Emerging disease-modifying therapies for the treatment of motor neuron disease/amyotropic lateral sclerosis

The Synergistic Effects of 5-Aminosalicylic Acid and Vorinostat in the Treatment of Ulcerative Colitis

Background: The drug 5-aminosalicylic acid (5-ASA) is the first-line therapy for the treatment of patients with mild-to-moderate ulcerative colitis (UC). However, in some cases, 5-ASA cannot achieve the desired therapeutic effects. Therefore, patients have to undergo therapies that include corticosteroids, monoclonal antibodies or immunosuppressants, which are expensive and may be accompanied by significant side effects. Synergistic drug combinations can achieve greater therapeutic effects than individual drugs while contributing to combating drug resistance and lessening toxic side effects. Thus, in this study, we sought to identify synergistic drugs that can act synergistically with 5-ASA. Methods: We started our study with protein-metabolite analysis based on peroxisome proliferator-activated receptor gamma (PPARG), the therapeutic target of 5-ASA, to identify more additional potential drug targets. Then, we further evaluated the possibility of their synergy with PPARG by integrating Kyoto Encyclopedia of Genes and Genome (KEGG) pathway enrichment analysis, pathway-pathway interaction analysis, and semantic similarity analysis. Finally, we validated the synergistic effects with in vitro and in vivo experiments. Results: The combination of 5-ASA and vorinostat (SAHA) showed lower toxicity and mRNA expression of p65 in human colonic epithelial cell lines (Caco-2 and HCT-116), and more efficiently alleviated the symptoms of dextran sulfate sodium (DSS)-induced colitis than treatment with 5-ASA and SAHA alone. Conclusion: SAHA can exert effective synergistic effects with 5-ASA in the treatment of UC. One possible mechanism of synergism may be synergistic inhibition of the nuclear factor kappa B (NF-kB) signaling pathway. Moreover, the metabolite-butyric acid may be involved.

Oxidative Stress in Amyotrophic Lateral Sclerosis: Pathophysiology and Opportunities for Pharmacological Intervention

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease or Charcot disease, is a fatal neurodegenerative disease that affects motor neurons (MNs) and leads to death within 2–5 years of diagnosis, without any effective therapy available. Although the pathological mechanisms leading to ALS are still unknown, a wealth of evidence indicates that an excessive reactive oxygen species (ROS) production associated with an inefficient antioxidant defense represents an important pathological feature in ALS. Substantial evidence indicates that oxidative stress (OS) is implicated in the loss of MNs and in mitochondrial dysfunction, contributing decisively to neurodegeneration in ALS. Although the modulation of OS represents a promising approach to protect MNs from degeneration, the fact that several antioxidants with beneficial effects in animal models failed to show any therapeutic benefit in patients raises several questions that should be analyzed. Using specific queries for literature search on PubMed, we review here the role of OS-related mechanisms in ALS, including the involvement of altered mitochondrial function with repercussions in neurodegeneration. We also describe antioxidant compounds that have been mostly tested in preclinical and clinical trials of ALS, also describing their respective mechanisms of action. While the description of OS mechanism in the different mutations identified in ALS has as principal objective to clarify the contribution of OS in ALS, the description of positive and negative outcomes for each antioxidant is aimed at paving the way for novel opportunities for intervention. In conclusion, although antioxidant strategies represent a very promising approach to slow the progression of the disease, it is of utmost need to invest on the characterization of OS profiles representative of each subtype of patient, in order to develop personalized therapies, allowing to understand the characteristics of antioxidants that have beneficial effects on different subtypes of patients.

Emerging Drugs for the Treatment of Amyotrophic Lateral Sclerosis: A Focus on Recent Phase 2 Trials

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disease involving both upper and lower motor neurons and resulting in increasing disability and death 3-5 years after onset of symptoms. Over 40 large clinical trials for ALS have been negative, except for Riluzole that offers a modest survival benefit, and Edaravone that modestly reduces disease progression in patients with specific characteristics. Thus, the discovery of efficient disease modifying therapy is an urgent need.

AREAS COVERED

Although the cause of ALS remains unclear, many studies have demonstrated that neuroinflammation, proteinopathies, glutamate-induced excitotoxicity, microglial activation, oxidative stress, and mitochondrial dysfunction may play a key role in the pathogenesis. This review highlights recent discoveries relating to these diverse mechanisms and their implications for the development of therapy. Ongoing phase 2 clinical trials aimed to interfere with these pathophysiological mechanisms are discussed.

EXPERT OPINION

This review describes the challenges that the discovery of an efficient drug therapy faces and how these issues may be addressed. With the continuous advances coming from basic research, we provided possible suggestions that may be considered to improve performance of clinical trials and turn ALS research into a 'fertile ground' for drug development for this devastating disease.

Potential new complication in drug therapy development for amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron degeneration in the brain and spinal cord. Treatment development for ALS is complicated by complex underlying disease factors. Areas covered: Numerous tested drug compounds have shown no benefits in ALS patients, although effective in animal models. Discrepant results of pre-clinical animal studies and clinical trials for ALS have primarily been attributed to limitations of ALS animal models for drug-screening studies and methodological inconsistencies in human trials. Current status of pre-clinical and clinical trials in ALS is summarized. Specific blood-CNS barrier damage in ALS patients, as a novel potential reason for the clinical failures in drug therapies, is discussed. Expert commentary: Pathological perivascular collagen IV accumulation, one unique characteristic of barrier damage in ALS patients, could be hindering transport of therapeutics to the CNS. Restoration of B-CNS-B integrity would foster delivery of therapeutics to the CNS.

The ER mitochondria calcium cycle and ER stress response as therapeutic targets in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive loss of upper and lower motor neurons. Although the etiology remains unclear, disturbances in calcium homoeostasis and protein folding are essential features of neurodegeneration in this disorder. Here, we review recent research findings on the interaction between endoplasmic reticulum (ER) and mitochondria, and its effect on calcium signaling and oxidative stress. We further provide insights into studies, providing evidence that structures of the ER mitochondria calcium cycle serve as a promising targets for therapeutic approaches for treatment of ALS.

Analysis of start-up, retention, and adherence in ALS clinical trials

OBJECTIVE

To investigate predictors of trial start-up times, high attrition, and poor protocol adherence in amyotrophic lateral sclerosis (ALS) trials.

METHODS

Retrospective analysis of start-up times, retention, and protocol adherence was performed on 5 clinical studies conducted by the Northeast ALS Consortium and 50 ALS clinical trials identified by PubMed search. Predictors of start-up times were estimated by accelerated failure time models with random effects. Predictors of retention and protocol deviations were estimated by mixed-model logistic regression.

RESULTS

Median times for contract execution and institutional review board (IRB) approval were 105 days and 125 days, respectively. Contract execution was faster at sites with more ongoing trials (p = 0.005), and more full-time (p = 0.006) and experienced (p < 0.001) coordinators. IRB approval was faster at sites with more ongoing trials (p = 0.010) and larger ALS clinics (p = 0.038). Site activation after IRB approval was faster at sites with more full-time (p = 0.038) and experienced (p < 0.001) coordinators. Twenty-two percent of surviving participants withdrew before completing the trial. Better participant functional score at baseline was an independent predictor of trial completion (odds ratio 1.29, p = 0.002) and fewer protocol deviations (odds ratio 0.86, p = 0.030).

CONCLUSION

Delays in IRB review contribute the most to prolonged trial start-up times, and these timelines are faster in sites with more experienced staff. Strategies to improve protocol adherence and participants' retention may include enrolling people at early disease stages.

Strategy for treating motor neuron diseases using a fusion protein of botulinum toxin binding domain and streptavidin for viral vector access: work in progress

Although advances in understanding of the pathogenesis of amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA) have suggested attractive treatment strategies, delivery of agents to motor neurons embedded within the spinal cord is problematic. We have designed a strategy based on the specificity of botulinum toxin, to direct entry of viral vectors carrying candidate therapeutic genes into motor neurons. We have engineered and expressed fusion proteins consisting of the binding domain of botulinum toxin type A fused to streptavidin (SAv). This fusion protein will direct biotinylated viral vectors carrying therapeutic genes into motor nerve terminals where they can enter the acidified endosomal compartments, be released and undergo retrograde transport, to deliver the genes to motor neurons. Both ends of the fusion proteins are shown to be functionally intact. The binding domain end binds to mammalian nerve terminals at neuromuscular junctions, ganglioside GT1b (a target of botulinum toxin), and a variety of neuronal cells including primary chick embryo motor neurons, N2A neuroblastoma cells, NG108-15 cells, but not to NG CR72 cells, which lack complex gangliosides. The streptavidin end binds to biotin, and to a biotinylated Alexa 488 fluorescent tag. Further studies are in progress to evaluate the delivery of genes to motor neurons in vivo, by the use of biotinylated viral vectors.

Uridine ameliorates the pathological phenotype in transgenic G93A-ALS mice

There is strong evidence from studies in humans and animal models to suggest the involvement of energy metabolism defects in neurodegenerative diseases. Uridine, a pyrimidine nucleoside, has been suggested to be neuroprotective in neurological disorders by improving bioenergetic effects, increasing ATP levels and enhancing glycolytic energy production. We assessed whether uridine treatment extended survival and improved the behavioral and neuropathological phenotype observed in G93A-ALS mice. In vitro and in vivo pharmacokinetic analyses in mutant SOD models provided optimal dose and assurance that uridine entered the brain. A dose-ranging efficacy trial in G93A mice was performed using survival, body weight, open-field analysis, and neuropathology as outcome measures. Urinary levels of 8-hydroxy-2'-deoxyguanosine, identifying DNA oxidative damage, were measured and used as a pharmacodynamic biomarker. Uridine administration significantly extended survival in a dose-dependent manner in G93A mice, while improving the behavioral and neuropathological phenotype. Uridine increased survival by 17.4%, ameliorated body weight loss, enhanced motor performance, reduced gross lumbar and ventral horn atrophy, attenuated lumbar ventral horn neuronal cell death, and decreased reactive astrogliosis. Consistent with a therapeutic effect, uridine significantly reduced urinary 8-hydroxy-2'-deoxyguanosine in G93A mice. These data suggest that uridine may be a therapeutic candidate in ALS patients.

Managing amyotrophic lateral sclerosis: slowing disease progression and improving patient quality of life

It is now possible to slow the disease progression of amyotrophic lateral sclerosis (ALS), but documented improvement in the quality of life of ALS patients has been difficult to quantitate. Putative mechanisms involved in motor neuron degeneration in ALS include oxidative damage, mitochondrial dysfunction, neuroinflammation, growth factor deficiency, and glutamate excitotoxicity. Several pharmacological agents that target these potential targets have demonstrated therapeutic potential in animal models with mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1). Many treatments that have been moderately effective in this animal model have not been successfully translated into effective treatments for humans with ALS. Only the glutamate modulator riluzole has demonstrated efficacy in clinical trials and is approved for treating ALS. Combination treatments may represent a potential therapeutic strategy to more robustly prolong life and preserve function, but only vitamin E with riluzole has been formally studied in clinical trials, and to date, no combination treatments have been found to be more effective than currently available single agents.

Amyotrophic lateral sclerosis: clinical management and research update

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that selectively affects the motor neurons of the brain and spinal cord. ALS occurs in about 1 in 100,000 individuals. Although recent advances have been made in understanding the pathogenesis of ALS, there has been no new effective pharmacotherapy since the approval of riluzole more than 10 years ago. The mainstay of clinical management includes pharmacologic management of symptoms, management of dysphagia and respiratory symptoms, palliative care, and multidisciplinary care clinics. In this review, we discuss the clinical management of ALS, recent modifications to the diagnostic criteria, and current clinical trials.

Current and emerging treatments for amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a relatively rare neurodegenerative disorder of both upper and lower motoneurons. Currently, the management of ALS is essentially symptoms-based, and riluzole, an antiglutamatergic agent, is the only drug for the treatment of ALS approved by the food and drug administration.

OBJECTIVE

We reviewed current literature concerning emerging treatments for amyotrophic lateral sclerosis.

METHODS

A Medline literature search was performed to identify all studies on ALS treatment published from January 1st, 1986 through August 31st, 2009. We selected papers concerning only disease-modifying therapy.

RESULTS

Forty-eight compounds were identified and reviewed in this study.

CONCLUSIONS

Riluzole is the only compound that demonstrated a beneficial effect on ALS patients, but with only modest increase in survival. Although several drugs showed effective results in the animal models for ALS, none of them significantly prolonged survival or improved quality of life of ALS patients. Several factors have been implicated in explaining the predominantly negative results of numerous randomized clinical trials in ALS, including methodological problems in the use of animal-drug screening, the lack of assessment of pharmacokinetic profile of the drugs, and methodological pitfalls of clinical trials in ALS patients.

Scrutinizing enrollment in ALS clinical trials: room for improvement?

Enrollment in ALS trials has not been systematically studied. We surveyed the ALS Research Group (ALSRG) to learn their impressions of enrollment at ALS clinics across North America. We also reviewed completed ALS trials to determine an enrollment rate (subjects per site per month), its variability across trials, whether it is changing over time, and whether it is influenced by 'trial factors'. ALSRG members were polled via an online survey. ALS trials were identified by literature review and investigator contact. Enrollment rate versus publication year was plotted for each trial. Models were created to examine how 'trial factors' were associated with enrollment rate. By survey, percent enrollment is 25% and highly variable (range 0-75%). By literature review, enrollment rate is 2.2 participants/site/month and highly variable (range 0.1-7.5). Enrollment is not improving over time; no 'trial factor' explains the variability in enrollment across trials. Behaviors among clinic directors and patients were identified that may influence enrollment. In conclusion, ALS trial enrollment rate is low, highly variable and not influenced by trial design factors. 'Patient factors' and 'physician factors' may play more important roles in influencing enrollment, as in oncology trials. Our survey data support this idea, and provide potential mechanisms for improving enrollment.