Safety and Efficacy of Edonerpic Maleate for Patients With Mild to Moderate Alzheimer Disease: A Phase 2 Randomized Clinical Trial

GLP-1/Sigma/RAGE receptors: An evolving picture of Alzheimer's disease pathology and treatment

According to the facts and figures 2023stated that 6.7 million Americans over the age of 65 have Alzheimer's disease (AD). The scenario of AD has reached up to the maximum, of 4.1 million individuals, 2/3rd are female patients, and approximately 1 in 9 adults over the age of 65 have dementia with AD dementia. The fact that there are now no viable treatments for AD indicates that the underlying disease mechanisms are not fully understood. The progressive neurodegenerative disease, AD is characterized by amyloid plaques and neurofibrillary tangles (NFTs) of abnormally hyperphosphorylated tau protein and senile plaques (SPs), which are brought on by the buildup of amyloid beta (Aβ). Numerous attempts have been made to produce compounds that interfere with these characteristics because of significant research efforts into the primary pathogenic hallmark of this disorder. Here, we summarize several research that highlights interesting therapy strategies and the neuroprotective effects of GLP-1, Sigma, and, AGE-RAGE receptors in pre-clinical and clinical AD models.

Consistency between Treatment Effects on Clinical and Brain Atrophy Outcomes in Alzheimer's Disease Trials

BACKGROUND

Longitudinal changes in volumetric MRI outcome measures have been shown to correlate well with longitudinal changes in clinical instruments and have been widely used as biomarker outcomes in clinical trials for Alzheimer's disease (AD). While instances of discordant findings have been noted in some trials, especially the recent amyloid-removing therapies, the overall relationship between treatment effects on brain atrophy and clinical outcomes, and how it might depend on treatment target or mechanism, clinical instrument or imaging variable is not yet clear.

OBJECTIVE

To systematically assess the consistency and therapeutic class-dependence of treatment effects on clinical outcomes and on brain atrophy in published reports of clinical trials conducted in mild cognitive impairment (MCI) and/or AD.

DESIGN

Quantitative review of the published literature. The consistency of treatment effects on clinical and brain atrophy outcomes was assessed in terms of statistical agreement with hypothesized equal magnitude effects (e.g., 30% slowing of both) and nominal directional concordance, as a function of therapeutic class.

SETTING

Interventional randomized clinical trials.

PARTICIPANTS

MCI or AD trial participants.

INTERVENTION

Treatments included were those that involved ingestion or injection of a putatively active substance into the body, encompassing both pharmacological and controlled dietary interventions.

MEASUREMENTS

Each trial included in the analysis reported at least one of the required clinical outcomes (ADAS-Cog, CDR-SB or MMSE) and at least one of the required imaging outcomes (whole brain, ventricular or hippocampal volume).

RESULTS

Data from 35 trials, comprising 185 pairwise comparisons, were included. Overall, the 95% confidence bounds overlapped with the line of identity for 150/185 (81%) of the imaging-clinical variable pairs. The greatest proportion of outliers was found in trials of anti-amyloid antibodies that have been shown to dramatically reduce the level of PET-detectable amyloid plaques, for which only 13/33 (39%) of observations overlapped the identity line. A Deming regression calculated using all data points yielded a slope of 0.54, whereas if data points from the amyloid remover class were excluded, the Deming regression line had a slope of 0.92. Directional discordance of treatment effects was also most pronounced for the amyloid-removing class, and for comparisons involving ventricular volume.

CONCLUSION

Our results provide a frame of reference for the interpretation of clinical and brain atrophy results from future clinical trials and highlight the importance of mechanism of action in the interpretation of imaging results.

An inclusive study of recent advancements in Alzheimer's disease: A comprehensive review

Alzheimer's disease (AD) has remained elusive in revealing its pathophysiology and mechanism of development. In this review paper, we attempt to highlight several theories that abound about the exact pathway of AD development. The number of cases worldwide has prompted a constant flow of research to detect high-risk patients, slow the progression of the disease and discover improved methods of treatment that may prove effective. We shall focus on the two main classes of drugs that are currently in use; and emerging ones with novel mechanisms that are under development. As of late there has also been increased attention towards factors that were previously thought to be unrelated to AD, such as the gut microbiome, lifestyle habits, and diet. Studies have now shown that all these factors make an impact on AD progression, thus bringing to our attention more areas that could hold the key to combating this disease. This paper covers all the aforementioned factors concisely. We also briefly explore the relationship between mental health and AD, both before and after the diagnosis of the disease.

T817MA Regulates Mitochondrial Dynamics via Sirt1 and Arc Following Subarachnoid Hemorrhage

Spontaneous subarachnoid hemorrhage (SAH) is an acute neurologic emergency with poor outcomes, and mitochondrial dysfunction is known as one of the key pathological mechanisms underlying the SAH-induced early brain injury (EBI). 1-{3-[2-(1-benzothiophen-5-yl)ethoxy]propyl} azetidin-3-ol maleate (T817MA) is a newly synthesized neurotrophic compound that has been demonstrated to exert protective effects against brain injury. Here, we investigated the effect of T817MA in neuronal injury following experimental SAH both in vitro and in vivo. Primary cultured cortical neurons were treated with oxyhemoglobin (OxyHb) to mimic SAH in vitro, and T817MA at concentrations higher than 0.1 μM reduced OxyHb-induced neuronal injury. T817MA treatment significantly inhibited lipid peroxidation, reduced neuronal apoptosis and attenuated mitochondrial fragmentation. The results of western blot showed that T817MA markedly reduced the expression of mitochondrial fission proteins, fission protein 1 (Fis-1) and dynamin-related GTPase-1 (Drp-1), but prolonged the expression of the postsynaptic protein activity-regulated cytoskeleton-associated protein (Arc). In addition, T817MA significantly increased the expression of sirtuin 1 (Sirt1), which was accompanied by preserved enzymatic of isocitrate dehydrogenase (IDH2) and superoxide dismutase (SOD). Knockdown of Sirt1 and Arc via small interfere RNA (siRNA) transfection partially prevented the T817MA-induced protection in cortical neurons. Furthermore, treatment with T817MA in vivo significantly reduced brain damage and preserved neurological function in rats. The decreased expression of Fis-1 and Drp-1, as well as the increased expression of Arc and Sirt1 were also observed in vivo. Taken together, these data indicate that the neuroprotective agent T817MA protects against SAH-induced brain injury via Sirt1- and Arc-mediated regulation of mitochondrial dynamics.

FDA-approved machine learning algorithms in neuroradiology: A systematic review of the current evidence for approval

Over the past decade, machine learning (ML) and artificial intelligence (AI) have become increasingly prevalent in the medical field. In the United States, the Food and Drug Administration (FDA) is responsible for regulating AI algorithms as "medical devices" to ensure patient safety. However, recent work has shown that the FDA approval process may be deficient. In this study, we evaluate the evidence supporting FDA-approved neuroalgorithms, the subset of machine learning algorithms with applications in the central nervous system (CNS), through a systematic review of the primary literature. Articles covering the 53 FDA-approved algorithms with applications in the CNS published in PubMed, EMBASE, Google Scholar and Scopus between database inception and January 25, 2022 were queried. Initial searches identified 1505 studies, of which 92 articles met the criteria for extraction and inclusion. Studies were identified for 26 of the 53 neuroalgorithms, of which 10 algorithms had only a single peer-reviewed publication. Performance metrics were available for 15 algorithms, external validation studies were available for 24 algorithms, and studies exploring the use of algorithms in clinical practice were available for 7 algorithms. Papers studying the clinical utility of these algorithms focused on three domains: workflow efficiency, cost savings, and clinical outcomes. Our analysis suggests that there is a meaningful gap between the FDA approval of machine learning algorithms and their clinical utilization. There appears to be room for process improvement by implementation of the following recommendations: the provision of compelling evidence that algorithms perform as intended, mandating minimum sample sizes, reporting of a predefined set of performance metrics for all algorithms and clinical application of algorithms prior to widespread use. This work will serve as a baseline for future research into the ideal regulatory framework for AI applications worldwide.

Targeted to neuronal organelles for CNS drug development

Significant evidences indicate that sub-cellular organelle dynamics is critical for both physiological and pathological events and therefore may be attractive drug targets displaying great therapeutic potential. Although the basic biological mechanism underlying the dynamics of intracellular organelles has been extensively studied, relative drug development is still limited. In the present review, we show that due to the development of technical advanced imaging tools, especially live cell imaging methods, intracellular organelle dynamics (including mitochondrial dynamics and membrane contact sites) can be dissected at the molecular level. Based on these identified molecular targets, we review and discuss the potential of drug development to target organelle dynamics, especially mitochondria dynamics and ER-organelle membrane contact dynamics, in the central nervous system for treating human diseases, including neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis.

Mapping new pharmacological interventions for cognitive function in Alzheimer's disease: a systematic review of randomized clinical trials

Background and Objective: Alzheimer's disease (AD) is a progressive neurodegenerative disorder, that is, characterized by cognitive decline. To date, there are no effective treatments for AD. Therefore, the objective of this study was to map new perspectives on the effects of pharmacological treatment on cognitive function and the overall psychological state in patients with AD. Methods: Two independent researchers searched for randomized clinical trials (RCTs) exploring new pharmacological approaches related to cognition in Alzheimer's disease in adults from 2018 to 2023 in PubMed, Web of Science, Scopus, and Cochrane Library databases. A total of 17 RCTs were included in this review. Results: The results show that in recent years, new drugs have been tested in patients with Alzheimer's disease, including masitinib, methylphenidate, levetiracetam, Jiannao Yizhi, and Huannao Yicong formulas. Most studies have been conducted in populations with mild to moderate Alzheimer's disease. Conclusion: Although some of the drugs found suggested improvement in cognitive function, the scarcity of available studies highlights the need for further research in this area. Systematic review registration: [www.crd.york.ac.uk/prospero], identifier [CRD42023409986].

Targeting Sigma Receptors for the Treatment of Neurodegenerative and Neurodevelopmental Disorders

The sigma-1 receptor is a 223 amino acid-long protein with a recently identified structure. The sigma-2 receptor is a genetically unrelated protein with a similarly shaped binding pocket and acts to influence cellular activities similar to the sigma-1 receptor. Both proteins are highly expressed in neuronal tissues. As such, they have become targets for treating neurological diseases, including Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), multiple sclerosis (MS), Rett syndrome (RS), developmental and epileptic encephalopathies (DEE), and motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). In recent years, there have been many pre-clinical and clinical studies of sigma receptor (1 and 2) ligands for treating neurological disease. Drugs such as blarcamesine, dextromethorphan and pridopidine, which have sigma-1 receptor activity as part of their pharmacological profile, are effective in treating multiple aspects of several neurological diseases. Furthermore, several sigma-2 receptor ligands are under investigation, including CT1812, rivastigmine and SAS0132. This review aims to provide a current and up-to-date analysis of the current clinical and pre-clinical data of drugs with sigma receptor activities for treating neurological disease.

Role of Tau in Various Tauopathies, Treatment Approaches, and Emerging Role of Nanotechnology in Neurodegenerative Disorders

A few protein kinases and phosphatases regulate tau protein phosphorylation and an imbalance in their enzyme activity results in tau hyper-phosphorylation. Aberrant tau phosphorylation causes tau to dissociate from the microtubules and clump together in the cytosol to form neurofibrillary tangles (NFTs), which lead to the progression of neurodegenerative disorders including Alzheimer's disease (AD) and other tauopathies. Hence, targeting hyperphosphorylated tau protein is a restorative approach for treating neurodegenerative tauopathies. The cyclin-dependent kinase (Cdk5) and the glycogen synthase kinase (GSK3β) have both been implicated in aberrant tau hyperphosphorylation. The limited transport of drugs through the blood-brain barrier (BBB) for reaching the central nervous system (CNS) thus represents a significant problem in the development of drugs. Drug delivery systems based on nanocarriers help solve this problem. In this review, we discuss the tau protein, regulation of tau phosphorylation and abnormal hyperphosphorylation, drugs in use or under clinical trials, and treatment strategies for tauopathies based on the critical role of tau hyperphosphorylation in the pathogenesis of the disease. Pathology of neurodegenerative disease due to hyperphosphorylation and various therapeutic approaches including nanotechnology for its treatment.

A systematic review on drugs for synaptic plasticity in the treatment of dementia

The aim of the present systematic review (SR) was to provide an overview of all published and unpublished clinical trials investigating the safety and efficacy of disease-modifying drugs targeting synaptic plasticity in dementia. Searches on CT.gov and EuCT identified 27 trials (4 phase-1, 1 phase-1/2, 18 phase-2, 1 phase-2/3, 1 phase-3, 1 phase-4, and 1 not reported). Twenty of them completed, and seven are currently active or enrolling. The structured bibliographic searches yielded 3585 records. A total of 12 studies were selected on Levetiracetam, Masitinib, Saracatinib, BI 40930, Bryostatin 1, PF-04447943 and Edonerpic drugs. We used RoB tool for quality analysis of randomized studies. Efficacy was assessed as a primary outcome in all studies except one and the main scale used was ADAS-Cog (7 studies), MMSE and CDR (4 studies). Safety and tolerability were reported in eleven studies. The incidence of SAEs was similar between treatment and placebo. At the moment, only one molecule reached phase-3. This could suggest that research on these drugs is still preliminary. Of all, three studies reported promising results on Levetiracetam, Bryostatin 1 and Masitinib.

Small-molecule drugs development for Alzheimer's disease

Alzheimer's disease (AD) is an irreversible, progressive neurodegenerative brain disorder with no effective therapeutic drugs currently. The complicated pathophysiology of AD is not well understood, although beta-amyloid (Aβ) cascade and hyperphosphorylated tau protein were regarded as the two main causes of AD. Other mechanisms, such as oxidative stress, deficiency of central cholinergic neurotransmitters, mitochondrial dysfunction, and inflammation, were also proposed and studied as targets in AD. This review aims to summarize the small-molecule drugs that were developed based on the pathogenesis and gives a deeper understanding of the AD. We hope that it could help scientists find new and better treatments to gradually conquer the problems related to AD in future.

The Potential of Small Molecules to Modulate the Mitochondria–Endoplasmic Reticulum Interplay in Alzheimer’s Disease

Alzheimer’s disease (AD) is the most common neurodegenerative disease affecting a growing number of elderly individuals. No disease-modifying drugs have yet been identified despite over 30 years of research on the topic, showing the need for further research on this multifactorial disease. In addition to the accumulation of amyloid β-peptide (Aβ) and hyperphosphorylated tau (p-tau), several other alterations have been associated with AD such as calcium (Ca2+) signaling, glucose-, fatty acid-, cholesterol-, and phospholipid metabolism, inflammation, and mitochondrial dysfunction. Interestingly, all these processes have been associated with the mitochondria–endoplasmic reticulum (ER) contact site (MERCS) signaling hub. We and others have hypothesized that the dysregulated MERCS function may be one of the main pathogenic pathways driving AD pathology. Due to the variety of biological processes overseen at the MERCS, we believe that they constitute unique therapeutic targets to boost the neuronal function and recover neuronal homeostasis. Thus, developing molecules with the capacity to correct and/or modulate the MERCS interplay can unleash unique therapeutic opportunities for AD. The potential pharmacological intervention using MERCS modulators in different models of AD is currently under investigation. Here, we survey small molecules with the potential to modulate MERCS structures and functions and restore neuronal homeostasis in AD. We will focus on recently reported examples and provide an overview of the current challenges and future perspectives to develop MERCS modulators in the context of translational research.

Brain-derived neurotrophic factor for high-throughput evaluation of selective Sigma-1 receptor ligands

The Sigma-1 receptor (S1R) is an endoplasmic reticulum (ER) chaperone protein that has been implicated in attenuating inflammatory stress-mediated brain injuries. Selective S1R agonists represent a new class of therapeutic agent for treating neuropsychiatric and neurodegenerative disorders, however, to date, no S1R ligand has been approved for therapeutic purposes. We used three potential methods on known and potential S1R ligands to develop an unambiguous high-throughput cell screen for S1R activity. We screened known and potential S1R ligands using radioligand binding and previously reported markers of S1R activity including BDNF release, modulation of IP3 mediated calcium release, and modulation of NGF-induced neurite sprouting. Here, we present results several prototypical S1R compounds and some compounds with the potential for drug repurposing. Using an in-situ ELISA approach we demonstrated that these compounds could stimulate S1R-mediated BDNF release, which is a valuable therapeutic property since BDNF plays a critical role in neuronal support. These compounds were classified as S1R agonists because the BDNF response was comparable to the prototypical agonist 4-PPBP and because it could be reversed by a S1R selective concentration of the antagonist BD1063. When modulation of IP3 mediated calcium response and NGF-induced neurite sprouting were used as a measure of S1R activation, we were unable to reproduce the published results and determined that they are not reliable measures for evaluating functional properties of S1R ligands.

Proportion of Women and Reporting of Outcomes by Sex in Clinical Trials for Alzheimer Disease: A Systematic Review and Meta-analysis

IMPORTANCE

Women represent two-thirds of patients with Alzheimer disease (AD), and sex differences might affect results of randomized clinical trials (RCTs). However, little information exists on differences in sex as reported in RCTs for AD.

OBJECTIVE

To assess the ratio of females to males and the reporting of sex-stratified data in large pharmaceutical RCTs for AD.

DATA SOURCES

A search for pharmaceutical RCTs for AD was conducted on September 4, 2019, using ClinicalTrials.gov with the key word Alzheimer disease, and articles related to those trials were identified using the PubMed, Scopus, and Google Scholar databases. Searches were conducted between September 4 and October 31, 2019, and between April 15 and May 31, 2020.

STUDY SELECTION

Controlled RCTs that had more than 100 participants and tested the efficacy of drugs or herbal extracts were included. Of 1047 RCTs identified, 409 were published and therefore screened. A total of 77 articles were included in the final analysis, including 56 primary articles on AD, 13 secondary articles on AD, and 8 articles on mild cognitive impairment.

DATA EXTRACTION AND SYNTHESIS

The location and date of publication; number, sex, and age of patients enrolled; disease severity; experimental or approved status of the drug; and whether the study included a sex-stratified analysis in the protocol, methods, or results were extracted by 1 reviewer for each article, and the meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. Data were analyzed using a mixed-effects model.

MAIN OUTCOMES AND MEASURES

The mean proportion of women enrolled in the trials and the associations between prespecified variables were analyzed. The proportion of articles that included sex-stratified results and the temporal trends in the reporting of these results were also studied.

RESULTS

In this review of 56 RCTs for AD involving 39 575 participants, 23 348 women (59.0%) were included. The mean (SD) proportion of women in RCTs of approved drugs was 67.3% (6.9%), and in RCTs of experimental drugs was 57.9% (5.9%). The proportion of women in RCTs of experimental drugs was significantly lower than the proportion of women in the general population with AD in the US (62.1%; difference, -4.56% [95% CI, -6.29% to -2.87%]; P < .001) and Europe (68.2%; difference, -10.67% [95% CI, -12.39% to -8.97%]; P < .001). Trials of approved drugs had a higher probability of including women than trials of experimental drugs (odds ratio [OR], 1.26; 95% CI, 1.05-1.52; P = .02). Both the severity of AD at baseline and the trial location were associated with the probability of women being enrolled in trials (severity: OR, 0.98; 95% CI, 0.97-1.00; P = .02; location in Europe: OR, 1.26; 95% CI, 1.05-1.52; P = .01; location in North America: OR, 0.81; 95% CI, 0.71-0.93; P = .002). Only 7 articles (12.5%) reported sex-stratified results, with an increasing temporal trend (R, 0.30; 95% CI, 0.05-0.59; P = .03).

CONCLUSIONS AND RELEVANCE

In this systematic review and meta-analysis, the proportion of women in RCTs for AD, although higher than the proportion of men, was significantly lower than that in the general population. Only a small proportion of trials reported sex-stratified results. These findings support strategies to improve diversity in enrollment and data reporting in RCTs for AD.

Sigma receptors and neurological disorders

Sigma receptors were identified relatively recently, and their presence has been confirmed in the central nervous system and peripheral organs. Changes in sigma receptor function or expression may be involved in neurological diseases, and thus sigma receptors represent a potential target for treating central nervous system disorders. Many substances that are ligands for sigma receptors are widely used in therapies for neurological disorders. In the present review, we discuss the roles of sigma receptors, especially in the central nervous system disorders, and related therapies.

The emerging role of the sigma-1 receptor in autophagy: hand-in-hand targets for the treatment of Alzheimer's

INTRODUCTION

Autophagy is a cellular catabolic mechanism that helps clear damaged cellular components and is essential for normal cellular and tissue function. The sigma-1 receptor (σ-1R) is a chaperone protein involved in signal transduction, neurite outgrowth, and plasticity, improving memory, and neuroprotection. Recent evidence shows that σ-1R can promote autophagy. Autophagy activation by the σ-1Rs along with other neuroprotective effects makes it an interesting target for the treatment of Alzheimer's disease. AF710B, T-817 MA, and ANAVEX2-73 are some of the σ-1R agonists which have shown promising results and have entered clinical trials. These molecules have also been found to induce autophagy and show cytoprotective effects in cellular models.

AREAS COVERED

This review provides insight into the current understanding of σ-1R functions related to autophagy and their role in alleviating AD.

EXPERT OPINION

We propose a mechanism through which the activation of σ-1R and autophagy could alter amyloid precursor protein processing to inhibit amyloid-β production by reconstituting cholesterol and gangliosides in the lipid raft to offer neuroprotection against AD. Future AD treatment could involve the combined targeting of the σ-1R and autophagy activation. We suggest that future studies investigate the link between autophagy the σ-1R and AD.

Bi-phasic dose response in the preclinical and clinical developments of sigma-1 receptor ligands for the treatment of neurodegenerative disorders

Introduction: The sigma-1 receptor (S1R) is attracting much attention for disease-modifying therapies in neurodegenerative diseases. It is a conserved protein, present in plasma and endoplasmic reticulum (ER) membranes and enriched in mitochondria-associated ER membranes (MAMs). It modulates ER-mitochondria Ca2+ transfer and ER stress pathways. Mitochondrial and MAM dysfunctions contribute to neurodegenerative processes in diseases such as Alzheimer, Parkinson, Huntington or Amyotrophic Lateral Sclerosis. Interestingly, the S1R can be activated by small druggable molecules and accumulating preclinical data suggest that S1R agonists are effective protectants in these neurodegenerative diseases.Area covered: In this review, we will present the data showing the high therapeutic potential of S1R drugs for the treatment of neurodegenerative diseases, focusing on pridopidine as a potent and selective S1R agonist under clinical development. Of particular interest is the bi-phasic (bell-shaped) dose-response effect, representing a common feature of all S1R agonists and described in numerous preclinical models in vitro, in vivo and in clinical trials.Expert opinion: S1R agonists modulate inter-organelles communication altered in neurodegenerative diseases and activate intracellular survival pathways. Research will continue growing in the future. The particular cellular nature of this chaperone protein must be better understood to facilitate the clinical developement of promising molecules.

Small Molecules Selectively Targeting Sigma-1 Receptor for the Treatment of Neurological Diseases

The sigma-1 (σ1) receptor, an enigmatic protein originally classified as an opioid receptor subtype, is now understood to possess unique structural and functional features of its own and play critical roles to widely impact signaling transduction by interacting with receptors, ion channels, lipids, and kinases. The σ1 receptor is implicated in modulating learning, memory, emotion, sensory systems, neuronal development, and cognition and accordingly is now an actively pursued drug target for various neurological and neuropsychiatric disorders. Evaluation of the five selective σ1 receptor drug candidates (pridopidine, ANAVEX2-73, SA4503, S1RA, and T-817MA) that have entered clinical trials has shown that reaching clinical approval remains an evasive and important goal. This review provides up-to-date information on the selective targeting of σ1 receptors, including their history, function, reported crystal structures, and roles in neurological diseases, as well as a useful collation of new chemical entities as σ1 selective orthosteric ligands or allosteric modulators.

TLR4-TAK1-p38 MAPK pathway and HDAC6 regulate the expression of sigma-1 receptors in rat primary cultured microglia

Microglia maintain brain homeostasis as the main immune cells in the central nervous system. Activation of sigma-1 receptor (Sig1R) plays neuroprotective and anti-inflammatory roles in microglia. Recent studies showed that Sig1R expression level has been reduced in the brain of the patients with neurodegenerative diseases including Alzheimer's disease. However, the mechanisms underlying the down regulation of the Sig1R has not been clear. Treatment of rat primary cultured microglia with the inflammogen lipopolysaccharide (LPS) significantly decreased the expression of Sig1R mRNA in a concentration and time-dependent manner. The effects of LPS were blocked by pretreatment with TAK-242, a toll-like receptor 4 (TLR4) antagonist. Furthermore, inhibitors of transforming growth factor beta-activated kinase 1 (TAK1), p38 mitogen-activated protein kinase (MAPK) and histone deacetylase 6 (HDAC6) restored the LPS-induced downregulation of Sig1R. Thus, the current findings demonstrate that TLR4 activation leads to the downregulation of the Sig1R expression via TLR4-TAK1-p38 MAPK pathway and the inhibition of HDAC6 can increase Sig1R expression in microglia. The current findings suggest that downregulation of Sig1R may contribute to neuroinflammation-induced microglial dysfunction, regulation of microglial Sig1R may be novel therapeutic drug candidates for neurodegenerative and neuroinflammatory diseases.

Using sigma-ligands as part of a multi-receptor approach to target diseases of the brain

INTRODUCTION

The sigma receptors are found abundantly in the central nervous system and are targets for the treatment of various diseases, including Alzheimer's (AD), Parkinson's (PD), Huntington's disease (HD), depression, amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). However, for many of these diseases, other receptors and targets have been the focus of the most, such as acetylcholine esterase inhibitors in Alzheimer's and dopamine replacement in Parkinson's. The currently available drugs for these diseases have limited success resulting in the requirement of an alternative approach to their treatment.

AREAS COVERED

In this review, we discuss the potential role of the sigma receptors and their ligands as part of a multi receptor approach in the treatment of the diseases mentioned above. The literature reviewed was obtained through searches in databases, including PubMed, Web of Science, Google Scholar, and Scopus.

EXPERT OPINION

Given sigma receptor agonists provide neuroprotection along with other benefits such as potentiating the effects of other receptors, further development of multi-receptor targeting ligands, and or the development of multi-drug combinations to target multiple receptors may prove beneficial in the future treatment of degenerative diseases of the CNS, especially when coupled with better diagnostic techniques.

A randomized, controlled clinical trial of plasma exchange with albumin replacement for Alzheimer's disease: Primary results of the AMBAR Study

Introduction

This phase 2b/3 trial examined the effects of plasma exchange (PE) in patients with mild‐to‐moderate Alzheimer's disease (AD).

Methods

Three hundred forty‐seven patients (496 screened) were randomized (1:1:1:1) into three PE treatment arms with different doses of albumin and intravenous immunoglobulin replacement (6‐week period of weekly conventional PE followed by a 12‐month period of monthly low‐volume PE), and placebo (sham).

Results

PE‐treated patients performed significantly better than placebo for the co‐primary endpoints: change from baseline of Alzheimer's Disease Cooperative Study–Activities of Daily Living (ADCS‐ADL; P = .03; 52% less decline) with a trend for Alzheimer's Disease Assessment Scale–Cognitive Subscale (ADAS‐Cog; P = .06; 66% less decline) scores at month 14. Moderate‐AD patients (baseline Mini‐Mental State Examination [MMSE] 18‐21) scored better on ADCS‐ADL (P = .002) and ADAS‐Cog (P = .05), 61% less decline both. There were no changes in mild‐AD patients (MMSE 22‐26). PE‐treated patients scored better on the Clinical Dementia Rating Sum of Boxes (CDR‐sb) (P = .002; 71% less decline) and Alzheimer's Disease Cooperative Study‐Clinical Global Impression of Change (ADCS‐CGIC) (P < .0001; 100% less decline) scales.

Discussion

This trial suggests that PE with albumin replacement could slow cognitive and functional decline in AD, although further studies are warranted.

Alzheimer's disease drug development pipeline: 2020

INTRODUCTION

Alzheimer's disease (AD) is a growing public health concern affecting millions of patients worldwide and costing billions of dollars annually. We review the pipeline of drugs and biologics in clinical trials for the treatment of AD. We use the Common Alzheimer's and Related Dementias Research Ontology (CADRO) to classify treatment targets and mechanisms of action. We review our annual pipeline reports for the past 5 years to provide longitudinal insight into clinical trials and drug development for AD.

METHODS

We reviewed ClinicalTrials.gov as of February 27, 2020, and identified all trials of pharmacologic agents currently being developed for treatment of AD as represented on this widely used U.S. Food and Drug Administration registry.

RESULTS

There are 121 agents in clinical trials for the treatment of AD. Twenty-nine agents are in 36 Phase 3 trials, 65 agents are in 73 Phase 2 trials, and 27 agents are in 27 Phase 1 trials. Twelve agents in trials target cognitive enhancement and 12 are intended to treat neuropsychiatric and behavioral symptoms. There are 97 agents in disease modification trials. Compared to the 2019 pipeline, there is an increase in the number of disease-modifying agents targeting pathways other than amyloid or tau.

DISCUSSION

The 2020 pipeline has innovations in clinical trials and treatment targets that provide hope for greater success in AD drug development programs. Review of clinical trials over the past 5 years show that there is progressive emphasis on non-amyloid targets, including candidate treatments for inflammation, synapse and neuronal protection, vascular factors, neurogenesis, and epigenetic interventions. There has been a marked growth in repurposed agents in the pipeline.

Evaluation of edonerpic maleate as a CRMP2 inhibitor for pain relief

We have previously reported that the microtubule-associated collapsin response mediator protein 2 (CRMP2) is necessary for the expression of chronic pain. CRMP2 achieves this control of nociceptive signaling by virtue of its ability to regulate voltage-gated calcium and sodium channels. To date, however, no drugs exist that target CRMP2. Recently, the small molecule edonerpic maleate (1 -{3-[2-(1-benzothiophen-5-yl)ethoxy]propyl}azetidin-3-ol maleate), a candidate therapeutic for Alzheimer’s disease was reported to be a novel CRMP2 binding compound with the potential to decrease its phosphorylation level in cortical tissues in vivo. Here we sought to determine the mechanism of action of edonerpic maleate and test its possible effect in a rodent model of chronic pain. We observed: (i) no binding between human CRMP2 and edonerpic maleate; (ii) edonerpic maleate had no effect on CRMP2 expression and phosphorylation in dorsal root ganglion (DRG) neurons; (iii) edonerpic maleate-decreased calcium but increased sodium current density in DRG neurons; and (iv) edonerpic maleate was ineffective in reversing post-surgical allodynia in male and female mice. Thus, while CRMP2 inhibiting compounds remain a viable strategy for developing new mechanism-based pain inhibitors, edonerpic maleate is an unlikely candidate.

Pharmacotherapy of Alzheimer's Disease: Seeking Clarity in a Time of Uncertainty

Alzheimer's disease (AD) is recognized as a major health hazard that mostly affects people older than 60 years. AD is one of the biggest medical, economic, and social concerns to patients and their caregivers. AD was ranked as the 5th leading cause of global deaths in 2016 by the World Health Organization (WHO). Many drugs targeting the production, aggregation, and clearance of Aβ plaques failed to give any conclusive clinical outcomes. This mainly stems from the fact that AD is not a disease attributed to a single-gene mutation. Two hallmarks of AD, Aβ plaques and neurofibrillary tangles (NFTs), can simultaneously induce other AD etiologies where every pathway is a loop of consequential events. Therefore, the focus of recent AD research has shifted to exploring other etiologies, such as neuroinflammation and central hyperexcitability. Neuroinflammation results from the hyperactivation of microglia and astrocytes that release pro-inflammatory cytokines due to the neurological insults caused by Aβ plaques and NFTs, eventually leading to synaptic dysfunction and neuronal death. This review will report the failures and side effects of many anti-Aβ drugs. In addition, emerging treatments targeting neuroinflammation in AD, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and receptor-interacting serine/threonine protein kinase 1 (RIPK1), that restore calcium dyshomeostasis and microglia physiological function in clearing Aβ plaques, respectively, will be deliberately discussed. Other novel pharmacotherapy strategies in treating AD, including disease-modifying agents (DMTs), repurposing of medications used to treat non-AD illnesses, and multi target-directed ligands (MTDLs) are also reviewed. These approaches open new doors to the development of AD therapy, especially combination therapy that can cater for several targets simultaneously, hence effectively slowing or stopping AD.