Infectious diseases. Debate erupts on 'repurposed' drugs for Ebola

Screening and Identification of HTNVpv Entry Inhibitors with High-throughput Pseudovirus-based Chemiluminescence

Hantaviruses, such as Hantaan virus (HTNV) and Seoul virus, are the causative agents of Hantavirus cardiopulmonary syndrome (HCPS) and hemorrhagic fever with renal syndrome (HFRS), and are important zoonotic pathogens. China has the highest incidence of HFRS, which is mainly caused by HTNV and Seoul virus. No approved antiviral drugs are available for these hantaviral diseases. Here, a chemiluminescence-based high-throughput-screening (HTS) assay was developed and used to screen HTNV pseudovirus (HTNV_pv) inhibitors in a library of 1813 approved drugs and 556 small-molecule compounds from traditional Chinese medicine sources. We identified six compounds with in vitro anti-HTNV_pv activities in the low-micromolar range (EC₅₀ values of 0.1–2.2 ​μmol/L; selectivity index of 40–900). Among the six selected compounds, cepharanthine not only showed good anti-HTNV_pv activity in vitro but also inhibited HTNV_pv-fluc infection in Balb/c mice 5 ​h after infection by 94% (180 ​mg/kg/d, P ​< ​0.01), 93% (90 ​mg/kg/d, P ​< ​0.01), or 92% (45 ​mg/kg/d, P ​< ​0.01), respectively, in a bioluminescent imaging mouse model. A time-of-addition analysis suggested that the antiviral mechanism of cepharanthine involves the membrane fusion and entry phases. Overall, we have established a HTS method for antiviral drugs screening, and shown that cepharanthine is a candidate for HCPS and HFRS therapy. These findings may offer a starting point for the treatment of patients infected with hantaviruses.

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A chemiluminescence-based high-throughput-screening (HTS) assay was used to screen HTNV pseudovirus (HTNV_pv) inhibitors.

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Cepharanthine showed good anti-HTNV_pv activity in vitro and in vivo.

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A time-of-addition analysis suggested that cepharanthine involves the membrane fusion and entry phases.

High-Throughput Screening and Identification of Human Adenovirus Type 5 Inhibitors

Human adenovirus infections can develop into diffuse multi-organ diseases in young children and immunocompromised patients, and severe cases can lead to death. However, there are no approved antiviral drugs available to treat adenovirus diseases. In this study, a chemiluminescence-based, high-throughput screening (HTS) assay was developed and applied to screen human adenovirus 5(HAdV5)inhibitors from 1,813 approved drug library and 556 traditional Chinese medicine-sourced small-molecule compounds. We identified three compounds with in vitro anti-HAdV5 activities in the low-micromolar range (EC50 values 0.3-4.5 μM, selectivity index values 20-300) that also showed inhibitory effects on HAdV3. Cardamomin (CDM) had good anti-HAdV5 activity in vitro. Furthermore, three dilutions of CDM (150, 75, and 37.5 mg/kg/d) administered to BALB/c mouse models inhibited HAdV5-fluc infection at 1 day post-infection by 80% (p < 0.05), 76% (p < 0.05), and 58% (p < 0.05), respectively. HE-staining of pathological tissue sections of mice infected with a wildtype adenoviral strain showed that CDM had a protective effect on tissues, especially in the liver, and greatly inhibited virus-induced necrosis of liver tissue. Thus, CDM inhibits adenovirus replication in vivo and in vitro. This study established a high-throughput screening method for anti-HAdV5 drugs and demonstrated CDM to be a candidate for HAdV5 therapy, potentially providing a new treatment for patients infected with adenoviruses.

Brief Overview of Approaches and Challenges in New Antibiotic Development: A Focus On Drug Repurposing

Drug repurposing, or identifying new uses for existing drugs, has emerged as an alternative to traditional drug discovery processes involving de novo synthesis. Drugs that are currently approved or under development for non-antibiotic indications may possess antibiotic properties, and therefore may have repurposing potential, either alone or in combination with an antibiotic. They might also serve as "antibiotic adjuvants" to enhance the activity of certain antibiotics.

Challenges and Benefits of Repurposing Products for Use during a Radiation Public Health Emergency: Lessons Learned from Biological Threats and other Disease Treatments

The risk of a radiological or nuclear public health emergency is a major growing concern of the U.S. government. To address a potential incident and ensure that the government is prepared to respond to any subsequent civilian or military casualties, the U.S. Department of Health and Human Services and the Department of Defense have been charged with the development of medical countermeasures (MCMs) to treat the acute and delayed injuries that can result from radiation exposure. Because of the limited budgets in research and development and the high costs associated with bring promising approaches from the bench through advanced product development activities, and ultimately, to regulatory approval, the U.S. government places a priority on repurposing products for which there already exists relevant safety and other important information concerning their use in humans. Generating human data can be a costly and time-consuming process; therefore, the U.S. government has interest in drugs for which such relevant information has been established (e.g., products for another indication), and in determining if they could be repurposed for use as MCMs to treat radiation injuries as well as chemical and biological insults. To explore these possibilities, the National Institute of Allergy and Infectious Diseases (NIAID) convened a workshop including U.S. government, industry and academic subject matter experts, to discuss the challenges and benefits of repurposing products for a radiation indication. Topics covered included a discussion of U.S. government efforts (e.g. funding, stockpiling and making products available for study), as well unique regulatory and other challenges faced when repurposing patent protected or generic drugs. Other discussions involved lessons learned from industry on repurposing pre-license, pipeline products within drug development portfolios. This report reviews the information presented, as well as an overview of discussions from the meeting.

What treating Ebola means for pandemic influenza

Almost all new treatments being developed for the next influenza pandemic target the virus. During the Ebola crisis in West Africa, patients were treated with an inexpensive generic statin/angiotensin receptor blocker combination that appeared to greatly improve survival. These drugs target the host response, not the virus, and probably reverse endothelial dysfunction. Scientists and health officials have shown little interest in this idea. Yet, during the early months of the next pandemic, vaccines will be unavailable and treatment options will be limited. Physicians should be prepared to undertake clinical trials of widely available generic drugs to determine whether they improve survival in patients with seasonal influenza, other emerging virus diseases, and other forms of acute critical illness. Public health officials should give these studies their strong support. If successful, they will suggest a 'bottom up' approach to patient care that could be implemented worldwide on the first pandemic day.

Ethics review of studies during public health emergencies - the experience of the WHO ethics review committee during the Ebola virus disease epidemic

BACKGROUND

Between 2013 and 2016, West Africa experienced the largest ever outbreak of Ebola Virus Disease. In the absence of registered treatments or vaccines to control this lethal disease, the World Health Organization coordinated and supported research to expedite identification of interventions that could control the outbreak and improve future control efforts. Consequently, the World Health Organization Research Ethics Review Committee (WHO-ERC) was heavily involved in reviews and ethics discussions. It reviewed 24 new and 22 amended protocols for research studies including interventional (drug, vaccine) and observational studies.

WHO-ERC REVIEWS

WHO-ERC provided the reviews within on average 6 working days. The WHO-ERC often could not provide immediate approval of protocols for reasons which were not Ebola Virus Disease specific but related to protocol inconsistencies, missing information and complex informed consents. WHO-ERC considerations on Ebola Virus Disease specific issues (benefit-risk assessment, study design, exclusion of pregnant women and children from interventional studies, data and sample sharing, collaborative partnerships including international and local researchers and communities, community engagement and participant information) are presented.

CONCLUSIONS

To accelerate study approval in future public health emergencies, we recommend: (1) internally consistent and complete submissions with information documents in language participants are likely to understand, (2) close collaboration between local and international researchers from research inception, (3) generation of template agreements for data and sample sharing and use during the ongoing global consultations on bio-banks, (4) formation of Joint Scientific Advisory and Data Safety Review Committees for all studies linked to a particular intervention or group of interventions, (5) formation of a Joint Ethics Review Committee with representatives of the Ethics Committees of all institutions and countries involved to strengthen reviews through the different perspectives provided without the 'opportunity costs' for time to final approval of multiple, independent reviews, (6) direct information exchange between the chairs of advisory, safety review and ethics committees, (7) more Ethics Committee support for investigators than is standard and (8) a global consultation on criteria for inclusion of pregnant women and children in interventional studies for conditions which put them at particularly high risk of mortality or other irreversible adverse outcomes under standard-of-care.

Repurposed Therapeutic Agents Targeting the Ebola Virus: A Systematic Review

BACKGROUND

The Ebola virus has been responsible for numerous outbreaks since the 1970s, with the most recent outbreak taking place between 2014 and 2016 and causing an international public health emergency. Ebola virus disease (EVD) has a high mortality rate and no approved targeted treatment exists to date. A number of established drugs are being considered as potential therapeutic agents for the treatment of EVD.

OBJECTIVE

We aimed to identify potential drug repositioning candidates and to assess the scientific evidence available on their efficacy.

METHODS

We conducted a systematic literature search in MEDLINE, Embase, and other relevant trial registry platforms for studies published between January 1976 and January 2017. We included drug screening, preclinical studies, and clinical studies on repurposed drugs for the treatment of EVD. The risk of bias for animal studies and nonrandomized clinical studies was assessed. The quality of reporting for case series and case reports was evaluated. Finally, we selected drugs approved by established regulatory authorities, which have positive in vitro study outcomes and at least one additional animal or clinical trial.

RESULTS

We identified 3301 publications, of which 37 studies fulfilled our inclusion criteria. Studies were highly heterogeneous in terms of study type, methodology, and intervention. The risk of bias was high for 13 out of 14 animal studies. We selected 11 drugs with potential anti-EVD therapeutic effects and summarized their evidence.

CONCLUSIONS

Several established drugs may have therapeutic effects on EVD, but the quality and quantity of current scientific evidence is lacking. This review highlights the need for well-designed and conducted preclinical and clinical research to establish the efficacy of potential repurposed drugs against EVD.

Treating the host response to emerging virus diseases: lessons learned from sepsis, pneumonia, influenza and Ebola

There is an ongoing threat of epidemic or pandemic diseases that could be caused by influenza, Ebola or other emerging viruses. It will be difficult and costly to develop new drugs that target each of these viruses. Statins and angiotensin receptor blockers (ARBs) have been effective in treating patients with sepsis, pneumonia and influenza, and a statin/ARB combination appeared to dramatically reduce mortality during the recent Ebola outbreak. These drugs target (among other things) the endothelial dysfunction found in all of these diseases. Most scientists work on new drugs that target viruses, and few accept the idea of treating the host response with generic drugs. A great deal of research will be needed to show conclusively that these drugs work, and this will require the support of public agencies and foundations. Investigators in developing countries should take an active role in this research. If the next Public Health Emergency of International Concern is caused by an emerging virus, a "top down" approach to developing specific new drug treatments is unlikely to be effective. However, a "bottom up" approach to treatment that targets the host response to these viruses by using widely available and inexpensive generic drugs could reduce mortality in any country with a basic health care system. In doing so, it would make an immeasurable contribution to global equity and global security.

Treating Ebola patients: a 'bottom up' approach using generic statins and angiotensin receptor blockers

The international community has responded to the Ebola outbreak in West Africa with a 'top down' approach. This has contributed to outbreak control, but has done much less to reduce the high mortality rate in individual patients. Ebola patients experience a breakdown in endothelial barrier integrity that leads to massive fluid losses and vascular collapse. Statins and angiotensin receptor blockers (ARBs) maintain or restore endothelial barrier integrity. Local physicians in Sierra Leone have treated approximately 100 consecutive Ebola patients with atorvastatin and irbesartan, and all but two inadequately treated patients have survived. The results of this experience have not been released and they need to be reviewed and validated. Unlike other treatments that target the Ebola virus itself, this 'bottom up' approach to treatment represents a paradigm shift by targeting the host response to infection. Treatment with these safe, inexpensive generic agents could be implemented readily throughout West Africa.

A web-based resource for designing therapeutics against Ebola Virus

In this study, we describe a web-based resource, developed for assisting the scientific community in designing an effective therapeutics against the Ebola virus. Firstly, we predicted and identified experimentally validated epitopes in each of the antigens/proteins of the five known ebolaviruses. Secondly, we generated all the possible overlapping 9mer peptides from the proteins of ebolaviruses. Thirdly, conserved peptides across all the five ebolaviruses (four human pathogenic species) with no identical sequence in the human proteome, based on 1000 Genomes project, were identified. Finally, we identified peptide or epitope-based vaccine candidates that could activate both the B- and T-cell arms of the immune system. In addition, we also identified efficacious siRNAs against the mRNA transcriptome (absent in human transcriptome) of all the five ebolaviruses. It was observed that three species can potentially be targeted by a single siRNA (19mer) and 75 siRNAs can potentially target at least two species. A web server, EbolaVCR, has been developed that incorporates all the above information and useful computational tools (http://crdd.osdd.net/oscadd/ebola/).

Lessons from the Ebola Outbreak: Action Items for Emerging Infectious Disease Preparedness and Response

As the Ebola outbreak in West Africa wanes, it is time for the international scientific community to reflect on how to improve the detection of and coordinated response to future epidemics. Our interdisciplinary team identified key lessons learned from the Ebola outbreak that can be clustered into three areas: environmental conditions related to early warning systems, host characteristics related to public health, and agent issues that can be addressed through the laboratory sciences. In particular, we need to increase zoonotic surveillance activities, implement more effective ecological health interventions, expand prediction modeling, support medical and public health systems in order to improve local and international responses to epidemics, improve risk communication, better understand the role of social media in outbreak awareness and response, produce better diagnostic tools, create better therapeutic medications, and design better vaccines. This list highlights research priorities and policy actions the global community can take now to be better prepared for future emerging infectious disease outbreaks that threaten global public health and security.

Repurposed therapeutic agents targeting the Ebola virus: a protocol for a systematic review

BACKGROUND

The recent Ebola epidemic in western Africa developed into an acute public health emergency of unprecedented level in modern times. The treatment provided in most cases has been limited to supportive care, as no approved therapies are available to date. Several established, licenced drugs have been suggested as potential repurposed therapeutic agents for Ebola. However, scientific data on their efficacy in treating Ebola is limited. The purpose of this review is to systematically assess scientific evidence on potential drugs targeting Ebola. In specific, we aim to (1) identify drug library screens involving therapeutic agents targeting the Ebola virus, (2) list potential approved drugs identified from drug screens and review their mechanism of action against the Ebola virus and (3) summarise the outcome of preclinical and clinical trials investigating approved drugs targeting the Ebola virus.

METHODS/DESIGN

We will develop comprehensive systematic search strategies and will perform a systematic literature search in MEDLINE, Embase and Cochrane Central Register of Controlled Trials (CENTRAL). Two authors will independently screen the titles, abstracts and the references of all selected articles on the basis of inclusion criteria. These include any available drug screening, preclinical studies and clinical studies examining the efficacy of approved therapeutic agents targeting the Ebola virus. There will be no restrictions on the type of participants, the type of comparator, time or setting. Data extraction and quality assessment will be undertaken by two review authors working independently.

DISCUSSION

This systematic review will provide systematic knowledge on potential repurposed therapeutic agents targeting Ebola. It aims to help guide future investigations on repurposed drugs and avoid repetitive studies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015024349.

Addressing Therapeutic Options for Ebola Virus Infection in Current and Future Outbreaks

Ebola virus can cause severe hemorrhagic disease with high fatality rates. Currently, no specific therapeutic agent or vaccine has been approved for treatment and prevention of Ebola virus infection of humans. Although the number of Ebola cases has fallen in the last few weeks, multiple outbreaks of Ebola virus infection and the likelihood of future exposure highlight the need for development and rapid evaluation of pre- and postexposure treatments. Here, we briefly review the existing and future options for anti-Ebola therapy, based on the data coming from rare clinical reports, studies on animals, and results from in vitro models. We also project the mechanistic hypotheses of several potential drugs against Ebola virus, including small-molecule-based drugs, which are under development and being tested in animal models or in vitro using various cell types. Our paper discusses strategies toward identifying and testing anti-Ebola virus properties of known and medically approved drugs, especially those that can limit the pathological inflammatory response in Ebola patients and thereby provide protection from mortality. We underline the importance of developing combinational therapy for better treatment outcomes for Ebola patients.

Preclinical discovery and development of maraviroc for the treatment of HIV

INTRODUCTION

Maraviroc is a first-in-class antiretroviral (ARV) drug acting on a host cell target (CCR5), which blocks the entry of the HIV virus into the cell. Maraviroc is currently indicated for combination ARV treatment in adults infected only with CCR5-tropic HIV-1.

AREAS COVERED

This drug discovery case history focuses on the key studies that led to the discovery and approval of maraviroc, as well as on post-launch clinical reports. The article is based on the data reported in published preclinical and clinical studies, conference posters and on drug package data.

EXPERT OPINION

The profound understanding of HIV's entry mechanisms has provided a strong biological rationale for targeting the chemokine receptor CCR5. The CCR5-antagonist mariviroc, with its unique mode of action and excellent safety profile, is an important therapeutic option for HIV patients. In general, the authors believe that targeting host factors is a useful approach for combating new and re-emerging transmissible diseases, as well as pathogens that easily become resistant to common antiviral drugs. Maraviroc, offering a potent and safe cellular receptor-mediated pharmacological response to HIV, has paved the way for the development of a new generation of host-targeting antivirals.

A survey of current trends in computational drug repositioning

Computational drug repositioning or repurposing is a promising and efficient tool for discovering new uses from existing drugs and holds the great potential for precision medicine in the age of big data. The explosive growth of large-scale genomic and phenotypic data, as well as data of small molecular compounds with granted regulatory approval, is enabling new developments for computational repositioning. To achieve the shortest path toward new drug indications, advanced data processing and analysis strategies are critical for making sense of these heterogeneous molecular measurements. In this review, we show recent advancements in the critical areas of computational drug repositioning from multiple aspects. First, we summarize available data sources and the corresponding computational repositioning strategies. Second, we characterize the commonly used computational techniques. Third, we discuss validation strategies for repositioning studies, including both computational and experimental methods. Finally, we highlight potential opportunities and use-cases, including a few target areas such as cancers. We conclude with a brief discussion of the remaining challenges in computational drug repositioning.

Virtual screen for repurposing approved and experimental drugs for candidate inhibitors of EBOLA virus infection

The ongoing Ebola virus epidemic has presented numerous challenges with respect to control and treatment because there are no approved drugs or vaccines for the Ebola virus disease (EVD). Herein is proposed simple theoretical criterion for fast virtual screening of molecular libraries for candidate inhibitors of Ebola virus infection. We performed a repurposing screen of 6438 drugs from DrugBank using this criterion and selected 267 approved and 382 experimental drugs as candidates for treatment of EVD including 15 anti-malarial drugs and 32 antibiotics. An open source Web server allowing screening of molecular libraries for candidate drugs for treatment of EVD was also established.

Examining the ethics of clinical use of unproven interventions outside of clinical trials during the Ebola epidemic

The recent Ebola outbreak in West Africa began in the spring of 2014 and has since caused the deaths of over 6,000 people. Since there are no approved treatments or prevention modalities specifically targeted at Ebola Virus Disease (EVD), debate has focused on whether unproven interventions should be offered to Ebola patients outside of clinical trials. Those engaged in the debate have responded rapidly to a complex and evolving crisis, however, and this debate has not provided much opportunity for in-depth analysis. Additionally, the existing literature on access to unproven therapies has focused on contexts like HIV/AIDS and oncology, which are very different than the Ebola epidemic. In this paper, we examine the ethical issues surrounding access to unproven therapies in the context of the recent Ebola outbreak to yield new insights about this controversial and unsettled issue. We argue first that, in this context, the interests of patients in obtaining access to unproven therapies are not fully aligned with the interests of their providers and drug developers. Second, we focus on the resource constraints facing providers, funders, and patients and conclude that they often counsel against the use of unproven interventions against EVD.