Trial of Antisense Oligonucleotide Tofersen for SOD1 ALS.

BACKGROUND: The intrathecally administered antisense oligonucleotide tofersen reduces synthesis of the superoxide dismutase 1 (SOD1) protein and is being studied in patients with amyotrophic lateral sclerosis (ALS) associated with mutations in SOD1 (SOD1 ALS). METHODS: In this phase 3 trial, we randomly assigned adults with SOD1 ALS in a 2:1 ratio to receive eight doses of tofersen (100 mg) or placebo over a period of 24 weeks. The primary end point was the change from baseline to week 28 in the total score on the ALS Functional Rating Scale-Revised (ALSFRS-R; range, 0 to 48, with higher scores indicating better function) among participants predicted to have faster-progressing disease. Secondary end points included changes in the total concentration of SOD1 protein in cerebrospinal fluid (CSF), in the concentration of neurofilament light chains in plasma, in slow vital capacity, and in handheld dynamometry in 16 muscles. A combined analysis of the randomized component of the trial and its open-label extension at 52 weeks compared the results in participants who started tofersen at trial entry (early-start cohort) with those in participants who switched from placebo to the drug at week 28 (delayed-start cohort). RESULTS: A total of 72 participants received tofersen (39 predicted to have faster progression), and 36 received placebo (21 predicted to have faster progression). Tofersen led to greater reductions in concentrations of SOD1 in CSF and of neurofilament light chains in plasma than placebo. In the faster-progression subgroup (primary analysis), the change to week 28 in the ALSFRS-R score was -6.98 with tofersen and -8.14 with placebo (difference, 1.2 points; 95% confidence interval [CI], -3.2 to 5.5; P = 0.97). Results for secondary clinical end points did not differ significantly between the two groups. A total of 95 participants (88%) entered the open-label extension. At 52 weeks, the change in the ALSFRS-R score was -6.0 in the early-start cohort and -9.5 in the delayed-start cohort (difference, 3.5 points; 95% CI, 0.4 to 6.7); non-multiplicity-adjusted differences favoring early-start tofersen were seen for other end points. Lumbar puncture-related adverse events were common. Neurologic serious adverse events occurred in 7% of tofersen recipients. CONCLUSIONS: In persons with SOD1 ALS, tofersen reduced concentrations of SOD1 in CSF and of neurofilament light chains in plasma over 28 weeks but did not improve clinical end points and was associated with adverse events. The potential effects of earlier as compared with delayed initiation of tofersen are being further evaluated in the extension phase. (Funded by Biogen; VALOR and OLE ClinicalTrials.gov numbers, NCT02623699 and NCT03070119; EudraCT numbers, 2015-004098-33 and 2016-003225-41.).

Protective Effects of Lovastatin in a Population-Based ALS Study and Mouse Model.

OBJECTIVE: The objective of this study was to use a novel combined pharmacoepidemiologic and amyotrophic lateral sclerosis (ALS) mouse model approach to identify potential motor neuron protective medications. METHODS: We constructed a large, population-based case-control study to investigate motor neuron disease (MND) among US Medicare beneficiaries aged 66 to 90 in 2009. We included 1,128 incident MND cases and 56,400 age, sex, race, and ethnicity matched controls. We calculated MND relative risk for >1,000 active ingredients represented in Part D (pharmacy) claims in 2006 to 2007 (>1 year before diagnosis/reference). We then applied a comprehensive screening approach to select medications for testing in SOD1G93A mice: sulfasalazine, telmisartan, and lovastatin. We treated mice with the human dose equivalent of the medication or vehicle via subcutaneous osmotic pump before onset of weakness. We then assessed weight, gait, and survival. In additional mice, we conducted histological studies. RESULTS: We observed previously established medical associations for MND and an inverse dose-response association between lovastatin and MND, with 28% reduced risk at 40 mg/day. In SOD1G93A mouse studies, sulfasalazine and telmisartan conferred no benefit, whereas lovastatin treatment delayed onset and prolonged survival. Lovastatin treated mice also had less microgliosis, misfolded SOD1, and spinal motor neuron loss in the ventral horn. INTERPRETATION: Lovastatin reduced the risk of ALS in humans, which was confirmed in an ALS mouse model by delayed symptom onset, prolonged survival, and preservation of motor neurons. Although further studies to understand the mechanism are required, lovastatin may represent a potential neuroprotective therapy for patients with ALS. These data demonstrate the utility of a combined pharmacoepidemiologic and mouse model approach. ANN NEUROL 2023;93:881-892.

Access for ALL in ALS: A large-scale, inclusive, collaborative consortium to unlock the molecular and genetic mechanisms of amyotrophic lateral sclerosis.

Recent progress in therapeutics for amyotrophic lateral sclerosis (ALS) has spurred development and imbued the field of ALS with hope for more breakthroughs, yet substantial scientific gaps persist. This unmet need remains a stark reminder that innovative paradigms are needed to invigorate ALS research. To move toward more informative, targeted, and personalized drug development, the National Institutes of Health (NIH) established a national ALS clinical research consortium called Access for ALL in ALS (ALL ALS). This new consortium is a multi-institutional effort that aims to organize the ALS clinical research landscape in the United States. ALL ALS is operating in partnership with several stakeholders to operationalize the recommendations of the Accelerating Access to Critical Therapies for ALS Act (ACT for ALS) Public Private Partnership. ALL ALS will provide a large-scale, centralized, and readily accessible infrastructure for the collection and storage of a wide range of data from people living with ALS (symptomatic cohort) or who may be at risk of developing ALS (asymptomatic ALS gene carriers). Importantly, ALL ALS is designed to encourage community engagement, equity, and inclusion. The consortium is prioritizing the enrollment of geographically, ethnoculturally, and socioeconomically diverse participants. Collected data include longitudinal clinical data and biofluids, genomic, and digital biomarkers that will be harmonized and linked to the central Accelerating Medicines Partnership for ALS (AMP ALS) portal for sharing with the research community. The aim of ALL ALS is to deliver a comprehensive, inclusive, open-science dataset to help researchers answer important scientific questions of clinical relevance in ALS.

Acute Trem2 reduction triggers increased microglial phagocytosis, slowing amyloid deposition in mice.

Heterozygous genetic variants within the TREM2 gene show a strong association with increased Alzheimer's disease (AD) risk. Amyloid beta-depositing mouse models haploinsufficient or null for Trem2 have identified important relationships among TREM2, microglia, and AD pathology; however, results are challenging to interpret in the context of varying microglial phenotypes and disease progression. We hypothesized that acute Trem2 reduction may alter amyloid pathology and microglial responses independent of genetic Trem2 deletion in mouse models. We developed antisense oligonucleotides (ASOs) that potently but transiently lower Trem2 messenger RNA throughout the brain and administered them to APP/PS1 mice at varying stages of plaque pathology. Late-stage ASO-mediated Trem2 knockdown significantly reduced plaque deposition and attenuated microglial association around plaque deposits when evaluated 1 mo after ASO injection. Changes in microglial gene signatures 1 wk after ASO administration and phagocytosis measured in ASO-treated cells together indicate that microglia may be activated with short-term Trem2 reduction. These results suggest a time- and/or dose-dependent role for TREM2 in mediating plaque deposition and microglial responses in which loss of TREM2 function may be beneficial for microglial activation and plaque removal in an acute context.

Trial of Sodium Phenylbutyrate-Taurursodiol for Amyotrophic Lateral Sclerosis.

BACKGROUND: Sodium phenylbutyrate and taurursodiol have been found to reduce neuronal death in experimental models. The efficacy and safety of a combination of the two compounds in persons with amyotrophic lateral sclerosis (ALS) are not known. METHODS: In this multicenter, randomized, double-blind trial, we enrolled participants with definite ALS who had had an onset of symptoms within the previous 18 months. Participants were randomly assigned in a 2:1 ratio to receive sodium phenylbutyrate-taurursodiol (3 g of sodium phenylbutyrate and 1 g of taurursodiol, administered once a day for 3 weeks and then twice a day) or placebo. The primary outcome was the rate of decline in the total score on the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R; range, 0 to 48, with higher scores indicating better function) through 24 weeks. Secondary outcomes were the rates of decline in isometric muscle strength, plasma phosphorylated axonal neurofilament H subunit levels, and the slow vital capacity; the time to death, tracheostomy, or permanent ventilation; and the time to death, tracheostomy, permanent ventilation, or hospitalization. RESULTS: A total of 177 persons with ALS were screened for eligibility, and 137 were randomly assigned to receive sodium phenylbutyrate-taurursodiol (89 participants) or placebo (48 participants). In a modified intention-to-treat analysis, the mean rate of change in the ALSFRS-R score was -1.24 points per month with the active drug and -1.66 points per month with placebo (difference, 0.42 points per month; 95% confidence interval, 0.03 to 0.81; P = 0.03). Secondary outcomes did not differ significantly between the two groups. Adverse events with the active drug were mainly gastrointestinal. CONCLUSIONS: Sodium phenylbutyrate-taurursodiol resulted in slower functional decline than placebo as measured by the ALSFRS-R score over a period of 24 weeks. Secondary outcomes were not significantly different between the two groups. Longer and larger trials are necessary to evaluate the efficacy and safety of sodium phenylbutyrate-taurursodiol in persons with ALS. (Funded by Amylyx Pharmaceuticals and others; CENTAUR ClinicalTrials.gov number, NCT03127514.).

Lumbar punctures are safe in patients with ALS and have a risk profile similar to that in the non-ALS population.

INTRODUCTION/AIMS: Analysis of biofluids, especially cerebrospinal fluid (CSF), is critically important for amyotrophic lateral sclerosis (ALS) research. Collection of CSF is typically performed by lumbar puncture (LP). Previous studies have demonstrated the safety of LPs in patients with other neurodegenerative diseases, such as Alzheimer's disease, although there are no published studies of the safety of LPs in patients with ALS. We performed a retrospective analysis of complications resulting from LPs. METHODS: This is a retrospective study of LPs performed between 2015 and 2021 on a total of 233 participants (healthy controls [n = 63], ALS [n = 154], and disease controls [n = 16]) as part of clinical research studies at the Washington University ALS Center. We used bivariate logistical analyses looking for associations between participant characteristics and adverse events (AEs), and likelihood ratio tests were used for significance testing. RESULTS: We found an overall AE rate of 21.03%. AEs included headache, back pain, vasovagal syncope, and severe headache requiring epidural blood patch. Participants with ALS were not more likely to experience post-LP AEs compared to controls (odds ratio [OR] 0.61 [0.32-1.18]). Post-LP headaches were significantly less likely in participants with ALS (OR 0.36 [0.15-0.83]). DISCUSSION: Our findings demonstrate that LP is a safe procedure for participants with ALS, with a similar or lower rate of AEs than in participants without ALS.

Specific RNA interactions promote TDP-43 multivalent phase separation and maintain liquid properties.

TDP-43 is an RNA-binding protein that forms ribonucleoprotein condensates via liquid-liquid phase separation (LLPS) and regulates gene expression through specific RNA interactions. Loss of TDP-43 protein homeostasis and dysfunction are tied to neurodegenerative disorders, mainly amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Alterations of TDP-43 LLPS properties may be linked to protein aggregation. However, the mechanisms regulating TDP-43 LLPS are ill-defined, particularly how TDP-43 association with specific RNA targets regulates TDP-43 condensation remains unclear. We show that RNA binding strongly promotes TDP-43 LLPS through sequence-specific interactions. RNA-driven condensation increases with the number of adjacent TDP-43-binding sites and is also mediated by multivalent interactions involving the amino and carboxy-terminal TDP-43 domains. The physiological relevance of RNA-driven TDP-43 condensation is supported by similar observations in mammalian cellular lysate. Importantly, we find that TDP-43-RNA association maintains liquid-like properties of the condensates, which are disrupted in the presence of ALS-linked TDP-43 mutations. Altogether, RNA binding plays a central role in modulating TDP-43 condensation while maintaining protein solubility, and defects in this RNA-mediated activity may underpin TDP-43-associated pathogenesis.

A viral toolkit for recording transcription factor-DNA interactions in live mouse tissues.

Transcription factors (TFs) enact precise regulation of gene expression through site-specific, genome-wide binding. Common methods for TF-occupancy profiling, such as chromatin immunoprecipitation, are limited by requirement of TF-specific antibodies and provide only end-point snapshots of TF binding. Alternatively, TF-tagging techniques, in which a TF is fused to a DNA-modifying enzyme that marks TF-binding events across the genome as they occur, do not require TF-specific antibodies and offer the potential for unique applications, such as recording of TF occupancy over time and cell type specificity through conditional expression of the TF-enzyme fusion. Here, we create a viral toolkit for one such method, calling cards, and demonstrate that these reagents can be delivered to the live mouse brain and used to report TF occupancy. Further, we establish a Cre-dependent calling cards system and, in proof-of-principle experiments, show utility in defining cell type-specific TF profiles and recording and integrating TF-binding events across time. This versatile approach will enable unique studies of TF-mediated gene regulation in live animal models.

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

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

Incidence of amyotrophic lateral sclerosis in older adults.

INTRODUCTION/AIMS: We investigated the age- and sex-specific incidence and survival of Medicare beneficiaries with amyotrophic lateral sclerosis (ALS) in patients 66 to 90 years of age. METHODS: We identified all incident ALS cases within a population-based sample of Medicare beneficiaries in 2009 (total: 22 000 177 person-years at risk for ALS). We calculated age- and sex-specific incidence in 2009 according to multiple, progressively more stringent case definitions. Our most inclusive definition required one ALS code, whereas the most restrictive definition required at least one additional ALS code more than 6 months after the first code, including one from a neurologist. We identified associated imaging studies and electrodiagnostic testing and followed all cases through the end of 2014 to determine survival. RESULTS: The overall incidence for our most inclusive definition was 22.84 per 100 000 person-years for men and 16.05 per 100 000 person-years for women. The overall incidence was 5.72 per 100 000 person-years for men and 3.99 per 100 000 person-years for women for our most restrictive definition. For our most inclusive definition, fewer than 39.7% of cases ever had an ALS diagnosis from a neurologist, more than 50% had an electrodiagnostic test or imaging study, and 40.1% survived less than 1 year after diagnosis, with 25.5% of these cases surviving no more than 6 months. Cases not meeting the most restrictive definition were more likely than those who did meet the restrictive definition to be older, black, or Asian. DISCUSSION: The oldest and marginalized Medicare beneficiaries diagnosed with ALS are less likely to be included in epidemiological studies with restrictive definitions, but future studies will need to assess the accuracy of diagnosis.

Smartphone data during the COVID-19 pandemic can quantify behavioral changes in people with ALS.

INTRODUCTION: Passive data from smartphone sensors may be useful for health-care research. Our aim was to use the coronavirus disease-2019 (COVID-19) pandemic as a positive control to assess the ability to quantify behavioral changes in people with amyotrophic lateral sclerosis (ALS) from smartphone data. METHODS: Eight participants used the Beiwe smartphone application, which passively measured their location during the COVID-19 outbreak. We used an interrupted time series to quantify the effect of the US state of emergency declaration on daily home time and daily distance traveled. RESULTS: After the state of emergency declaration, median daily home time increased from 19.4 (interquartile range [IQR], 15.4-22.0) hours to 23.7 (IQR, 22.2-24.0) hours and median distance traveled decreased from 42 (IQR, 13-83) km to 3.7 (IQR, 1.5-10.3) km. The participant with the lowest functional ability changed behavior earlier. This participant stayed at home more and traveled less than the participant with highest functional ability, both before and after the state of emergency. DISCUSSION: We provide evidence that smartphone-based digital phenotyping can quantify the behavior of people with ALS. Although participants spent large amounts of time at home at baseline, the COVID-19 state of emergency declaration reduced their mobility further. Given participants' high level of daily home time, it is possible that their exposure to COVID-19 could be less than that of the general population.

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

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

Amyotrophic lateral sclerosis care and research in the United States during the COVID-19 pandemic: Challenges and opportunities.

Coronavirus disease 2019 has created unprecedented challenges for amyotrophic lateral sclerosis (ALS) clinical care and research in the United States. Traditional evaluations for making an ALS diagnosis, measuring progression, and planning interventions rely on in-person visits that may now be unsafe or impossible. Evidence- and experience-based treatment options, such as multidisciplinary team care, feeding tubes, wheelchairs, home health, and hospice, have become more difficult to obtain and in some places are unavailable. In addition, the pandemic has impacted ALS clinical trials by impairing the ability to obtain measurements for trial eligibility, to monitor safety and efficacy outcomes, and to dispense study drug, as these also often rely on in-person visits. We review opportunities for overcoming some of these challenges through telemedicine and novel measurements. These can reoptimize ALS care and research in the current setting and during future events that may limit travel and face-to-face interactions.

Motor neuron-derived microRNAs cause astrocyte dysfunction in amyotrophic lateral sclerosis.

We recently demonstrated that microRNA-218 (miR-218) is greatly enriched in motor neurons and is released extracellularly in amyotrophic lateral sclerosis model rats. To determine if the released, motor neuron-derived miR-218 may have a functional role in amyotrophic lateral sclerosis, we examined the effect of miR-218 on neighbouring astrocytes. Surprisingly, we found that extracellular, motor neuron-derived miR-218 can be taken up by astrocytes and is sufficient to downregulate an important glutamate transporter in astrocytes [excitatory amino acid transporter 2 (EAAT2)]. The effect of miR-218 on astrocytes extends beyond EAAT2 since miR-218 binding sites are enriched in mRNAs translationally downregulated in amyotrophic lateral sclerosis astrocytes. Inhibiting miR-218 with antisense oligonucleotides in amyotrophic lateral sclerosis model mice mitigates the loss of EAAT2 and other miR-218-mediated changes, providing an important in vivo demonstration of the relevance of microRNA-mediated communication between neurons and astrocytes. These data define a novel mechanism in neurodegeneration whereby microRNAs derived from dying neurons can directly modify the glial phenotype and cause astrocyte dysfunction.

MicroRNA Profiling Reveals Marker of Motor Neuron Disease in ALS Models.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder marked by the loss of motor neurons (MNs) in the brain and spinal cord, leading to fatally debilitating weakness. Because this disease predominantly affects MNs, we aimed to characterize the distinct expression profile of that cell type to elucidate underlying disease mechanisms and to identify novel targets that inform on MN health during ALS disease time course. microRNAs (miRNAs) are short, noncoding RNAs that can shape the expression profile of a cell and thus often exhibit cell-type-enriched expression. To determine MN-enriched miRNA expression, we used Cre recombinase-dependent miRNA tagging and affinity purification in mice. By defining the in vivo miRNA expression of MNs, all neurons, astrocytes, and microglia, we then focused on MN-enriched miRNAs via a comparative analysis and found that they may functionally distinguish MNs postnatally from other spinal neurons. Characterizing the levels of the MN-enriched miRNAs in CSF harvested from ALS models of MN disease demonstrated that one miRNA (miR-218) tracked with MN loss and was responsive to an ALS therapy in rodent models. Therefore, we have used cellular expression profiling tools to define the distinct miRNA expression of MNs, which is likely to enrich future studies of MN disease. This approach enabled the development of a novel, drug-responsive marker of MN disease in ALS rodents.SIGNIFICANCE STATEMENT Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which motor neurons (MNs) in the brain and spinal cord are selectively lost. To develop tools to aid in our understanding of the distinct expression profiles of MNs and, ultimately, to monitor MN disease progression, we identified small regulatory microRNAs (miRNAs) that were highly enriched or exclusive in MNs. The signal for one of these MN-enriched miRNAs is detectable in spinal tap biofluid from an ALS rat model, where its levels change as disease progresses, suggesting that it may be a clinically useful marker of disease status. Furthermore, rats treated with ALS therapy have restored expression of this MN RNA marker, making it an MN-specific and drug-responsive marker for ALS rodents.

MicroRNA signature of central nervous system-infiltrating dendritic cells in an animal model of multiple sclerosis.

Innate immune cells are integral to the pathogenesis of several diseases of the central nervous system (CNS), including multiple sclerosis (MS). Dendritic cells (DCs) are potent CD11c+ antigen-presenting cells that are critical regulators of adaptive immune responses, particularly in autoimmune diseases such as MS. The regulation of DC function in both the periphery and CNS compartment has not been fully elucidated. One limitation to studying the role of CD11c+ DCs in the CNS is that microglia can upregulate CD11c during inflammation, making it challenging to distinguish bone marrow-derived DCs (BMDCs) from microglia. Selective expression of microRNAs (miRNAs) has been shown to distinguish populations of innate cells and regulate their function within the CNS during neuro-inflammation. Using the experimental autoimmune encephalomyelitis (EAE) murine model of MS, we characterized the expression of miRNAs in CD11c+ cells using a non-biased murine array. Several miRNAs, including miR-31, were enriched in CD11c+ cells within the CNS during EAE, but not LysM+ microglia. Moreover, to distinguish CD11c+ DCs from microglia that upregulate CD11c, we generated bone marrow chimeras and found that miR-31 expression was specific to BMDCs. Interestingly, miR-31-binding sites were enriched in mRNAs downregulated in BMDCs that migrated into the CNS, and a subset was confirmed to be regulated by miR-31. Finally, miR-31 was elevated in DCs migrating through an in vitro blood-brain barrier. Our findings suggest miRNAs, including miR-31, may regulate entry of DCs into the CNS during EAE, and could potentially represent therapeutic targets for CNS autoimmune diseases such as MS.

Poly-dipeptides encoded by the C9ORF72 repeats block global protein translation.

The expansion of the GGGGCC hexanucleotide repeat in the non-coding region of the Chromosome 9 open-reading frame 72 (C9orf72) gene is the most common genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). This genetic alteration leads to the accumulation of five types of poly-dipeptides translated from the GGGGCC hexanucleotide repeat. Among these, poly-proline-arginine (poly-PR) and poly-glycine-arginine (poly-GR) peptides are known to be neurotoxic. However, the mechanisms of neurotoxicity associated with these poly-dipeptides are not clear. A proteomics approach identified a number of interacting proteins with poly-PR peptide, including mRNA-binding proteins, ribosomal proteins, translation initiation factors and translation elongation factors. Immunostaining of brain sections from patients with C9orf72 ALS showed that poly-GR was colocalized with a mRNA-binding protein, hnRNPA1. In vitro translation assays showed that poly-PR and poly-GR peptides made insoluble complexes with mRNA, restrained the access of translation factors to mRNA, and blocked protein translation. Our results demonstrate that impaired protein translation mediated by poly-PR and poly-GR peptides plays a role in neurotoxicity and reveal that the pathways altered by the poly-dipeptides-mRNA complexes are potential therapeutic targets for treatment of C9orf72 FTD/ALS.

Emerging antisense oligonucleotide and viral therapies for amyotrophic lateral sclerosis.

PURPOSE OF REVIEW: Amyotrophic lateral sclerosis (ALS) is a rapidly fatal disease for which there is currently no effective therapy. The present review describes the current progress of existing molecular therapies in the clinical trial pipeline and highlights promising future antisense oligonucleotide (ASO) and viral therapeutic strategies for treating ALS. RECENT FINDINGS: The immense progress in the design of clinical trials and generation of ASO therapies directed towards superoxide dismutase-1 (SOD1) and chromosome 9 open reading frame 72 (C9orf72) repeat expansion related disease have been propelled by fundamental work to identify the genetic underpinnings of familial ALS and develop relevant disease models. Preclinical studies have also identified promising targets for sporadic ALS (sALS). Moreover, encouraging results in adeno-associated virus (AAV)-based therapies for spinal muscular atrophy (SMA) provide a roadmap for continued improvement in delivery and design of molecular therapies for ALS. SUMMARY: Advances in preclinical and clinical studies of ASO and viral directed approaches to neuromuscular disease, particularly ALS, indicate that these approaches have high specificity and are relatively well tolerated.

Phosphorylated neurofilament heavy chain: A biomarker of survival for C9ORF72-associated amyotrophic lateral sclerosis.

As potential treatments for C9ORF72-associated amyotrophic lateral sclerosis (c9ALS) approach clinical trials, the identification of prognostic biomarkers for c9ALS becomes a priority. We show that levels of phosphorylated neurofilament heavy chain (pNFH) in cerebrospinal fluid (CSF) predict disease status and survival in c9ALS patients, and are largely stable over time. Moreover, c9ALS patients exhibit higher pNFH levels, more rapid disease progression, and shorter survival after disease onset than ALS patients without C9ORF72 expansions. These data support the use of CSF pNFH as a prognostic biomarker for clinical trials, which will increase the likelihood of successfully developing a treatment for c9ALS. Ann Neurol 2017;82:139-146.

CK-2127107 amplifies skeletal muscle response to nerve activation in humans.

INTRODUCTION: Three studies evaluated safety, tolerability, pharmacokinetics, and pharmacodynamics of CK-2127107 (CK-107), a next-generation fast skeletal muscle troponin activator (FSTA), in healthy participants. We tested the hypothesis that CK-107 would amplify the force-frequency response of muscle in humans. METHODS: To assess the force-frequency response, participants received single doses of CK-107 and placebo in a randomized, double-blind, 4-period, crossover study. The force-frequency response of foot dorsiflexion following stimulation of the deep fibular nerve to activate the tibialis anterior muscle was assessed. RESULTS: CK-107 significantly increased tibialis anterior muscle response with increasing dose and plasma concentration in a frequency-dependent manner; the largest increase in peak force was ∼60% at 10 Hz. DISCUSSION: CK-107 appears more potent and produced larger increases in force than tirasemtiv-a first-generation FSTA-in a similar pharmacodynamic study, thereby supporting its development for improvement of muscle function of patients. Muscle Nerve 57: 729-734, 2018.