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

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.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Skeletal muscle dysfunction in amyotrophic lateral sclerosis: a mitochondrial perspective and therapeutic approaches

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neuromuscular disease that results in the loss of motor neurons and severe skeletal muscle atrophy. The etiology of ALS is linked to skeletal muscle, which can activate a retrograde signaling cascade that destroys motor neurons. This is why satellite cells and mitochondria play a crucial role in the health and performance of skeletal muscles. This review presents current knowledge on the involvement of mitochondrial dysfunction, skeletal muscle atrophy, muscle satellite cells, and neuromuscular junction (NMJ) in ALS. It also discusses current therapeutic strategies, including exercise, drugs, stem cells, gene therapy, and the prospective use of mitochondrial transplantation as a viable therapeutic strategy.

Sodium Phenylbutyrate and Taurursodiol: A New Therapeutic Option for the Treatment of Amyotrophic Lateral Sclerosis

OBJECTIVE

To review the safety and efficacy of sodium phenylbutyrate and taurursodiol (SP + T) in slowing progression of amyotrophic lateral sclerosis (ALS) compared with pre-existing therapies.

DATA SOURCES

A PubMed (from January 1, 2009, to April 13, 2023) and ClinicalTrials.gov search conducted using sodium phenylbutyrate, taurursodiol, AMX0035, riluzole, and edaravone. Additional articles were identified by hand from references.

DATA SELECTION AND DATA EXTRACTION

This included English-language articles evaluating SP + T efficacy or safety in humans for decreasing neuronal death and slowing the progression of ALS.

DATA SYNTHESIS

In one phase II clinical trial that encompassed an open-label extension phase, disease severity, assessed by the rate of decline in overall score on the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised with higher scores indicating more functional ability, was -1.24 points per month with active drug and -1.66 points per month with placebo (difference, 0.42 points per month; 95% CI, 0.03-0.81; P = 0.03). Post hoc analysis found survival benefit of median 4.8 months with active medication compared with placebo.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE IN COMPARISON WITH EXISTING DRUGS

SP + T is a new US Food and Drug Administration-approved oral suspension for the treatment of ALS. Patients who received active medication through the phase II trial showed decreased rates of disease progression. Overall, SP + T could be considered a potential agent for the treatment of ALS which has a high unmet need.

CONCLUSION

SP + T is an option for the treatment of ALS; however, additional data regarding efficacy in phase III trials with long-term safety profile considerations, as well as trials to compare current therapy with SP + T, are needed.

UndERACting ion channels in neurodegeneration

In a recent study, Guo and colleagues characterised the function of an elusive endoplasmic reticulum (ER) anion channel protein, Chloride Channel CLiC Like 1 (CLCC1), and identified rare CLCC1 variants in people with amyotrophic lateral sclerosis (ALS). CLCC1 mutants disrupted ER function in vitro and promoted ALS-like pathology and neurodegeneration in mice. This work reveals a previously uncharacterised pathway involved in ER calcium release and highlights new pathogenic mechanisms underlying neurodegeneration.

[Promising approaches to the pathogenetic therapy of amyotrophic lateral sclerosis]

Amyotrophic lateral sclerosis is a severe incurable disease of the nervous system. Currently only methods of palliative care for the patients with this disease are available. Few medications for the pathogenetic therapy are registered in some countries, i.e. riluzole, edaravon, sodium phenylbutyrate/taurursodiol as well as tofersen (conditionally). Their efficacy is relatively low. The main directions in the development of pathogenetic therapy of ALS include gene therapy, use of stem cells, immunomodulators, agents affecting gut microbiota. A search is also underway for low-molecular compounds with neuroprotective and antioxidant properties. Perspective direction is prevention of ALS. This will be possible when biomarkers for identification of patients in pre-manifest/prodromal stage are detected.

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.

Tauro-Urso-Deoxycholic Acid Trials in Amyotrophic Lateral Sclerosis: What is Achieved and What to Expect

Phase II studies on tauro-urso-deoxycholic acid (TUDCA) raised the promise of safety and efficacy in patients with amyotrophic lateral sclerosis, a currently incurable and devastating disease. We review the available evidence on the efficacy and safety of TUDCA, administered alone or in combination, by analyzing and comparing published and ongoing studies on amyotrophic lateral sclerosis. Two independent phase II studies (using TUDCA solo or combined with sodium phenylbutyrate) showed similar efficacy in slowing disease progression measured by functional scales. One open-label follow-up TUDCA+sodium phenylbutyrate study suggested a benefit on survival. Two subsequent phase III studies with TUDCA (solo or combined with sodium phenylbutyrate) have been initiated and are currently ongoing. Their completion is expected by the end of 2023 and beginning of 2024. Evidence collected by phase II studies indicates that there are no safety concerns in patients with amyotrophic lateral sclerosis. The efficacy shown in phase II studies was considered sufficient to grant approval in some countries but not in others, owing to discrepant views on the strength of evidence. It will be necessary to wait for the results of ongoing phase III studies to attain a full appreciation of these data.

Intrathecal delivery of AAV-NDNF ameliorates disease progression of ALS mice

Amyotrophic lateral sclerosis (ALS) is a uniformly lethal neurodegenerative disease characterized by progressive deterioration of motor neurons and neuromuscular denervation. Adeno-associated virus (AAV)-mediated delivery of trophic factors is being considered as a potential disease-modifying therapeutic avenue. Here we show a marked effect of AAV-mediated over-expression of neuron-derived neurotrophic factor (NDNF) on SOD1G93A ALS model mice. First, we adopt AAV-PHP.eB capsid to enable widespread expression of target proteins in the brain and spinal cord when delivered intrathecally. Then we tested the effects of AAV-NDNF on SOD1G93A mice at different stages of disease. Interestingly, AAV-NDNF markedly improved motor performance and alleviated weight loss when delivered at early post-symptomatic stage. Injection in the middle post-symptomatic stages still improved the locomotion ability, although it did not alleviate the loss of body weight. Injection in the late stage also extended the life span of SOD1G93A mice. Furthermore, NDNF expression promoted the survival of spinal motoneurons, reduced abnormal protein aggregation, and preserved the innervated neuromuscular functions. We further analyzed the signaling pathways of NDNF expression and found that it activates cell survival and growth-associated mammalian target of rapamycin signaling pathway and downregulates apoptosis-related pathways. Thus, intrathecally AAV-NDNF delivery has provided a potential strategy for the treatment of ALS.

Effect of tauroursodeoxycholic acid on survival and safety in amyotrophic lateral sclerosis: a retrospective population-based cohort study

Background

Oral tauroursodeoxycholic acid (TUDCA) is a commercial drug currently tested in patients with amyotrophic lateral sclerosis (ALS) both singly and combined with sodium phenylbutyrate. This retrospective study aimed to investigate, in a real-world setting, whether TUDCA had an impact on the overall survival of patients with ALS who were treated with this drug compared to those patients who received standard care only.

Methods

This propensity score-matched study was conducted in the Emilia Romagna Region (Italy), which has had an ALS regional registry since 2009. Out of 627 patients with ALS diagnosed from January 1st, 2015 to June 30th, 2021 and recorded in the registry with available information on death/tracheostomy, 86 patients took TUDCA and were matched in a 1:2 ratio with patients who received only usual care according to age at onset, sex, phenotype, diagnostic latency, ALS Functional Rating Scale-Revised (ALSFRS-R) at first visit, disease progression rate at first visit, and BMI at diagnosis. The primary outcome was survival difference (time from onset of symptoms to tracheostomy/death) between TUDCA exposed and unexposed patients.

Findings

A total of 86 patients treated with TUDCA were matched to 172 patients who did not receive treatment. TUDCA-exposed patients were stratified based on dosage (less than or equal to 1000 mg/day or greater) and duration (less than or equal to 12 months or longer) of treatment. The median overall survival was 49.6 months (95% CI 41.7-93.5) among those treated with TUDCA and 36.2 months (95% CI 32.7-41.6) in the control group, with a reduced risk of death observed in patients exposed to a higher dosage (defined as ≥ 1000 mg/day) of TUDCA (HR 0.56; 95% CI 0.38-0.83; p = 0.0042) compared to both the control group and those with lower TUDCA dosages (defined as < 1000 mg/day). TUDCA was generally well-tolerated, except for a minority of patients (n = 7, 8.1%) who discontinued treatment due to side effects, primarily gastrointestinal and mild in severity; only 2 adverse events required hospital access but resolved without sequelae.

Interpretation

In this population-based exploratory study, patients with ALS who were treated with TUDCA may have prolonged survival compared to patients receiving standard care only. Additional prospective randomized studies are needed to confirm the efficacy and safety of this drug.

Funding

Emilia-Romagna Region.

Microglia and Astrocytes in Amyotrophic Lateral Sclerosis: Disease-Associated States, Pathological Roles, and Therapeutic Potential

Microglial and astrocytic reactivity is a prominent feature of amyotrophic lateral sclerosis (ALS). Microglia and astrocytes have been increasingly appreciated to play pivotal roles in disease pathogenesis. These cells can adopt distinct states characterized by a specific molecular profile or function depending on the different contexts of development, health, aging, and disease. Accumulating evidence from ALS rodent and cell models has demonstrated neuroprotective and neurotoxic functions from microglia and astrocytes. In this review, we focused on the recent advancements of knowledge in microglial and astrocytic states and nomenclature, the landmark discoveries demonstrating a clear contribution of microglia and astrocytes to ALS pathogenesis, and novel therapeutic candidates leveraging these cells that are currently undergoing clinical trials.

Amyotrophic Lateral Sclerosis and Other Motor Neuron Diseases

OBJECTIVE

This article reviews the clinical spectrum of amyotrophic lateral sclerosis (ALS), its variant presentations, and the approach to diagnosis and management. This review includes a detailed discussion of current and emerging disease-modifying therapies and the management of respiratory and bulbar manifestations of disease. An updated review of ALS genetics and pathophysiology is also provided. This article also touches on several other important motor neuron diseases.

LATEST DEVELOPMENTS

A new set of simplified diagnostic criteria may help identify patients at earlier stages of the disease. A coformulation of sodium phenylbutyrate and tauroursodeoxycholic acid has been shown to have a significant benefit on disease progression and survival, leading to approval by regulatory authorities in the United States and Canada. An oral formulation of edaravone and an antisense oligonucleotide to a SOD1 gene variation (tofersen) have also recently been approved by the US Food and Drug Administration (FDA). Phase 3 trials of intrathecal mesenchymal stem cells failed to meet primary end points for efficacy. Updated American Academy of Neurology quality measures for the care of patients with ALS were published in 2023.

ESSENTIAL POINTS

There has been continued progress in ALS genetics, diagnosis, and disease-modifying therapies. However, we still lack a definitive biomarker or a treatment that can halt the progression or reverse the course of disease. The evolving understanding of the genetic and pathophysiologic underpinnings of disease offers promise for more effective and clinically meaningful treatments in the future.

Exploring the Potential Utility of Psychedelic Therapy for Patients With Amyotrophic Lateral Sclerosis

Background: Amyotrophic lateral sclerosis (ALS) is an aggressive, terminal neurodegenerative disease that causes death of motor neurons and has an average survival time of 3-4 years. ALS is the most common motor neuron degenerative disease and is increasing in prevalence. There is a pressing need for more effective ALS treatments as available pharmacotherapies do not reverse disease progression or provide substantial clinical benefit. Furthermore, despite psychological distress being highly prevalent in ALS patients, psychological treatments remain understudied. Psychedelics (i.e., serotonergic psychedelics and related compounds like ketamine) have seen a resurgence of research into therapeutic applications for treating a multitude of neuropsychiatric conditions, including psychiatric and existential distress in life-threatening illnesses. Methods: We conducted a narrative review to examine the potential of psychedelic assisted-psychotherapy (PAP) to alleviate psychiatric and psychospiritual distress in ALS. We also discussed the safety of using psychedelics in this population and proposed putative neurobiological mechanisms that may therapeutically intervene on ALS neuropathology. Results: PAP has the potential to treat psychological dimensions and may also intervene on neuropathological dimensions of ALS. Robust improvements in psychiatric and psychospiritual distress from PAP in other populations provide a strong rationale for utilizing this therapy to treat ALS-related psychiatric and existential distress. Furthermore, relevant neuroprotective properties of psychedelics warrant future preclinical trials to investigate this area in ALS models. Conclusion: PAP has the potential to serve as an effective treatment in ALS. Given the lack of effective treatment options, researchers should rigorously explore this therapy for ALS in future trials.

Novel small molecules inhibit proteotoxicity and inflammation: Mechanistic and therapeutic implications for Alzheimer's Disease, healthspan and lifespan- Aging as a consequence of glycolysis

Inflammation drives many age-related, especially neurological, diseases, and likely mediates age-related proteotoxicity. For example, dementia due to Alzheimer's Disease (AD), cerebral vascular disease, many other neurodegenerative conditions is increasingly among the most devastating burdens on the American (and world) health system and threatens to bankrupt the American health system as the population ages unless effective treatments are developed. Dementia due to either AD or cerebral vascular disease, and plausibly many other neurodegenerative and even psychiatric conditions, is driven by increased age-related inflammation, which in turn appears to mediate Abeta and related proteotoxic processes. The functional significance of inflammation during aging is also supported by the fact that Humira, which is simply an antibody to the pro-inflammatory cytokine TNF-a, is the best-selling drug in the world by revenue. These observations led us to develop parallel high-throughput screens to discover small molecules which inhibit age-related Abeta proteotoxicity in a C. elegans model of AD AND LPS-induced microglial TNF-a. In the initial screen of 2560 compounds (Microsource Spectrum library) to delay Abeta proteotoxicity, the most protective compounds were, in order, phenylbutyrate, methicillin, and quetiapine, which belong to drug classes (HDAC inhibitors, beta lactam antibiotics, and tricyclic antipsychotics, respectably) already robustly implicated as promising to protect in neurodegenerative diseases, especially AD. RNAi and chemical screens indicated that the protective effects of HDAC inhibitors to reduce Abeta proteotoxicity are mediated by inhibition of HDAC2, also implicated in human AD, dependent on the HAT Creb binding protein (Cbp), which is also required for the protective effects of both dietary restriction and the daf-2 mutation (inactivation of IGF-1 signaling) during aging. In addition to methicillin, several other beta lactam antibiotics also delayed Abeta proteotoxicity and reduced microglial TNF-a. In addition to quetiapine, several other tricyclic antipsychotic drugs also delayed age-related Abeta proteotoxicity and increased microglial TNF-a, leading to the synthesis of a novel congener, GM310, which delays Abeta as well as Huntingtin proteotoxicity, inhibits LPS-induced mouse and human microglial and monocyte TNF-a, is highly concentrated in brain after oral delivery with no apparent toxicity, increases lifespan, and produces molecular responses highly similar to those produced by dietary restriction, including induction of Cbp inhibition of inhibitors of Cbp, and genes promoting a shift away from glycolysis and toward metabolism of alternate (e.g., lipid) substrates. GM310, as well as FDA-approved tricyclic congeners, prevented functional impairments and associated increase in TNF-a in a mouse model of stroke. Robust reduction of glycolysis by GM310 was functionally corroborated by flux analysis, and the glycolytic inhibitor 2-DG inhibited microglial TNF-a and other markers of inflammation, delayed Abeta proteotoxicity, and increased lifespan. These results support the value of phenotypic screens to discover drugs to treat age-related, especially neurological and even psychiatric diseases, including AD and stroke, and to clarify novel mechanisms driving neurodegeneration (e.g., increased microglial glycolysis drives neuroinflammation and subsequent neurotoxicity) suggesting novel treatments (selective inhibitors of microglial glycolysis).

Economic evaluation of Motor Neuron Diseases: a nationwide cross-sectional analysis in Germany

BACKGROUND AND OBJECTIVES

Motor Neuron Diseases (MND) are rare diseases but have a high impact on affected individuals and society. This study aims to perform an economic evaluation of MND in Germany.

METHODS

Primary patient-reported data were collected including individual impairment, the use of medical and non-medical resources, and self-rated Health-Related Quality of Life (HRQoL). Annual socio-economic costs per year as well as Quality-Adjusted Life Years (QALYs) were calculated.

RESULTS

404 patients with a diagnosis of Amyotrophic Lateral Sclerosis (ALS), Spinal Muscular Atrophy (SMA) or Hereditary Spastic Paraplegia (HSP) were enrolled. Total annual costs per patient were estimated at 83,060€ in ALS, 206,856€ in SMA and 27,074€ in HSP. The main cost drivers were informal care (all MND) and disease-modifying treatments (SMA). Self-reported HRQoL was best in patients with HSP (mean EuroQoL Five Dimension Five Level (EQ-5D-5L) index value 0.67) and lowest in SMA patients (mean EQ-5D-5L index value 0.39). QALYs for patients with ALS were estimated to be 1.89 QALYs, 23.08 for patients with HSP and 14.97 for patients with SMA, respectively. Cost-utilities were estimated as follows: 138,960€/QALY for ALS, 525,033€/QALY for SMA, and 49,573€/QALY for HSP. The main predictors of the high cost of illness and low HRQoL were disease progression and loss of individual autonomy.

CONCLUSION

As loss of individual autonomy was the main cost predictor, therapeutic and supportive measures to maintain this autonomy may contribute to reducing high personal burden and also long-term costs, e.g., care dependency and absenteeism from work.

Nutritional and metabolic factors in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disease that is classically thought to impact the motor system. Over the past 20 years, research has started to consider the contribution of non-motor symptoms and features of the disease, and how they might affect ALS prognosis. Of the non-motor features of the disease, nutritional status (for example, malnutrition) and metabolic balance (for example, weight loss and hypermetabolism) have been consistently shown to contribute to more rapid disease progression and/or earlier death. Several complex cellular changes observed in ALS, including mitochondrial dysfunction, are also starting to be shown to contribute to bioenergetic failure. The resulting energy depletion in high energy demanding neurons makes them sensitive to apoptosis. Given that nutritional and metabolic stressors at the whole-body and cellular level can impact the capacity to maintain optimal function, these factors present avenues through which we can identify novel targets for treatment in ALS. Several clinical trials are now underway evaluating the effectiveness of modifying energy balance in ALS, making this article timely in reviewing the evidence base for metabolic and nutritional interventions.

Neuroprotection by upregulation of the major histocompatibility complex class I (MHC I) in SOD1G93A mice

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that progressively affects motoneurons, causing muscle atrophy and evolving to death. Astrocytes inhibit the expression of MHC-I by neurons, contributing to a degenerative outcome. The present study verified the influence of interferon β (IFN β) treatment, a proinflammatory cytokine that upregulates MHC-I expression, in SOD1G93A transgenic mice. For that, 17 days old presymptomatic female mice were subjected to subcutaneous application of IFN β (250, 1,000, and 10,000 IU) every other day for 20 days. Rotarod motor test, clinical score, and body weight assessment were conducted every third day throughout the treatment period. No significant intergroup variations were observed in such parameters during the pre-symptomatic phase. All mice were then euthanized, and the spinal cords collected for comparative analysis of motoneuron survival, reactive gliosis, synapse coverage, microglia morphology classification, cytokine analysis by flow cytometry, and RT-qPCR quantification of gene transcripts. Additionally, mice underwent Rotarod motor assessment, weight monitoring, and neurological scoring. The results show that IFN β treatment led to an increase in the expression of MHC-I, which, even at the lowest dose (250 IU), resulted in a significant increase in neuronal survival in the ALS presymptomatic period which lasted until the onset of the disease. The treatment also influenced synaptic preservation by decreasing excitatory inputs and upregulating the expression of AMPA receptors by astrocytes. Microglial reactivity quantified by the integrated density of pixels did not decrease with treatment but showed a less activated morphology, coupled with polarization to an M1 profile. Disease progression upregulated gene transcripts for pro- and anti-inflammatory cytokines, and IFN β treatment significantly decreased mRNA expression for IL4. Overall, the present results demonstrate that a low dosage of IFN β shows therapeutic potential by increasing MHC-I expression, resulting in neuroprotection and immunomodulation.

New Approaches to the Treatment of Frontotemporal Dementia

Frontotemporal dementia (FTD) comprises a diverse group of clinical neurodegenerative syndromes characterized by progressive changes in behavior, personality, executive function, language, and motor function. Approximately 20% of FTD cases have a known genetic cause. The three most common genetic mutations causing FTD are discussed. Frontotemporal lobar degeneration refers to the heterogeneous group of neuropathology underlying FTD clinical syndromes. While there are no current disease-modifying treatments for FTD, management includes off-label pharmacotherapy and non-pharmacological approaches to target symptoms. The utility of several different drug classes is discussed. Medications used in the treatment of Alzheimer's disease have no benefit in FTD and can worsen neuropsychiatric symptoms. Non-pharmacological approaches to management include lifestyle modifications, speech-, occupational-, and physical therapy, peer and caregiver support, and safety considerations. Recent developments in the understanding of the genetics, pathophysiology, neuropathology, and neuroimmunology underlying FTD clinical syndromes have expanded possibilities for disease-modifying and symptom-targeted treatments. Different pathogenetic mechanisms are targeted in several active clinical trials, opening up exciting possibilities for breakthrough advances in treatment and management of FTD spectrum disorders.

CNM-Au8: an experimental agent for the treatment of amyotrophic lateral sclerosis (ALS)

INTRODUCTION

Two established disease-specific therapies for the treatment of amyotrophic lateral sclerosis (ALS) are riluzole and edaravone. Limitations of these medications include minimal progression slowing or survival benefit, and effectiveness only in selected populations, particularly for edaravone. AMX0035 and tofersen received US FDA approval in September 2022 and April 2023, respectively. However, phase 3 trials, further examining both medications' efficacy, are ongoing. CNM-Au8 is an efficient catalyst of energy metabolism and is therefore a potential disease-modifying treatment for ALS, a neurodegenerative condition in which there is bioenergetics impairment.

AREAS COVERED

In this review, we provide an overview of the current ALS treatment market, followed by a description of the pharmacodynamics and pharmacokinetics of CNM-Au8. The main preclinical and available early clinical evidence of CNM-Au8 is then described, as well as its potential as an ALS treatment.

EXPERT OPINION

Oral treatment with CNM-Au8 failed to meet primary clinical and electrodiagnostic endpoints in phase 2/3 clinical trials. Despite this failure, a number of exploratory endpoints included in phase 2/3 trials suggest CNM-Au8 has the potential to significantly slow clinical worsening, improve quality of life, and prolong survival in ALS. Further study of CNM-Au8 in a phase 3 clinical trial is currently underway.

Iranian clinical practice guideline for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegeneration involving motor neurons. The 3-5 years that patients have to live is marked by day-to-day loss of motor and sometimes cognitive abilities. Enormous amounts of healthcare services and resources are necessary to support patients and their caregivers during this relatively short but burdensome journey. Organization and management of these resources need to best meet patients' expectations and health system efficiency mandates. This can only occur in the setting of multidisciplinary ALS clinics which are known as the gold standard of ALS care worldwide. To introduce this standard to the care of Iranian ALS patients, which is an inevitable quality milestone, a national ALS clinical practice guideline is the necessary first step. The National ALS guideline will serve as the knowledge base for the development of local clinical pathways to guide patient journeys in multidisciplinary ALS clinics. To this end, we gathered a team of national neuromuscular experts as well as experts in related specialties necessary for delivering multidisciplinary care to ALS patients to develop the Iranian ALS clinical practice guideline. Clinical questions were prepared in the Patient, Intervention, Comparison, and Outcome (PICO) format to serve as a guide for the literature search. Considering the lack of adequate national/local studies at this time, a consensus-based approach was taken to evaluate the quality of the retrieved evidence and summarize recommendations.

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.

Evidence of Metabolic Dysfunction in Amyotrophic Lateral Sclerosis (ALS) Patients and Animal Models

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that affects motor neurons, leading to muscle weakness, paralysis, and eventual death. Research from the past few decades has appreciated that ALS is not only a disease of the motor neurons but also a disease that involves systemic metabolic dysfunction. This review will examine the foundational research of understanding metabolic dysfunction in ALS and provide an overview of past and current studies in ALS patients and animal models, spanning from full systems to various metabolic organs. While ALS-affected muscle tissue exhibits elevated energy demand and a fuel preference switch from glycolysis to fatty acid oxidation, adipose tissue in ALS undergoes increased lipolysis. Dysfunctions in the liver and pancreas contribute to impaired glucose homeostasis and insulin secretion. The central nervous system (CNS) displays abnormal glucose regulation, mitochondrial dysfunction, and increased oxidative stress. Importantly, the hypothalamus, a brain region that controls whole-body metabolism, undergoes atrophy associated with pathological aggregates of TDP-43. This review will also cover past and present treatment options that target metabolic dysfunction in ALS and provide insights into the future of metabolism research in ALS.

Masitinib: The promising actor in the next season of the Amyotrophic Lateral Sclerosis treatment series

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease with high mortality and morbidity rate affecting both upper and lower motor neurons (MN). Muscle force reduction, behavioral change, pseudobulbar affect, and cognitive impairments are the most common clinical manifestations of ALS. The main physiopathology of ALS is still unclear, though several studies have identified that oxidative stress, proteinopathies, glutamate-related excitotoxicity, microglial activation, and neuroinflammation may be involved in the pathogenesis of ALS. From 1995 until October 2022, only Riluzole, Dextromethorphan Hydrobromide (DH) with Quinidine sulfate (Q), Edaravone, and Sodium phenylbutyrate with Taurursodiol (PB/TUDCO) have achieved FDA approval for ALS treatment. Despite the use of these four approved agents, the survival rate and quality of life of ALS patients are still low. Thus, finding novel treatments for ALS patients is an urgent requirement. Masitinib, a tyrosine kinase inhibitor, emphasizes the neuro-inflammatory activity of ALS by targeting macrophages, mast cells, and microglia cells. Masitinib downregulates the proinflammatory cytokines, indirectly reduces inflammation, and induces neuroprotection. Also, it was effective in phase 2/3 and 3 clinical trials (CTs) by increasing overall survival and delaying motor, bulbar, and respiratory function deterioration. This review describes the pathophysiology of ALS, focusing on Masitinib's mechanism of action and explaining why Masitinib could be a promising actor in the treatment of ALS patients. In addition, Masitinib CTs and other competitor drugs in phase 3 CTs have been discussed.

SBT-272 improves TDP-43 pathology in ALS upper motor neurons by modulating mitochondrial integrity, motility, and function

Mitochondrial defects are one of the common underlying causes of neuronal vulnerability in neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), and TDP-43 pathology is the most commonly observed proteinopathy. Disrupted inner mitochondrial membrane (IMM) reported in the upper motor neurons (UMNs) of ALS patients with TDP-43 pathology is recapitulated in the UMNs of well-characterized hTDP-43 mouse model of ALS. The construct validity, such as shared and common cellular pathology in mice and human, offers a unique opportunity to test treatment strategies that may translate to patients. SBT-272 is a well-tolerated brain-penetrant small molecule that stabilizes cardiolipin, a phospholipid found in IMM, thereby restoring mitochondrial structure and respiratory function. We investigated whether SBT-272 can improve IMM structure and health in UMNs diseased with TDP-43 pathology in our well-characterized UMN reporter line for ALS. We found that SBT-272 significantly improved mitochondrial structural integrity and restored mitochondrial motility and function. This led to improved health of diseased UMNs in vitro. In comparison to edaravone and AMX0035, SBT-272 appeared more effective in restoring health of diseased UMNs. Chronic treatment of SBT-272 for sixty days starting at an early symptomatic stage of the disease in vivo led to a significant reduction in astrogliosis, microgliosis, and TDP-43 pathology in the ALS motor cortex. Our results underscore the therapeutic potential of SBT-272, especially within the context of TDP-43 pathology and mitochondrial dysfunction.

Liver's influence on the brain through the action of bile acids

The liver partakes as a sensor and effector of peripheral metabolic changes and a regulator of systemic blood and nutrient circulation. As such, abnormalities arising from liver dysfunction can influence the brain in multiple ways, owing to direct and indirect bilateral communication between the liver and the brain. Interestingly, altered bile acid composition resulting from perturbed liver cholesterol metabolism influences systemic inflammatory responses, blood-brain barrier permeability, and neuron synaptic functions. Furthermore, bile acids produced by specific bacterial species may provide a causal link between dysregulated gut flora and neurodegenerative disease pathology through the gut-brain axis. This review will cover the role of bile acids-an often-overlooked category of active metabolites-in the development of neurological disorders associated with neurodegeneration. Further studies into bile acid signaling in the brain may provide insights into novel treatments against neurological disorders.

Comparing therapeutic modulators of the SOD1 G93A Amyotrophic Lateral Sclerosis mouse pathophysiology

Introduction

Amyotrophic Lateral Sclerosis (ALS) is a paralyzing, multifactorial neurodegenerative disease with limited therapeutics and no known cure. The study goal was to determine which pathophysiological treatment targets appear most beneficial.

Methods

A big data approach was used to analyze high copy SOD1 G93A experimental data. The secondary data set comprised 227 published studies and 4,296 data points. Treatments were classified by pathophysiological target: apoptosis, axonal transport, cellular chemistry, energetics, neuron excitability, inflammation, oxidative stress, proteomics, or systemic function. Outcome assessment modalities included onset delay, health status (rotarod performance, body weight, grip strength), and survival duration. Pairwise statistical analysis (two-tailed t-test with Bonferroni correction) of normalized fold change (treatment/control) assessed significant differences in treatment efficacy. Cohen's d quantified pathophysiological treatment category effect size compared to "all" (e.g., all pathophysiological treatment categories combined).

Results

Inflammation treatments were best at delaying onset (d = 0.42, p > 0.05). Oxidative stress treatments were significantly better for prolonging survival duration (d = 0.18, p < 0.05). Excitability treatments were significantly better for prolonging overall health status (d = 0.22, p < 0.05). However, the absolute best pathophysiological treatment category for prolonging health status varied with disease progression: oxidative stress was best for pre-onset health (d = 0.18, p > 0.05); excitability was best for prolonging function near onset (d = 0.34, p < 0.05); inflammation was best for prolonging post-onset function (d = 0.24, p > 0.05); and apoptosis was best for prolonging end-stage function (d = 0.49, p > 0.05). Finally, combination treatments simultaneously targeting multiple pathophysiological categories (e.g., polytherapy) performed significantly (p < 0.05) better than monotherapies at end-stage.

Discussion

In summary, the most effective pathophysiological treatments change as function of assessment modality and disease progression. Shifting pathophysiological treatment category efficacy with disease progression supports the homeostatic instability theory of ALS disease progression.

Boosting Mitochondrial Potential: An Imperative Therapeutic Intervention in Amyotrophic Lateral Sclerosis

BACKGROUND

Amyotrophic Lateral Sclerosis (ALS) is a progressive and terminal neurodegenerative disorder. Mitochondrial dysfunction, imbalance of cellular bioenergetics, electron chain transportation and calcium homeostasis are deeply associated with the progression of this disease. Impaired mitochondrial functions are crucial in rapid neurodegeneration. The mitochondria of ALS patients are associated with deregulated Ca2+ homeostasis and elevated levels of reactive oxygen species (ROS), leading to oxidative stress. Overload of mitochondrial calcium and ROS production leads to glutamatereceptor mediated neurotoxicity. This implies mitochondria are an attractive therapeutic target.

OBJECTIVE

The aim of this review is to brief the latest developments in the understanding of mitochondrial pathogenesis in ALS and emphasize the restorative capacity of therapeutic candidates.

RESULTS

In ALS, mitochondrial dysfunction is a well-known phenomenon. Various therapies targeted towards mitochondrial dysfunction aim at decreasing ROS generation, increasing mitochondrial biogenesis, and inhibiting apoptotic pathways. Some of the therapies briefed in this review may be categorized as synthetic, natural compounds, genetic materials, and cellular therapies.

CONCLUSION

The overarching goals of mitochondrial therapies in ALS are to benefit ALS patients by slowing down the disease progression and prolonging overall survival. Despite various therapeutic approaches, there are many hurdles in the development of a successful therapy due to the multifaceted nature of mitochondrial dysfunction and ALS progression. Intensive research is required to precisely elucidate the molecular pathways involved in the progression of mitochondrial dysfunctions that ultimately lead to ALS. Because of the multifactorial nature of ALS, a combination therapy approach may hold the key to cure and treat ALS in the future.

An evaluation of the combination of sodium phenylbutyrate and taurursodiol for the treatment of amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive, fatal neurodegenerative motor neuron disease. Despite the overwhelming need for effective therapeutics for ALS, riluzole and edaravone were the only two FDA-approved disease-modifying therapies prior to 2022. The randomized, double-blind, multicenter, placebo-controlled CENTAUR trial demonstrated the safety and efficacy of sodium phenylbutyrate-taurursodiol (PB-TURSO) in persons with ALS (PALS), leading to its conditional approval in Canada in June 2022 and full approval in the USA in September 2022.

AREAS COVERED

Herein, the authors provide a review of the pharmacology and clinical trials evaluating sodium phenylbutyrate and/or taurursodiol in PALS.

EXPERT OPINION

The safety and tolerability of both PB and TURSO were previously demonstrated in small PALS trials. The phase 2 CENTAUR study and its open-label extension demonstrated the safety and efficacy of AMX0035 (a sachet containing a fixed co-formulation of 3 g of PB and 1 g of TURSO given twice daily) in PALS. A phase 3 PHOENIX trial (NCT05021536) will offer more insight into safety and efficacy of AMX0035. AMX0035 currently costs $ 158,000 annually in the US, which may become a financial barrier for PALS to receive the medication.

Drug discovery and amyotrophic lateral sclerosis: Emerging challenges and therapeutic opportunities

Amyotrophic lateral sclerosis (ALS) is characterized by the degeneration of upper and lower motor neurons (MNs) leading to paralysis and, ultimately, death by respiratory failure 3-5 years after diagnosis. Edaravone and Riluzole, the only drugs currently approved for ALS treatment, only provide mild symptomatic relief to patients. Extraordinary progress in understanding the biology of ALS provided new grounds for drug discovery. Over the last two decades, mitochondria and oxidative stress (OS), iron metabolism and ferroptosis, and the major regulators of hypoxia and inflammation - HIF and NF-κB - emerged as promising targets for ALS therapeutic intervention. In this review, we focused our attention on these targets to outline and discuss current advances in ALS drug development. Based on the challenges and the roadblocks, we believe that the rational design of multi-target ligands able to modulate the complex network of events behind the disease can provide effective therapies in a foreseeable future.

Remodeling of astrocyte secretome in amyotrophic lateral sclerosis: uncovering novel targets to combat astrocyte-mediated toxicity

Amyotrophic lateral sclerosis (ALS) is an adult-onset paralytic disease characterized by progressive degeneration of upper and lower motor neurons in the motor cortex, brainstem and spinal cord. Motor neuron degeneration is typically caused by a combination of intrinsic neuronal (cell autonomous) defects as well as extrinsic (non-cell autonomous) factors such as astrocyte-mediated toxicity. Astrocytes are highly plastic cells that react to their microenvironment to mediate relevant responses. In neurodegeneration, astrocytes often turn reactive and in turn secrete a slew of factors to exert pro-inflammatory and neurotoxic effects. Various efforts have been carried out to characterize the diseased astrocyte secretome over the years, revealing that pro-inflammatory chemokines, cytokines and microRNAs are the main players in mediating neuronal death. As metabolomic technologies mature, these studies begin to shed light on neurotoxic metabolites such as secreted lipids. In this focused review, we will discuss changes in the astrocyte secretome during ALS. In particular, we will discuss the components of the reactive astrocyte secretome that contribute to neuronal death in ALS.

New developments and opportunities in drugs being trialed for amyotrophic lateral sclerosis from 2020 to 2022

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that primarily affects motor neurons in the brain and spinal cord. In the recent past, there have been just two drugs approved for treatment, riluzole and edaravone, which only prolong survival by a few months. However, there are many novel experimental drugs in development. In this review, we summarize 53 new drugs that have been evaluated in clinical trials from 2020 to 2022, which we have classified into eight mechanistic groups (anti-apoptotic, anti-inflammatory, anti-excitotoxicity, regulated integrated stress response, neurotrophic factors and neuroprotection, anti-aggregation, gene therapy and other). Six were tested in phase 1 studies, 31 were in phase 2 studies, three failed in phase 3 studies and stopped further development, and the remaining 13 drugs were being tested in phase 3 studies, including methylcobalamin, masitinib, MN-166, verdiperstat, memantine, AMX0035, trazodone, CNM-Au8, pridopidine, SLS-005, IONN363, tofersen, and reldesemtiv. Among them, five drugs, including methylcobalamin, masitinib, AMX0035, CNM-Au8, and tofersen, have shown potent therapeutic effects in clinical trials. Recently, AMX0035 has been the third medicine approved by the FDA for the treatment of ALS after riluzole and edaravone.

Sodium Phenylbutyrate and Ursodoxicoltaurine: First Approval

An oral, fixed-dose coformulation of sodium phenylbutyrate and ursodoxicoltaurine (ALBRIOZA^™; hereafter denoted sodium phenylbutyrate/ursodoxicoltaurine) is being developed by Amylyx Pharmaceuticals for the treatment of neurodegenerative diseases. In June 2022, the coformulation received its first approval with conditions in Canada for the treatment of amyotrophic lateral sclerosis (ALS) in adults. The approval was based on results from the multicentre, phase II CENTAUR trial, in which slowing of ALS progression was demonstrated with sodium phenylbutyrate/ursodoxicoltaurine relative to placebo. This article summarizes the milestones in the development of sodium phenylbutyrate/ursodoxicoltaurine leading to this first approval.