Using intracerebral microdialysis to probe the efficacy of repurposed drugs in Alzheimer′s disease pathology

All disease-targeting drug trials completed to date have fallen short of meeting the clinical endpoint of significantly slowing cognitive decline in Alzheimer′s disease patients. Even the recently approved drug Aducanumab, has proven effective in removing amyloid-β, but does not reduce cognitive decline. This emphasizes the urgent need for novel therapeutic approaches that could reduce several AD neuropathologies simultaneously, eventually leading to improved cognitive performance. To validate whether our mouse model replicates AD neuropathology as observed in patients, we characterized the 3xTg AD mouse model to avoid premature translation of successful results. In this study we have repurposed two FDA-approved drugs, Fasudil and Lonafarnib, targeting the Wnt signaling and endosomal-lysosomal pathway respectively, to test their potential to attenuate AD pathology. Using intracerebral microdialysis, we simultaneously infused these disease-targeting drugs between 1-2 weeks, separately and also in combination, while collecting cerebrospinal fluid. We found that Fasudil reduces intracellular amyloid-β in young, and amyloid plaques in old animals, and overall cerebrospinal fluid amyloid-β. Lonafarnib reduces tau neuropathology and cerebrospinal fluid tau biomarkers in young and old animals. Co-infusion of both drugs was more effective in reducing intracellular amyloid-β than either drug alone, and appeared to improve contextual memory performance. However, an unexpected finding was that Lonafarnib treatment increased amyloid plaque size, suggesting that activating the endosomal-lysosomal system may inadvertently increase amyloid-β pathology if administered too late in the AD continuum. Taken together, these findings lend support to the application of repurposed drugs to attenuate AD neuropathology at various therapeutic time windows.

Integrative In Silico Investigation Reveals the Host-Virus Interactions in Repurposed Drugs Against SARS-CoV-2

The ongoing COVID-19 outbreak have posed a significant threat to public health worldwide. Recently Toll-like receptor (TLR) has been proposed to be the drug target of SARS-CoV-2 treatment, the specificity and efficacy of such treatments remain unknown. In the present study we performed the investigation of repurposed drugs via a framework comprising of Search Tool for Interacting Chemicals (STITCH), Kyoto Encyclopedia of Genes and Genomes (KEGG), molecular docking, and virus-host-drug interactome mapping. Chloroquine (CQ) and hydroxychloroquine (HCQ) were utilized as probes to explore the interaction network that is linked to SARS-CoV-2. 47 drug targets were shown to be overlapped with SARS-CoV-2 network and were enriched in TLR signaling pathway. Molecular docking analysis and molecular dynamics simulation determined the direct binding affinity of TLR9 to CQ and HCQ. Furthermore, we established SARS-CoV-2-human-drug protein interaction map and identified the axis of TLR9-ERC1-Nsp13 and TLR9-RIPK1-Nsp12. Therefore, the elucidation of the interactions of SARS-CoV-2 with TLR9 axis will not only provide pivotal insights into SARS-CoV-2 infection and pathogenesis but also improve the treatment against COVID-19.

Repurposing of Drugs for SARS-CoV-2 Using Inverse Docking Fingerprints

Severe acute respiratory syndrome coronavirus 2 or SARS-CoV-2 is a virus that belongs to the Coronaviridae family. This group of viruses commonly causes colds but possesses a tremendous pathogenic potential. In humans, an outbreak of SARS caused by the SARS-CoV virus was first reported in 2003, followed by 2012 when the Middle East respiratory syndrome coronavirus (MERS-CoV) led to an outbreak of Middle East respiratory syndrome (MERS). Moreover, COVID-19 represents a serious socioeconomic and global health problem that has already claimed more than four million lives. To date, there are only a handful of therapeutic options to combat this disease, and only a single direct-acting antiviral, the conditionally approved remdesivir. Since there is an urgent need for active drugs against SARS-CoV-2, the strategy of drug repurposing represents one of the fastest ways to achieve this goal. An in silico drug repurposing study using two methods was conducted. A structure-based virtual screening of the FDA-approved drug database on SARS-CoV-2 main protease was performed, and the 11 highest-scoring compounds with known 3CLpro activity were identified while the methodology was used to report further 11 potential and completely novel 3CLpro inhibitors. Then, inverse molecular docking was performed on the entire viral protein database as well as on the Coronaviridae family protein subset to examine the hit compounds in detail. Instead of target fishing, inverse docking fingerprints were generated for each hit compound as well as for the five most frequently reported and direct-acting repurposed drugs that served as controls. In this way, the target-hitting space was examined and compared and we can support the further biological evaluation of all 11 newly reported hits on SARS-CoV-2 3CLpro as well as recommend further in-depth studies on antihelminthic class member compounds. The authors acknowledge the general usefulness of this approach for a full-fledged inverse docking fingerprint screening in the future.

Current Drug Repurposing Strategies for Rare Neurodegenerative Disorders

Rare diseases are life-threatening or chronically debilitating low-prevalent disorders caused by pathogenic mutations or particular environmental insults. Due to their high complexity and low frequency, important gaps still exist in their prevention, diagnosis, and treatment. Since new drug discovery is a very costly and time-consuming process, leading pharmaceutical companies show relatively low interest in orphan drug research and development due to the high cost of investments compared to the low market return of the product. Drug repurposing–based approaches appear then as cost- and time-saving strategies for the development of therapeutic opportunities for rare diseases. In this article, we discuss the scientific, regulatory, and economic aspects of the development of repurposed drugs for the treatment of rare neurodegenerative disorders with a particular focus on Huntington’s disease, Friedreich’s ataxia, Wolfram syndrome, and amyotrophic lateral sclerosis. The role of academia, pharmaceutical companies, patient associations, and foundations in the identification of candidate compounds and their preclinical and clinical evaluation will also be discussed.

Minimum manufacturing costs, national prices and estimated global availability of new repurposed therapies for COVID-19

Background Currently, only dexamethasone, tocilizumab and sarilumab have conclusively been shown to reduce mortality of COVID-19. Safe and effective treatments will need to be both affordable and widely available globally to be used alongside vaccination programmes. This analysis will estimate and compare potential generic minimum costs of a selection of approved COVID-19 drug candidates with available international list prices. Methods We searched for repurposed drugs that have been approved by at least one of the WHO, FDA or NICE, or at least given emergency use authorisation or recommended for off-label prescription. Drug prices were searched for, for dexamethasone, budesonide, baricitinib, tocilizumab, casirivimab and imdevimab, and sarilumab using active pharmaceutical ingredients (API) data extracted from global shipping records. This was compared with national pricing data from a range of low, medium, and high-income countries. Annual API export volumes from India were used to estimate the current availability of each drug. Results Repurposed therapies can be generically manufactured for some treatments at very low per-course costs, ranging from $2.58 for IV dexamethasone (or $0.19 orally) and $4.34 for inhaled budesonide. No export price data was available for baricitinib, tocilizumab, casirivimab and imdevimab or sarilumab, but courses of these treatments are priced highly, ranging from $6.67 for baricitinib to $875.5 for sarilumab. When comparing international list prices, we found wide variations between countries. Conclusions Successful management of COVID-19 will require equitable access to treatment for all populations, not just those able to pay high prices. Dexamethasone and budesonide are widely available and affordable, whilst monoclonal antibodies and IV treatment courses are more expensive.

A Study on the Potential Pathways for Existing Drugs against COVID-19

Coronavirus infectious disease 2019 (COVID-19) is a global pandemic declared by the World Health Organization (WHO) in March 2020. This emerging infectious disease is rapidly transmitted and does not only pose a global threat to public health but also badly affects the economy. At present, there is no effective drug to treat COVID-19, leading to a significant challenge upon current global attempts at restraining the outbreak. There are several currently available drugs, also considered as the repurposed drugs are in use for treatment against COVID-19. However, these drugs are not as efficient as it is hoped. Therefore, this study is conducted to further explore into other established antivirus that could function better for COVID-19 treatment. In addition, the pathways that associated with the drugs are identified and potential targeted proteins for the repurposed drugs are also pointed out. The articles for review were selected from several search engine databases, which are ScienceDirect, SpringerLink, PubMed, and Scopus including the keywords COVID-19, SARS, MERS, potential pathways for antiviral drugs as well as repurposed drugs, with more than 50 primary research articles identified. Findings and analysis have discovered potential repurposed drugs that could be used for COVID-19, namely bisoxatin, nitazoxanide and teicoplanin which could be involved in corona-related pathways. Meanwhile, the associated pathways are JAK-STAT, Neprilysin (NEP) and cGAS-STING that counteract excessive immune response and act as a medium for the drugs to access antiviral activities. The repurposed drugs target protein identification is also a critical significance, and it was found that S-protein, TMPRSS2, RdRp and RDB which are the signalling protein can be interrupted by the repurposed drugs, presenting a promising antivirus against SARS-CoV-2. It is concluded that this study will provide information to assist logical design of the repurposed drug for its effectiveness as antivirus against COVID-19

Repurposing Market Drugs to Target Epigenetic Enzymes in Human Diseases

Drug discovery is an exciting yet highly costly endeavor. In the United States, developing a new prescription medicine that gains marketing approval takes near a decade and costs drugmakers for near 3 billion. More challengingly, the success rate of a compound entering phase I trials is just slightly under 10%. Because of these mounting hurdles, repurposing market approved drugs to new clinical indications has been a new trend on the rise. Another merit to this approach is the already confirmed toxicity profiles of the drugs and their possession of drug-like features. Thus, repurposed drugs can reach the market approved stage in a much faster, cheaper, and more efficient way. Notably, epigenetic enzymes play a critical role in the etiology and progression of different diseases. Researchers are now assessing the possibilities of using market approved drugs to target epigenetic enzymes as a novel strategy to curtail disease progression. Thus, in this book chapter, we will provide an outlook on repurposing market drugs to target epigenetic enzymes in various diseases. Consequently, this book chapter will not only provide the readers with current knowledge in this specific field, but also will shed light on the pathway forward for repurposing market drugs to target epigenetic enzymes in human diseases.

Drug Repurposing for Glioblastoma and Current Advances in Drug Delivery—A Comprehensive Review of the Literature

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with an extremely poor prognosis. There is a dire need to develop effective therapeutics to overcome the intrinsic and acquired resistance of GBM to current therapies. The process of developing novel anti-neoplastic drugs from bench to bedside can incur significant time and cost implications. Drug repurposing may help overcome that obstacle. A wide range of drugs that are already approved for clinical use for the treatment of other diseases have been found to target GBM-associated signaling pathways and are being repurposed for the treatment of GBM. While many of these drugs are undergoing pre-clinical testing, others are in the clinical trial phase. Since GBM stem cells (GSCs) have been found to be a main source of tumor recurrence after surgery, recent studies have also investigated whether repurposed drugs that target these pathways can be used to counteract tumor recurrence. While several repurposed drugs have shown significant efficacy against GBM cell lines, the blood–brain barrier (BBB) can limit the ability of many of these drugs to reach intratumoral therapeutic concentrations. Localized intracranial delivery may help to achieve therapeutic drug concentration at the site of tumor resection while simultaneously minimizing toxicity and side effects. These strategies can be considered while repurposing drugs for GBM.

Mitochondrially-Targeted Therapeutic Strategies for Alzheimer's Disease

: Alzheimer's disease (AD) is an irreversible, progressive neurodegenerative disease and the most common cause of dementia among older adults. There are no effective treatments avail- able for the disease, and it is associated with great societal concern because of the substantial costs of providing care to its sufferers, whose numbers will increase as populations age. While multiple causes have been proposed to be significant contributors to the onset of sporadic AD, increased age is a unifying risk factor. In addition to amyloid-β (Aβ) and tau protein playing a key role in the initi- ation and progression of AD, impaired mitochondrial bioenergetics and dynamics are likely major etiological factors in AD pathogenesis and have many potential origins, including Aβ and tau. Mito- chondrial dysfunction is evident in the central nervous system (CNS) and systemically early in the disease process. Addressing these multiple mitochondrial deficiencies is a major challenge of mito- chondrial systems biology. We review evidence for mitochondrial impairments ranging from mito- chondrial DNA (mtDNA) mutations to epigenetic modification of mtDNA, altered gene expres- sion, impaired mitobiogenesis, oxidative stress, altered protein turnover and changed organelle dy- namics (fission and fusion). We also discuss therapeutic approaches, including repurposed drugs, epigenetic modifiers, and lifestyle changes that target each level of deficiency which could poten- tially alter the course of this progressive, heterogeneous Disease while being cognizant that success- ful future therapeutics may require a combinatorial approach.