Effects of Chronic Masitinib Treatment in APPswe/PSEN1dE9 Transgenic Mice Modeling Alzheimer’s Disease

Recent updates on immunotherapy in neurodegenerative diseases

Neurodegeneration is a progressive event leading to specific neuronal loss due to the accumulation of aberrant proteins. These pathologic forms of proteins further worsen and interfere with normal physiologic mechanisms, which can lead to abnormal proliferation of immune cells and subsequent inflammatory cascades and ultimately neuronal loss. Recently, immunotherapies targeting abnormal, pathologic forms of protein have shown a promising approach to modify the progression of neurodegeneration. Recent advances in immunotherapy have led to the development of novel antibodies against the proteinopathies which can eradicate aggregations of protein as evident from preclinical and clinical studies. Nonetheless, only a few of them have successfully received clinical approval, while others have been discontinued due to a lack of clinical efficacy endpoints. The current review discusses the status of investigational antibodies under clinical trials, their targets for therapeutic action, and evidence for failure or success.

Approaches for studying neuroimmune interactions in Alzheimer's disease

Peripheral immune cells play an important role in the pathology of Alzheimer's disease (AD), impacting processes such as amyloid and tau protein aggregation, glial activation, neuronal integrity, and cognitive decline. Here, we examine cutting-edge strategies - encompassing animal and cellular models - used to investigate the roles of peripheral immune cells in AD. Approaches such as antibody-mediated depletion, genetic ablation, and bone marrow chimeras in mouse models have been instrumental in uncovering T, B, and innate immune cell disease-modifying functions. However, challenges such as specificity, off-target effects, and differences between human and mouse immune systems underscore the need for more human-relevant models. Emerging multicellular models replicating critical aspects of human brain tissue and neuroimmune interactions increasingly offer fresh insights into the role of immune cells in AD pathogenesis. Refining these methodologies can deepen our understanding of immune cell contributions to AD and support the development of novel immune-related therapeutic interventions.

New Insights into the Development of Donepezil-Based Hybrid and Natural Molecules as Multi-Target Drug Agents for Alzheimer's Disease Treatment

Alzheimer's disease (AD) involves a complex pathophysiology with multiple interconnected subpathologies, including protein aggregation, impaired neurotransmission, oxidative stress, and microglia-mediated neuroinflammation. Current treatments, which generally target a single subpathology, have failed to modify the disease's progression, providing only temporary symptom relief. Multi-target drugs (MTDs) address several subpathologies, including impaired aggregation of pathological proteins. In this review, we cover hybrid molecules published between 2014 and 2024. We offer an overview of the strategies employed in drug design and approaches that have led to notable improvements and reduced hepatotoxicity. Our aim is to offer insights into the potential development of new Alzheimer's disease drugs. This overview highlights the potential of multi-target drugs featuring heterocycles with N-benzylpiperidine fragments and natural compounds in improving Alzheimer's disease treatment.

c-KIT inhibitors reduce pathology and improve behavior in the Tg(SwDI) model of Alzheimer's disease

Treatments for Alzheimer's disease have primarily focused on removing brain amyloid plaques to improve cognitive outcomes in patients. We developed small compounds, known as BK40143 and BK40197, and we hypothesize that these drugs alleviate microglial-mediated neuroinflammation and induce autophagic clearance of neurotoxic proteins to improve behavior in models of neurodegeneration. Specificity binding assays of BK40143 and BK40197 showed primary binding to c-KIT/Platelet Derived Growth Factor Receptors (PDGFR)α/β, whereas BK40197 also differentially binds to FYVE finger-containing phosphoinositide kinase (PIKFYVE). Both compounds penetrate the CNS, and treatment with these drugs inhibited the maturation of peripheral mast cells in transgenic mice, correlating with cognitive improvements on measures of memory and anxiety. In the brain, microglial activation was profoundly attenuated and amyloid-beta and tau were reduced via autophagy. Multi-kinase inhibition, including c-KIT, exerts multifunctional effects to reduce neurodegenerative pathology via autophagy and microglial activity and may represent a potential therapeutic option for neurodegeneration.

Antineoplastics for treating Alzheimer's disease and dementia: Evidence from preclinical and observational studies

As the world population ages, there will be an increasing need for effective therapies for aging-associated neurodegenerative disorders, which remain untreatable. Dementia due to Alzheimer's disease (AD) is one of the leading neurological diseases in the aging population. Current therapeutic approaches to treat this disorder are solely symptomatic, making the need for new molecular entities acting on the causes of the disease extremely urgent. One of the potential solutions is to use compounds that are already in the market. The structures have known pharmacokinetics, pharmacodynamics, toxicity profiles, and patient data available in several countries. Several drugs have been used successfully to treat diseases different from their original purposes, such as autoimmunity and peripheral inflammation. Herein, we divulge the repurposing of drugs in the area of neurodegenerative diseases, focusing on the therapeutic potential of antineoplastics to treat dementia due to AD and dementia. We briefly touch upon the shared pathological mechanism between AD and cancer and drug repurposing strategies, with a focus on artificial intelligence. Next, we bring out the current status of research on the development of drugs, provide supporting evidence from retrospective, clinical, and preclinical studies on antineoplastic use, and bring in new areas, such as repurposing drugs for the prion-like spreading of pathologies in treating AD.

Tyrosine kinases: multifaceted receptors at the intersection of several neurodegenerative disease-associated processes

Tyrosine kinases (TKs) are catalytic enzymes activated by auto-phosphorylation that function by phosphorylating tyrosine residues on downstream substrates. Tyrosine kinase inhibitors (TKIs) have been heavily exploited as cancer therapeutics, primarily due to their role in autophagy, blood vessel remodeling and inflammation. This suggests tyrosine kinase inhibition as an appealing therapeutic target for exploiting convergent mechanisms across several neurodegenerative disease (NDD) pathologies. The overlapping mechanisms of action between neurodegeneration and cancer suggest that TKIs may play a pivotal role in attenuating neurodegenerative processes, including degradation of misfolded or toxic proteins, reduction of inflammation and prevention of fibrotic events of blood vessels in the brain. In this review, we will discuss the distinct roles that select TKs have been shown to play in various disease-associated processes, as well as identify TKs that have been explored as targets for therapeutic intervention and associated pharmacological agents being investigated as treatments for NDDs.

Multi-target drugs for Alzheimer's disease

Alzheimer's disease (AD), a leading cause of dementia, increasingly challenges our healthcare systems and society. Traditional therapies aimed at single targets have fallen short owing to the complex, multifactorial nature of AD that necessitates simultaneous targeting of various disease mechanisms for clinical success. Therefore, targeting multiple pathologies at the same time could provide a synergistic therapeutic effect. The identification of new disease targets beyond the classical hallmarks of AD offers a fertile ground for the design of new multi-target drugs (MTDs), and building on existing compounds have the potential to yield in successful disease modifying therapies. This review discusses the evolving landscape of MTDs, focusing on their potential as AD therapeutics. Analysis of past and current trials of compounds with multi-target activity underscores the capacity of MTDs to offer synergistic therapeutic effects, and the flourishing genetic understanding of AD will inform and inspire the development of MTD-based AD therapies.

Masitinib as a neuroprotective agent: a scoping review of preclinical and clinical evidence

OBJECTIVES

Masitinib, originally developed as a tyrosine kinase inhibitor for cancer treatment, has shown potential neuroprotective effects in various neurological disorders by modulating key pathways implicated in neurodegeneration. This scoping review aimed to summarize the current evidence of masitinib's neuroprotective activities from preclinical to clinical studies.

METHODS

This scoping review was conducted following the guidelines described by Arksey and O'Malley and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The inclusion criteria covered all original studies reporting on the neuroprotective effects of masitinib, including clinical studies, animal studies, and in vitro studies.

RESULTS

A total of 16 studies met the inclusion criteria and were included in the review. These comprised five randomized controlled trials (RCTs), one post-hoc analysis study, one case report, and nine animal studies. The RCTs focused on Alzheimer's disease (two studies), multiple sclerosis (two studies), and amyotrophic lateral sclerosis (one study). Across all included studies, masitinib consistently demonstrated neuroprotective properties. However, the majority of RCTs reported concerns regarding the safety profile of masitinib. Preclinical studies revealed the neuroprotective mechanisms of masitinib, which include inhibition of certain kinases interfering with cell proliferation and survival, reduction of neuroinflammation, and exhibition of antioxidant activity.

CONCLUSION

The current evidence suggests a promising therapeutic benefit of masitinib in neurodegenerative diseases. However, further research is necessary to validate and expand upon these findings, particularly regarding the precise mechanisms through which masitinib exerts its therapeutic effects. Future studies should also focus on addressing the safety concerns associated with masitinib use.

Neuregulin-1 and ALS19 (ERBB4): at the crossroads of amyotrophic lateral sclerosis and cancer

BACKGROUND

Neuregulin-1 (NRG1) is implicated in both cancer and neurologic diseases such as amyotrophic lateral sclerosis (ALS); however, to date, there has been little cross-field discussion between neurology and oncology in regard to these genes and their functions.

MAIN BODY

Approximately 0.15-0.5% of cancers harbor NRG1 fusions that upregulate NRG1 activity and hence that of the cognate ERBB3/ERBB4 (HER3/HER4) receptors; abrogating this activity with small molecule inhibitors/antibodies shows preliminary tissue-agnostic anti-cancer activity. Notably, ERBB/HER pharmacologic suppression is devoid of neurologic toxicity. Even so, in ALS, attenuated ERBB4/HER4 receptor activity (due to loss-of-function germline mutations or other mechanisms in sporadic disease) is implicated; indeed, ERBB4/HER4 is designated ALS19. Further, secreted-type NRG1 isoforms may be upregulated (perhaps via a feedback loop) and could contribute to ALS pathogenesis through aberrant glial cell stimulation via enhanced activity of other (e.g., ERBB1-3/HER1-3) receptors and downstream pathways. Hence, pan-ERBB inhibitors, already in use for cancer, may be agents worthy of testing in ALS.

CONCLUSION

Common signaling cascades between cancer and ALS may represent novel therapeutic targets for both diseases.

Critical thinking of Alzheimer's transgenic mouse model: current research and future perspective

Transgenic models are useful tools for studying the pathogenesis of and drug development for Alzheimer's Disease (AD). AD models are constructed usually using overexpression or knock-in of multiple pathogenic gene mutations from familial AD. Each transgenic model has its unique behavioral and pathological features. This review summarizes the research progress of transgenic mouse models, and their progress in the unique mechanism of amyloid-β oligomers, including the first transgenic mouse model built in China based on a single gene mutation (PSEN1 V97L) found in Chinese familial AD. We further summarized the preclinical findings of drugs using the models, and their future application in exploring the upstream mechanisms and multitarget drug development in AD.

Targeting NLRP3 inflammasome for neurodegenerative disorders

Neuroinflammation is a key pathological feature in neurological diseases, including Alzheimer's disease (AD). The nucleotide-binding domain leucine-rich repeat-containing proteins (NLRs) belong to the pattern recognition receptors (PRRs) family that sense stress signals, which play an important role in inflammation. As a member of NLRs, the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) is predominantly expressed in microglia, the principal innate immune cells in the central nervous system (CNS). Microglia release proinflammatory cytokines to cause pyroptosis through activating NLRP3 inflammasome. The active NLRP3 inflammasome is involved in a variety of neurodegenerative diseases (NDs). Recent studies also indicate the key role of neuronal NLRP3 in the pathogenesis of neurological disorders. In this article, we reviewed the mechanisms of NLRP3 expression and activation and discussed the role of active NLRP3 inflammasome in the pathogenesis of NDs, particularly focusing on AD. The studies suggest that targeting NLRP3 inflammasome could be a novel approach for the disease modification.

Clinical trials of new drugs for Alzheimer disease: a 2020-2023 update

Alzheimer's disease (AD) is the leading cause of dementia, presenting a significant unmet medical need worldwide. The pathogenesis of AD involves various pathophysiological events, including the accumulation of amyloid and tau, neuro-inflammation, and neuronal injury. Clinical trials focusing on new drugs for AD were documented in 2020, but subsequent developments have emerged since then. Notably, the US-FDA has approved Aducanumab and Lecanemab, both antibodies targeting amyloid, marking the end of a nearly two-decade period without new AD drugs. In this comprehensive report, we review all trials listed in clinicaltrials.gov, elucidating their underlying mechanisms and study designs. Ongoing clinical trials are investigating numerous promising new drugs for AD. The main trends in these trials involve pathophysiology-based, disease-modifying therapies and the recruitment of participants in earlier stages of the disease. These trends underscore the significance of conducting fundamental research on pathophysiology, prevention, and intervention prior to the occurrence of brain damage caused by AD.

Alzheimer's Disease: Novel Targets and Investigational Drugs for Disease Modification

Novel agents addressing non-amyloid, non-tau targets in Alzheimer's Disease (AD) comprise 70% of the AD drug development pipeline of agents currently in clinical trials. Most of the target processes identified in the Common Alzheimer's Disease Research Ontology (CADRO) are represented by novel agents in trials. Inflammation and synaptic plasticity/neuroprotection are the CADRO categories with the largest number of novel candidate therapies. Within these categories, there are few overlapping targets among the test agents. Additional categories being evaluated include apolipoprotein E [Formula: see text] 4 (APOE4) effects, lipids and lipoprotein receptors, neurogenesis, oxidative stress, bioenergetics and metabolism, vascular factors, cell death, growth factors and hormones, circadian rhythm, and epigenetic regulators. We highlight current drugs being tested within these categories and their mechanisms. Trials will be informative regarding which targets can be modulated to produce a slowing of clinical decline. Possible therapeutic combinations of agents may be suggested by trial outcomes. Biomarkers are evolving in concert with new targets and novel agents, and biomarker outcomes offer a means of supporting disease modification by the putative treatment. Identification of novel targets and development of corresponding therapeutics offer an important means of advancing new treatments for AD.

Mast cell deficiency improves cognition and enhances disease-associated microglia in 5XFAD mice

Emerging evidence suggests that peripheral immune cells contribute to Alzheimer's disease (AD) neuropathogenesis. Among these, mast cells are known for their functions in allergic reactions and neuroinflammation; however, little is known about their role in AD. Here, we crossed 5XFAD mice with mast cell-deficient strains and observed the effects on AD-related neuropathology and cognitive impairment. We found that mast cell depletion improved contextual fear conditioning in 5XFAD mice without affecting cued fear conditioning, anxiety-like behavior, or amyloid burden. Furthermore, mast cell depletion led to an upregulation of transcriptomic signatures for putatively protective disease-associated microglia and resulted in reduced markers indicative of reactive astrocytes. We hypothesize a system of bidirectional communication between dural mast cells and the brain, where mast cells respond to signals from the brain environment by expressing immune-regulatory mediators, impacting cognition and glial cell function. These findings highlight mast cells as potential therapeutic targets for AD.

Treatment of Alzheimer's Disease: Beyond Symptomatic Therapies

In an ever-increasing aged world, Alzheimer's disease (AD) represents the first cause of dementia and one of the first chronic diseases in elderly people. With 55 million people affected, the WHO considers AD to be a disease with public priority. Unfortunately, there are no final cures for this pathology. Treatment strategies are aimed to mitigate symptoms, i.e., acetylcholinesterase inhibitors (AChEI) and the N-Methyl-D-aspartate (NMDA) antagonist Memantine. At present, the best approaches for managing the disease seem to combine pharmacological and non-pharmacological therapies to stimulate cognitive reserve. Over the last twenty years, a number of drugs have been discovered acting on the well-established biological hallmarks of AD, deposition of β-amyloid aggregates and accumulation of hyperphosphorylated tau protein in cells. Although previous efforts disappointed expectations, a new era in treating AD has been working its way recently. The Food and Drug Administration (FDA) gave conditional approval of the first disease-modifying therapy (DMT) for the treatment of AD, aducanumab, a monoclonal antibody (mAb) designed against Aβ plaques and oligomers in 2021, and in January 2023, the FDA granted accelerated approval for a second monoclonal antibody, Lecanemab. This review describes ongoing clinical trials with DMTs and non-pharmacological therapies. We will also present a future scenario based on new biomarkers that can detect AD in preclinical or prodromal stages, identify people at risk of developing AD, and allow an early and curative treatment.

Novel therapeutic approaches to target neurodegeneration

Ageing is the main risk factor common to most primary neurodegenerative disorders. Indeed, age-related brain alterations have been long considered to predispose to neurodegeneration. Although protein misfolding and the accumulation of toxic protein aggregates have been considered as causative events in neurodegeneration, several other biological pathways affected by brain ageing also contribute to pathogenesis. Here, we discuss the evidence showing the involvement of the mechanisms controlling neuronal structure, gene expression, autophagy, cell metabolism and neuroinflammation in the onset and progression of neurodegenerative disorders. Furthermore, we review the therapeutic strategies currently under development or as future approaches designed to normalize these pathways, which may then increase brain resilience to cope with toxic protein species. In addition to therapies targeting the insoluble protein aggregates specifically associated with each neurodegenerative disorder, these novel pharmacological approaches may be part of combined therapies designed to rescue brain function.

The contribution of the peripheral immune system to neurodegeneration

Microglial cells are the major immune cells of the central nervous system (CNS), and directly react to neurodegeneration, but other immune cell types are also able to react to pathology and can modify the course of neurodegenerative processes. These mainly include monocytes/macrophages and lymphocytes. While these peripheral immune cells were initially considered to act only after infiltrating the CNS, recent evidence suggests that some of them can also act directly from the periphery. We will review the existing and emerging evidence for a role of peripheral immune cells in neurodegenerative diseases, both with and without CNS infiltration. Our focus will be on amyotrophic lateral sclerosis, but we will also compare to Alzheimer's disease and Parkinson's disease to highlight similarities or differences. Peripheral immune cells are easily accessible, and therefore may be an attractive therapeutic target for neurodegenerative diseases. Thus, understanding how these peripheral immune cells communicate with the CNS deserves deeper investigation.

Masitinib: The promising actor in the next season of the Amyotrophic Lateral Sclerosis treatment series

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease with high mortality and morbidity rate affecting both upper and lower motor neurons (MN). Muscle force reduction, behavioral change, pseudobulbar affect, and cognitive impairments are the most common clinical manifestations of ALS. The main physiopathology of ALS is still unclear, though several studies have identified that oxidative stress, proteinopathies, glutamate-related excitotoxicity, microglial activation, and neuroinflammation may be involved in the pathogenesis of ALS. From 1995 until October 2022, only Riluzole, Dextromethorphan Hydrobromide (DH) with Quinidine sulfate (Q), Edaravone, and Sodium phenylbutyrate with Taurursodiol (PB/TUDCO) have achieved FDA approval for ALS treatment. Despite the use of these four approved agents, the survival rate and quality of life of ALS patients are still low. Thus, finding novel treatments for ALS patients is an urgent requirement. Masitinib, a tyrosine kinase inhibitor, emphasizes the neuro-inflammatory activity of ALS by targeting macrophages, mast cells, and microglia cells. Masitinib downregulates the proinflammatory cytokines, indirectly reduces inflammation, and induces neuroprotection. Also, it was effective in phase 2/3 and 3 clinical trials (CTs) by increasing overall survival and delaying motor, bulbar, and respiratory function deterioration. This review describes the pathophysiology of ALS, focusing on Masitinib's mechanism of action and explaining why Masitinib could be a promising actor in the treatment of ALS patients. In addition, Masitinib CTs and other competitor drugs in phase 3 CTs have been discussed.

Emerging therapeutics agents and recent advances in drug repurposing for Alzheimer's disease

Alzheimer's disease (AD) is a multivariate and diversified disease and affects the most sensitive areas of the brain, the cerebral cortex, and the hippocampus. AD is a progressive age-related neurodegenerative disease most often associated with memory deficits and cognition that get more worsen over time. The central theory on the pathophysiological hallmark features of AD is characterized by the accumulation of amyloid β (Aβ) peptides, also associated with tau proteins (τ) dysfunctioning which leads to distorted microtubular structure, affects the cholinergic system, and mitochondrial biogenesis. This review emphasizes how simple it is to find novel treatments for AD and focuses on several recently developed medications through repurposing that can speed up traditional drug development.

Masitinib for mild-to-moderate Alzheimer's disease: results from a randomized, placebo-controlled, phase 3, clinical trial

BACKGROUND

Masitinib is an orally administered tyrosine kinase inhibitor that targets activated cells of the neuroimmune system (mast cells and microglia). Study AB09004 evaluated masitinib as an adjunct to cholinesterase inhibitor and/or memantine in patients with mild-to-moderate dementia due to probable Alzheimer's disease (AD).

METHODS

Study AB09004 was a randomized, double-blind, two parallel-group (four-arm), placebo-controlled trial. Patients aged ≥50 years, with clinical diagnosis of mild-to-moderate probable AD and a Mini-Mental State Examination (MMSE) score of 12-25 were randomized (1:1) to receive masitinib 4.5 mg/kg/day (administered orally as two intakes) or placebo. A second, independent parallel group (distinct for statistical analysis and control arm), randomized patients (2:1) to masitinib at an initial dose of 4.5 mg/kg/day for 12 weeks that was then titrated to 6.0 mg/kg/day, or equivalent placebo. Multiple primary outcomes (each tested at a significance level of 2.5%) were least-squares mean change from baseline to week 24 in the Alzheimer's Disease Assessment Scale - cognitive subscale (ADAS-cog), or the Alzheimer's Disease Cooperative Study Activities of Daily Living Inventory scale (ADCS-ADL). Safety for each masitinib dose level was compared against a pooled placebo population.

RESULTS

Masitinib (4.5 mg/kg/day) (n=182) showed significant benefit over placebo (n=176) according to the primary endpoint of ADAS-cog, -1.46 (95% CI [-2.46, -0.45]) (representing an overall improvement in cognition) versus 0.69 (95% CI [-0.36, 1.75]) (representing increased cognitive deterioration), respectively, with a significant between-group difference of -2.15 (97.5% CI [-3.48, -0.81]); p<0.001. For the ADCS-ADL primary endpoint, the between-group difference was 1.82 (97.5% CI [-0.15, 3.79]); p=0.038 (i.e., 1.01 (95% CI [-0.48, 2.50]) (representing an overall functional improvement) versus -0.81 (95% CI [-2.36, 0.74]) (representing increased functional deterioration), respectively). Safety was consistent with masitinib's known profile (maculo-papular rash, neutropenia, hypoalbuminemia). Efficacy results from the independent parallel group of titrated masitinib 6.0 mg/kg/day versus placebo (n=186 and 91 patients, respectively) were inconclusive and no new safety signal was observed.

CONCLUSIONS

Masitinib (4.5 mg/kg/day) may benefit people with mild-to-moderate AD. A confirmatory study has been initiated to substantiate these data.

TRIAL REGISTRATION

EudraCT: 2010-021218-50.

CLINICALTRIALS

gov : NCT01872598.

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.

The synapse as a treatment avenue for Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder with devastating symptoms, including memory impairments and cognitive deficits. Hallmarks of AD pathology are amyloid-beta (Aβ) deposition forming neuritic plaques and neurofibrillary tangles (NFTs). For many years, AD drug development has mainly focused on directly targeting the Aβ aggregation or the formation of tau tangles, but this disease has no cure so far. Other common characteristics of AD are synaptic abnormalities and dysfunctions such as synaptic damage, synaptic loss, and structural changes in the synapse. Those anomalies happen in the early stages of the disease before behavioural symptoms have occurred. Therefore, better understanding the mechanisms underlying the synaptic dysfunction found in AD and targeting the synapse, especially using early treatment windows, can lead to finding novel and more effective treatments that could improve the lives of AD patients. Researchers have recently started developing different disease-modifying treatments targeting the synapse to rescue and prevent synaptic dysfunction in AD. The main objectives of these new strategies are to halt synaptic loss, strengthen synaptic connections, and improve synaptic density, potentially leading to the rescue or prevention of cognitive impairments. This article aims to address the mechanisms of synaptic degeneration in AD and discuss current strategies that focus on the synapse for AD therapy. Alzheimer's disease (AD) is a neurodegenerative disorder that significantly impairs memory and causes cognitive and behavioural deficits. Scientists worldwide have tried to find a treatment that can reverse or rescue AD symptoms, but there is no cure so far. One prominent characteristic of AD is the brain atrophy caused by significant synaptic loss and overall neuronal damage, which starts at the early stages of the disease before other AD hallmarks such as neuritic plaques and NFTs. The present review addresses the underlying mechanisms behind synaptic loss and dysfunction in AD and discusses potential strategies that target the synapse.

Efficacy and Safety of Masitinib in Progressive Forms of Multiple Sclerosis: A Randomized, Phase 3, Clinical Trial

BACKGROUND AND OBJECTIVES

Masitinib is a selective tyrosine kinase inhibitor, targeting innate immune cells (mast cells and microglia) that are involved in the pathophysiology of progressive multiple sclerosis (MS). Study AB07002 assessed oral masitinib in patients with progressive MS who were progressing but not clinically active.

METHODS

This randomized, double-blind, 2 parallel-group, placebo-controlled trial assessing 2 dose levels of masitinib vs equivalent placebo was conducted at 116 hospital clinics and specialized MS centers in 20 countries. Randomization (2:1) with minimization was performed centrally using an automated system. Patients, physicians, and outcome assessors remained masked to treatment group allocation. Patients with primary progressive MS (PPMS) or nonactive secondary progressive MS (nSPMS) without relapse for ≥2 years, aged 18-75 years, with baseline Expanded Disability Status Scale (EDSS) 2.0-6.0, and regardless of time from onset were treated for 96 weeks. The primary end point was overall EDSS change from baseline using repeated measures (generalized estimating equation, timeframe W12-W96, measured every 12 weeks), with positive values indicating increased clinical deterioration. Efficacy and safety were assessed in all randomly assigned and treated patients.

RESULTS

A total of 611 patients were randomized; 301 in the masitinib 4.5 mg/kg/d parallel group and 310 in the uptitrated masitinib 6.0 mg/kg/d parallel group. Masitinib (4.5 mg/kg/d) (n = 199) showed significant benefit over placebo (n = 101) according to the primary end point, 0.001 vs 0.098, respectively, with a between-group difference of -0.097 (97% CI -0.192 to -0.002); p = 0.0256. Safety was consistent with masitinib's known profile (diarrhea, nausea, rash, and hematologic events), with no elevated risk of infection. Efficacy results from the independent uptitrated masitinib 6.0 mg/kg/d parallel group were inconclusive, and no new safety signal was observed.

DISCUSSION

Masitinib (4.5 mg/kg/d) can benefit people with PPMS and nSPMS. A confirmatory phase 3 study will be initiated to substantiate these data.

TRIAL REGISTRATION INFORMATION

The first participant was randomized to study AB07002 on August 25, 2011. The trial was registered with the European Clinical Trials Database (#EudraCT 2010-021219-17) on July 1, 2011 (clinicaltrialsregister.eu/ctr-search/trial/2010-021219-17/ES) and with ClinicalTrials.gov (#NCT01433497) on September 14, 2011 (clinicaltrials.gov/ct2/show/NCT01433497).

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that masitinib 4.5 mg/kg/d decreased progression of disability, measured by the EDSS, in adults with PPMS or patients with nSPMS (with no exacerbations in the last 2 years).

Enhancing autophagy in Alzheimer's disease through drug repositioning

Alzheimer's disease (AD) is one of the biggest human health threats due to increases in aging of the global population. Unfortunately, drugs for treating AD have been largely ineffective. Interestingly, downregulation of macroautophagy (autophagy) plays an essential role in AD pathogenesis. Therefore, targeting autophagy has drawn considerable attention as a therapeutic approach for the treatment of AD. However, developing new therapeutics is time-consuming and requires huge investments. One of the strategies currently under consideration for many diseases is "drug repositioning" or "drug repurposing". In this comprehensive review, we have provided an overview of the impact of autophagy on AD pathophysiology, reviewed the therapeutics that upregulate autophagy and are currently used in the treatment of other diseases, including cancers, and evaluated their repurposing as a possible treatment option for AD. In addition, we discussed the potential of applying nano-drug delivery to neurodegenerative diseases, such as AD, to overcome the challenge of crossing the blood brain barrier and specifically target molecules/pathways of interest with minimal side effects.

Masitinib for the treatment of Alzheimer's disease

The actual standard treatment for mild-to-moderately severe Alzheimer's disease only attacks its symptoms. Masitinib is a potent and selective phenylaminothiazole-type tyrosine kinase inhibitor which is currently in Phase III studies for the treatment of Alzheimer's disease (AD) with the aim of modifying its evolution and with multiple pharmacological targets such as inhibition of mast cells activity, inhibition of microglia activation, modulation of Aβ and Tau protein signaling pathway and prevention of synaptic damage. Here, we review the preclinical and clinical studies that investigated the administration of masitinib treatment in monotherapy in AD. All research studies revealed positive effects concerning the cognitive functions in AD and generally with good safety and tolerability.

Therapy for Alzheimer's disease: Missing targets and functional markers?

The development of the next generation therapy for Alzheimer's disease (AD) presents a huge challenge given the number of promising treatment candidates that failed in trials, despite recent advancements in understanding of genetic, pathophysiologic and clinical characteristics of the disease. This review reflects some of the most current concepts and controversies in developing disease-modifying and new symptomatic treatments. It elaborates on recent changes in the AD research strategy for broadening drug targets, and potentials of emerging non-pharmacological treatment interventions. Established and novel biomarkers are discussed, including emerging cerebrospinal fluid and plasma biomarkers reflecting tau pathology, neuroinflammation and neurodegeneration. These fluid biomarkers together with neuroimaging findings can provide innovative objective assessments of subtle changes in brain reflecting disease progression. A particular emphasis is given to neurophysiological biomarkers which are well-suited for evaluating the brain overall neural network integrity and function. Combination of multiple biomarkers, including target engagement and outcome biomarkers will empower translational studies and facilitate successful development of effective therapies.

Anticancer drugs repurposed for Alzheimer's disease: a systematic review

Background

The relationship between cancer and dementia is triggering growing research interest. Several preclinical studies have provided the biological rationale for the repurposing of specific anticancer agents in Alzheimer’s disease (AD), and a growing number of research protocols are testing their efficacy and safety/tolerability in patients with AD.

Methods

The aim of the present systematic review was to provide an overview on the repurposing of approved anticancer drugs in clinical trials for AD by considering both ongoing and completed research protocols in all phases. In parallel, a systematic literature review was conducted on PubMed, ISI Web, and the Cochrane Library to identify published clinical studies on repurposed anticancer agents in AD.

Results

Based on a structured search on the ClinicalTrials.gov and the EudraCT databases, we identified 13 clinical trials testing 11 different approved anticancer agents (five tyrosine kinase inhibitors, two retinoid X receptor agonists, two immunomodulatory agents, one histone deacetylase inhibitor, and one monoclonal antibody) in the AD continuum. The systematic literature search led to the identification of five published studies (one phase I, three phase II, and one phase IIb/III) reporting the effects of antitumoral treatments in patients with mild cognitive impairment or AD dementia. The clinical findings and the methodological characteristics of these studies are described and discussed.

Conclusion

Anticancer agents are triggering growing interest in the context of repurposed therapies in AD. Several clinical trials are underway, and data are expected to be available in the near future. To date, data emerging from published clinical studies are controversial. The promising results emerging from preclinical studies and identified research protocols should be confirmed and extended by larger, adequately designed, and high-quality clinical trials.

Bidirectional communication between mast cells and the gut-brain axis in neurodegenerative diseases: Avenues for therapeutic intervention

Although the global incidence of neurodegenerative diseases has been steadily increasing, especially in adults, there are no effective therapeutic interventions. Neurodegeneration is a heterogeneous group of disorders that is characterized by the activation of immune cells in the central nervous system (CNS) (e.g., mast cells and microglia) and subsequent neuroinflammation. Mast cells are found in the brain and the gastrointestinal tract and play a role in "tuning" neuroimmune responses. The complex bidirectional communication between mast cells and gut microbiota coordinates various dynamic neuro-cellular responses, which propagates neuronal impulses from the gastrointestinal tract into the CNS. Numerous inflammatory mediators from degranulated mast cells alter intestinal gut permeability and disrupt blood-brain barrier, which results in the promotion of neuroinflammatory processes leading to neurological disorders, thereby offsetting the balance in immune-surveillance. Emerging evidence supports the hypothesis that gut-microbiota exert a pivotal role in inflammatory signaling through the activation of immune and inflammatory cells. Communication between inflammatory cytokines and neurocircuits via the gut-brain axis (GBA) affects behavioral responses, activates mast cells and microglia that causes neuroinflammation, which is associated with neurological diseases. In this comprehensive review, we focus on what is currently known about mast cells and the gut-brain axis relationship, and how this relationship is connected to neurodegenerative diseases. We hope that further elucidating the bidirectional communication between mast cells and the GBA will not only stimulate future research on neurodegenerative diseases but will also identify new opportunities for therapeutic interventions.

Therapeutic Advances in Diabetes, Autoimmune, and Neurological Diseases

Since 2015, 170 small molecules, 60 antibody-based entities, 12 peptides, and 15 gene- or cell-therapies have been approved by FDA for diverse disease indications. Recent advancement in medicine is facilitated by identification of new targets and mechanisms of actions, advancement in discovery and development platforms, and the emergence of novel technologies. Early disease detection, precision intervention, and personalized treatments have revolutionized patient care in the last decade. In this review, we provide a comprehensive overview of current and emerging therapeutic modalities developed in the recent years. We focus on nine diseases in three major therapeutics areas, diabetes, autoimmune, and neurological disorders. The pathogenesis of each disease at physiological and molecular levels is discussed and recently approved drugs as well as drugs in the clinic are presented.

Mast Cell and Astrocyte Hemichannels and Their Role in Alzheimer's Disease, ALS, and Harmful Stress Conditions

Considered relevant during allergy responses, numerous observations have also identified mast cells (MCs) as critical effectors during the progression and modulation of several neuroinflammatory conditions, including Alzheimer’s disease (AD) and amyotrophic lateral sclerosis (ALS). MC granules contain a plethora of constituents, including growth factors, cytokines, chemokines, and mitogen factors. The release of these bioactive substances from MCs occurs through distinct pathways that are initiated by the activation of specific plasma membrane receptors/channels. Here, we focus on hemichannels (HCs) formed by connexins (Cxs) and pannexins (Panxs) proteins, and we described their contribution to MC degranulation in AD, ALS, and harmful stress conditions. Cx/Panx HCs are also expressed by astrocytes and are likely involved in the release of critical toxic amounts of soluble factors—such as glutamate, adenosine triphosphate (ATP), complement component 3 derivate C3a, tumor necrosis factor (TNFα), apoliprotein E (ApoE), and certain miRNAs—known to play a role in the pathogenesis of AD, ALS, and other neurodegenerative disorders. We propose that blocking HCs on MCs and glial cells offers a promising novel strategy for ameliorating the progression of neurodegenerative diseases by reducing the release of cytokines and other pro-inflammatory compounds.

Recent advances on drug development and emerging therapeutic agents for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative old age disease that is complex, multifactorial, unalterable, and progressive in nature. The currently approved therapy includes cholinesterase inhibitors, NMDA-receptor antagonists and their combination therapy provides only temporary symptomatic relief. Sincere efforts have been made by the researchers globally to identify new targets, discover, and develop novel therapeutic agents for the treatment of AD. This brief review article is intended to cover the recent advances in drug development and emerging therapeutic agents for AD acting at different targets. The article is compiled using various scientific online databases and by referring to clinicaltrials.gov and ALZFORUM (alzforum.org) websites. The upcoming therapies act on one or more targets including amyloids (secretases, Aβ₄₂ production, amyloid deposition, and immunotherapy), tau proteins (tau phosphorylation/aggregation and immunotherapy) and neuroinflammation in addition to other miscellaneous targets. Despite the tremendous improvement in our understanding of the underlying pathophysiology of AD, only aducanumab was approved by FDA for the treatment of AD in 18 years i.e., since 2003. Hence, it is concluded that novel therapeutic strategies are required to discover and develop therapeutic agents to fight against the century old AD.