. We also consider the steps needed to complete the translation of neurofilaments from the laboratory to the management of neurological diseases in clinical practice.

Multifocal motor neuropathy as a mimic of amyotrophic lateral sclerosis: Serum neurofilament light chain as a reliable diagnostic biomarker

INTRODUCTION/AIMS

The clinical presentation of multifocal motor neuropathy (MMN) may mimic early amyotrophic lateral sclerosis (ALS) with predominant lower motor neuron (LMN) involvement, posing a diagnostic challenge. Both diseases have specific treatments and prognoses, highlighting the importance of early diagnosis. The aim of this study was to assess the diagnostic value of serum neurofilament light chain (NfL) in differentiating MMN from LMN dominant ALS.

METHODS

NfL was measured in serum in n = 37 patients with MMN and n = 37 age- and sex-matched patients with LMN dominant ALS, to determine the diagnostic accuracy. Clinical and demographic data were obtained at the time of NfL sampling.

RESULTS

Serum NfL concentration was significantly lower in MMN patients compared to ALS patients (mean 20.7 pg/mL vs. 59.4 pg/mL, p < .01). NfL demonstrated good diagnostic value in discriminating the two groups (AUC 0.985 [95% CI 0.963-1.000], sensitivity 94.6%, specificity 100%, cut-off 44.00 pg/mL).

DISCUSSION

NfL could be a helpful tool in differentiating MMN from LMN dominant ALS in those patients in whom electrophysiological and clinical examinations remain inconclusive early in the diagnostic process.

Data-independent acquisition proteomics of cerebrospinal fluid implicates endoplasmic reticulum and inflammatory mechanisms in amyotrophic lateral sclerosis

While unbiased proteomics of human cerebrospinal fluid (CSF) has been used successfully to identify biomarkers of amyotrophic lateral sclerosis (ALS), high-abundance proteins mask the presence of lower abundance proteins that may have diagnostic and prognostic value. However, developments in mass spectrometry (MS) proteomic data acquisition methods offer improved protein depth. In this study, MS with library-free data-independent acquisition (DIA) was used to compare the CSF proteome of people with ALS (n = 40), healthy (n = 15) and disease (n = 8) controls. Quantified protein groups were subsequently correlated with clinical variables. Univariate analysis identified 7 proteins, all significantly upregulated in ALS versus healthy controls, and 9 with altered abundance in ALS versus disease controls (FDR < 0.1). Elevated chitotriosidase-1 (CHIT1) was common to both comparisons and was proportional to ALS disability progression rate (Pearson r = 0.41, FDR-adjusted p = 0.035) but not overall survival. Ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1; upregulated in ALS versus healthy controls) was proportional to disability progression rate (Pearson r = 0.53, FDR-adjusted p = 0.003) and survival (Kaplan Meier log-rank p = 0.013) but not independently in multivariate proportional hazards models. Weighted correlation network analysis was used to identify functionally relevant modules of proteins. One module, enriched for inflammatory functions, was associated with age at symptom onset (Pearson r = 0.58, FDR-adjusted p = 0.005) and survival (Hazard Ratio = 1.78, FDR = 0.065), and a second module, enriched for endoplasmic reticulum proteins, was negatively correlated with disability progression rate (r = -0.42, FDR-adjusted p = 0.109). DIA acquisition methodology therefore strengthened the biomarker candidacy of CHIT1 and UCHL1 in ALS, while additionally highlighted inflammatory and endoplasmic reticulum proteins as novel sources of prognostic biomarkers.

The value of routine blood work-up in clinical stratification and prognosis of patients with amyotrophic lateral sclerosis

BACKGROUND

There is an unmet need in amyotrophic lateral sclerosis (ALS) to provide specific biomarkers for the disease. Due to their easy availability, we aimed to investigate whether routine blood parameters provide useful clues for phenotypic classification and disease prognosis.

METHODS

We analyzed a large inpatient cohort of 836 ALS patients who underwent deep phenotyping with evaluation of the clinical and neurophysiological burden of upper (UMN) and lower (LMN) motor neuron signs. Disability and progression rate were measured through the revised ALS Functional Rating Scale (ALSFRS-R) and its changes during time. Cox regression analysis was performed to assess survival associations.

RESULTS

Creatinine significantly correlated with LMN damage (r = 0.38), active (r = 0.18) and chronic (r = 0.24) denervation and baseline ALSFRS-R (r = 0.33). Creatine kinase (CK), alanine (ALT) and aspartate (AST) transaminases correlated with active (r = 0.35, r = 0.27, r = 0.24) and chronic (r = 0.37, r = 0.20, r = 0.19) denervation, while albumin and C-reactive protein significantly correlated with LMN score (r = 0.20 and r = 0.17). Disease progression rate showed correlations with chloride (r = -0.19) and potassium levels (r = -0.16). After adjustment for known prognostic factors, total protein [HR 0.70 (95% CI 0.57-0.86)], creatinine [HR 0.86 (95% CI 0.81-0.92)], chloride [HR 0.95 (95% CI 0.92-0.99)], lactate dehydrogenase [HR 0.99 (95% CI 0.99-0.99)], and AST [HR 1.02 (95% CI 1.01-1.02)] were independently associated with survival.

CONCLUSIONS

Creatinine is a reliable biomarker for ALS, associated with clinical features, disability and survival. Markers of nutrition/inflammation may offer additional prognostic information and partially correlate with clinical features. AST and chloride could further assist in predicting progression rate and survival.

Neurodegenerative biomarkers outperform neuroinflammatory biomarkers in amyotrophic lateral sclerosis

OBJECTIVE

To describe the diagnostic and prognostic performance, and longitudinal trajectories, of potential biomarkers of neuroaxonal degeneration and neuroinflammation in amyotrophic lateral sclerosis (ALS).

METHODS

This case-control study included 192 incident ALS patients, 42 ALS mimics, 114 neurological controls, and 117 healthy controls from Stockholm, Sweden. Forty-four ALS patients provided repeated measurements. We assessed biomarkers of (1)neuroaxonal degeneration: neurofilament light (NfL) and phosphorylated neurofilament heavy (pNfH) in cerebrospinal fluid (CSF) and NfL in serum, and (2)neuroinflammation: chitotriosidase-1 (CHIT1) and monocyte chemoattractant protein 1 (MCP-1) in CSF. To evaluate diagnostic performance, we calculated the area under the curve (AUC). To estimate prognostic performance, we applied quantile regression and Cox regression. We used linear regression models with robust standard errors to assess temporal changes over time.

RESULTS

Neurofilaments performed better at differentiating ALS patients from mimics (AUC: pNfH 0.92, CSF NfL 0.86, serum NfL 0.91) than neuroinflammatory biomarkers (AUC: CHIT1 0.71, MCP-1 0.56). Combining biomarkers did not improve diagnostic performance. Similarly, neurofilaments performed better than neuroinflammatory biomarkers at predicting functional decline and survival. The stratified analysis revealed differences according to the site of onset: in bulbar patients, neurofilaments and CHIT1 performed worse at predicting survival and correlations were lower between biomarkers. Finally, in bulbar patients, neurofilaments and CHIT1 increased longitudinally but were stable in spinal patients.

CONCLUSIONS

Biomarkers of neuroaxonal degeneration displayed better diagnostic and prognostic value compared with neuroinflammatory biomarkers. However, in contrast to spinal patients, in bulbar patients neurofilaments and CHIT1 performed worse at predicting survival and seemed to increase over time.

Biomarker Qualification for Neurofilament Light Chain in Amyotrophic Lateral Sclerosis: Theory and Practice

OBJECTIVE

To explore whether the utility of neurofilament light chain (NfL), as a biomarker to aid amyotrophic lateral sclerosis (ALS) therapy development, would be enhanced by obtaining formal qualification from the US Food and Drug Administration for a defined context-of-use.

METHODS

Consensus discussion among academic, industry, and patient advocacy group representatives.

RESULTS

A wealth of scientific evidence supports the use of NfL as a prognostic, response, and potential safety biomarker in the broad ALS population, and as a risk/susceptibility biomarker among the subset of SOD1 pathogenic variant carriers. Although NfL has not yet been formally qualified for any of these contexts-of-use, the US Food and Drug Administration has provided accelerated approval for an SOD1-lowering antisense oligonucleotide, based partially on the recognition that a reduction in NfL is reasonably likely to predict a clinical benefit.

INTERPRETATION

The increasing incorporation of NfL into ALS therapy development plans provides evidence that its utility-as a prognostic, response, risk/susceptibility, and/or safety biomarker-is already widely accepted by the community. The willingness of the US Food and Drug Administration to base regulatory decisions on rigorous peer-reviewed data-absent formal qualification, leads us to conclude that formal qualification, despite some benefits, is not essential for ongoing and future use of NfL as a tool to aid ALS therapy development. Although the balance of considerations for and against seeking NfL biomarker qualification will undoubtedly vary across different diseases and contexts-of-use, the robustness of the published data and careful deliberations of the ALS community may offer valuable insights for other disease communities grappling with the same issues. ANN NEUROL 2024;95:211-216.

A fluid biomarker reveals loss of TDP-43 splicing repression in presymptomatic ALS-FTD

Although loss of TAR DNA-binding protein 43 kDa (TDP-43) splicing repression is well documented in postmortem tissues of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), whether this abnormality occurs during early-stage disease remains unresolved. Cryptic exon inclusion reflects loss of function of TDP-43, and thus detection of proteins containing cryptic exon-encoded neoepitopes in cerebrospinal fluid (CSF) or blood could reveal the earliest stages of TDP-43 dysregulation in patients. Here we use a newly characterized monoclonal antibody specific to a TDP-43-dependent cryptic epitope (encoded by the cryptic exon found in HDGFL2) to show that loss of TDP-43 splicing repression occurs in ALS-FTD, including in presymptomatic C9orf72 mutation carriers. Cryptic hepatoma-derived growth factor-like protein 2 (HDGFL2) accumulates in CSF at significantly higher levels in familial ALS-FTD and sporadic ALS compared with controls and is elevated earlier than neurofilament light and phosphorylated neurofilament heavy chain protein levels in familial disease. Cryptic HDGFL2 can also be detected in blood of individuals with ALS-FTD, including in presymptomatic C9orf72 mutation carriers, and accumulates at levels highly correlated with those in CSF. Our findings indicate that loss of TDP-43 cryptic splicing repression occurs early in disease progression, even presymptomatically, and that detection of the HDGFL2 cryptic neoepitope serves as a potential diagnostic biomarker for ALS, which should facilitate patient recruitment and measurement of target engagement in clinical trials.

Peripheral immunity relate to disease progression and prognosis in amyotrophic lateral sclerosis

Background: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Abnormalities in the peripheral immune system in ALS have been paid attention; however, the results of changes in peripheral immune parameters were inconsistent. Methods: A total of 1109 ALS patients were enrolled in the study. All patients received clinical evaluation and peripheral immune parameters measurement. The outcomes were analyzed by correlation analysis, multiple linear regression and cox survival analysis. Results: We found that ALS patients had significantly higher percentage of CD4+ T cells (39.3 vs. 37.1%, p < 0.001) and CD4+/CD8+ ratio (1.88 vs. 1.72, p = 0.011), significantly lower IgG (11.73 vs.12.82, p < 0.001) and IgA (2130.70 vs. 2284.8, p = 0.013) compared with the health controls. In the multivariate linear model, we found that each increase of 1.262, 0.278, and 4.44E-4 in ALSFRS-R scores were significantly associated with each increment of lymphocyte count, IgG, and IgA, respectively. However, each decrease of 0.341, 0.068, and 0.682 in ALSFRS-R score was associated with each increment in neutrophils, CD4+ T cells, and CD4+/CD8+ ratio, respectively. Cox survival regression analysis showed that the death risk of ALS patients was related to the levels of C3 (HR 0.592, 95% CI 0.361-0.973). Conclusion: We found that there were differences in peripheral immune parameters of ALS patients with the severity of the disease, especially neutrophil, lymphocyte, CD4+ T, and IgG; C3 is an independent predictor of survival in ALS patients. More studies are needed to elucidate the mechanisms associated with altered immune parameters in ALS.

Fluid biomarkers for amyotrophic lateral sclerosis: a review

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the loss of upper and lower motor neurons. Presently, three FDA-approved drugs are available to help slow functional decline for patients with ALS, but no cure yet exists. With an average life expectancy of only two to five years after diagnosis, there is a clear need for biomarkers to improve the care of patients with ALS and to expedite ALS treatment development. Here, we provide a review of the efforts made towards identifying diagnostic, prognostic, susceptibility/risk, and response fluid biomarkers with the intent to facilitate a more rapid and accurate ALS diagnosis, to better predict prognosis, to improve clinical trial design, and to inform interpretation of clinical trial results. Over the course of 20 + years, several promising fluid biomarker candidates for ALS have emerged. These will be discussed, as will the exciting new strategies being explored for ALS biomarker discovery and development.

Emerging perspectives of synaptic biomarkers in ALS and FTD

Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD) are debilitating neurodegenerative diseases with shared pathological features like transactive response DNA-binding protein of 43 kDa (TDP-43) inclusions and genetic mutations. Both diseases involve synaptic dysfunction, contributing to their clinical features. Synaptic biomarkers, representing proteins associated with synaptic function or structure, offer insights into disease mechanisms, progression, and treatment responses. These biomarkers can detect disease early, track its progression, and evaluate therapeutic efficacy. ALS is characterized by elevated neurofilament light chain (NfL) levels in cerebrospinal fluid (CSF) and blood, correlating with disease progression. TDP-43 is another key ALS biomarker, its mislocalization linked to synaptic dysfunction. In FTD, TDP-43 and tau proteins are studied as biomarkers. Synaptic biomarkers like neuronal pentraxins (NPs), including neuronal pentraxin 2 (NPTX2), and neuronal pentraxin receptor (NPTXR), offer insights into FTD pathology and cognitive decline. Advanced technologies, like machine learning (ML) and artificial intelligence (AI), aid biomarker discovery and drug development. Challenges in this research include technological limitations in detection, variability across patients, and translating findings from animal models. ML/AI can accelerate discovery by analyzing complex data and predicting disease outcomes. Synaptic biomarkers offer early disease detection, personalized treatment strategies, and insights into disease mechanisms. While challenges persist, technological advancements and interdisciplinary efforts promise to revolutionize the understanding and management of ALS and FTD. This review will explore the present comprehension of synaptic biomarkers in ALS and FTD and discuss their significance and emphasize the prospects and obstacles.

Unsupervised machine learning identifies distinct ALS molecular subtypes in post-mortem motor cortex and blood expression data

Amyotrophic lateral sclerosis (ALS) displays considerable clinical and genetic heterogeneity. Machine learning approaches have previously been utilised for patient stratification in ALS as they can disentangle complex disease landscapes. However, lack of independent validation in different populations and tissue samples have greatly limited their use in clinical and research settings. We overcame these issues by performing hierarchical clustering on the 5000 most variably expressed autosomal genes from motor cortex expression data of people with sporadic ALS from the KCL BrainBank (N = 112). Three molecular phenotypes linked to ALS pathogenesis were identified: synaptic and neuropeptide signalling, oxidative stress and apoptosis, and neuroinflammation. Cluster validation was achieved by applying linear discriminant analysis models to cases from TargetALS US motor cortex (N = 93), as well as Italian (N = 15) and Dutch (N = 397) blood expression datasets, for which there was a high assignment probability (80-90%) for each molecular subtype. The ALS and motor cortex specificity of the expression signatures were tested by mapping KCL BrainBank controls (N = 59), and occipital cortex (N = 45) and cerebellum (N = 123) samples from TargetALS to each cluster, before constructing case-control and motor cortex-region logistic regression classifiers. We found that the signatures were not only able to distinguish people with ALS from controls (AUC 0.88 ± 0.10), but also reflect the motor cortex-based disease process, as there was perfect discrimination between motor cortex and the other brain regions. Cell types known to be involved in the biological processes of each molecular phenotype were found in higher proportions, reinforcing their biological interpretation. Phenotype analysis revealed distinct cluster-related outcomes in both motor cortex datasets, relating to disease onset and progression-related measures. Our results support the hypothesis that different mechanisms underpin ALS pathogenesis in subgroups of patients and demonstrate potential for the development of personalised treatment approaches. Our method is available for the scientific and clinical community at https://alsgeclustering.er.kcl.ac.uk .

Serum Neurofilaments in Motor Neuron Disease and Their Utility in Differentiating ALS, PMA and PLS

Neurofilament levels are elevated in many neurodegenerative diseases and have shown promise as diagnostic and prognostic biomarkers in Amyotrophic Lateral Sclerosis (ALS), the most common form of Motor Neuron Disease (MND). This study assesses serum neurofilament light (NFL) and neurofilament heavy (NFH) chain concentrations in patients with ALS, other variants of motor neuron disease such as Progressive Muscular Atrophy (PMA) and Primary Lateral Sclerosis (PLS), and a range of other neurological diseases. It aims to evaluate the use of NFL and NFH to differentiate these conditions and for the prognosis of MND disease progression. NFL and NFH levels were quantified using electrochemiluminescence immunoassays (ECLIA). Both were elevated in 47 patients with MND compared to 34 patients with other neurological diseases and 33 healthy controls. NFL was able to differentiate patients with MND from the other groups with a Receiver Operating Characteristic (ROC) curve area under the curve (AUC) of 0.90 (p < 0.001). NFL correlated with the rate of disease progression in MND (rho 0.758, p < 0.001) and with the ALS Functional Rating Scale (rho -0.335, p = 0.021). NFL levels were higher in patients with ALS compared to both PMA (p = 0.032) and PLS (p = 0.012) and were able to distinguish ALS from both PMA and PLS with a ROC curve AUC of 0.767 (p = 0.005). These findings support the use of serum NFL to help diagnose and differentiate types of MND, in addition to providing prognostic information to patients and their families.

Current State and Future Directions in the Therapy of ALS

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder affecting upper and lower motor neurons, with death resulting mainly from respiratory failure three to five years after symptom onset. As the exact underlying causative pathological pathway is unclear and potentially diverse, finding a suitable therapy to slow down or possibly stop disease progression remains challenging. Varying by country Riluzole, Edaravone, and Sodium phenylbutyrate/Taurursodiol are the only drugs currently approved in ALS treatment for their moderate effect on disease progression. Even though curative treatment options, able to prevent or stop disease progression, are still unknown, recent breakthroughs, especially in the field of targeting genetic disease forms, raise hope for improved care and therapy for ALS patients. In this review, we aim to summarize the current state of ALS therapy, including medication as well as supportive therapy, and discuss the ongoing developments and prospects in the field. Furthermore, we highlight the rationale behind the intense research on biomarkers and genetic testing as a feasible way to improve the classification of ALS patients towards personalized medicine.

Limited value of serum neurofilament light chain in diagnosing amyotrophic lateral sclerosis

A biomarker specific for the diagnosis of amyotrophic lateral sclerosis must be sensitive across a spectrum of clinical heterogeneity. Neurofilament light chain levels in amyotrophic lateral sclerosis correlate with the rate of disability progression. Previous attempts to establish a diagnostic role for neurofilament light chain have been limited to comparison with healthy individuals or controls with alternative diagnoses unlikely to be confused with amyotrophic lateral sclerosis in real-world clinical practice. In a tertiary amyotrophic lateral sclerosis referral clinic, at first visit, serum was taken for neurofilament light chain measurement after prospectively recording the clinical diagnosis as 'amyotrophic lateral sclerosis', 'primary lateral sclerosis', 'alternative' or 'currently uncertain'. Of 133 referrals, 93 patients were diagnosed with amyotrophic lateral sclerosis (median neurofilament light chain 218.1 pg/ml, interquartile range 130.7-311.9), three primary lateral sclerosis (65.6, 51.5-106.9) and 19 alternative diagnoses (45.2, 13.5-71.9) at first visit. Of 18 initially uncertain diagnoses, eight were subsequently diagnosed with amyotrophic lateral sclerosis (98.5, 45.3-300.1). Neurofilament light chain ≥110.9 pg/ml had a positive predictive value of 0.92 for amyotrophic lateral sclerosis; <110.9 pg/ml had a negative predictive value of 0.48. In a specialized clinic, neurofilament light chain is largely confirmatory to clinical judgement in diagnosing amyotrophic lateral sclerosis and has limited ability to exclude alternative diagnoses. The current, important, value of neurofilament light chain is its potential to stratify patients with amyotrophic lateral sclerosis by disease activity and as a biomarker in therapeutic trials.

Opinion: more mouse models and more translation needed for ALS

Amyotrophic lateral sclerosis is a complex disorder most of which is 'sporadic' of unknown origin but approximately 10% is familial, arising from single mutations in any of more than 30 genes. Thus, there are more than 30 familial ALS subtypes, with different, often unknown, molecular pathologies leading to a complex constellation of clinical phenotypes. We have mouse models for many genetic forms of the disorder, but these do not, on their own, necessarily show us the key pathological pathways at work in human patients. To date, we have no models for the 90% of ALS that is 'sporadic'. Potential therapies have been developed mainly using a limited set of mouse models, and through lack of alternatives, in the past these have been tested on patients regardless of aetiology. Cancer researchers have undertaken therapy development with similar challenges; they have responded by producing complex mouse models that have transformed understanding of pathological processes, and they have implemented patient stratification in multi-centre trials, leading to the effective translation of basic research findings to the clinic. ALS researchers have successfully adopted this combined approach, and now to increase our understanding of key disease pathologies, and our rate of progress for moving from mouse models to mechanism to ALS therapies we need more, innovative, complex mouse models to address specific questions.

Biofluid Biomarkers in the Prognosis of Amyotrophic Lateral Sclerosis: Recent Developments and Therapeutic Applications

Amyotrophic lateral sclerosis is a neurodegenerative disease characterized by the degeneration of motor neurons for which effective therapies are lacking. One of the most explored areas of research in ALS is the discovery and validation of biomarkers that can be applied to clinical practice and incorporated into the development of innovative therapies. The study of biomarkers requires an adequate theoretical and operational framework, highlighting the "fit-for-purpose" concept and distinguishing different types of biomarkers based on common terminology. In this review, we aim to discuss the current status of fluid-based prognostic and predictive biomarkers in ALS, with particular emphasis on those that are the most promising ones for clinical trial design and routine clinical practice. Neurofilaments in cerebrospinal fluid and blood are the main prognostic and pharmacodynamic biomarkers. Furthermore, several candidates exist covering various pathological aspects of the disease, such as immune, metabolic and muscle damage markers. Urine has been studied less often and should be explored for its possible advantages. New advances in the knowledge of cryptic exons introduce the possibility of discovering new biomarkers. Collaborative efforts, prospective studies and standardized procedures are needed to validate candidate biomarkers. A combined biomarkers panel can provide a more detailed disease status.

Performance of serum neurofilament light chain in a wide spectrum of clinical courses of amyotrophic lateral sclerosis-a cross-sectional multicenter study

BACKGROUND AND PURPOSE

The objective was to assess the performance of serum neurofilament light chain (sNfL) in amyotrophic lateral sclerosis (ALS) in a wide range of disease courses, in terms of progression, duration and tracheostomy invasive ventilation (TIV).

METHODS

A prospective cross-sectional study at 12 ALS centers in Germany was performed. sNfL concentrations were age adjusted using sNfL Z scores expressing the number of standard deviations from the mean of a control reference database and correlated to ALS duration and ALS progression rate (ALS-PR), defined by the decline of the ALS Functional Rating Scale.

RESULTS

In the total ALS cohort (n = 1378) the sNfL Z score was elevated (3.04; 2.46-3.43; 99.88th percentile). There was a strong correlation of sNfL Z score with ALS-PR (p < 0.001). In patients with long (5-10 years, n = 167) or very long ALS duration (>10 years, n = 94) the sNfL Z score was significantly lower compared to the typical ALS duration of <5 years (n = 1059) (p < 0.001). Furthermore, in patients with TIV, decreasing sNfL Z scores were found in correlation with TIV duration and ALS-PR (p = 0.002; p < 0.001).

CONCLUSIONS

The finding of moderate sNfL elevation in patients with long ALS duration underlined the favorable prognosis of low sNfL. The strong correlation of sNfL Z score with ALS-PR strengthened its value as progression marker in clinical management and research. The lowering of sNfL in correlation with long TIV duration could reflect a reduction either in disease activity or in the neuroaxonal substrate of biomarker formation during the protracted course of ALS.

Amyotrophic lateral sclerosis: a neurodegenerative disorder poised for successful therapeutic translation

Amyotrophic lateral sclerosis (ALS) is a devastating disease caused by degeneration of motor neurons. As with all major neurodegenerative disorders, development of disease-modifying therapies has proven challenging for multiple reasons. Nevertheless, ALS is one of the few neurodegenerative diseases for which disease-modifying therapies are approved. Significant discoveries and advances have been made in ALS preclinical models, genetics, pathology, biomarkers, imaging and clinical readouts over the last 10-15 years. At the same time, novel therapeutic paradigms are being applied in areas of high unmet medical need, including neurodegenerative disorders. These developments have evolved our knowledge base, allowing identification of targeted candidate therapies for ALS with diverse mechanisms of action. In this Review, we discuss how this advanced knowledge, aligned with new approaches, can enable effective translation of therapeutic agents from preclinical studies through to clinical benefit for patients with ALS. We anticipate that this approach in ALS will also positively impact the field of drug discovery for neurodegenerative disorders more broadly.

Label-free fibre optic Raman spectroscopy with bounded simplex-structured matrix factorization for the serial study of serum in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease in urgent need of disease biomarkers for the assessment of promising therapeutic candidates in clinical trials. Raman spectroscopy is an attractive technique for identifying disease related molecular changes due to its simplicity. Here, we describe a fibre optic fluid cell for undertaking spontaneous Raman spectroscopy studies of human biofluids that is suitable for use away from a standard laboratory setting. Using this system, we examined serum obtained from patients with ALS at their first presentation to our centre (n = 66) and 4 months later (n = 27). We analysed Raman spectra using bounded simplex-structured matrix factorization (BSSMF), a generalisation of non-negative matrix factorisation which uses the distribution of the original data to limit the factorisation modes (spectral patterns). Biomarkers associated with ALS disease such as measures of symptom severity, respiratory function and inflammatory/immune pathways (C3/C-reactive protein) correlated with baseline Raman modes. Between visit spectral changes were highly significant (p = 0.0002) and were related to protein structure. Comparison of Raman data with established ALS biomarkers as a trial outcome measure demonstrated a reduction in required sample size with BSSMF Raman. Our portable, simple to use fibre optic system allied to BSSMF shows promise in the quantification of disease-related changes in ALS over short timescales.

Safety and tolerability of bosutinib in patients with amyotrophic lateral sclerosis (iDReAM study): A multicentre, open-label, dose-escalation phase 1 trial

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease caused by the loss of motor neurons, and development of effective medicines is urgently required. Induced pluripotent stem cell (iPSC)-based drug repurposing identified the Src/c-Abl inhibitor bosutinib, which is approved for the treatment of chronic myelogenous leukemia (CML), as a candidate for the molecular targeted therapy of ALS.

METHODS

An open-label, multicentre, dose-escalation phase 1 study using a 3 + 3 design was conducted in 4 hospitals in Japan to evaluate the safety and tolerability of bosutinib in patients with ALS. Furthermore, the exploratory efficacy was evaluated using Revised ALS Functional Rating Scale (ALSFRS-R), predictive biomarkers including plasma neurofilament light chain (NFL) were explored, and single-cell RNA sequencing of iPSC-derived motor neurons was conducted. Patients, whose total ALSFRS-R scores decreased by 1-3 points during the 12-week, received escalating doses starting from 100 mg quaque die (QD) up to 400 mg QD based on dose-limiting toxicity (DLT) occurrence, and all participants who received one dose of the study drug were included in the primary analysis. This trial is registered with ClinicalTrials.gov, NCT04744532, as Induced pluripotent stem cell-based Drug Repurposing for Amyotrophic Lateral Sclerosis Medicine (iDReAM) study.

FINDINGS

Between March 29, 2019 and May 7, 2021, 20 patients were enrolled, 13 of whom received bosutinib treatment and 12 were included in the safety and efficacy analyses. No DLTs were observed up to 300 mg QD, but DLTs were observed in 3/3 patients of the 400 mg QD cohort. In all patients receiving 100 mg-400 mg, the prevalent adverse events (AEs) were gastrointestinal AEs in 12 patients (92.3%), liver function related AEs in 7 patients (53.8%), and rash in 3 patients (23.1%). The safety profile was consistent with that known for CML treatment, and ALS-specific AEs were not observed. A subset of patients (5/9 patients) was found to respond well to bosutinib treatment over the 12-week treatment period. It was found that the treatment-responsive patients could be distinguished by their lower levels of plasma NFL. Furthermore, single-cell RNA sequencing of iPSC-derived motor neurons revealed the pathogenesis related molecular signature in patients with ALS showing responsiveness to bosutinib.

INTERPRETATION

This is the first trial of a Src/c-Abl inhibitor, bosutinib, for patients with ALS. The safety and tolerability of bosutinib up to 300 mg, not 400 mg, in ALS were described, and responsiveness of patients on motor function was observed. Since this was an open-label trial within a short period with a limited number of patients, further clinical trials will be required.

FUNDING

AMED and iPS Cell Research Fund.

Creatine kinase and prognosis in amyotrophic lateral sclerosis: a literature review and multi-centre cohort analysis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a prognostically heterogeneous neurodegenerative disease. Blood creatine kinase (CK) level has been inconsistently reported as a prognostic biomarker and raised levels in some ALS patients have been presumed to reflect muscle wasting, which is also variable.

METHODS

MEDLINE was systematically searched for papers related to CK in ALS and the relevant studies were reviewed. Using data from 222 ALS patients in a multi-centre, prospective, longitudinal cohort, survival analyses using Kaplan-Meier and Cox proportional hazards models were undertaken in relation to CK and other prognostic factors.

RESULTS

Twenty-five studies investigating CK in ALS were identified, of which 10 specifically studied the link between CK and survival. Five studies observed no association, four found that higher CK levels were associated with longer survival and one, the opposite. In our cohort (n = 222), 39% of patients had a CK level above the laboratory reference range. Levels were higher in males compared to females (p < 0.001), in patients with limb versus bulbar onset of symptoms (p < 0.001) and in patients with higher lower motor neuron burden (p < 0.001). There was no significant trend in longitudinal CK values. Although a higher standardised log (CK) at first visit was associated with longer survival in univariate analysis (hazard ratio 0.75, p = 0.003), there was no significant association after adjusting for other prognostic covariates.

CONCLUSION

While raised CK levels in ALS do reflect lower motor neuron denervation to a large extent, they are not independently associated with survival when measured in the symptomatic phase of the disease.

Blood biomarkers in ALS: challenges, applications and novel frontiers

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease among adults. With diagnosis reached relatively late into the disease process, extensive motor cell loss narrows the window for therapeutic opportunities. Clinical heterogeneity in ALS and the lack of disease-specific biomarkers have so far led to large-sized clinical trials with long follow-up needed to define clinical outcomes. In advanced ALS patients, there is presently limited scope to use imaging or invasive cerebrospinal fluid (CSF) collection as a source of disease biomarkers. The development of more patient-friendly and accessible blood biomarker assays is hampered by analytical hurdles like the matrix effect of blood components. However, blood also provides the opportunity to identify disease-specific adaptive changes of the stoichiometry and conformation of target proteins and the endogenous immunological response to low-abundance brain peptides, such as neurofilaments (Nf). Among those biomarkers under investigation in ALS, the change in concentration before or after diagnosis of Nf has been shown to aid prognostication and to allow the a priori stratification of ALS patients into smaller sized and clinically more homogeneous cohorts, supporting more affordable clinical trials. Here, we discuss the technical hurdles affecting reproducible and sensitive biomarker measurement in blood. We also summarize the state of the art of non-CSF biomarkers in the study of prognosis, disease progression, and treatment response. We will then address the potential as disease-specific biomarkers of the newly discovered cryptic peptides which are formed down-stream of TDP-43 loss of function, the hallmark of ALS pathobiology.

Trial of Antisense Oligonucleotide Tofersen for SOD1 ALS

BACKGROUND

The intrathecally administered antisense oligonucleotide tofersen reduces synthesis of the superoxide dismutase 1 (SOD1) protein and is being studied in patients with amyotrophic lateral sclerosis (ALS) associated with mutations in SOD1 (SOD1 ALS).

METHODS

In this phase 3 trial, we randomly assigned adults with SOD1 ALS in a 2:1 ratio to receive eight doses of tofersen (100 mg) or placebo over a period of 24 weeks. The primary end point was the change from baseline to week 28 in the total score on the ALS Functional Rating Scale-Revised (ALSFRS-R; range, 0 to 48, with higher scores indicating better function) among participants predicted to have faster-progressing disease. Secondary end points included changes in the total concentration of SOD1 protein in cerebrospinal fluid (CSF), in the concentration of neurofilament light chains in plasma, in slow vital capacity, and in handheld dynamometry in 16 muscles. A combined analysis of the randomized component of the trial and its open-label extension at 52 weeks compared the results in participants who started tofersen at trial entry (early-start cohort) with those in participants who switched from placebo to the drug at week 28 (delayed-start cohort).

RESULTS

A total of 72 participants received tofersen (39 predicted to have faster progression), and 36 received placebo (21 predicted to have faster progression). Tofersen led to greater reductions in concentrations of SOD1 in CSF and of neurofilament light chains in plasma than placebo. In the faster-progression subgroup (primary analysis), the change to week 28 in the ALSFRS-R score was -6.98 with tofersen and -8.14 with placebo (difference, 1.2 points; 95% confidence interval [CI], -3.2 to 5.5; P = 0.97). Results for secondary clinical end points did not differ significantly between the two groups. A total of 95 participants (88%) entered the open-label extension. At 52 weeks, the change in the ALSFRS-R score was -6.0 in the early-start cohort and -9.5 in the delayed-start cohort (difference, 3.5 points; 95% CI, 0.4 to 6.7); non-multiplicity-adjusted differences favoring early-start tofersen were seen for other end points. Lumbar puncture-related adverse events were common. Neurologic serious adverse events occurred in 7% of tofersen recipients.

CONCLUSIONS

In persons with SOD1 ALS, tofersen reduced concentrations of SOD1 in CSF and of neurofilament light chains in plasma over 28 weeks but did not improve clinical end points and was associated with adverse events. The potential effects of earlier as compared with delayed initiation of tofersen are being further evaluated in the extension phase. (Funded by Biogen; VALOR and OLE ClinicalTrials.gov numbers, NCT02623699 and NCT03070119; EudraCT numbers, 2015-004098-33 and 2016-003225-41.).