A phase II trial of talampanel in subjects with amyotrophic lateral sclerosis

Synthesis and characterization of N-glucosylated dithiadiazepine derivatives through carbon-sulfur bond formation

New 4,7-bis(arylamino)-2-tetra-O-acetyl-β-d-glucopyranosylimino-1,3,5,6-dithiadiazepines were synthesized via reaction of N-tetra-O-acetyl-β-d-glucopyranosyl isocyanodichloride with 1,6-diaryl-2,5-dithio-bis-ureas without using any catalyst. Thus, the synthesis of 7-membered heterocycles containing two sulfur and two nitrogen atoms through carbon-sulfur bond formation was explored. The chemical structures of these new compounds were elucidated by IR, 1H NMR, 13C NMR, mass spectral, and elemental analyses.

A retrospective review of the progress in amyotrophic lateral sclerosis drug discovery over the last decade and a look at the latest strategies

INTRODUCTION

Drug discovery for amyotrophic lateral sclerosis (ALS) has experienced a surge in clinical studies and remarkable preclinical milestones utilizing a variety of mutant superoxide dismutase 1 model systems. Of the drugs that were tested and showed positive preclinical effects, none demonstrated therapeutic benefits to ALS patients in clinical settings.

AREAS COVERED

This review discusses the advances made in drug discovery for ALS and highlights why drug development is proving to be so difficult. It also discusses how a closer look at both preclinical and clinical studies could uncover the reasons why these preclinical successes have yet to result in the availability of an effective drug for clinical use.

EXPERT OPINION

Valuable lessons from the numerous preclinical and clinical studies supply the biggest advantage in the monumental task of finding a cure for ALS. Obviously, a single design type for ALS clinical trials has not yielded success. The authors suggest a two-pronged approach that may prove essential to achieve clinical efficacy in the identification of novel targets and preclinical testing in multiple models to identify biomarkers that can function in diagnostic, predictive and prognostic roles, and changes to clinical trial design and patient recruitment criteria. The advancement of technology and invention of more powerful tools will further enhance the above. This will give rise to more sophisticated clinical trials with consideration of a range of criteria from: optimum dose, route of delivery, specific biomarkers, pharmacokinetics, pharmacodynamics and toxicology to biomarkers, timing for trial and patients' clinical status.

Potential therapeutic drugs and methods for the treatment of amyotrophic lateral sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disorder caused by damage of motoneurons leading to paralysis state and long term disability. Riluzole is currently the only FDA-approved drug for the treatment of ALS. The proposed mechanisms of ALS include glutamate excitotoxicity, oxidative stress, mitochondrial dysfunction, protein aggregation, SOD1 accumulations, and neuronal death. In this review, we discuss potential biomarkers for the identification of patients with ALS. We further emphasize potential therapy involving the uses of neurotrophic factors such as IGFI, GDNF, VEGF, ADNF-9, colivelin and angiogenin in the treatment of ALS. Moreover, we described several existing drugs such as talampanel, ceftriaxone, pramipexole, dexpramipexole and arimoclomol potential compounds for the treatment of ALS. Interestingly, the uses of stem cell therapy and immunotherapy are promising for the treatment of ALS.

ABC transporter-driven pharmacoresistance in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a slowly progressing neurodegenerative disease that affects motor neurons of the nervous system. Despite the identification of many potential therapeutics targeting pathogenic mechanisms in in vitro models, there has been limited progress in translating them into a successful pharmacotherapy in the animal model of ALS. Further, efforts to translate any promising results from preclinical trials to effective pharmacotherapies for patients have been unsuccessful, with the exception of riluzole, the only FDA-approved medication, which only modestly extends survival both in the animal model and in patients. Thus, it is essential to reconsider the strategies for developing ALS pharmacotherapies. Growing evidence suggests that problems identifying highly effective ALS treatments may result from an underestimated issue of drug bioavailability and disease-driven pharmacoresistance, mediated by the ATP-binding cassette (ABC) drug efflux transporters. ABC transporters are predominately localized to the lumen of endothelial cells of the blood-brain and blood-spinal cord barriers (BBB, BSCB) where they limit the entry into the central nervous system (CNS) of a wide range of neurotoxicants and xenobiotics, but also therapeutics. In ALS, expression and function of ABC transporters is increased at the BBB/BSCB and their expression has been detected on neurons and glia in the CNS parenchyma, which may further reduce therapeutic action in target cells. Understanding and accounting for the contribution of these transporters to ALS pharmacoresistance could both improve the modest effects of riluzole and set in motion a re-evaluation of previous ALS drug disappointments. In addition, identifying pathogenic mechanisms regulating ABC transporter expression and function in ALS may lead to the development of new therapeutic strategies. It is likely that novel pharmacological approaches require counteracting pharmacoresistance to improve therapeutic efficacy. This article is part of a Special Issue entitled ALS complex pathogenesis.

Being PRO-ACTive: What can a Clinical Trial Database Reveal About ALS?

Advancing research and clinical care, and conducting successful and cost-effective clinical trials requires characterizing a given patient population. To gather a sufficiently large cohort of patients in rare diseases such as amyotrophic lateral sclerosis (ALS), we developed the Pooled Resource Open-Access ALS Clinical Trials (PRO-ACT) platform. The PRO-ACT database currently consists of >8600 ALS patient records from 17 completed clinical trials, and more trials are being incorporated. The database was launched in an open-access mode in December 2012; since then, >400 researchers from >40 countries have requested the data. This review gives an overview on the research enabled by this resource, through several examples of research already carried out with the goal of improving patient care and understanding the disease. These examples include predicting ALS progression, the simulation of future ALS clinical trials, the verification of previously proposed predictive features, the discovery of novel predictors of ALS progression and survival, the newly identified stratification of patients based on their disease progression profiles, and the development of tools for better clinical trial recruitment and monitoring. Results from these approaches clearly demonstrate the value of large datasets for developing a better understanding of ALS natural history, prognostic factors, patient stratification, and more. The increasing use by the community suggests that further analyses of the PRO-ACT database will continue to reveal more information about this disease that has for so long defied our understanding.

Sassafras oil, carrot bits and microwaves: green lessons learned from the formal total synthesis of (−)-talampanel

A formal total synthesis of (−)-talampanel (1), a 2,3-benzodiazepine is described. This work was undertaken to utilize greener reaction conditions.

The El Escorial criteria: strengths and weaknesses

The El Escorial criteria for the diagnosis of amyotrophic lateral sclerosis (ALS) were established 20 years ago and have been used as inclusion criteria for clinical trials. However, concerns have been raised concerning their use as diagnostic criteria in clinical practice. Moreover, as modern genetics have shed new light on the heterogeneity of ALS and the close relationship between ALS and frontotemporal dementia (FTD) recognized, the World Federation of Neurology Research Group on ALS/MND has initiated discussions to amend and update the criteria, while preserving the essential components for clinical trial enrolment purposes.

Predicting success: optimizing phase II ALS trials for the transition to phase III

Amyotrophic lateral sclerosis (ALS) research is advancing quickly, but the transition from phase II to phase III trials remains particularly challenging. In part, this is because of the paradox of phase II ALS trials - they are expected to inform researchers about safety, tolerability, dosage selection, and efficacy using a small number of patients, and relying on essentially the same outcome measures used in phase III trials. We examined pharmacokinetics in the cerebrospinal fluid and pharmacodynamic markers to demonstrate target engagement. In addition, primary outcome measures are often not specified or do not reach pre-specified goals for significance. We conclude that future trials should include pharmacokinetic (preferably in CSF) and pharmacodynamic markers of target engagement when possible. Primary endpoints should be pre-specified. Inclusion criteria should be used to reduce heterogeneity and target a relevant subpopulation of people with ALS when possible. Multiple phase II trials might be required before moving to a large phase III trial.

The PRO-ACT database: design, initial analyses, and predictive features

OBJECTIVE

To pool data from completed amyotrophic lateral sclerosis (ALS) clinical trials and create an open-access resource that enables greater understanding of the phenotype and biology of ALS.

METHODS

Clinical trials data were pooled from 16 completed phase II/III ALS clinical trials and one observational study. Over 8 million de-identified longitudinally collected data points from over 8,600 individuals with ALS were standardized across trials and merged to create the Pooled Resource Open-Access ALS Clinical Trials (PRO-ACT) database. This database includes demographics, family histories, and longitudinal clinical and laboratory data. Mixed effects models were used to describe the rate of disease progression measured by the Revised ALS Functional Rating Scale (ALSFRS-R) and vital capacity (VC). Cox regression models were used to describe survival data. Implementing Bonferroni correction, the critical p value for 15 different tests was p = 0.003.

RESULTS

The ALSFRS-R rate of decline was 1.02 (±2.3) points per month and the VC rate of decline was 2.24% of predicted (±6.9) per month. Higher levels of uric acid at trial entry were predictive of a slower drop in ALSFRS-R (p = 0.01) and VC (p < 0.0001), and longer survival (p = 0.02). Higher levels of creatinine at baseline were predictive of a slower drop in ALSFRS-R (p = 0.01) and VC (p < 0.0001), and longer survival (p = 0.01). Finally, higher body mass index (BMI) at baseline was associated with longer survival (p < 0.0001).

CONCLUSION

The PRO-ACT database is the largest publicly available repository of merged ALS clinical trials data. We report that baseline levels of creatinine and uric acid, as well as baseline BMI, are strong predictors of disease progression and survival.

Confirmatory double-blind, parallel-group, placebo-controlled study of efficacy and safety of edaravone (MCI-186) in amyotrophic lateral sclerosis patients

Our objective was to confirm the efficacy and safety of edaravone in amyotrophic lateral sclerosis (ALS) patients. We conducted a 36-week confirmatory study, consisting of 12-week pre-observation period followed by 24-week treatment period. Patients received placebo or edaravone i.v. infusion over 60 min for the first 14 days in cycle 1, and for 10 of the first 14 days during cycles 2 to 6. The efficacy primary endpoint was changed in the revised ALS functional rating scale (ALSFRS-R) scores during the 24-week treatment. Patients were treated with placebo (n = 104) and edaravone (n = 102). Changes in ALSFRS-R during the 24-week treatment were -6.35 ± 0.84 in the placebo group (n = 99) and -5.70 ± 0.85 in the edaravone group (n = 100), with a difference of 0.65 ± 0.78 (p = 0.411). Adverse events amounted to 88.5% (92/104) in the placebo group and 89.2% (91/102) in the edaravone group. In conclusion, the reduction of ALSFRS-R was smaller in the edaravone group than in the placebo group, but efficacy of edaravone for treatment of ALS was not demonstrated. Levels and frequencies of reported adverse events were similar in the two groups.

Assessment of disease progression and functional benefit in neurodegenerative disease: can we tell the difference?

Therapeutic strategies for neurodegenerative diseases include modalities intended to modulate disease progression as well as those whose intent is to improve or maintain functional capacity. As the search for pharmacodynamic markers has proved elusive, treatment outcomes most commonly reflect patient function. As a result, even when clinical trials show a beneficial effect, the underlying etiology of that benefit can be difficult to determine. This review summarizes recent trials in ALS and Parkinson's disease, with the goal of increasing understanding of how the choice of outcome measures influences what can be concluded from the results. Although most ALS trials have been negative in recent years, outcomes are reviewed in terms of potential conclusions that could have been drawn. Functional benefit has been established in a number of recent trials; however, the outcomes used have lead to uncertainty as to whether specific agents modify disease or alter function. In the absence of specific markers sensitive to alteration of disease specific pathways, the distinction between agents that alter underlying disease versus those that affect function may depend on underlying hypotheses rather than clinical trial results.

Sensory-motor assessment in clinical research trials

The assessment of changes in sensory-motor function in clinical research presents a unique set of difficulties. Clinimetrics is the science of measurement as related to the identification of a clinical disorder, the tracing of the progression of the condition under study, and calculation of its impact. The selection of appropriate measures for clinical studies of sensory-motor function must consider validity, sensitivity, specificity, responsiveness, reliability, and feasibility. Reasonable measures of motor function in clinical research include manual examination of muscle strength, electrophysiology, functional scales, patient-reported outcomes (e.g., quality of life), and for severe conditions such as ALS, survival. The assessment of sensory function includes targeted electrophysiology and QOL, as well as more focused measures such as quantitative sensory testing and the scoring of positive symptoms. Each individual measure and each combination of endpoints has its strengths and limitations.

Therapeutic neuroprotective agents for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal chronic neurodegenerative disease whose hallmark is proteinaceous, ubiquitinated, cytoplasmic inclusions in motor neurons and surrounding cells. Multiple mechanisms proposed as responsible for ALS pathogenesis include dysfunction of protein degradation, glutamate excitotoxicity, mitochondrial dysfunction, apoptosis, oxidative stress, and inflammation. It is therefore essential to gain a better understanding of the underlying disease etiology and search for neuroprotective agents that might delay disease onset, slow progression, prolong survival, and ultimately reduce the burden of disease. Because riluzole, the only Food and Drug Administration (FDA)-approved treatment, prolongs the ALS patient's life by only 3 months, new therapeutic agents are urgently needed. In this review, we focus on studies of various small pharmacological compounds targeting the proposed pathogenic mechanisms of ALS and discuss their impact on disease progression.

Neuroprotection in multiple sclerosis: a therapeutic approach

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system that is pathologically characterized by inflammatory demyelination and neurodegeneration. Axonal damage, along with neuronal loss, occurs from disease onset and may lead to progressive and permanent disability. In contrast with the inflammatory pathways, the molecular mechanisms leading to MS neurodegeneration remain largely elusive. With improved understanding of these mechanisms, new potential therapeutic targets for neuroprotection have emerged. We review the current understanding of neurodegenerative processes at play in MS and discuss potential outcome measures and targets for neuroprotection trials.

Rodent models of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterised by the degeneration of upper and lower motor neurons. Recent advances in our understanding of some of the genetic causes of ALS, such as mutations in SOD1, TARDBP, FUS and VCP have led to the generation of rodent models of the disease, as a strategy to help our understanding of the pathophysiology of ALS and to assist in the development of therapeutic strategies. This review provides detailed descriptions of TDP-43, FUS and VCP models of ALS, and summarises potential therapeutics which have been recently trialled in rodent models of the disease. This article is part of a Special Issue entitled: Animal Models of Disease.

[Amyotrophic lateral sclerosis: update on etiological treatment]

Amyotrophic lateral sclerosis is a rare neurodegenerative disease. It is characterized by motoneurons progressive degeneration. Associated with a paralysis of the legs, arms and the respiratory muscles, its evolution is lethal. Riluzole is the only drug available with an marketing authorisation (autorisation de mise sur le marché [AMM]) in this indication. In the beginning stages of the disease it demonstrated a modest efficacy by prolonging survival for a few months. Although the physiopathological mechanisms of this disease have not been totally solved, the progression of knowledge in recent years in this area led to the development of a large number of neuroprotective agents which showed effective results in animal models of ALS and which could be good candidates for the treatment of ALS. Several clinical trials have been conducted about antiglutamatergic, antioxidant, antiapoptotic agents and growing cell factors but they failed to demonstrate efficacy on survival or quality of life. Therefore, clinical trials using innovative therapeutics and stem cells are ongoing and offer more distant hope.

Enhancing clinical trials in neurodegenerative disorders: lessons from amyotrophic lateral sclerosis

PURPOSE OF REVIEW

This review article is focused on strategies that may enhance clinical trial efficiency in neurodegenerative disorders, as demonstrated within the research field of amyotrophic lateral sclerosis (ALS).

RECENT FINDINGS

Unravelling ALS pathophysiology will result in an increased number of candidate therapeutics. Recent ALS clinical trials have employed novel study designs that expedite the drug development process and limit sample size, including futility, lead-in, selection, adaptive and sequential designs. The search for sensitive and specific biomarkers in ALS continues to develop, and they are essential in accelerating the drug discovery process. Several candidate cerebrospinal fluid (CSF), neuroimaging and electrophysiological biomarkers have been recently described in ALS, and some have been successfully employed as secondary outcome measures in clinical trials. The advent of web-based technologies has provided a complementary platform to expedite clinical trials, through electronic data capture, teleconferencing and online registries. In addition, the formation of ALS consortia has enhanced collaborative multicentre studies.

SUMMARY

ALS research studies have employed novel strategies to accelerate the efficiency and pace of drug discovery. The importance of adapting to novel measures that enhance study efficiency is not unique to ALS and can be applied to other neurodegenerative diseases in search of effective treatments.

Mechanism of inhibition of the GluA2 AMPA receptor channel opening by talampanel and its enantiomer: the stereochemistry of the 4-methyl group on the diazepine ring of 2,3-benzodiazepine derivatives

Stereoselectivity of 2,3-benzodiazepine compounds provides a unique way for the design of stereoisomers as more selective and more potent inhibitors as drug candidates for treatment of the neurological diseases involving excessive activity of AMPA receptors. Here we investigate a pair of enantiomers known as Talampanel and its (+) counterpart about their mechanism of inhibition and selectivity toward four AMPA receptor subunits or GluA1-4. We show that Talampanel is the eutomer with the endismic ratio being 14 for the closed-channel and 10 for the open-channel state of GluA2. Kinetic evidence supports that Talampanel is a noncompetitive inhibitor and it binds to the same site for those 2,3-benzodiazepine compounds with the C-4 methyl group on the diazepine ring. This site, which we term as the "M" site, recognizes preferentially those 2,3-benzodiazepine compounds with the C-4 methyl group being in the R configuration, as in the chemical structure of Talampanel. Given that Talampanel inhibits GluA1 and GluA2, but is virtually ineffective on the GluA3 and GluA4 AMPA receptor subunits, we hypothesize that the "M" site(s) on GluA1 and GluA2 to which Talampanel binds is different from that on GluA3 and GluA4. If the molecular properties of the AMPA receptors and Talampanel are used for selecting an inhibitor as a single drug candidate for controlling the activity of all AMPA receptors in vivo, Talampanel is not ideal. Our results further suggest that addition of longer acyl groups to the N-3 position should produce more potent 2,3-benzodiazepine inhibitors for the "M" site.

CDP-choline is not protective in the SOD1-G93A mouse model of ALS

Important pathogenic factors in ALS include excitotoxicity and oxidative stress. Cytidine 5-diphosphocholine (CDP-choline) has recently been reported to have neuroprotective effects in animal models for neurodegenerative diseases, attributable to its anti-glutamatergic, anti-excitotoxic, anti-apoptotic and membrane-preserving properties. In this study we administered either CDP-choline or vehicle to transgenic SOD1-G93A mice daily via intraperitoneal (i.p.) injection starting before disease onset (day 30). By monitoring of survival, motor function, weight and general condition we examined possible therapeutic effects. Additional animals were used for histological studies to determine the effect of CDP-choline on motor neuron survival, astrocytosis and myelination in the spinal cord. Results showed that CDP-choline treatment modified neither the deterioration of general condition nor the loss of body weight. Survival of CDP-choline treated animals was not prolonged compared to vehicle treated controls. None of the behavioural motor function tests revealed differences between groups and no differences in motor neuron survival, astrocytosis or myelination were detected by histological analyses. In conclusion, our data from the transgenic mouse model do not strongly support further clinical validation of CDP-choline for the treatment of ALS.

Treatment for cramps in amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Cramps are painful, involuntary muscle contractions. They commonly affect people with amyotrophic lateral sclerosis/motor neuron disease (ALS/MND) at all stages of the disease. To date, the treatment of muscle cramps in ALS has been largely empirical without any evidence from randomised controlled trials.

OBJECTIVES

To systematically assess the effect of interventions on muscle cramps as a primary or secondary endpoint or adverse event in people with ALS/MND.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (14 February 2011), the Cochrane Central Register of Controlled Trials (Issue 1, 2011 in The Cochrane Library), MEDLINE (January 1966 to January 2011) and EMBASE (January 1980 to January 2011) and reference lists of articles searched using the terms motor neuron disease, motor neurone disease, motoneuron disease or amyotrophic lateral sclerosis. We contacted authors of trials for further information.

SELECTION CRITERIA

We included all randomised and quasi-randomised trials of oral medications in people with ALS which assessed cramps as a primary or secondary outcome measure or as an adverse event. We also included trials using subcutaneous or intravenous medications or physical therapy.

DATA COLLECTION AND ANALYSIS

All authors applied the selection criteria and assessed study quality independently, and all authors performed independent data extraction.

MAIN RESULTS

Twenty studies including 4789 participants were identified. Only one trial, of tetrahydrocannabinol (THC), assessed cramps as the primary endpoint. Thirteen studies assessed cramps as a secondary endpoint. The medications comprised vitamin E, baclofen, riluzole, L-threonine, xaliproden, indinavir, and memantine. Six studies assessed cramps as an adverse event. The medications comprised creatine, gabapentin, dextromethorphan, quinidine, and lithium. In all 20 studies no favourable effect for the treatment of cramps in ALS/MND could be demonstrated, but many studies were underpowered to draw a definite conclusion. A meta-analysis of two small studies showed a statistically nonsignificant result for the amino acid L-threonine for the treatment of cramps in ALS/MND. No study was identified using physical therapy as a therapeutic intervention for cramps.

AUTHORS' CONCLUSIONS

There is no evidence to support the use of any intervention for muscle cramps in ALS/MND. More and larger randomised controlled trials evaluating treatments for muscle cramps in ALS/MND are needed.

Current and prospective disease-modifying therapies for amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a devastating illness of unclear etiology affecting motor neurons. It causes unremitting muscle paralysis, atrophy and death usually within 3 - 5 years from diagnosis. The human and economic costs for those affected are sobering. To date, tremendous efforts have failed to find a cure.

AREAS COVERED

An extensive literature search was undertaken using Medline and the Cochrane Systematic Review and Clinical Trial databases. Riluzole and investigational ALS drugs are discussed. Riluzole is the only approved disease-modifying therapy despite its modest effect on survival. Recent research has produced promising agents aimed at better disease control if not a cure. This review discusses agents targeting neuronal glutamate excitotoxicity, protein misfolding and accumulation, autophagy, apoptosis, mitochondrial dysfunction, free radical oxidative injury, immunomodulation, mutant mRNA counteraction, muscle physiology, neurotrophic factors and stem cell applications. The challenges in ALS drug development are highlighted.

EXPERT OPINION

Riluzole should be used for patients with definite, probable, suspected or possible ALS by World Federation of Neurology diagnostic criteria. Systematic monitoring for hepatic dysfunction, neutropenia and other serious adverse effects should be done routinely as outlined. All ALS patients should consider genetic screening and enrollment in ALS trials guided by the data reviewed.

How can we improve clinical trials in amyotrophic lateral sclerosis?

Since the approval of riluzole for the treatment of amyotrophic lateral sclerosis (ALS) 17 years ago, more than 30 large clinical trials have been conducted, but none has proved successful. The failure to translate positive preclinical results into the clinical setting raises questions about the validity of the rodent model that is used to study ALS, and about the quality of both preclinical and clinical studies. However, the greatest challenge is the disease itself as, with rare exceptions, the causes are unknown. In this Perspectives article, we highlight key issues related to the pathophysiology, preclinical studies and clinical trials that should be addressed in the future. These areas include the relationships between different disease mechanisms, the challenges presented by the heterogeneity of the disease, and the need for early intervention, optimal dose selection and effective biomarkers.

Emerging drugs for amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disease that results in increasing disability and that is uniformly fatal. Since its approval in the 1990s, riluzole remains the sole treatment for ALS offering modest survival benefit. While significant advances have been made in the symptomatic management of the disease, more effective drug therapy targeting disease progression is sorely needed.

AREAS COVERED

Advances in the understanding of pathogenic mechanisms involved in disease development and progression have provided multiple avenues for developing effective treatment strategies. This review highlights recent discoveries relating to these diverse mechanisms and their implications for the development of drug therapy. Previous human clinical trials that have targeted these pathways are mentioned and ongoing drug trials are discussed.

EXPERT OPINION

The search for effective drug therapy faces important challenges in the areas of basic science and animal research, translation of these results into human clinical trials, inherent bias in human studies and issues related to delays in clinical diagnosis. How these issues may be addressed and why ALS research constitutes fertile grounds for drug development not only for this devastating disease, but also for other more prevalent neurodegenerative diseases, is discussed in this review.

Talampanel reduces the level of motoneuronal calcium in transgenic mutant SOD1 mice only if applied presymptomatically

We tested the efficacy of treatment with talampanel in a mutant SOD1 mouse model of ALS by measuring intracellular calcium levels and loss of spinal motor neurons. We intended to mimic the clinical study; hence, treatment was started when the clinical symptoms were already present. The data were compared with the results of similar treatment started at a presymptomatic stage. Transgenic and wild-type mice were treated either with talampanel or with vehicle, starting in pre-symptomatic or symptomatic stages. The density of motor neurons was determined by the physical disector, and their intracellular calcium level was assayed electron microscopically. Results showed that motor neurons in the SOD1 mice exhibited an elevated calcium level, which could be reduced, but not restored, with talampanel only when the treatment was started presymptomatically. Treatment in either presymptomatic or symptomatic stages failed to rescue the motor neurons. We conclude that talampanel reduces motoneuronal calcium in a mouse model of ALS, but its efficacy declines as the disease progresses, suggesting that medication initiation in the earlier stages of the disease might be more effective.

Research advances in amyotrophic lateral sclerosis, 2009 to 2010

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of upper and lower motor neurons that causes progressive weakness and death. The breadth of research in ALS continues to grow with exciting new discoveries in disease pathogenesis and potential future therapeutics. There is a growing list of identified mutations in familial ALS, including those in genes encoding TDP-43 and FUS/TLS, which are expanding our understanding of the role of RNA modulation in ALS pathogenesis. There is a greater appreciation for the role of glial cells in motor neuron disease. Mitochondrial dysfunction is also being shown to be critical for motor neuron degeneration. In addition to pharmacotherapy, there are promising early developments with therapeutic implications in the areas of RNA interference, stem cell therapies, viral vector-mediated gene therapy, and immunotherapy. With greater understanding of ALS pathogenesis and exciting new therapeutic technologies, there is hope for future progress in treating this disease.

Glutamate signaling in the pathophysiology and therapy of schizophrenia

Glutamatergic neurotransmission, particularly through the N-methyl-d-aspartate (NMDA) receptor, has drawn attention for its role in the pathophysiology of schizophrenia. This paper reviews the neurodevelopmental origin and genetic susceptibility of schizophrenia relevant to NMDA neurotransmission, and discusses the relationship between NMDA hypofunction and different domains of symptom in schizophrenia as well as putative treatment modality for the disorder. A series of clinical trials and a meta-analysis which compared currently available NMDA-enhancing agents suggests that glycine, d-serine, and sarcosine are more efficacious than d-cycloserine in improving the overall psychopathology of schizophrenia without side effect or safety concern. In addition, enhancing glutamatergic neurotransmission via activating the AMPA receptor, metabotropic glutamate receptor or inhibition of d-amino acid oxidase (DAO) is also reviewed. More studies are needed to determine the NMDA vulnerability in schizophrenia and to confirm the long-term efficacy, functional outcome, and safety of these NMDA-enhancing agents in schizophrenic patients, particularly those with refractory negative and cognitive symptoms, or serious adverse effects while taking the existing antipsychotic agents.

Amyotrophic lateral sclerosis: pathophysiology, diagnosis and management

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease associated with a life expectancy of approximately 3 years after symptom onset, but the range of survival extends from a few months for some to decades for approximately 5% of patients. There is no clear cause in the majority of cases and just one medication, riluzole, has been shown to modestly prolong survival. Research has identified some of the cellular processes that occur after disease onset, including mitochondrial dysfunction, protein aggregation, generation of free radicals, excitotoxicity, inflammation and apoptosis, but for most patients the underlying cause is unknown. While ALS is considered to be a complex genetic disorder in which multiple genes in combination with environmental exposures combine to render a person susceptible, few genetic or environmental risks have been discovered to date. The diagnosis is based on the history and examination showing progressive upper and lower motor neuron findings. The electromyogram can help confirm the diagnosis, and additional tests are used to exclude other conditions. Published practice parameters guide the care of patients with ALS. Until the elucidation of aetiologies leads to the development of more robust neuroprotective agents, both pharmacological and nonpharmacological treatments are directed at maintaining quality of life and prolonging life to the greatest extent possible. Riluzole, ventilatory support for those with respiratory insufficiency, gastrostomy for those with dysphagia and multidisciplinary care may help extend life. The off-label use of many symptomatic agents can have a meaningful impact for those with the illness. Palliative care ensures dignity toward the end stages of the disease. Clinical trials currently aim to slow disease progression by testing drugs that impact one or more of the processes that are initiated after disease onset. Novel therapies currently in trials include potential neuroprotective agents with differing mechanisms of action, vaccine therapies, stem cell injections and diaphragmatic pacing.

Amyotrophic lateral sclerosis pathogenesis: a journey through the secretory pathway

Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motoneuron degenerative disease characterized by the selective loss of motoneurons in the spinal ventral horn, most brainstem nuclei, and the cerebral cortex. Although approximately 90% of ALS cases are sporadic (sALS), analyses of familial ALS (fALS)-causative genes have generated relevant insight into molecular events involved in the pathology. Here we overview an emerging concept indicating the occurrence of secretory pathway stress in the disease process. These alterations include a failure in the protein folding machinery at the endoplasmic reticulum (ER), engagement of the unfolded protein response (UPR), modifications of the Golgi apparatus network, impaired vesicular trafficking, inhibition of protein quality control mechanisms, oxidative damage to ER proteins, and sustained activation of degradative pathways such as autophagy. A common feature predicted for most of these alterations is abnormal protein homeostasis associated with the accumulation of misfolded proteins at the ER, possibly leading to chronic ER stress and neuronal dysfunction. Signs of ER stress are observed even during presymptomatic stages in fALS mouse models, and pharmacological strategies to alleviate protein misfolding slow disease progression. Because the secretory pathway stress occurs in both sALS and several forms of fALS, it may offer a unique common target for possible therapeutic strategies to treat this devastating disease.

Amyotrophic lateral sclerosis: current practice and future treatments

PURPOSE OF REVIEW

Knowledge of amyotrophic lateral sclerosis, and in particular the care of patients with it, is evolving exponentially. More than 1700 articles with the phrase 'amyotrophic lateral sclerosis' have been published in the past 2 years; these form the basis for this timely review.

RECENT FINDINGS

In part 1, I give an update on the care of patients with amyotrophic lateral sclerosis, including ways to speed diagnosis, optimal use of riluzole, multidisciplinary teams, mechanical ventilation, gastrostomy tubes, lipid-lowering agents and symptom management. Although care has become more evidence-based, there remain a number of quandaries; for these, I will provide suggestions based upon my own experience. In part 2, I identify some exciting new treatment options that are under study. These include agents designed for novel targets within motor neurons and nonneuronal cells, agents designed for specific amyotrophic lateral sclerosis subtypes and interesting new technologies. Finally, in part 3, I define current barriers to developing even better therapeutics and offer ways around them.

SUMMARY

The care of patients with amyotrophic lateral sclerosis has evolved and is now more evidence-based than ever before. Exciting new therapies are currently being tested, which may revolutionize care even further. Barriers exist, but they are surmountable.

Reactive astrocytes as therapeutic targets for CNS disorders

Reactive astrogliosis has long been recognized as a ubiquitous feature of CNS pathologies. Although its roles in CNS pathology are only beginning to be defined, genetic tools are enabling molecular dissection of the functions and mechanisms of reactive astrogliosis in vivo. It is now clear that reactive astrogliosis is not simply an all-or-nothing phenomenon but, rather, is a finely gradated continuum of molecular, cellular, and functional changes that range from subtle alterations in gene expression to scar formation. These changes can exert both beneficial and detrimental effects in a context-dependent manner determined by specific molecular signaling cascades. Dysfunction of either astrocytes or the process of reactive astrogliosis is emerging as an important potential source of mechanisms that might contribute to, or play primary roles in, a host of CNS disorders via loss of normal or gain of abnormal astrocyte activities. A rapidly growing understanding of the mechanisms underlying astrocyte signaling and reactive astrogliosis has the potential to open doors to identifying many molecules that might serve as novel therapeutic targets for a wide range of neurological disorders. This review considers general principles and examines selected examples regarding the potential of targeting specific molecular aspects of reactive astrogliosis for therapeutic manipulations, including regulation of glutamate, reactive oxygen species, and cytokines.

AMPA receptor synaptic plasticity induced by psychostimulants: the past, present, and therapeutic future

Experience-dependent plasticity at excitatory synapses of the mesocorticolimbic system is a fundamental brain mechanism that enables adaptation to an ever-changing environment. These synaptic responses are critical for the planning and execution of adaptive behaviors that maximize survival. The mesocorticolimbic system mediates procurement of positive reinforcers such as food and sex; however, drugs of abuse resculpt this crucial circuitry to promote compulsive drug-seeking behavior. This review will discuss the long-term changes in glutamatergic neurotransmission that occur within the mesolimbic system following cocaine exposure. In addition, we will examine how these long-lasting neuroadaptations may drive the pathology of psychostimulant addiction. Finally, we review clinical trials that highlight antagonists at excitatory AMPA receptors as promising targets against cocaine abuse.

Moving toward a predictive and personalized clinical approach in amyotrophic lateral sclerosis: novel developments and future directions in diagnosis, genetics, pathogenesis and therapies

Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disease that affects upper and lower motor neurons in the brain and spinal cord, with progressive weakness and atrophy of most muscles in the body and is almost always fatal within 3–5 years. A small proportion of cases are familial, and remarkable achievements have been made during the last years in understanding the genetics of the disease. In spite of this, the basic pathogenic mechanisms underlying the sporadic disease are still poorly understood. There is urgent need for better understanding of the pathogenic processes in order to be able to develop effective treatments. The present review will focus on recent knowledge gained in diagnosis, genetics, pathogenesis and therapies in ALS. Future development of diagnostic technologies integrating genetic, environmental and individual information will enable us to predict a population at risk for ALS. New treatments actually in development will help improve the medical management of ALS patients, taking into consideration individual traits, as genetic background, and pave a way for a more effective personalized diagnostic and treatment approach.

Treatment for familial amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND), is a rare neurodegenerative disease. Approximately 5% to 7% of ALS/MND patients report a family history of a similarly affected relative. Superoxide dismutase-1 gene mutations are the cause in about 20% of familial cases. In those with non-familial (sporadic) ALS/MND the cause is unknown. Also unknown is whether patients with familial and sporadic ALS/MND respond differently to treatment.

OBJECTIVES

To systematically review the literature and to answer the specific question: 'Is there a difference in the response to treatment between patients with sporadic and familial forms of ALS?'

SEARCH STRATEGY

In May 2006 we searched the Cochrane Neuromuscular Disease Group Trials Register, MEDLINE (January 1966 to May 2006) and EMBASE (January 1980 to May 2006) for randomized controlled trials (RCTs). Two review authors read the titles and abstracts of all articles and reviewed the full text of all possibly relevant articles. We scanned references of all included trials to identify additional relevant articles. For all trials eligible for inclusion we contacted the authors to request the necessary raw data.

SELECTION CRITERIA

Studies had to meet two criteria: (a) randomized controlled study design, and (b) inclusion of patients with both familial and sporadic ALS/MND.

DATA COLLECTION AND ANALYSIS

We attempted to contact authors of all trials that met inclusion criteria. We obtained data regarding ALS/MND type (sporadic versus familial), treatment assignment (active versus placebo), survival and ALS Functional Rating Scale scores for four large RCTs that included 822 sporadic and 41 familial ALS patients. We could not obtain data from 25 potentially eligible studies (17 trial authors could not be contacted and eight were unwilling to provide data).

MAIN RESULTS

There was no statistical evidence for a different response to treatment in patients with familial ALS/MND compared to those with sporadic ALS/MND. The pooled estimate of the hazard ratio for the interaction term (treatment x familial ALS) suggested a more beneficial response with respect to survival among patients with familial ALS/MND, but the result was not statistically significant. Estimates of the rate of decline on the ALS Functional Rating Scale also suggested a slightly better response to treatment among those with familial ALS/MND, but the result was not statistically significant.

AUTHORS' CONCLUSIONS

Future RCTs should document whether patients with familial ALS/MND are included and the presence or absence of a mutation in the superoxide dismutase-1 gene amongst those with familial ALS/MND.