Trial of Antisense Oligonucleotide Tofersen for SOD1 ALS

Multifaceted superoxide dismutase 1 expression in amyotrophic lateral sclerosis patients: a rare occurrence?

Amyotrophic lateral sclerosis (ALS) is a neuromuscular condition resulting from the progressive degeneration of motor neurons in the cortex, brainstem, and spinal cord. While the typical clinical phenotype of ALS involves both upper and lower motor neurons, human and animal studies over the years have highlighted the potential spread to other motor and non-motor regions, expanding the phenotype of ALS. Although superoxide dismutase 1 (SOD1) mutations represent a minority of ALS cases, the SOD1 gene remains a milestone in ALS research as it represents the first genetic target for personalized therapies. Despite numerous single case reports or case series exhibiting extramotor symptoms in patients with ALS mutations in SOD1 (SOD1-ALS), no studies have comprehensively explored the full spectrum of extramotor neurological manifestations in this subpopulation. In this narrative review, we analyze and discuss the available literature on extrapyramidal and non-motor features during SOD1-ALS. The multifaceted expression of SOD1 could deepen our understanding of the pathogenic mechanisms, pointing towards a multidisciplinary approach for affected patients in light of new therapeutic strategies for SOD1-ALS.

Nuclear pore dysfunction and disease: a complex opportunity

The separation of genetic material from bulk cytoplasm has enabled the evolution of increasingly complex organisms, allowing for the development of sophisticated forms of life. However, this complexity has created new categories of dysfunction, including those related to the movement of material between cellular compartments. In eukaryotic cells, nucleocytoplasmic trafficking is a fundamental biological process, and cumulative disruptions to nuclear integrity and nucleocytoplasmic transport are detrimental to cell survival. This is particularly true in post-mitotic neurons, where nuclear pore injury and errors to nucleocytoplasmic trafficking are strongly associated with neurodegenerative disease. In this review, we summarize the current understanding of nuclear pore biology in physiological and pathological contexts and discuss potential therapeutic approaches for addressing nuclear pore injury and dysfunctional nucleocytoplasmic transport.

Clinical and patient-reported outcomes and neurofilament response during tofersen treatment in SOD1-related ALS-A multicenter observational study over 18 months

INTRODUCTION/AIMS

In amyotrophic lateral sclerosis (ALS) caused by SOD1 mutations (SOD1-ALS), tofersen received accelerated approval in the United States and is available via expanded access programs (EAP) outside the United States. This multicenter study investigates clinical and patient-reported outcomes (PRO) and serum neurofilament light chain (sNfL) during tofersen treatment in an EAP in Germany.

METHODS

Sixteen SOD1-ALS patients receiving tofersen for at least 6 months were analyzed. The ALS progression rate (ALS-PR), as measured by the monthly change of the ALS functional rating scale-revised (ALSFRS-R), slow vital capacity (SVC), and sNfL were investigated. PRO included the Measure Yourself Medical Outcome Profile (MYMOP2), Treatment Satisfaction Questionnaire for Medication (TSQM-9), and Net Promoter Score (NPS).

RESULTS

Mean tofersen treatment was 11 months (6-18 months). ALS-PR showed a mean change of -0.2 (range 0 to -1.1) and relative reduction by 25%. Seven patients demonstrated increased ALSFRS-R. SVC was stable (mean 88%, range -15% to +28%). sNfL decreased in all patients except one heterozygous D91A-SOD1 mutation carrier (mean change of sNfL -58%, range -91 to +27%, p < .01). MYMOP2 indicated improved symptom severity (n = 10) or yet perception of partial response (n = 6). TSQM-9 showed high global treatment satisfaction (mean 83, SD 16) although the convenience of drug administration was modest (mean 50, SD 27). NPS revealed a very high recommendation rate for tofersen (NPS +80).

DISCUSSION

Data from this EAP supported the clinical and sNfL response to tofersen in SOD1-ALS. PRO suggested a favorable patient perception of tofersen treatment in clinical practice.

Cerebrospinal fluid and blood neurofilament light chain levels in amyotrophic lateral sclerosis and frontotemporal degeneration: A meta-analysis

BACKGROUND AND PURPOSE

Neurofilament light chain (NFL) has been shown to be increased in amyotrophic lateral sclerosis (ALS) and, to a lesser extent, in frontotemporal dementia (FTD). A meta-analysis of NFL in ALS and FTD was performed.

METHODS

Available studies comparing cerebrospinal fluid and blood NFL levels in ALS versus neurologically healthy controls (NHCs), other neurological diseases (ONDs) and ALS mimics, as well as in FTD and related entities (behavioural variant of FTD and frontotemporal lobar degeneration syndromes) versus NHCs, ONDs and other dementias were evaluated.

RESULTS

In ALS, both cerebrospinal fluid and blood levels of NFL were higher compared to other categories. In FTD, behavioural variant of FTD and frontotemporal lobar degeneration syndromes, NFL levels were consistently higher compared to NHCs; however, several comparisons with ONDs and other dementias did not demonstrate significant differences.

DISCUSSION

Amyotrophic lateral sclerosis is characterized by higher NFL levels compared to most other conditions. In contrast, NFL is not as good at discriminating FTD from other dementias.

Serum neurofilament light chain in distinct phenotypes of amyotrophic lateral sclerosis: A longitudinal, multicenter study

OBJECTIVE

To assess the performance of serum neurofilament light chain (sNfL) in clinical phenotypes of amyotrophic lateral sclerosis (ALS).

METHODS

In 2949 ALS patients at 16 ALS centers in Germany and Austria, clinical characteristics and sNfL were assessed. Phenotypes were differentiated for two anatomical determinants: (1) upper and/or lower motor involvement (typical, typMN; upper/lower motor neuron predominant, UMNp/LMNp; primary lateral sclerosis, PLS) and (2) region of onset and propagation of motor neuron dysfunction (bulbar, limb, flail-arm, flail-leg, thoracic onset). Phenotypes were correlated to sNfL, progression, and survival.

RESULTS

Mean sNfL was - compared to typMN (75.7 pg/mL, n = 1791) - significantly lower in LMNp (45.1 pg/mL, n = 413), UMNp (58.7 pg/mL n = 206), and PLS (37.6 pg/mL, n = 84). Also, sNfL significantly differed in the bulbar (92.7 pg/mL, n = 669), limb (64.1 pg/mL, n = 1305), flail-arm (46.4 pg/mL, n = 283), flail-leg (53.6 pg/mL, n = 141), and thoracic (74.5 pg/mL, n = 96) phenotypes. Binary logistic regression analysis showed highest contribution to sNfL elevation for faster progression (odds ratio [OR] 3.24) and for the bulbar onset phenotype (OR 1.94). In contrast, PLS (OR 0.20), LMNp (OR 0.45), and thoracic onset (OR 0.43) showed reduced contributions to sNfL. Longitudinal sNfL (median 12 months, n = 2862) showed minor monthly changes (<0.2%) across all phenotypes. Correlation of sNfL with survival was confirmed (p < 0.001).

CONCLUSIONS

This study underscored the correlation of ALS phenotypes - differentiated for motor neuron involvement and region of onset/propagation - with sNfL, progression, and survival. These phenotypes demonstrated a significant effect on sNfL and should be recognized as independent confounders of sNfL analyses in ALS trials and clinical practice.

Clinical characterization of common pathogenic variants of SOD1-ALS in Germany

Pathogenic variants in the Cu/Zn superoxide dismutase (SOD1) gene can be detected in approximately 2% of sporadic and 11% of familial amyotrophic lateral sclerosis (ALS) patients in Europe. We analyzed the clinical phenotypes of 83 SOD1-ALS patients focusing on patients carrying the most frequent (likely) pathogenic variants (R116G, D91A, L145F) in Germany. Moreover, we describe the effect of tofersen treatment on ten patients carrying these variants. R116G patients showed the most aggressive course of disease with a median survival of 22.0 months compared to 198.0 months in D91A and 87.0 months in L145F patients (HR 7.71, 95% CI 2.89-20.58 vs. D91A; p < 0.001 and HR 4.25, 95% CI 1.55-11.67 vs. L145F; p = 0.02). Moreover, R116G patients had the fastest median ALSFRS-R progression rate with 0.12 (IQR 0.07-0.20) points lost per month. Median diagnostic delay was 10.0 months (IQR 5.5-11.5) and therefore shorter compared to 57.5 months (IQR 14.0-83.0) in D91A (p < 0.001) and 21.5 months (IQR 5.8-38.8) in L145F (p = 0.21) carriers. As opposed to D91A carriers (50.0%), 96.2% of R116G (p < 0.001) and 100.0% of L145F (p = 0.04) patients reported a positive family history. During tofersen treatment, all patients showed a reduction of neurofilament light chain (NfL) serum levels, independent of the SOD1 variant. Patients with SOD1-ALS carrying R116G, D91A, or L145F variants show commonalities, but also differences in their clinical phenotype, including a faster progression rate with shorter survival in R116G, and a comparatively benign disease course in D91A carriers.

A patient-derived amyotrophic lateral sclerosis blood-brain barrier model for focused ultrasound-mediated anti-TDP-43 antibody delivery

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing neurodegenerative disorder with minimally effective treatment options. An important hurdle in ALS drug development is the non-invasive therapeutic access to the motor cortex currently limited by the presence of the blood-brain barrier (BBB). Focused ultrasound and microbubble (FUS+ MB) treatment is an emerging technology that was successfully used in ALS patients to temporarily open the cortical BBB. However, FUS+ MB-mediated drug delivery across ALS patients' BBB has not yet been reported. Similarly, the effects of FUS+ MB on human ALS BBB cells remain unexplored.

METHODS

Here we established the first FUS+ MB-compatible, fully-human ALS patient-cell-derived BBB model based on induced brain endothelial-like cells (iBECs) to study anti-TDP-43 antibody delivery and FUS+ MB bioeffects in vitro.

RESULTS

Generated ALS iBECs recapitulated disease-specific hallmarks of BBB pathology, including reduced BBB integrity and permeability, and TDP-43 proteinopathy. The results also identified differences between sporadic ALS and familial (C9orf72 expansion carrying) ALS iBECs reflecting patient heterogeneity associated with disease subgroups. Studies in these models revealed successful ALS iBEC monolayer opening in vitro with no adverse cellular effects of FUS+ MB as reflected by lactate dehydrogenase (LDH) release viability assay and the lack of visible monolayer damage or morphology change in FUS+ MB treated cells. This was accompanied by the molecular bioeffects of FUS+ MB in ALS iBECs including changes in expression of tight and adherens junction markers, and drug transporter and inflammatory mediators, with sporadic and C9orf72 ALS iBECs generating transient specific responses. Additionally, we demonstrated an effective increase in the delivery of anti-TDP-43 antibody with FUS+ MB in C9orf72 (2.7-fold) and sporadic (1.9-fold) ALS iBECs providing the first proof-of-concept evidence that FUS+ MB can be used to enhance the permeability of large molecule therapeutics across the BBB in a human ALS in vitro model.

CONCLUSIONS

Together, this study describes the first characterisation of cellular and molecular responses of ALS iBECs to FUS+ MB and provides a fully-human platform for FUS+ MB-mediated drug delivery screening on an ALS BBB in vitro model.

Mass spectrometry imaging of SOD1 protein-metal complexes in SOD1G93A transgenic mice implicates demetalation with pathology

Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of motor neurons in the central nervous system (CNS). Mutations in the metalloenzyme SOD1 are associated with inherited forms of ALS and cause a toxic gain of function thought to be mediated by dimer destabilization and misfolding. SOD1 binds two Cu and two Zn ions in its homodimeric form. We have applied native ambient mass spectrometry imaging to visualize the spatial distributions of intact metal-bound SOD1G93A complexes in SOD1G93A transgenic mouse spinal cord and brain sections and evaluated them against disease pathology. The molecular specificity of our approach reveals that metal-deficient SOD1G93A species are abundant in CNS structures correlating with ALS pathology whereas fully metalated SOD1G93A species are homogenously distributed. Monomer abundance did not correlate with pathology. We also show that the dimer-destabilizing post-translational modification, glutathionylation, has limited influence on the spatial distribution of SOD1 dimers.

Axonopathy Underlying Amyotrophic Lateral Sclerosis: Unraveling Complex Pathways and Therapeutic Insights

Amyotrophic Lateral Sclerosis (ALS) is a complex neurodegenerative disorder characterized by progressive axonopathy, jointly leading to the dying back of the motor neuron, disrupting both nerve signaling and motor control. In this review, we highlight the roles of axonopathy in ALS progression, driven by the interplay of multiple factors including defective trafficking machinery, protein aggregation, and mitochondrial dysfunction. Dysfunctional intracellular transport, caused by disruptions in microtubules, molecular motors, and adaptors, has been identified as a key contributor to disease progression. Aberrant protein aggregation involving TDP-43, FUS, SOD1, and dipeptide repeat proteins further amplifies neuronal toxicity. Mitochondrial defects lead to ATP depletion, oxidative stress, and Ca2+ imbalance, which are regarded as key factors underlying the loss of neuromuscular junctions and axonopathy. Mitigating these defects through interventions including neurotrophic treatments offers therapeutic potential. Collaborative research efforts aim to unravel ALS complexities, opening avenues for holistic interventions that target diverse pathological mechanisms.

Stem cell therapeutics and gene therapy for neurologic disorders

Rapid advances in biological knowledge and technological innovation have greatly advanced the fields of stem cell and gene therapies to combat a broad spectrum of neurologic disorders. Researchers are currently exploring a variety of stem cell types (e.g., embryonic, progenitor, induced pluripotent) and various transplantation strategies, each with its own advantages and drawbacks. Similarly, various gene modification techniques (zinc finger, TALENs, CRISPR-Cas9) are employed with various delivery vectors to modify underlying genetic contributors to neurologic disorders. While these two individual fields continue to blaze new trails, it is the combination of these technologies which enables genetically engineered stem cells and vastly increases investigational and therapeutic opportunities. The capability to culture and expand stem cells outside the body, along with their potential to correct genetic abnormalities in patient-derived cells or enhance cells with extra gene products, unleashes the full biological potential for innovative, multifaceted approaches to treat complex neurological disorders. In this review, we provide an overview of stem cell and gene therapies in the context of neurologic disorders, highlighting recent advances and current shortcomings, and discuss prospects for future therapies in clinical settings.

Rapid classification of a novel ALS-causing I149S variant in superoxide dismutase-1

Variants of the oxygen free radical scavenging enzyme superoxide dismutase-1 (SOD1) are associated with the neurodegenerative disease amyotrophic lateral sclerosis (ALS). These variants occur in roughly 20% of familial ALS cases, and 1% of sporadic ALS cases. Here, we identified a novel SOD1 variant in a patient in their 50s who presented with movement deficiencies and neuropsychiatric features. The variant was heterozygous and resulted in the isoleucine at position 149 being substituted with a serine (I149S). In silico analysis predicted the variant to be destabilizing to the SOD1 protein structure. Expression of the SOD1I149S variant with a C-terminal EGFP tag in neuronal-like NSC-34 cells resulted in extensive inclusion formation and reduced cell viability. Immunoblotting revealed that the intramolecular disulphide between Cys57 and Cys146 was fully reduced for SOD1I149S. Furthermore, SOD1I149S was highly susceptible to proteolytic digestion, suggesting a large degree of instability to the protein fold. Finally, fluorescence correlation spectroscopy and native-PAGE of cell lysates showed that SOD1I149S was monomeric in solution in comparison to the dimeric SOD1WT. This experimental data was obtained within 3 months and resulted in the rapid re-classification of the variant from a variant of unknown significance (VUS) to a clinically actionable likely pathogenic variant.

[Smell the smoke before one sees the fire-The oligosymptomatic prodromal phase of neurodegenerative diseases]

BACKGROUND

With the increasing development of disease-modifying causative treatment, the importance of early diagnosis and detection of asymptomatic or oligosymptomatic early stages of neurodegenerative diseases is increasing.

OBJECTIVE

Presentation of early stages of neurodegenerative diseases, diagnostic procedures for the early detection and possible treatment consequences.

MATERIAL AND METHODS

Selective literature search, discussion of basic research and expert recommendations.

RESULTS

Many neurodegenerative diseases have a prodromal phase preceding the manifest disease that can be diagnosed with current criteria. In this prodromal phase, those affected are often oligosymptomatic but in some cases can already be identified using biomarkers. These developments are already taken into account in diagnostic criteria for some of these prodromal phases. The prodromal phase, in turn, is preceded by an asymptomatic phase which, however, already shows molecular changes and can be identified by biomarkers in some diseases. The early identification and stratification of patients is particularly important when planning studies for disease-modifying treatment, and biomarkers are already being used in clinical trials for this purpose.

DISCUSSION

Biomarker-based identification of individuals in the prodromal phase of neurodegenerative diseases is already possible for some entities. People who show the first signs of a neurodegenerative disease can be referred to centers for clinical trials and observational studies.

Spatial enrichment and genomic analyses reveal the link of NOMO1 with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a severe motor neuron disease with uncertain genetic predisposition in most sporadic cases. The spatial architecture of cell types and gene expression are the basis of cell-cell interactions, biological function and disease pathology, but are not well investigated in the human motor cortex, a key ALS-relevant brain region. Recent studies indicated single nucleus transcriptomic features of motor neuron vulnerability in ALS motor cortex. However, the brain regional vulnerability of ALS-associated genes and the genetic link between region-specific genes and ALS risk remain largely unclear. Here, we developed an entropy-weighted differential gene expression matrix-based tool (SpatialE) to identify the spatial enrichment of gene sets in spatial transcriptomics. We benchmarked SpatialE against another enrichment tool (multimodal intersection analysis) using spatial transcriptomics data from both human and mouse brain tissues. To investigate regional vulnerability, we analysed three human motor cortex and two dorsolateral prefrontal cortex tissues for spatial enrichment of ALS-associated genes. We also used Cell2location to estimate the abundance of cell types in ALS-related cortex layers. To dissect the link of regionally expressed genes and ALS risk, we performed burden analyses of rare loss-of-function variants detected by whole-genome sequencing in ALS patients and controls, then analysed differential gene expression in the TargetALS RNA-sequencing dataset. SpatialE showed more accurate and specific spatial enrichment of regional cell type markers than multimodal intersection analysis in both mouse brain and human dorsolateral prefrontal cortex. Spatial transcriptomic analyses of human motor cortex showed heterogeneous cell types and spatial gene expression profiles. We found that 260 manually curated ALS-associated genes are significantly enriched in layer 5 of the motor cortex, with abundant expression of upper motor neurons and layer 5 excitatory neurons. Burden analyses of rare loss-of-function variants in Layer 5-associated genes nominated NOMO1 as a novel ALS-associated gene in a combined sample set of 6814 ALS patients and 3324 controls (P = 0.029). Gene expression analyses in CNS tissues revealed downregulation of NOMO1 in ALS, which is consistent with a loss-of-function disease mechanism. In conclusion, our integrated spatial transcriptomics and genomic analyses identified regional brain vulnerability in ALS and the association of a layer 5 gene (NOMO1) with ALS risk.

Failure of C9orf72 sense repeat-targeting antisense oligonucleotides: lessons learned and the path forward

The recent failure of two independent clinical trials targeting C9orf72 sense repeat-containing RNAs with antisense oligonucleotides was a great disappointment for the field. Cammack et al. discuss the data from these trials, possible reasons for the failures, and the future of C9orf72 therapeutic targeting moving forward.

Aberrant protein aggregation in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal disease. As its pathological mechanisms are not well understood, there are no efficient therapeutics for it at present. While it is highly heterogenous both etiologically and clinically, it has a common salient hallmark, i.e., aberrant protein aggregation (APA). The upstream pathogenesis and the downstream effects of APA in ALS are sophisticated and the investigation of this pathology would be of consequence for understanding ALS. In this paper, the pathomechanism of APA in ALS and the candidate treatment strategies for it are discussed.

Genotypes and phenotypes of motor neuron disease: an update of the genetic landscape in Scotland

BACKGROUND

Using the Clinical Audit Research and Evaluation of Motor Neuron Disease (CARE-MND) database and the Scottish Regenerative Neurology Tissue Bank, we aimed to outline the genetic epidemiology and phenotypes of an incident cohort of people with MND (pwMND) to gain a realistic impression of the genetic landscape and genotype-phenotype associations.

METHODS

Phenotypic markers were identified from the CARE-MND platform. Sequence analysis of 48 genes was undertaken. Variants were classified using a structured evidence-based approach. Samples were also tested for C9orf72 hexanucleotide expansions using repeat-prime PCR methodology.

RESULTS

339 pwMND donated a DNA sample: 44 (13.0%) fulfilled criteria for having a pathogenic variant/repeat expansion, 53.5% of those with a family history of MND and 9.3% of those without. The majority (30 (8.8%)) had a pathogenic C9orf72 repeat expansion, including two with intermediate expansions. Having a C9orf72 expansion was associated with a significantly lower Edinburgh Cognitive and Behavioural ALS Screen ALS-Specific score (p = 0.0005). The known pathogenic SOD1 variant p.(Ile114Thr), frequently observed in the Scottish population, was detected in 9 (2.7%) of total cases but in 17.9% of familial cases. Rare variants were detected in FUS and NEK1. One individual carried both a C9orf72 expansion and SOD1 variant.

CONCLUSIONS

Our results provide an accurate summary of MND demographics and genetic epidemiology. We recommend early genetic testing of people with cognitive impairment to ensure that C9orf72 carriers are given the best opportunity for informed treatment planning. Scotland is enriched for the SOD1 p.(Ile114Thr) variant and this has significant implications with regards to future genetically-targeted treatments.

Brain-body mechanisms contribute to sexual dimorphism in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common form of human motor neuron disease. It is characterized by the progressive degeneration of upper and lower motor neurons, leading to generalized motor weakness and, ultimately, respiratory paralysis and death within 3-5 years. The disease is shaped by genetics, age, sex and environmental stressors, but no cure or routine biomarkers exist for the disease. Male individuals have a higher propensity to develop ALS, and a different manifestation of the disease phenotype, than female individuals. However, the mechanisms underlying these sex differences remain a mystery. In this Review, we summarize the epidemiology of ALS, examine the sexually dimorphic presentation of the disease and highlight the genetic variants and molecular pathways that might contribute to sex differences in humans and animal models of ALS. We advance the idea that sexual dimorphism in ALS arises from the interactions between the CNS and peripheral organs, involving vascular, metabolic, endocrine, musculoskeletal and immune systems, which are strikingly different between male and female individuals. Finally, we review the response to treatments in ALS and discuss the potential to implement future personalized therapeutic strategies for the disease.

Long-term treatment of SOD1 ALS with tofersen: a multicentre experience in 17 patients

BACKGROUND

In Amyotrophic Lateral Sclerosis (ALS) patients with SOD1 mutation the intrathecal administration of tofersen slowed down the progression of disease in a controlled clinical study, but results were not statistically significant.

METHODS

In this multicentre, observational study, we evaluated a cohort of 27 ALS-SOD1 patients who were treated with tofersen, focussing on 17 patients who were followed for at least 48 weeks (median period of 84 weeks, range 48-108). We compared the clinical slopes, as measured by ALSFRS-R, MRC scale and Forced Vital Capacity, during tofersen treatment with retrospective data at 1 year prior to therapy. Cerebrospinal fluid (CSF) and serum neurofilament light chains (NFL) were measured in all patients.

RESULTS

Cumulative evaluation of the ALSFRS-R and MRC progression rates showed a statistically significant change during treatment with respect to the period prior to therapy (p = 0.023 and p = 0.007, respectively). The analysis of individual patients showed that nine of the seventeen patients substantially stabilized or slightly improved. Four patients deteriorated during treatment, while in the remaining patients the very slow course did not allow to identify significant changes. CSF and serum NFL concentration markedly decreased in the near totality of patients. Increased levels of white blood cells and proteins in the CSF were found in 60% of patients. Such alterations were clinically asymptomatic in all but two patients who showed an acute pure motor radiculitis, which responded to steroid therapy.

CONCLUSIONS

Clinical findings and NFL analysis strongly suggest that tofersen may have a disease-modifying effect in a subset of SOD1-ALS patients.

Tofersen decreases neurofilament levels supporting the pathogenesis of the SOD1 p.D91A variant in amyotrophic lateral sclerosis patients

BACKGROUND

Since the antisense oligonucleotide tofersen has recently become available for the treatment of amyotrophic lateral sclerosis (ALS) caused by mutations in SOD1, determining the causality of the over 230 SOD1 variants has become even more important. The most common SOD1 variant worldwide is p.D91A (c.272A > C), whose causality for ALS is contested when in a heterozygous state. The reason is the high allele frequency of SOD1D91A in Europe, exceeding 1% in Finno-Scandinavia.

METHODS

We present the clinical disease course and serum neurofilament light chain (NfL) results of treating 11 patients either homo- or heterozygous for the SOD1D91A allele for up to 16 months with tofersen.

RESULTS

Tofersen decreases serum neurofilament levels (sNFL), which are associated with the ALS progression rate, in the 6 ALS patients homozygous for SOD1D91A. We observe significantly lower sNfL levels in the 5 patients heterozygous for SOD1D91A. The results indicate that both mono- and bi-allelic SOD1D91A are causally relevant targets, with a possibly reduced effect size of SOD1D91Ahet.

CONCLUSIONS

The finding is relevant for decision making regarding tofersen treatment, patient counseling and inclusion of SOD1D91A patients in drug trials. As far as we are aware, the approach is conceptually new since it provides evidence for the causality of an ALS variant based on a biomarker response to gene-specific treatment.

predicTTE: An accessible and optimal tool for time-to-event prediction in neurological diseases

Time-to-event prediction is a key task for biological discovery, experimental medicine, and clinical care. This is particularly true for neurological diseases where development of reliable biomarkers is often limited by difficulty visualising and sampling relevant cell and molecular pathobiology. To date, much work has relied on Cox regression because of ease-of-use, despite evidence that this model includes incorrect assumptions. We have implemented a set of deep learning and spline models for time-to-event modelling within a fully customizable 'app' and accompanying online portal, both of which can be used for any time-to-event analysis in any disease by a non-expert user. Our online portal includes capacity for end-users including patients, Neurology clinicians, and researchers, to access and perform predictions using a trained model, and to contribute new data for model improvement, all within a data-secure environment. We demonstrate a pipeline for use of our app with three use-cases including imputation of missing data, hyperparameter tuning, model training and independent validation. We show that predictions are optimal for use in downstream applications such as genetic discovery, biomarker interpretation, and personalised choice of medication. We demonstrate the efficiency of an ensemble configuration, including focused training of a deep learning model. We have optimised a pipeline for imputation of missing data in combination with time-to-event prediction models. Overall, we provide a powerful and accessible tool to develop, access and share time-to-event prediction models; all software and tutorials are available at www.predictte.org.

Safety, tolerability, and pharmacokinetics of antisense oligonucleotide BIIB078 in adults with C9orf72-associated amyotrophic lateral sclerosis: a phase 1, randomised, double blinded, placebo-controlled, multiple ascending dose study

BACKGROUND

Hexanucleotide repeat expansion of C9orf72 is a common genetic cause of amyotrophic lateral sclerosis (ALS). No C9orf72-targeted treatments are available. BIIB078 is an investigational antisense oligonucleotide targeting C9orf72 sense RNA. We aimed to assess the safety, tolerability, and pharmacokinetics of BIIB078 in participants with C9orf72-associated ALS.

METHODS

This phase 1, randomised controlled trial was done at 22 sites in six countries (Canada, Ireland, Netherlands, Switzerland, UK, and USA). Adults with ALS and a pathogenic repeat expansion in C9orf72 were randomly assigned within six cohorts, via Interactive Response Technology in a 3:1 ratio per cohort, to receive BIIB078 (5 mg, 10 mg, 20 mg, 35 mg, 60 mg, or 90 mg in cohorts 1-6, respectively) or placebo, via an intrathecal bolus injection. The treatment period consisted of three loading doses of study treatment, administered approximately once every 2 weeks, followed by monthly maintenance doses during a treatment period of about 3 months for cohorts 1-3 and about 6 months for cohorts 4-6. Patients and investigators were masked to treatment assignment. The primary endpoint was the incidence of adverse events and serious adverse events. This trial was registered with ClinicalTrials.gov (NCT03626012) and is completed.

FINDINGS

Between Sept 10, 2018, and Nov 17, 2021, 124 patients were screened for inclusion in the study. 18 patients were excluded and 106 participants were enrolled and randomly assigned to receive 5 mg (n=6), 10 mg (n=9), 20 mg (n=9), 35 mg (n=19), 60 mg (n=18), or 90 mg (n=18) of BIIB078, or placebo (n=27). 58 (55%) of 106 patients were female. All patients received at least one dose of study treatment and were included in all analyses. All participants had at least one adverse event; most adverse events were mild or moderate in severity and did not lead to treatment discontinuation. The most common adverse events in BIIB078-treated participants were falls, procedural pain, headache, and post lumbar puncture syndrome. 14 (18%) of 79 patients who received any dose of BIIB078 reported serious adverse events, compared with nine (33%) of 27 patients who received placebo. Five participants who received BIIB078 and three participants who received placebo had fatal adverse events: respiratory failure in a participant who received 10 mg BIIB078, ALS worsening in two participants who received 35 mg BIIB078, traumatic intracerebral haemorrhage in one participant who received 35 mg BIIB078, pulmonary embolism in one participant who received 60 mg BIIB078, and respiratory failure in three participants who received placebo. All deaths were assessed as not related to the study treatment by the reporting investigator.

INTERPRETATION

On the basis of these phase 1 study results, including secondary and exploratory findings showing no reduction in neurofilament levels and no benefit on clinical outcomes relative to the placebo cohort, BIIB078 clinical development has been discontinued. However, these results will be informative in furthering our understanding of the complex pathobiology of C9orf72-associated ALS.

FUNDING

Biogen.

Changes in Cerebrospinal Fluid Concentrations of Selenium Species Induced by Tofersen Administration in Subjects with Amyotrophic Lateral Sclerosis Carrying SOD1 Gene Mutations

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting the brain and spinal cord motor neurons. On 25 April 2023, the drug tofersen, an antisense oligonucleotide, received the US Food and Drug Administration approval for treating ALS in adults carrying mutations of the SOD1 gene. We aimed at assessing whether cerebrospinal fluid concentrations of selenium, an element of both toxicological and nutritional interest possibly involved in disease etiology and progression, are modified by tofersen administration. We determined concentrations of selenium species by anion exchange chromatography hyphenated to inductively coupled plasma-dynamic reaction cell-mass spectrometry and overall selenium by using inductively coupled plasma sector-field mass spectrometry, at baseline and 6 months after active tofersen treatment in ten Italian ALS patients carrying the SOD1 gene mutation. Concentrations of total selenium and many selenium species substantially increased after the intervention, particularly of inorganic (tetravalent and hexavalent) selenium and of the organic species selenomethionine and a compound co-eluting with the selenocystine standard. Overall, these findings suggest that tofersen treatment markedly alters selenium status and probably the redox status within the central nervous system, possibly due to a direct effect on neurons and/or the blood-brain barrier. Further studies are required to investigate the biological and clinical relevance of these findings and how they might relate to the pharmacological effects of the drug and to disease progression.

Head-to-head comparison of four plasma neurofilament light chain (NfL) immunoassays

BACKGROUND

Neurofilament Light Chain (NfL) is an emerging blood biomarker of neuro-axonal injury and neurodegeneration with the potential to be used in the clinical management of various neurological conditions. Various NfL immunoassays are in development on high-throughput automated systems, but little information is available related to the comparability between assays. In this study, we performed a head-to-head comparison of four NfL immunoassays using plasma samples from individuals with various neurological conditions.

METHODS

EDTA plasma samples in which NfL was ordered clinically were stratified according to diagnosis. NfL concentrations (pg/mL) in plasma were obtained using the Quanterix Simoa®, the Roche Elecsys, the Siemens Healthineers Atellica®IM, and the Fujirebio Lumipulse® NfL assays. Passing-Bablok regression analyses were performed to assess the correlation and bias between methods. Additionally, the distribution of NfL concentrations for each assay was assessed in three disease groups: amyotrophic lateral sclerosis (ALS) upon initial diagnosis, ALS treated, and multiple sclerosis (MS).

RESULTS

The R2 between assays were all ≥ 0.95, however, significant proportional bias was observed between some assays. In particular, the Roche Elecsys assay NfL concentrations were significantly lower (∼85 %) when compared against the other three assays. The four assays were comparable with regards to the percentage of patients that were identified as having an elevated NfL result in the various clinical groups: ALS initial diagnoses (83-94 %), ALS untreated (93-100 %), and MS (8-18 %).

CONCLUSIONS

This is the first study describing a head-to-head comparison of four automated NfL immunoassays. We demonstrate that there is a strong correlation between assays but a lack of standardization which is evident by the bias observed between some of the evaluated methods. These analytical differences will be important to consider when using NfL as a biomarker of neurodegeneration.

Specialist referrals and diagnostic delays in motor neurone disease: Mapping patients' journey through hoops and hurdles in healthcare

Motor neuron disease (MND) is an uncommon but invariably fatal condition, with a median survival of 24-48 months from symptom onset. Although there is no cure at the moment, early diagnosis is crucial to enable timely access to multidisciplinary care, and enrolment in clinical trials utilising investigational therapies. Unfortunately, diagnostic delays remain common, and the average delay between symptom onset and diagnosis is 12 months. Large numbers of specialist referrals have been suggested as a key contributor to diagnostic delays. We conducted a retrospective review of the medical records of patients diagnosed with MND in Lancashire and South Cumbria, to investigate whether large numbers of specialty referrals are a common occurrence in MND. Our review identified that 35% of patients with MND were seen by two or more specialties before being referred to neurology. This rose to 49% when patients with bulbar onset disease were considered. 9% of cases saw three or more specialists. There was a statistically significant correlation between the number of specialist referrals and delays in neurology referral. We hope our findings will increase awareness of the importance of early neurology referral in the diagnosis of MND and promote the use of the MND Red Flag tool as a means of identifying patients in need of prompt neurological evaluation.

Copper toxicity and deficiency: the vicious cycle at the core of protein aggregation in ALS

The pathophysiology of ALS involves many signs of a disruption in copper homeostasis, with both excess free levels and functional deficiency likely occurring simultaneously. This is crucial, as many important physiological functions are performed by cuproenzymes. While it is unsurprising that many ALS symptoms are related to signs of copper deficiency, resulting in vascular, antioxidant system and mitochondrial oxidative respiration deficiencies, there are also signs of copper toxicity such as ROS generation and enhanced protein aggregation. We discuss how copper also plays a key role in proteostasis and interacts either directly or indirectly with many of the key aggregate-prone proteins implicated in ALS, such as TDP-43, C9ORF72, SOD1 and FUS as well as the effect of their aggregation on copper homeostasis. We suggest that loss of cuproprotein function is at the core of ALS pathology, a condition that is driven by a combination of unbound copper and ROS that can either initiate and/or accelerate protein aggregation. This could trigger a positive feedback cycle whereby protein aggregates trigger the aggregation of other proteins in a chain reaction that eventually captures elements of the proteostatic mechanisms in place to counteract them. The end result is an abundance of aggregated non-functional cuproproteins and chaperones alongside depleted intracellular copper stores, resulting in a general lack of cuproenzyme function. We then discuss the possible aetiology of ALS and illustrate how strong risk factors including environmental toxins such as BMAA and heavy metals can functionally behave to promote protein aggregation and disturb copper metabolism that likely drives this vicious cycle in sporadic ALS. From this synthesis, we propose restoration of copper balance using copper delivery agents in combination with chaperones/chaperone mimetics, perhaps in conjunction with the neuroprotective amino acid serine, as a promising strategy in the treatment of this incurable disease.

The genetics of amyotrophic lateral sclerosis

PURPOSE OF REVIEW

Amyotrophic lateral sclerosis (ALS) has a strong genetic basis, but the genetic landscape of ALS appears to be complex. The purpose of this article is to review recent developments in the genetics of ALS.

RECENT FINDINGS

Large-scale genetic studies have uncovered more than 40 genes contributing to ALS susceptibility. Both rare variants with variable effect size and more common variants with small effect size have been identified. The most common ALS genes are C9orf72, SOD1, TARDBP and FUS. Some of the causative genes of ALS are shared with frontotemporal dementia, confirming the molecular link between both diseases. Access to diagnostic gene testing for ALS has to improve, as effective gene silencing therapies for some genetic subtypes of ALS are emerging, but there is no consensus about which genes to test for.

SUMMARY

Our knowledge about the genetic basis of ALS has improved and the first effective gene silencing therapies for specific genetic subtypes of ALS are underway. These therapeutic advances underline the need for better access to gene testing for people with ALS. Further research is needed to further map the genetic heterogeneity of ALS and to establish the best strategy for gene testing in a clinical setting.

Targeting calciumopathy for neuroprotection: focus on calcium channels Cav1, Orai1 and P2X7

As the uncontrolled entry of calcium ions (Ca2+) through plasmalemmal calcium channels is a cell death trigger, the conjecture is here raised that mitigating such an excess of Ca2+ entry should rescue from death the vulnerable neurons in neurodegenerative diseases (NDDs). However, this supposition has failed in some clinical trials (CTs). Thus, a recent CT tested whether isradipine, a blocker of the Cav1 subtype of voltage-operated calcium channels (VOCCs), exerted a benefit in patients with Parkinson's disease (PD); however, outcomes were negative. This is one more of the hundreds of CTs done under the principle of one-drug-one-target, that have failed in Alzheimer's disease (AD) and other NDDs during the last three decades. As there are myriad calcium channels to let Ca2+ ions gain the cell cytosol, it seems reasonable to predict that blockade of Ca2+ entry through a single channel may not be capable of preventing the Ca2+ flood of cells by the uncontrolled Ca2+ entry. Furthermore, as Ca2+ signaling is involved in the regulation of myriad functions in different cell types, it seems also reasonable to guess that a therapy should be more efficient by targeting different cells with various drugs. Here, we propose to mitigate Ca2+ entry by the simultaneous partial blockade of three quite different subtypes of plasmalemmal calcium channels that is, the Cav1 subtype of VOCCs, the Orai1 store-operated calcium channel (SOCC), and the purinergic P2X7 calcium channel. All three channels are expressed in both microglia and neurons. Thus, by targeting the three channels with a combination of three drug blockers we expect favorable changes in some of the pathogenic features of NDDs, namely (i) to mitigate Ca2+ entry into microglia; (ii) to decrease the Ca2+-dependent microglia activation; (iii) to decrease the sustained neuroinflammation; (iv) to decrease the uncontrolled Ca2+ entry into neurons; (v) to rescue vulnerable neurons from death; and (vi) to delay disease progression. In this review we discuss the arguments underlying our triad hypothesis in the sense that the combination of three repositioned medicines targeting Cav1, Orai1, and P2X7 calcium channels could boost neuroprotection and delay the progression of AD and other NDDs.

The MuSK agonist antibody protects the neuromuscular junction and extends the lifespan in C9orf72-ALS mice

The disassembly of the neuromuscular junction (NMJ) is an early event in amyotrophic lateral sclerosis (ALS), ultimately leading to motor dysfunction and lethal respiratory paralysis. The hexanucleotide GGGGCC repeat expansion in the C9orf72 gene is the most common genetic mutation, and the dipeptide repeat (DPR) proteins have been shown to cause neurodegeneration. While no drugs can treat ALS patients efficiently, new treatment strategies are urgently needed. Here, we report that a MuSK agonist antibody alleviates poly-PR-induced NMJ deficits in C9orf72-ALS mice. The HB9-PRF/F mice, which express poly-PR proteins in motor neurons, exhibited impaired motor behavior and NMJ deficits. Mechanistically, poly-PR proteins interacted with Agrin to disrupt the interaction between Agrin and Lrp4, leading to attenuated activation of MuSK. Treatment with a MuSK agonist antibody rescued NMJ deficits, and extended the lifespan of C9orf72-ALS mice. Moreover, impaired NMJ transmission was observed in C9orf72-ALS patients. These findings identify the mechanism by which poly-PR proteins attenuate MuSK activation and NMJ transmission, highlighting the potential of promoting MuSK activation with an agonist antibody as a therapeutic strategy to protect NMJ function and prolong the lifespan of ALS patients.

NLRP3 inflammasome signalling in Alzheimer's disease

Every year, 10 million people develop dementia, the most common of which is Alzheimer's disease (AD). To date, there is no way to prevent cognitive decline and therapies are limited. This review provides a neuroimmunological perspective on the progression of AD, and discusses the immune-targeted therapies that are in preclinical and clinical trials that may impact the development of this disease. Specifically, we look to the role of the NLRP3 inflammasome, its triggers in the brain and how its activation can contribute to the progression of dementia. We summarise the range of inhibitors targeting the NLRP3 inflammasome and its downstream pathways that are under investigation, and discuss future therapeutic perspectives for this devastating condition.

High Frequency of Cognitive and Behavioral Impairment in Amyotrophic Lateral Sclerosis Patients with SOD1 Pathogenic Variants

OBJECTIVE

While the cognitive-behavioral characteristics of amyotrophic lateral sclerosis (ALS) patients carrying C9orf72 pathological repeat expansion have been extensively studied, our understanding of those carrying SOD1 variants is mostly based on case reports. The aim of this paper is to extensively explore the cognitive-behavioral characteristics of a cohort of ALS patients carrying pathogenetic variants of SOD1 gene, comparing them to patients without pathogenetic variants of 46 ALS-related genes (wild-type [WT]-ALS) and healthy controls.

METHODS

All ALS patients seen at the Turin ALS expert center in the 2009-2021 period who underwent both cognitive/behavioral and extensive genetic testing were eligible to be included in the study. Only patients with SOD1 pathogenetic variants (n = 28) (SOD1-ALS) and WT-ALS (n = 829) were enrolled in the study. A series of 129 controls was also included.

RESULTS

Among the 28 SOD1-ALS patients, 16 (57.1%) had normal cognitive function, 5 (17.9%) isolated cognitive impairment (ALSci) (17.9%), 6 (21.4%) isolated behavioral impairment (ALSbi), 1 (3.6%) cognitive and behavioral impairment (ALScbi), and no one ALS-FTD. SOD1-ALS performed worse than controls in all explored domains, in particular Social Cognition and Language domains. SOD1-ALS patients had similar scores in all tests compared to WT-ALS, except the Story-based Empathy Task (SET), where they performed worse.

INTERPRETATION

Cognitive-behavioral impairment is much more common in SOD1 patients than previously assumed. SOD1-ALS are characterized by a more frequent impairment of Social Cognition and, less markedly, of Language domains. These findings have relevant implication both in the clinical and in the research setting, also considering recently approved treatment for SOD1-ALS. ANN NEUROL 2024;96:150-158.

Update on recent advances in amyotrophic lateral sclerosis

In the last few years, our understanding of disease molecular mechanisms underpinning ALS has advanced greatly, allowing the first steps in translating into clinical practice novel research findings, including gene therapy approaches. Similarly, the recent advent of assistive technologies has greatly improved the possibility of a more personalized approach to supportive and symptomatic care, in the context of an increasingly complex multidisciplinary line of actions, which remains the cornerstone of ALS management. Against this rapidly growing background, here we provide an comprehensive update on the most recent studies that have contributed towards our understanding of ALS pathogenesis, the latest results from clinical trials as well as the future directions for improving the clinical management of ALS patients.

Safety and efficacy of arimoclomol in patients with early amyotrophic lateral sclerosis (ORARIALS-01): a randomised, double-blind, placebo-controlled, multicentre, phase 3 trial

BACKGROUND

Amyotrophic lateral sclerosis is a progressive neurodegenerative disorder leading to muscle weakness and respiratory failure. Arimoclomol, a heat-shock protein-70 (HSP70) co-inducer, is neuroprotective in animal models of amyotrophic lateral sclerosis, with multiple mechanisms of action, including clearance of protein aggregates, a pathological hallmark of sporadic and familial amyotrophic lateral sclerosis. We aimed to evaluate the safety and efficacy of arimoclomol in patients with amyotrophic lateral sclerosis.

METHODS

ORARIALS-01 was a multinational, randomised, double-blind, placebo-controlled, parallel-group trial done at 29 centres in 12 countries in Europe and North America. Patients were eligible if they were aged 18 years or older and met El Escorial criteria for clinically possible, probable, probable laboratory-supported, definite, or familial amyotrophic lateral sclerosis; had an ALS Functional Rating Scale-Revised score of 35 or more; and had slow vital capacity at 70% or more of the value predicted on the basis of the participant's age, height, and sex. Patients were randomly assigned (2:1) in blocks of 6, stratified by use of a stable dose of riluzole or no riluzole use, to receive oral arimoclomol citrate 1200 mg/day (400 mg three times per day) or placebo. The Randomisation sequence was computer generated centrally. Investigators, study personnel, and study participants were masked to treatment allocation. The primary outcome was the Combined Assessment of Function and Survival (CAFS) rank score over 76 weeks of treatment. The primary outcome and safety were analysed in the modified intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT03491462, and is completed.

FINDINGS

Between July 31, 2018, and July 17, 2019, 287 patients were screened, 245 of whom were enrolled in the trial and randomly assigned. The modified intention-to-treat population comprised 239 patients (160 in the arimoclomol group and 79 in the placebo group): 151 (63%) were male and 88 (37%) were female; mean age was 57·6 years (SD 10·9). CAFS score over 76 weeks did not differ between groups (mean 0·51 [SD 0·29] in the arimoclomol group vs 0·49 [0·28] in the placebo group; p=0·62). Cliff's delta comparing the two groups was 0·039 (95% CI -0·116 to 0·194). Proportions of participants who died were similar between the treatment groups: 29 (18%) of 160 patients in the arimoclomol group and 18 (23%) of 79 patients in the placebo group. Most deaths were due to disease progression. The most common adverse events were gastrointestinal. Adverse events were more often deemed treatment-related in the arimoclomol group (104 [65%]) than in the placebo group (41 [52%]) and more often led to treatment discontinuation in the arimoclomol group (26 [16%]) than in the placebo group (four [5%]).

INTERPRETATION

Arimoclomol did not improve efficacy outcomes compared with placebo. Although available biomarker data are insufficient to preclude future strategies that target the HSP response, safety data suggest that a higher dose of arimoclomol would not have been tolerated.

FUNDING

Orphazyme.

Genetic diagnosis and detection rates using C9orf72 repeat expansion and a multi-gene panel in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder. It is mostly sporadic, with the C9orf72 repeat expansion being the most common genetic cause. While the prevalence of C9orf72-ALS in patients from different populations has been studied, data regarding the yield of C9orf72 compared to an ALS gene panel testing is limited.We aimed to explore the application of C9orf72 versus a gene panel in the general Israeli population. A total of 140 ALS patients attended our Neurogenetics Clinic throughout 2018-2023. Disease onset was between ages 60 and 69 years for most patients (34%); however, a quarter had an early-onset disease (< 50 years). Overall, 119 patients (85%) were genetically evaluated: 116 (97%) were tested for the C9orf72 repeat expansion and 64 (54%) underwent gene panel testing. The C9orf72 repeat expansion had a prevalence of 21% among Ashkenazi Jewish patients compared to 5.7% in non-Ashkenazi patients, while the gene panel had a higher yield in non-Ashkenazi patients with 14% disease-causing variants compared to 5.7% in Ashkenazi Jews. Among early-onset ALS patients, panel testing was positive in 12% compared to 2.9% for C9orf72.We suggest a testing strategy for the Israeli ALS patients: C9orf72 should be the first-tier test in Ashkenazi Jewish patients, while a gene panel should be considered as the first step in non-Ashkenazi and early-onset patients. Tiered testing has important implications for patient management, including prognosis, ongoing clinical trials, and prevention in future generations. Similar studies should be implemented worldwide to uncover the diverse ALS genetic architecture and facilitate tailored care.

Sodium Phenylbutyrate and Tauroursodeoxycholic Acid: A Story of Hope Turned to Disappointment in Amyotrophic Lateral Sclerosis Treatment

The absence of a definitive cure for amyotrophic lateral sclerosis (ALS) emphasizes the crucial need to explore new and improved treatment approaches for this fatal, progressive, and disabling neurodegenerative disorder. As at the end of 2023, five treatments - riluzole, edaravone, dextromethorphan hydrobromide + quinidine sulfate (DHQ), tofersen, and sodium phenylbutyrate-tauroursodeoxycholic acid (PB-TUDCA) - were FDA approved for the treatment of patients with ALS. Among them PB-TUDCA has been shown to impact DNA processing impairments, mitochondria dysfunction, endoplasmic reticulum stress, oxidative stress, and pathologic folded protein agglomeration defects, which have been associated with ALS pathophysiology. The Phase 2 CENTAUR trial demonstrated significant impact of PB-TUDCA on the ALS Functional Rating Scale-Revised (ALSFRS-R) risk of death, hospitalization, and the need for tracheostomy or permanent assisted ventilation in patients with ALS based on post hoc analyses. More recently, contrasting with the CENTAUR trial results, results from the Phase 3 PHOENIX trial (NCT05021536) showed no change in ALSFRS-R total score at 48 weeks. Consequently, the sponsor company initiated the process with the US FDA and Health Canada to voluntarily withdraw the marketing authorizations for PB-TUDCA. In the present article, we review ALS pathophysiology, with a focus on PB-TUDCA's proposed mechanisms of action and recent clinical trial results and discuss the implications of conflicting trial data for ALS and other neurological disorders.

The physiological and pathophysiological roles of copper in the nervous system

Copper is a critical trace element in biological systems due the vast number of essential enzymes that require the metal as a cofactor, including cytochrome c oxidase, superoxide dismutase and dopamine-β-hydroxylase. Due its key role in oxidative metabolism, antioxidant defence and neurotransmitter synthesis, copper is particularly important for neuronal development and proper neuronal function. Moreover, increasing evidence suggests that copper also serves important functions in synaptic and network activity, the regulation of circadian rhythms, and arousal. However, it is important to note that because of copper's ability to redox cycle and generate reactive species, cellular levels of the metal must be tightly regulated to meet cellular needs while avoiding copper-induced oxidative stress. Therefore, it is essential that the intricate system of copper transporters, exporters, copper chaperones and copper trafficking proteins function properly and in coordinate fashion. Indeed, disorders of copper metabolism such as Menkes disease and Wilson disease, as well as diseases linked to dysfunction of copper-requiring enzymes, such as SOD1-linked amyotrophic lateral sclerosis, demonstrate the dramatic neurological consequences of altered copper homeostasis. In this review, we explore the physiological importance of copper in the nervous system as well as pathologies related to improper copper handling.

Novel approaches to assessing upper motor neuron dysfunction in motor neuron disease/amyotrophic lateral sclerosis: IFCN handbook chapter

Identifying upper motor neuron (UMN) dysfunction is fundamental to the diagnosis and understanding of disease pathogenesis in motor neuron disease (MND). The clinical assessment of UMN dysfunction may be difficult, particularly in the setting of severe muscle weakness. From a physiological perspective, transcranial magnetic stimulation (TMS) techniques provide objective biomarkers of UMN dysfunction in MND and may also be useful to interrogate cortical and network function. Single, paired- and triple pulse TMS techniques have yielded novel diagnostic and prognostic biomarkers in MND, and have provided important pathogenic insights, particularly pertaining to site of disease onset. Cortical hyperexcitability, as heralded by reduced short interval intracortical inhibition (SICI) and increased short interval intracortical facilitation, has been associated with the onset of lower motor neuron degeneration, along with patterns of disease spread, development of specific clinical features such as the split hand phenomenon, and may provide an indication about the rate of disease progression. Additionally, reduction of SICI has emerged as a potential diagnostic aid in MND. The triple stimulation technique (TST) was shown to enhance the diagnostic utility of conventional TMS measures in detecting UMN dysfunction in MND. Separately, sophisticated brain imaging techniques have uncovered novel biomarkers of neurodegeneration that have bene associated with progression. The present review will discuss the utility of TMS and brain neuroimaging derived biomarkers of UMN dysfunction in MND, focusing on recently developed TMS techniques and advanced neuroimaging modalities that interrogate structural and functional integrity of the corticomotoneuronal system, with an emphasis on pathogenic, diagnostic, and prognostic utility.

Non-motor symptoms in patients with amyotrophic lateral sclerosis: current state and future directions

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive degeneration of both upper and lower motor neurons. A defining histopathological feature in approximately 97% of all ALS cases is the accumulation of phosphorylated trans-activation response (TAR) DNA-binding protein 43 protein (pTDP-43) aggregates in the cytoplasm of neurons and glial cells within the central nervous system. Traditionally, it was believed that the accumulation of TDP-43 aggregates and subsequent neurodegeneration primarily occurs in motor neurons. However, contemporary evidence suggests that as the disease progresses, other systems and brain regions are also affected. Despite this, there has been a limited number of clinical studies assessing the non-motor symptoms in ALS patients. These studies often employ various outcome measures, resulting in a wide range of reported frequencies of non-motor symptoms in ALS patients. The importance of assessing the non-motor symptoms reflects in a fact that they have a significant impact on patients' quality of life, yet they frequently go underdiagnosed and unreported during clinical evaluations. This review aims to provide an up-to-date overview of the current knowledge concerning non-motor symptoms in ALS. Furthermore, we address their diagnosis and treatment in everyday clinical practice.

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.

Preparing for Patient-Customized N-of-1 Antisense Oligonucleotide Therapy to Treat Rare Diseases

The process of developing therapies to treat rare diseases is fraught with financial, regulatory, and logistical challenges that have limited our ability to build effective treatments. Recently, a novel type of therapy called antisense therapy has shown immense potential for the treatment of rare diseases, particularly through single-patient N-of-1 trials. Several N-of-1 antisense therapies have been developed recently for rare diseases, including the landmark study of milasen. In response to the success of N-of-1 antisense therapy, the Food and Drug Administration (FDA) has developed unique guidelines specifically for the development of antisense therapy to treat N-of-1 rare diseases. This policy change establishes a strong foundation for future therapy development and addresses some of the major limitations that previously hindered the development of therapies for rare diseases.

Amyotrophic lateral sclerosis patients with various gene mutations show diverse motor phenotypes and survival in China

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder characterised by progressive degeneration of motor neurons. Genetic factors have a substantial impact on ALS. Therefore, this study aimed to explore the correlation between genotype (SOD1, TARDBP, FUS, C9orf72) and phenotype in ALS.

METHODS

Genetic analysis was performed on 2038 patients with ALS, among which 1696 patients with sporadic ALS (SALS) as controls for genotype-phenotype analysis, and 1602 SALS as controls for survival analysis. Logistic regression and Cox proportional hazards models were used for statistical analysis.

RESULTS

A total of 172 patients with ALS with the gene mutations were included in the statistical analysis (SOD1, n=65; FUS, n=43; TARDBP, n=27; C9orf72, n=37). SOD1 mutations were more frequent in flail leg phenotype (OR 7.317, p=0.001) and less in bulbar phenotype (OR 0.222, p=0.038). C9orf72 expansions exhibited higher frequency in bulbar phenotype (OR 2.770, p=0.008). SOD1 and FUS mutations were significantly associated with earlier age of onset (HR 2.039, p<0.001; HR 1.762, p=0.001). The patients with SOD1 mutations, C9orf72 expansions and those carrying pathogenic FUS mutations had significantly increased death risk (HR 2.217, p<0.001; HR 1.694, p=0.008; HR 1.652, p=0.036). The increased risk of death in ALS with C9orf72 expansions was significant in females (HR 2.419, p=0.014) but not in males (HR 1.442, p=0.128).

CONCLUSION

Our study revealed distinct motor phenotypic tendencies in patients with ALS with different genotypes, indicating variations in the vulnerability of motor neurons during the disease's progression. Furthermore, we made novel discoveries regarding survival of different gene mutations, warranting further investigation.

Seeding activity of human superoxide dismutase 1 aggregates in familial and sporadic amyotrophic lateral sclerosis postmortem neural tissues by real-time quaking-induced conversion

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disease with average lifespan of 2-5 years after diagnosis. The identification of novel prognostic and pharmacodynamic biomarkers are needed to facilitate therapeutic development. Metalloprotein human superoxide dismutase 1 (SOD1) is known to accumulate and form aggregates in patient neural tissue with familial ALS linked to mutations in their SOD1 gene. Aggregates of SOD1 have also been detected in other forms of ALS, including the sporadic form and the most common familial form linked to abnormal hexanucleotide repeat expansions in the Chromosome 9 open reading frame 72 (C9ORF72) gene. Here, we report the development of a real-time quaking-induced conversion (RT-QuIC) seed amplification assay using a recombinant human SOD1 substrate to measure SOD1 seeding activity in postmortem spinal cord and motor cortex tissue from persons with different ALS etiologies. Our SOD1 RT-QuIC assay detected SOD1 seeds in motor cortex and spinal cord dilutions down to 10-5. Importantly, we detected SOD1 seeding activity in specimens from both sporadic and familial ALS cases, with the latter having mutations in either their SOD1 or C9ORF72 genes. Analyses of RT-QuIC parameters indicated similar lag phases in spinal cords of sporadic and familial ALS patients, but higher ThT fluorescence maxima by SOD1 familial ALS specimens and sporadic ALS thoracic cord specimens. For a subset of sporadic ALS patients, motor cortex and spinal cords were examined, with seeding activity in both anatomical regions. Our results suggest SOD1 seeds are in ALS patient neural tissues not linked to SOD1 mutation, suggesting that SOD1 seeding activity may be a promising biomarker, particularly in sporadic ALS cases for whom genetic testing is uninformative.

Effect of sodium phenylbutyrate and taurursodiol on plasma concentrations of neuroinflammatory biomarkers in amyotrophic lateral sclerosis: results from the CENTAUR trial

BACKGROUND

An oral sodium phenylbutyrate and taurursodiol combination (PB and TURSO) significantly reduced functional decline in people living with amyotrophic lateral sclerosis (ALS) in the CENTAUR trial. Biomarkers linking clinical therapeutic effect with biological changes are of high interest in ALS. We performed analyses of neuroinflammatory biomarkers associated with ALS in the literature, including YKL-40 (also known as chitinase-3-like protein 1), chitinase 1 (CHIT1) and C reactive protein (CRP), in plasma samples collected in CENTAUR.

METHODS

Log10-transformed plasma biomarker measurements were analysed using a linear mixed-effects model. Correlation between paired biomarker concentrations and ALS Functional Rating Scale-Revised (ALSFRS-R) total scores was assessed via Pearson correlation coefficients.

RESULTS

By week 24, geometric least squares mean YKL-40 plasma concentration decreased by approximately 20% (p=0.008) and CRP by 30% (p=0.048) in the PB and TURSO versus placebo group. YKL-40 (r of -0.21; p<0.0001) and CRP (r of -0.19; p=0.0002) concentration correlated with ALSFRS-R total score. CHIT1 levels were not significantly different between groups.

CONCLUSIONS

YKL-40 and CRP plasma levels were significantly reduced in participants with ALS receiving PB and TURSO in CENTAUR and correlated with disease progression. These findings suggest YKL-40 and CRP could be treatment-sensitive biomarkers in ALS, pending further confirmatory studies.

TRIAL REGISTRATION NUMBER

https://clinicaltrials.gov/study/NCT03127514.

Age-dependent dynamics of neuronal VAPBALS inclusions in the adult brain

Amyotrophic Lateral Sclerosis (ALS) is a relentlessly progressive and fatal disease, caused by the degeneration of upper and lower motor neurons within the brain and spinal cord in the ageing human. The dying neurons contain cytoplasmic inclusions linked to the onset and progression of the disease. Here, we use a Drosophila model of ALS8 (VAPP58S) to understand the modulation of these inclusions in the ageing adult brain. The adult VAPP58S fly shows progressive deterioration in motor function till its demise 25 days post-eclosion. The density of VAPP58S-positive brain inclusions is stable for 5-15 days of age. In contrast, adding a single copy of VAPWT to the VAPP58S animal leads to a large decrease in inclusion density with concomitant rescue of motor function and lifespan. ER stress, a contributing factor in disease, shows reduction with ageing for the disease model. Autophagy, rather than the Ubiquitin Proteasome system, is the dominant mechanism for aggregate clearance. We explored the ability of Drosophila Valosin-containing protein (VCP/TER94), the ALS14 locus, which is involved in cellular protein clearance, to regulate age-dependent aggregation. Contrary to expectation, TER94 overexpression increased VAPP58S punctae density, while its knockdown led to enhanced clearance. Expression of a dominant positive allele, TER94R152H, further stabilised VAPP58S puncta, cementing roles for an ALS8-ALS14 axis. Our results are explained by a mechanism where autophagy is modulated by TER94 knockdown. Our study sheds light on the complex regulatory events involved in the neuronal maintenance of ALS8 aggregates, suggesting a context-dependent switch between proteasomal and autophagy-based mechanisms as the larvae develop into an adult. A deeper understanding of the nucleation and clearance of the inclusions, which affect cellular stress and function, is essential for understanding the initiation and progression of ALS.

Plasma proteomics in the UK Biobank reveals youthful brains and immune systems promote healthspan and longevity

Organ-derived plasma protein signatures derived from aptamer protein arrays track organ-specific aging, disease, and mortality in humans, but the robustness and clinical utility of these models and their biological underpinnings remain unknown. Here, we estimate biological age of 11 organs from 44,526 individuals in the UK Biobank using an antibody-based proteomics platform to model disease and mortality risk. Organ age estimates are associated with future onset of heart failure (heart age HR=1.83), chronic obstructive pulmonary disease (lung age HR=1.39), type II diabetes (kidney age HR=1.58), and Alzheimer's disease (brain age HR=1.81) and sensitive to lifestyle factors such as smoking and exercise, hormone replacement therapy, or supplements. Remarkably, the accrual of aged organs progressively increases mortality risk while a youthful brain and immune system are uniquely associated with disease-free longevity. These findings support the use of plasma proteins for monitoring organ health and the efficacy of drugs targeting organ aging disease.

Favorable efficacy and reduced acute neurotoxicity by antisense oligonucleotides with 2',4'-BNA/LNA with 9-(aminoethoxy)phenoxazine

An increasing number of antisense oligonucleotides (ASOs) have been approved for clinical use. However, improvements of both efficacy and safety in the central nervous system (CNS) are crucial for the treatment with CNS diseases. We aimed to overcome the crucial issues by our development of various gapmer ASOs with a novel nucleoside derivative including a 2',4'-BNA/LNA with 9-(aminoethoxy)phenoxazine (BNAP-AEO). The various gapmer ASOs with BNAP-AEO were evaluated for thermal stability, in vitro and in vivo efficacy, and acute CNS toxicity. Thermal stability analysis of the duplexes with their complementary RNAs showed that ASOs with BNAP-AEO had a higher binding affinity than those without BNAP-AEO. In vitro assays, when transfected into neuroblastoma cell lines, demonstrated that ASOs with BNAP-AEO, had a more efficient gene silencing effect than those without BNAP-AEO. In vivo assays, involving intracerebroventricular injections into mice, revealed ASOs with BNAP-AEO potently suppressed gene expression in the brain. Surprisingly, the acute CNS toxicity in mice, as assessed through open field tests and scoring systems, was significantly lower for ASOs with BNAP-AEO than for those without BNAP-AEO. This study underscores the efficient gene-silencing effect and low acute CNS toxicity of ASOs incorporating BNAP-AEO, indicating the potential for future therapeutic applications.