Amyotrophic lateral sclerosis: Recent advances and future therapies
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London and National Hospital for Neurology and Neurosurgery, London, UK. Current Opinion in Neurology
(Impact Factor: 5.31).
01/2006; 18(6):712-9. DOI: 10.1097/01.wco.0000187248.21103.c5
Amyotrophic lateral sclerosis is a rare but fatal motoneuron disorder. Despite intensive research riluzole remains the only available therapy, with only marginal effects on survival. Here we review some of the recent advances in the search for a disease-modifying therapy for amyotrophic lateral sclerosis.
A number of established agents have recently been re-investigated for their potential as neuroprotective agents, including beta-lactam antibiotics and minocycline. Progress has also been made in exploiting growth factors for the treatment of amyotrophic lateral sclerosis, partly due to advances in developing effective delivery systems to the central nervous system. A number of new therapies have also been identified, including a novel class of compounds, heat-shock protein co-inducers, which upregulate cell stress responses thereby mediating neuroprotection. Non-drug-based therapies are also under development, with progress in gene-silencing and stem cell therapies.
In the past few years, significant advances have been made in both our understanding of amyotrophic lateral sclerosis pathogenesis and the development of new therapeutic approaches. However, caution must be exercised in view of the long-standing failure to successfully transfer therapeutic compounds to the clinic. A deeper awareness in the research community of the need for clinically relevant preclinical studies, coupled with a better understanding of the issues surrounding clinical trial design for amyotrophic lateral sclerosis, offers hope that the growing list of validated preclinical therapeutics can finally yield an effective disease-modifying treatment.
Available from: Pierre Zwiegers
- "To date, discrepancies between various pre-clinical efficacy studies using transgenic hSOD1 mice have hampered clinical translation of potential therapeutic compounds. [18-20]. A survey of 25 studies involving line 29 G37R animals over the past two decades indicates that crucial information such as transgene copy number or level of enzyme activity are not usually quantifiably determined or reported (Figure 1). "
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In vivo animal models of familial amyotrophic lateral sclerosis (fALS) are widely used to delineate the potential role that genetic mutations play in the neurodegenerative process. While these models are extensively used for establishing the safety and efficacy of putative therapeutics during pre-clinical development, effective clinical translation of pharmacological interventions has been largely unsuccessful.
In this report we compare a recent cohort of G37R (line 29) mice generated from mating wild-type females with transgenic males obtained commercially to a previous set of offspring produced with transgenic male breeders from a colony established at a local collaborator’s facility. Commercially derived progeny presented with a tightly clustered genomic signature for the mutant human superoxide dismutase1 transgene (hSOD1) locus, and exhibited a greater than two-fold reduction in the number of transgene copies present in the genome compared to offspring derived locally. Decrease in transgene levels corresponded with delayed ALS progression and a significant increase in overall lifespan (146%).
These results highlight some key challenges inherent to the use of G37R (line 29) animals in pre-clinical studies for the development of ALS therapeutics. Without stringent assessment of mutant SOD1 copy number/protein levels, heterogeneity of transgene levels within cohorts may influence the behavioural and pathological presentation of disease and thus calls to question the validity of any detected therapeutic effects. Nuanced changes in mutant SOD1 copy number that currently remain unreported may undermine research endeavours, delay efforts for clinical translation, and compromise the rigor of animal studies by limiting reproducibility amongst research groups.
Available from: Silvia Rossi
- "sporadic form of ALS remains unclear, while progresses in understanding the mechanisms of disease have been made into the familial forms. Glutamate excitotoxicity, oxidative stress, microglial activation, and neuroinflammation have all been implicated in the pathogenesis of ALS (Bendotti and Carrı`, 2004; Bruijn et al., 2004; Nirmalananthan and Greensmith, 2005; Rao and Weiss, 2004). Interestingly, these pathological events are potentially modulated by endocannabinoids, possibly explaining the neuroprotective eVects of increasing endocannabinoid levels in ALS animal models. "
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ABSTRACT: Alterations of the endocannabinoid system (ECS) have been recently implicated in a number of neuroinflammatory and neurodegenerative conditions so that the pharmacological modulation of cannabinoid (CB) receptors and/or of the enzymes controlling synthesis, transport, and degradation of these substances has emerged as a valuable option to treat neurological diseases. Here, we describe the current knowledge concerning the rearrangement of ECS in a primarily inflammatory disorder of the central nervous system such as multiple sclerosis (MS), and in a primarily degenerative condition such as amyotrophic lateral sclerosis (ALS). Furthermore, the data supporting a therapeutic role of agents modulating CB receptors or endocannabinoid tone in these disorders will also be reviewed. Complex changes of ECS take place in both diseases, influencing crucial aspects of their pathophysiology and clinical manifestations. Neuroinflammation, microglial activation, oxidative stress, and excitotoxicity are variably combined in MS and in ALS and can be modulated by endocannabinoids or by drugs targeting the ECS.
Available from: gatech.edu
- "Currently, riluzole (Rilutek ® ) is the only drug treatment for ALS approved by the Food and Drug Administration (FDA). However, the drug only slows progression of ALS rather than curing the disease (Bruijn, Miller et al. 2004; Nirmalananthan and Greensmith 2005). Therefore, new treatment options are greatly needed for this devastating disease. "
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ABSTRACT: myotrophic lateral sclerosis (ALS) is a devastating disease. Currently, there is no cure for this disease, and effective treatment strategies are greatly needed. Calpain activation plays a major role in the motor neuron degeneration that causes ALS. Therefore, therapeutic strategies can inhibit calpain activity in the central nervous system (CNS) have great clinical potential. The calpain inhibitors AK295 and MDL-28170 have been demonstrated to be neuroprotective in animal models of neurological injury, and should have great potential to treat ALS; however delivery problems have hindered their clinical success. Therefore, development of a new strategy that can locally deliver the calpain inhibitors to the central nervous system could significantly improve the treatment of ALS. The objectives of my thesis research were (1) to develop high molecular weight polyketals that provide sustained release properties for hydrophobic molecules, (2) to formulate calpain inhibitor-encapsulated polyketal microparticles which have a release half life of one month in vitro, (3) and to evaluate the performance of polyketal microparticles for delivering calpain inhibitors to the spinal cord in vivo. In completing these specific aims, we have developed biodegradable polymeric microparticles for the delivery of calpain inhibitors, AK295 and MDL-28170 to treat ALS. The results of calpain assays showed that both AK-PKMs and MDL-PKMs maintained most of their inhibitory activities even after the robust emulsion process. The in vitro release profile of MDL-28170 in MDL-PKMs showed that 50 % of the drug was released in the first 30 days. Experiments using dye-encapsulated microparticles showed that polyketal microparticles (1-2 ìm) are not easily cleared in the neutral physiological environment and can have potential to continuously release drug from the injection sites in the spinal cord. The efficacy of calpain inhibitor-encapsulated PKMs were studied by evaluation the behavior and survival of SOD1G93A rats, a genetic rat model for ALS. We observed the trend toward improvements in grip strength and rotarod performance in the first two months from the AK-PKMs treated group, however, further improvements are needed to enhance their in vivo efficacy.
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