Clinical Bioavailability of the Novel BACE1 Inhibitor Lanabecestat (AZD3293): Assessment of Tablet Formulations Versus an Oral Solution and the Impact of Gastric pH on Pharmacokinetics

Mechanistic insights and emerging therapeutic stratagems for Alzheimer's disease

Alzheimer's disease (AD), a multi-factorial neurodegenerative disorder has affected over 30 million individuals globally and these numbers are expected to increase in the coming decades. Current therapeutic interventions are largely ineffective as they focus on a single target. Development of an effective drug therapy requires a deep understanding of the various factors influencing the onset and progression of the disease. Aging and genetic factors exert a major influence on the development of AD. Other factors like post-viral infections, iron overload, gut dysbiosis, and vascular dysfunction also exacerbate the onset and progression of AD. Further, post-translational modifications in tau, DRP1, CREB, and p65 proteins increase the disease severity through triggering mitochondrial dysfunction, synaptic loss, and differential interaction of amyloid beta with different receptors leading to impaired intracellular signalling. With advancements in neuroscience tools, new inter-relations that aggravate AD are being discovered including pre-existing diseases and exposure to other pathogens. Simultaneously, new therapeutic strategies involving modulation of gene expression through targeted delivery or modulation with light, harnessing the immune response to promote clearance of amyloid deposits, introduction of stem cells and extracellular vesicles to replace the destroyed neurons, exploring new therapeutic molecules from plant, marine and biological sources delivered in the free state or through nanoparticles and use of non-pharmacological interventions like music, transcranial stimulation and yoga. Polypharmacology approaches involving combination of therapeutic agents are also under active investigation for superior therapeutic outcomes. This review elaborates on various disease-causing factors, their underlying mechanisms, the inter-play between different disease-causing players, and emerging therapeutic options including those under clinical trials, for treatment of AD. The challenges involved in AD therapy and the way forward have also been discussed.

BACE1 Inhibitors for Alzheimer's Disease: The Past, Present and Any Future?

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder and the most common cause of dementia in the elderly. The complexity of AD has hindered the development of either a cure or a disease-modifying therapy to halt the disease progression. Numerous hypotheses were presented in order to explain the mechanisms underlying the pathogenesis of AD. Introduced in 1992, the "Amyloid Cascade Hypothesis" had a huge impact on the field and inspired the rise of various drug candidates, especially amyloid-beta (Aβ)-directed drugs; including beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitors. Adopted by a number of pharmaceutical companies, the development of BACE1 inhibitors has gained momentum in the past decade with promising results from experimental and early clinical-phase studies. Nevertheless, nearly all BACE1 inhibitors failed in later phases of clinical trials, due to safety and/or efficacy issues, and others were discontinued early in favor of second-generation small-molecule candidates. This paper aims to provide a comprehensive review of all BACE1 inhibitors to ever reach clinical trials, and we discuss the challenges and different perspectives on whether BACE1 inhibitors are to be reconsidered or revitalized in the future.

Insights for Alzheimer's disease pharmacotherapy and current clinical trials

Over the years, the scientific community has sought improvements in the life quality of patients diagnosed with Alzheimer's disease (AD). Synaptic loss and neuronal death observed in the regions responsible for cognitive functions represent an irreversible progressive disease that is clinically characterized by impaired cognitive and functional abilities, along with behavioral symptoms. Currently, image and body fluid biomarkers can provide early dementia diagnostic, being it the best way to slow the disease's progression. The first signs of AD development are still complex, the existence of individual genetic and phenotypic characteristics about the disease makes it difficult to standardize studies on the subject. The answer seems to be related between Aβ and tau proteins. Aβ deposition in the medial parietal cortex appears to be the initial stage of AD, but it does not have a strong correlation with neurodegeneration. The strongest link between symptoms occurs with tau aggregation, which antecede Aβ deposits in the medial temporal lobe, however, the protein can be found in cognitively healthy older people. The answer to the question may lie in some catalytic effect between both proteins. Amid so many doubts, Aducanumab was approved, which raised controversies and results intense debate in the scientific field. Abnormal singling of some blood biomarkers produced by adipocytes under high lipogenesis, such as TNFα, leptin, and interleukin-6, demonstrate to be linked to neuroinflammation worsens, diabetes, and also severe cases of COVID-19, howsoever, under higher lipolysis, seem to have therapeutic anti-inflammatory effects in the brain, which has increasingly contributed to the understanding of AD. In addition, the relationship of severe clinical complications caused by Sars-CoV-2 viral infection and AD, go beyond the term "risk group" and may be related to the development of dementia long-term. Thus, this review summarized the current emerging pharmacotherapies, alternative treatments, and nanotechnology applied in clinical trials, discussing relevant points that may contribute to a more accurate look.

Chalcone and its analogs: Therapeutic and diagnostic applications in Alzheimer's disease

Chalcone [(E)-1,3-diphenyl-2-propene-1-one], a small molecule with α, β unsaturated carbonyl group is a precursor or component of many natural flavonoids and isoflavonoids. It is one of the privileged structures in medicinal chemistry. It possesses a wide range of biological activities encouraging many medicinal chemists to study this scaffold for its usefulness to oncology, infectious diseases, virology and neurodegenerative diseases including Alzheimer's disease (AD). Small molecular size, convenient and cost-effective synthesis, and flexibility for modifications to modulate lipophilicity suitable for blood brain barrier (BBB) permeability make chalcones a preferred candidate for their therapeutic and diagnostic potential in AD. This review summarizes and highlights the importance of chalcone and its analogs as single target small therapeutic agents, multi-target directed ligands (MTDLs) as well as molecular imaging agents for AD. The information summarized here will guide many medicinal chemist and researchers involved in drug discovery to consider chalcone as a potential scaffold for the development of anti-AD agents including theranostics.

A Chronological Review of Potential Disease-Modifying Therapeutic Strategies for Alzheimer's Disease

Late-onset Alzheimer's disease (LOAD) is a neurodegenerative disorder that has become a worldwide health problem. This pathology has been classically characterized for its affectation on cognitive function and the presence of depositions of extracellular amyloid β-protein (Aβ) and intracellular neurofibrillary tangles (NFT) composed of hyperphosphorylated Tau protein. To this day, no effective treatment has been developed. Multiple strategies have been proposed over the years with the aim of finding new therapeutic approaches, such as the sequestration of Aβ in plasma or the administration of anti-inflammatory drugs. Also, given the significant role of the insulin receptor in the brain in the proper maintenance of cognitive function, drugs focused on the amelioration of insulin resistance have been proposed as potentially useful and effective in the treatment of AD. In the present review, taking into account the molecular complexity of the disease, it has been proposed that the most appropriate therapeutic strategy is a combinatory treatment of several drugs that will regulate a wide spectrum of the described altered pathological pathways.

Computational Approaches in Preclinical Studies on Drug Discovery and Development

Because undesirable pharmacokinetics and toxicity are significant reasons for the failure of drug development in the costly late stage, it has been widely recognized that drug ADMET properties should be considered as early as possible to reduce failure rates in the clinical phase of drug discovery. Concurrently, drug recalls have become increasingly common in recent years, prompting pharmaceutical companies to increase attention toward the safety evaluation of preclinical drugs. In vitro and in vivo drug evaluation techniques are currently more mature in preclinical applications, but these technologies are costly. In recent years, with the rapid development of computer science, in silico technology has been widely used to evaluate the relevant properties of drugs in the preclinical stage and has produced many software programs and in silico models, further promoting the study of ADMET in vitro. In this review, we first introduce the two ADMET prediction categories (molecular modeling and data modeling). Then, we perform a systematic classification and description of the databases and software commonly used for ADMET prediction. We focus on some widely studied ADMT properties as well as PBPK simulation, and we list some applications that are related to the prediction categories and web tools. Finally, we discuss challenges and limitations in the preclinical area and propose some suggestions and prospects for the future.

Acute exercise and brain BACE1 protein content: a time course study

Obesity and insulin resistance are risk factors in the development of neurodegenerative disorders. Previous work suggests that one acute bout of exercise may have beneficial neuro-protective effects in obese mice. The rate limiting enzyme in the production of amyloid-beta peptides, BACE1, was reduced in the prefrontal cortex 2 h post-exercise, however if these effects remain over time is unknown. We aimed to determine how long exercise-induced alterations persist in the prefrontal cortex and hippocampus following a single exercise bout. Male C57BL/6J mice were fed either a low (LFD, 10% kcals from lard) or a high fat diet (HFD, 60% kcals from lard) for 7 weeks. HFD mice then underwent an acute bout of treadmill running (15 m/min, 5% incline, 120 min) followed by 2-, 8-, or 24-h of recovery. The HFD increased body mass (LFD 27.8 ± 1.05 vs. HFD 41.7 ± 0.60 g; P < 0.05) and glucose intolerance (AUC LFD 63.27 ± 4.5 vs. HFD 128.9 ± 4.6; P < 0.05). Prefrontal cortex BACE1 content was reduced 2- and 8-h post-exercise compared to sedentary HFD mice, however BACE1 protein content at 24 h was not different. Hippocampal BACE1 content was reduced 8- and 24-h post-exercise. Compared to the LFD, the HFD had higher prefrontal cortex phosphorylation of p38, JNK, and AMPK, indicative of increased neuronal stress. Post-exercise prefrontal cortex p38 and JNK phosphorylation were no different between the HFD or LFD groups, while ERK phosphorylation was significantly reduced by 24 h. The HFD increased JNK phosphorylation in the hippocampus. These results demonstrate the direct and potent effects of exercise on reducing BACE1 prefrontal cortex and hippocampal content. However the reduction in prefrontal cortex BACE1 content is short lived.

A Close Look at BACE1 Inhibitors for Alzheimer's Disease Treatment

Alzheimer's disease (AD), the most common cause of age-dependent dementia, is one of the most significant healthcare problems worldwide. Aggravating this situation, drugs that are currently US Food and Drug Administration (FDA)-approved for AD treatment do not prevent or delay disease progression. Therefore, developing effective therapies for AD patients is of critical urgency. Human genetic and clinical studies over the past three decades have indicated that abnormal generation or accumulation of amyloid-β (Aβ) peptides is a likely culprit in AD pathogenesis. Aβ is generated from amyloid precursor protein (APP) via proteolytic cleavage by β-site APP cleaving enzyme 1 (BACE1) (memapsin 2, β-secretase, Asp 2 protease) and γ-secretase. Mice deficient in BACE1 show abrogated production of Aβ. Therefore, pharmacological inhibition of BACE1 is being intensively pursued as a therapeutic approach to treat AD patients. Recent setbacks in clinical trials with BACE1 inhibitors have highlighted the critical importance of understanding how to properly inhibit BACE1 to treat AD patients. This review summarizes the recent studies on the role of BACE1 in synaptic functions as well as our views on BACE1 inhibition as an effective AD treatment.