Clinical potential of the acyclic nucleoside phosphonates cidofovir, adefovir, and tenofovir in treatment of DNA virus and retrovirus infections

Adefovir dipivoxil induces DNA replication stress and augments ATR inhibitor-related cytotoxicity

Replication stress is a common feature of cancer cells. Ataxia telangiectasia-mutated (ATM) and Rad3-related (ATR) signalling, a DNA damage repair (DDR) pathway, is activated by regions of single-stranded DNA (ssDNA) that can arise during replication stress. ATR delays cell cycle progression and prevents DNA replication fork collapse, which prohibits cell death and promotes proliferation. Several ATR inhibitors have been developed in order to restrain this protective mechanism in tumours. It is known, however, that despite other effective anticancer chemotherapy treatments targeting DDR pathways, resistance occurs. This begets the need to identify combination treatments to overcome resistance and prevent tumour cell growth. We conducted a drug screen to identify potential synergistic combination treatments by screening an ATR inhibitor (VE822) together with compounds from a bioactive small molecule library. The screen identified adefovir dipivoxil, a reverse transcriptase inhibitor and nucleoside analogue, as a compound that has increased cytotoxicity in the presence of ATR, but not ATM or DNA-dependant protein kinase (DNA-PK) inhibition. Here we demonstrate that adefovir dipivoxil induces DNA replication stress, activates ATR signalling and stalls cells in S phase. This simultaneous induction of replication stress and inhibition of ATR signalling lead to a marked increase in pan-nuclear γH2AX-positive cells, ssDNA accumulation and cell death, indicative of replication catastrophe.

Nanomaterials Designed for Antiviral Drug Delivery Transport across Biological Barriers

Viral infections are a major global health problem, representing a significant cause of mortality with an unfavorable continuously amplified socio-economic impact. The increased drug resistance and constant viral replication have been the trigger for important studies regarding the use of nanotechnology in antiviral therapies. Nanomaterials offer unique physico-chemical properties that have linked benefits for drug delivery as ideal tools for viral treatment. Currently, different types of nanomaterials namely nanoparticles, liposomes, nanospheres, nanogels, nanosuspensions and nanoemulsions were studied either in vitro or in vivo for drug delivery of antiviral agents with prospects to be translated in clinical practice. This review highlights the drug delivery nanosystems incorporating the major antiviral classes and their transport across specific barriers at cellular and intracellular level. Important reflections on nanomedicines currently approved or undergoing investigations for the treatment of viral infections are also discussed. Finally, the authors present an overview on the requirements for the design of antiviral nanotherapeutics.

Phosphine boranes as less hydrophobic building blocks than alkanes and silanes: Structure-property relationship and estrogen-receptor-modulating potency of 4-phosphinophenol derivatives

Increasing structural options in medicinal chemistry is important for the development of novel and distinctive drug candidates. In this study, we focused on phosphorus-containing functionalities. We designed and synthesized a series of phosphinophenol derivatives and determined their physicochemical properties, including hydrophobicity parameter LogP, and their biological activity toward estrogen receptor (ER). Notably, the phosphine borane derivatives (9 and 14) exhibited potent ER-antagonistic activity, exceeding the potency of the corresponding alkane (15) and silane (16) derivatives, despite having a less hydrophobic nature. The determined physicochemical parameters will be helpful for the rational design of phosphorus-containing biologically active compounds. Our results indicate that phosphine boranes are a promising new chemical entry in the range of structural options for drug discovery.

Model of population pharmacokinetics of cidofovir in immunocompromised children with cytomegalovirus and adenovirus infection

Objectives

To describe cidofovir pharmacokinetics and assess the link between concentration and safety/efficacy in children.

Patients and methods

An observational study was conducted in 13 immunocompromised children receiving cidofovir for adenovirus and/or cytomegalovirus infection. A population pharmacokinetic model was built and AUC0-24 was derived for each patient. Virological success was defined as a decrease of the viraemia by ≥1 log10 copies/mL within 15 days of cidofovir initiation. The association between AUC0-24 and virological success was assessed using a Wilcoxon test. An AUC0-24 cut-off value was determined using a Fisher's exact test.

Results

Overall, 86 blood samples were analysed. A two-compartment model with first-order absorption and elimination best described the cidofovir data. Virological success (VS) was reached in 6/8 children with adenovirus viraemia and in 1/4 children with cytomegalovirus viraemia. Patients with VS displayed a non-significant higher median AUC0-24 compared with patients with virological failure: 48.6 (range 8.9-72.6) versus 19.1 (6.9-22.7) mg·h/L. Adenovirus-viraemic patients with an AUC0-24 value below 19.1 mg·h/L had a higher probability of treatment failure (P = 0.03). Aviraemic children with stool and/or nasopharyngeal adenovirus carriage cleared the viral carriage within a month of cidofovir initiation. During treatment, 1/13 children developed a tubulopathy but none of them had an increase in creatininaemia.

Conclusions

Cidofovir appears safe and reasonably well tolerated and seemed to have efficacy in a subset of patients with adenovirus/cytomegalovirus infection. Therapeutic drug monitoring may be useful in children receiving cidofovir and, in the case of adenovirus infection, targeting an AUC0-24 above 19.1 mg·h/L could be associated with higher probability of virological success.

Design, synthesis and antiviral evaluation of novel acyclic phosphonate nucleotide analogs with triazolo[4,5-b]pyridine, imidazo[4,5-b]pyridine and imidazo[4,5-b]pyridin-2(3H)-one systems

A new series of phosphonylated triazolo[4,5-b]pyridine (1-deaza-8-azapurine), imidazo[4,5-b]pyridine (1-deazapurine) and imidazo[4,5-b]pyridin-2(3H)-one (1-deazapurin-8-one) were synthesized from 2-chloro-3-nitropyridine and selected diethyl ɷ-aminoalkylphosphonates followed by reduction of the nitro group and cyclization. In the final step O,O-diethylphosphonates were transformed into the corresponding phosphonic acids. All synthesized compounds were evaluated in vitro for inhibitory activity against a broad variety of DNA and RNA viruses and their cytotoxic potencies were also established. Compound 12f showed marginal activity against cytomegalovirus Davis strain (EC₅₀ = 76.47 μM) in human embryonic lung (HEL) cells while compounds 10g (EC₅₀ = 52.53 μM) and 12l (EC₅₀ = 61.70 μM) were minimally active against the varicella-zoster virus Oka strain in HEL cells. Compounds under investigation were not cytotoxic at the maximum concentration evaluated (100 µM).

Flexibility-Not just for yoga anymore!

Over the past few years, nucleosides have maintained a prominent role as one of the cornerstones of antiviral and anticancer therapeutics, and many approaches to nucleoside drug design have been pursued. One such approach involves flexibility in the sugar moiety of nucleosides, for example, in the highly successful anti-HIV and HBV drug tenofovir. In contrast, introduction of flexibility to the nucleobase scaffold has only more recently gained significance with the invention of our fleximers. The history, development, and some biological relevance for this innovative class of nucleosides are detailed herein.

Targeting the Viral Polymerase of Diarrhea-Causing Viruses as a Strategy to Develop a Single Broad-Spectrum Antiviral Therapy

Viral gastroenteritis is an important cause of morbidity and mortality worldwide, being particularly severe for children under the age of five. The most common viral agents of gastroenteritis are noroviruses, rotaviruses, sapoviruses, astroviruses and adenoviruses, however, no specific antiviral treatment exists today against any of these pathogens. We here discuss the feasibility of developing a broad-spectrum antiviral treatment against these diarrhea-causing viruses. This review focuses on the viral polymerase as an antiviral target, as this is the most conserved viral protein among the diverse viral families to which these viruses belong to. We describe the functional and structural similarities of the different viral polymerases, the antiviral effect of reported polymerase inhibitors and highlight common features that might be exploited in an attempt of designing such pan-polymerase inhibitor.

A standardized approach to the evaluation of antivirals against DNA viruses: Polyomaviruses and lymphotropic herpesviruses

The search for new compounds with a broad spectrum of antiviral activity is important and requires the evaluation of many compounds against several distinct viruses. Researchers attempting to develop new antiviral therapies for DNA virus infections currently use a variety of cell lines, assay conditions and measurement methods to determine in vitro drug efficacy, making it difficult to compare results from within the same laboratory as well as between laboratories. In this paper, we describe the assessment of antiviral activity of a set of nucleoside analogs against BK polyomavirus, JC polyomavirus, Epstein-Barr virus, human herpesvirus 6B, and human herpesvirus 8 in an automated 384-well format and utilize qPCR assays to measure the accumulation of viral DNA. In an accompanying paper, we present a standardized approach to evaluating antivirals against additional herpesviruses, orthopoxviruses, and adenovirus. Together, they reveal new activities for reference compounds and help to define the spectrum of antiviral activity for a set of nucleoside analogs against a set of 12 DNA viruses that infect humans including representative human herpesviruses, orthopoxviruses, adenoviruses, and polyomaviruses. This analysis helps provide perspective on combinations of agents that would help provide broad coverage of significant pathogens in immunocompromised patients as well as against emerging infections.

In vitro evaluation of current and novel antivirals in combination against human cytomegalovirus

Human cytomegalovirus (HCMV) can cause severe disease in patients with compromised or immature immune systems. Currently approved pharmacotherapies for the treatment of systemic HCMV infections [ganciclovir (GCV), cidofovir (CDV), foscarnet] are limited by a high incidence of adverse effects and/or the development of drug resistance. Given that many of these drugs have the same viral target (HCMV-encoded DNA polymerase), cross-resistance is relatively common. The primary means to combat drug resistance is combination pharmacotherapy using therapeutics with different molecular mechanisms of action with the expectation that those combinations result in an additive or synergistic enhancement of effect; combinations that result in antagonism can, in many cases, be detrimental to the outcome of the patient. We therefore tested select combinations of approved (GCV, CDV, letermovir (LMV)) and experimental (brincidofovir (BCV), cyclopropavir (CPV), maribavir (MBV), BDCRB) drugs with the hypothesis that combinations of drugs with different and distinct molecular mechanisms of action will produce an additive and/or synergistic enhancement of antiviral effect against HCMV in vitro. Using MacSynergy II (a statistical package that measures enhancement or lessening of effect relative to zero/additive), select drug combination studies demonstrated combination indices ranging from 160 to 372 with 95% confidence intervals greater than zero indicating that these combinations elicit a synergistic enhancement of effect against HCMV in vitro. These data suggest that administration of a viral DNA polymerase inhibitor, MBV, and/or a viral terminase inhibitor in combination has the potential to address the resistance/cross-resistance problems associated with currently available therapeutics.

The evolution of nucleoside analogue antivirals: A review for chemists and non-chemists. Part 1: Early structural modifications to the nucleoside scaffold

This is the first of two invited articles reviewing the development of nucleoside-analogue antiviral drugs, written for a target audience of virologists and other non-chemists, as well as chemists who may not be familiar with the field. Rather than providing a simple chronological account, we have examined and attempted to explain the thought processes, advances in synthetic chemistry and lessons learned from antiviral testing that led to a few molecules being moved forward to eventual approval for human therapies, while others were discarded. The present paper focuses on early, relatively simplistic changes made to the nucleoside scaffold, beginning with modifications of the nucleoside sugars of Ara-C and other arabinose-derived nucleoside analogues in the 1960's. A future paper will review more recent developments, focusing especially on more complex modifications, particularly those involving multiple changes to the nucleoside scaffold. We hope that these articles will help virologists and others outside the field of medicinal chemistry to understand why certain drugs were successfully developed, while the majority of candidate compounds encountered barriers due to low-yielding synthetic routes, toxicity or other problems that led to their abandonment.

Synthesis and antiviral evaluation of base-modified deoxythreosyl nucleoside phosphonates

l-α-2'-Deoxythreosyl nucleoside phosphonates and their phosphonodiamidate prodrugs with a hypoxanthine, 2,6-diaminopurine, 2-amino-6-cyclopropylaminopurine, 7-deazaadenine, 5-fluorouracil and 5-methylcytosine heterocycle as a nucleobase were synthesized and evaluated for their inhibitory activity against HIV and HBV. The 2,6-diaminopurine modified analogue 23a displayed the most potent activity against HIV, with an EC₅₀ value of 11.17 μM against HIV-1 (III_B) and an EC₅₀ value of 8.15 μM against HIV-2 (ROD). The application of the prodrug strategy on nucleoside phosphonate 23a led to a 200-fold boost in anti-HIV potency. None of the compounds showed any activity against HBV at the highest concentration tested.

Injectable PLGA Adefovir microspheres; the way for long term therapy of chronic hepatitis-B

For patient convenience, sustained release Adefovir Poly-d,l-lactic-co-glycolic acid (PLGA) microspheres were formulated to relieve the daily use of the drug which is a problem for patients treated from chronic hepatitis-B. PLGA microspheres were prepared and characterized by entrapment efficiency, particle size distribution and scanning electron microscopy (SEM). In-vitro release and in-vivo studies were carried out. Factors such as drug: polymer ratio, polymer viscosity and polymer lactide content were found to be important variables for the preparation of PLGA Adefovir microspheres. Fourier transform infrared (FTIR) analysis and differential scanning calorimetry (DSC) were performed to determine any drug-polymer interactions. One way analysis of variance (ANOVA) was employed to analyze the pharmacokinetic parameters after intramuscular injection of the pure drug and the selected PLGA microspheres into rats. FTIR and DSC revealed a significant interaction between the drug and the polymer. Reports of SEM before and after 1 and 24 h release showed that the microspheres had nonporous smooth surface even after 24 h release. The entrapment efficiency ranged between 55.83 and 86.95% and in-vitro release studies were continued for 16, 31 and 90 days. The pharmacokinetic parameters and statistical analysis showed a significant increase in the T_max, AUC_0-t and MRT, and a significant decrease in the C_max of the tested formulation (p < 0.05). Results demonstrated that PLGA Adefovir microspheres could be used for long-term treatment of chronic hepatitis-B instead of the daily dose used by the patient.

A new computational model for the prediction of toxicity of phosphonate derivatives using QSPR

Structural and electronic properties of a series of 25 phosphonate derivatives were analyzed applying density functional theory, with the exchange-correlation functional PBEPBE in combination with the 6-311++G** basis set for all atoms. The chemical reactivity of these derivatives has been interpreted using quantum descriptors such as frontier molecular orbitals (HOMO, LUMO), Hirshfeld charges, molecular electrostatic potential, and the dual descriptor [[Formula: see text]]. These descriptors are directly related to experimental median lethal dose ([Formula: see text], expressed as its decimal logarithm [[Formula: see text]([Formula: see text]] through a multiple linear regression equation. The proposed model predicts the toxicity of phosphonates in function of the volume (V), the load of the most electronegative atom of the molecule (q), and the eigenvalue of the molecular orbital HOMO ([Formula: see text]. The obtained values in the internal validation of the model are: [Formula: see text]%, [Formula: see text]%, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]%. The toxicity of nine phosphonate derivatives used as test molecules was adequately predicted by the model. The theoretical results indicate that the oxygen atom of the O=P group plays an important role in the interaction mechanism between the phosphonate and the acetylcholinesterase enzyme, inhibiting the removal of the proton of the ser-200 residue by the his-440 residue.

The French Armed Forces Virology Unit: A Chronological Record of Ongoing Research on Orthopoxvirus

Since the official declaration of smallpox eradication in 1980, the general population vaccination has ceased worldwide. Therefore, people under 40 year old are generally not vaccinated against smallpox and have no cross protection against orthopoxvirus infections. This naïve population may be exposed to natural or intentional orthopoxvirus emergences. The virology unit of the Institut de Recherche Biomédicale des Armées (France) has developed research programs on orthopoxviruses since 2000. Its missions were conceived to improve the diagnosis capabilities, to foster vaccine development, and to develop antivirals targeting specific viral proteins. The role of the virology unit was asserted in 2012 when the responsibility of the National Reference Center for the Orthopoxviruses was given to the unit. This article presents the evolution of the unit activity since 2000, and the past and current research focusing on orthopoxviruses.

Herpes Zoster in the Older Adult

Herpes zoster (HZ) is the result of reactivation of latent varicella zoster virus (VZV) and occurs most frequently in older adults. Classically, HZ presents as a unilateral, selflimited, dermatomal rash. Postherpetic neuralgia (PHN) is a common sequela, presenting as severe pain that persists after the rash has resolved. In the elderly, PHN can be debilitating and requires a prompt diagnosis, treatment with antivirals, and adequate pain control. A longer-term pain management strategy is required if PHN occurs. A modestly effective vaccine exists and is recommended for older individuals.

Phosphonic acid: preparation and applications

The phosphonic acid functional group, which is characterized by a phosphorus atom bonded to three oxygen atoms (two hydroxy groups and one P=O double bond) and one carbon atom, is employed for many applications due to its structural analogy with the phosphate moiety or to its coordination or supramolecular properties. Phosphonic acids were used for their bioactive properties (drug, pro-drug), for bone targeting, for the design of supramolecular or hybrid materials, for the functionalization of surfaces, for analytical purposes, for medical imaging or as phosphoantigen. These applications are covering a large panel of research fields including chemistry, biology and physics thus making the synthesis of phosphonic acids a determinant question for numerous research projects. This review gives, first, an overview of the different fields of application of phosphonic acids that are illustrated with studies mainly selected over the last 20 years. Further, this review reports the different methods that can be used for the synthesis of phosphonic acids from dialkyl or diaryl phosphonate, from dichlorophosphine or dichlorophosphine oxide, from phosphonodiamide, or by oxidation of phosphinic acid. Direct methods that make use of phosphorous acid (H3PO3) and that produce a phosphonic acid functional group simultaneously to the formation of the P-C bond, are also surveyed. Among all these methods, the dealkylation of dialkyl phosphonates under either acidic conditions (HCl) or using the McKenna procedure (a two-step reaction that makes use of bromotrimethylsilane followed by methanolysis) constitute the best methods to prepare phosphonic acids.

Tenofovir Alafenamide: A Review in Chronic Hepatitis B

Tenofovir alafenamide (AF) [Vemlidy^®], an oral prodrug of tenofovir, was developed to optimize the antiviral potency and clinical safety of the active moiety tenofovir diphosphate (selective reverse transcriptase nucleotide inhibitor). In two identically designed, ongoing, multinational trials in treatment-naive and -experienced adult patients with hepatitis B e antigen (HBeAg)-positive or -negative chronic hepatitis B virus (HBV) infection, once-daily tenofovir AF 25 mg provided effective and sustained viral suppression (120-week analysis), and was generally well tolerated. In the primary 48-week analysis, tenofovir AF was noninferior to once-daily tenofovir disoproxil fumarate (DF) 300 mg in terms of the proportion of patients achieving viral suppression (HBV DNA <29 IU/mL) and was associated with significantly higher alanine aminotransferase (ALT) normalization rates than tenofovir DF based on AASLD criteria (but not central laboratory criteria). In pooled analyses and/or individual trials, ALT normalization rates by AASLD and central laboratory criteria were significantly higher in tenofovir AF than tenofovir DF recipients at most assessed timepoints up to 96 weeks. Given the bone and renal safety concerns associated with long-term tenofovir DF treatment, the more favourable pharmacological profile of tenofovir AF permits a marked reduction in the dosage of this tenofovir prodrug and thereby reduces systemic exposure to tenofovir, potentially improving the bone and renal safety of tenofovir AF versus tenofovir DF. Long-term clinical experience will more definitively establish the relative bone and renal safety of these tenofovir prodrugs. With its potential for an improved safety profile, tenofovir AF is an important emerging first-line option for the treatment of chronic HBV infection in adults and adolescents (aged ≥12 years and with a bodyweight of ≥35 kg).

Topical Formulation of Self-Assembled Antiviral Prodrug Nanomicelles for Targeted Retinal Delivery

Topical drug administration for back of the eye delivery is extremely challenging due to the presence of protection mechanisms and physiological barriers. Self-assembled polymeric nanomicelles have emerged as promising vehicles for drug delivery. Apart from serving as an inert nanocarrier for therapeutic agents, polymeric nanomicelles are known to bypass mononuclear phagocytic system (MPS) and efflux transporters thereby improving drug bioavailability. In this investigation, a highly efficacious biotinylated lipid prodrug of cyclic cidofovir (B-C12-cCDF) was formulated within polymeric nanomicelles as a carrier for targeted retinal delivery. Polymeric nanomicelles were prepared from polyoxyethylene hydrogenated castor oil 40 (HCO-40) and octoxynol 40 (OC-40). In vitro release studies revealed that B-C12-cCDF-loaded nanomicelles released B-C12-cCDF at a faster rate in stimulated tear fluid (STF) in comparison to PBST. MTT and LDH assays demonstrated negligible cytotoxicity of B-C12-cCDF-loaded nanomicelles relative to CDF and B-C12-cCDF in HRPE (human retinal pigment epithelial, D407), HCE-T (human corneal epithelial), and CCL 20.2 (human conjunctival epithelial) cells. Confocal laser scanning microscopy and flow cytometry analyses indicated that B-C12-cCDF-loaded nanomicelles were efficiently internalized into D407 and HCE-T cells in contrast to CDF and B-C12-cCDF. Moreover, little B-C12-cCDF was also observed in the nuclei after 24 h of incubation. Polymeric nanomicelles carrying the transporter targeted prodrug did not produce any cytotoxic effects and were internalized into the cells effectively. Permeability experiments across HCE-T cells further confirmed significant transport of prodrug loaded nanomicelles and their subsequent uptake into D407 cells. These findings indicate that HCO-40/OC-40 based polymeric nanomicelles could become a promising topical delivery system for ocular administration of antiviral agents.

Clinical effectiveness and cost-effectiveness of interventions for the treatment of anogenital warts: systematic review and economic evaluation

BACKGROUND

Typically occurring on the external genitalia, anogenital warts (AGWs) are benign epithelial skin lesions caused by human papillomavirus infection. AGWs are usually painless but can be unsightly and physically uncomfortable, and affected people might experience psychological distress. The evidence base on the clinical effectiveness and cost-effectiveness of treatments for AGWs is limited.

OBJECTIVES

To systematically review the evidence on the clinical effectiveness of medical and surgical treatments for AGWs and to develop an economic model to estimate the cost-effectiveness of the treatments.

DATA SOURCES

Electronic databases (MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, The Cochrane Library databases and Web of Science) were searched from inception (or January 2000 for Web of Science) to September 2014. Bibliographies of relevant systematic reviews were hand-searched to identify potentially relevant studies. The World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov were searched for ongoing and planned studies.

REVIEW METHODS

A systematic review of the clinical effectiveness literature was carried out according to standard methods and a mixed-treatment comparison (MTC) undertaken. The model implemented for each outcome was that with the lowest deviance information criterion. A de novo economic model was developed to assess cost-effectiveness from the perspective of the UK NHS. The model structure was informed through a systematic review of the economic literature and in consultation with clinical experts. Effectiveness data were obtained from the MTC. Costs were obtained from the literature and standard UK sources.

RESULTS

Of 4232 titles and abstracts screened for inclusion in the review of clinical effectiveness, 60 randomised controlled trials (RCTs) evaluating 19 interventions were included. Analysis by MTC indicated that ablative techniques were typically more effective than topical interventions at completely clearing AGWs at the end of treatment. Podophyllotoxin 0.5% solution (Condyline(®), Takeda Pharmaceutical Company Ltd; Warticon(®) solution, Stiefel Laboratories Ltd) was found to be the most effective topical treatment evaluated. Networks for other outcomes included fewer treatments, which restrict conclusions on the comparative effectiveness of interventions. In total, 84 treatment strategies were assessed using the economic model. Podophyllotoxin 0.5% solution first line followed by carbon dioxide (CO2) laser therapy second line if AGWs did not clear was most likely to be considered a cost-effective use of resources at a willingness to pay of £20,000-30,000 per additional quality-adjusted life-year gained. The result was robust to most sensitivity analyses conducted.

LIMITATIONS

Limited reporting in identified studies of baseline characteristics for the enrolled population generates uncertainty around the comparability of the study populations and therefore the generalisability of the results to clinical practice. Subgroup analyses were planned based on type, number and size of AGWs, all of which are factors thought to influence treatment effect. Lack of data on clinical effectiveness based on these characteristics precluded analysis of the differential effects of treatments in the subgroups of interest. Despite identification of 60 studies, most comparisons in the MTC are informed by only one RCT. Additionally, lack of head-to-head RCTs comparing key treatments, together with minimal reporting of results in some studies, precluded comprehensive analysis of all treatments for AGWs.

CONCLUSIONS

The results generated by the MTC are in agreement with consensus opinion that ablative techniques are clinically more effective at completely clearing AGWs after treatment. However, the evidence base informing the MTC is limited. A head-to-head RCT that evaluates the comparative effectiveness of interventions used in clinical practice would help to discern the potential advantages and disadvantages of the individual treatments. The results of the economic analysis suggest that podophyllotoxin 0.5% solution is likely to represent a cost-effective first-line treatment option. More expensive effective treatments, such as CO2 laser therapy or surgery, may represent cost-effective second-line treatment options. No treatment and podophyllin are unlikely to be considered cost-effective treatment options. There is uncertainty around the cost-effectiveness of treatment with imiquimod, trichloroacetic acid and cryotherapy.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005457.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Sn(ii)-Mediated facile approach for the synthesis of 2-aryl-2H-indazole-3-phosphonates and their anticancer activities

The efficient synthesis of 2-aryl-2H-indazole-3-phosphonates has been achieved successfully via a SnCl₂·2H₂O mediated one-pot method.

Circulating kidney injury molecule-1 is a novel diagnostic biomarker for renal dysfunction during long-term adefovir therapy in chronic hepatitis B

The aim of this study was to evaluate serum kidney injury molecule-1 (KIM-1) as a new diagnostic marker of renal dysfunction in chronic hepatitis B (CHB) patients receiving long-term adefovir dipivoxil (ADV) treatment.We retrospectively enrolled 85 patients treated with ADV and 85 patients treated with entecavir (ETV) monotherapy, for at least 6 months. The 2 groups were matched for baseline age (± 5 years), sex, and estimated glomerular filtration rate (eGFR). Serum creatinine, cystatin C, and KIM-1 concentrations were measured, and eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine-cystatin C equation, at baseline and last follow-up.eGFR decreased by 10-20% from baseline in 11/85 (14.1%) patients, 20-30% in 5/85 (5.9%), and ≥ 30% in 2/85 (2.4%) patients treated with ADV. Serum KIM-1 was more significantly increased after ADV treatment 86.53 (10.20-355.40) pg/mL than ETV treatment 61.54 (10.53-200.56) pg/mL (P < 0.01). Furthermore, serum KIM-1 was positively correlated with serum cystatin C (r = 0.47; P < 0.001) and negatively correlated with eGFR (r = -0.46; P < 0.001). The area under the receiver operating characteristic curve (AUC-ROC) of serum KIM-1 for identifying renal dysfunction in all enrolled patients was 0.94 (95% confidence interval [95% CI], 0.87 to 1.02; P < 0.001), while the AUC-ROC of serum creatinine was only 0.82 (95% CI, 0.60 to 1.03; P < 0.01).Serum KIM-1 is a promising new diagnostic biomarker of renal dysfunction during long-term ADV therapy for CHB patients.

How I treat resistant cytomegalovirus infection in hematopoietic cell transplantation recipients

Cytomegalovirus (CMV) infection is a significant complication in hematopoietic cell transplantation (HCT) recipients. Four antiviral drugs are used for preventing or treating CMV: ganciclovir, valganciclovir, foscarnet, and cidofovir. With prolonged and repeated use of these drugs, CMV can become resistant to standard therapy, resulting in increased morbidity and mortality, especially in HCT recipients. Antiviral drug resistance should be suspected when CMV viremia (DNAemia or antigenemia) fails to improve or continue to increase after 2 weeks of appropriately dosed and delivered antiviral therapy. CMV resistance is diagnosed by detecting specific genetic mutations. UL97 mutations confer resistance to ganciclovir and valganciclovir, and a UL54 mutation confers multidrug resistance. Risk factors for resistance include prolonged or previous anti-CMV drug exposure or inadequate dosing, absorption, or bioavailability. Host risk factors include type of HCT and degree of immunosuppression. Depending on the genotyping results, multiple strategies can be adopted to treat resistant CMV infections, albeit no randomized clinical trials exist so far, after reducing immunosuppression (if possible): ganciclovir dose escalation, ganciclovir and foscarnet combination, and adjunct therapy such as CMV-specific cytotoxic T-lymphocyte infusions. Novel therapies such as maribavir, brincidofovir, and letermovir should be further studied for treatment of resistant CMV.

Identification of an indol-based derivative as potent and selective varicella zoster virus (VZV) inhibitor

We report the synthesis and antiviral activity of a new family of non-nucleoside antivirals, derived from the indole nucleus. Modifications of this template through Mannich and Friedel-Crafts reactions, coupled with nucleophilic displacement and reductive aminations led to 23 final derivatives, which were pharmacologically tested. Tryptamine derivative 17a was found to have a selective inhibitory activity against human varicella zoster virus (VZV) replication in vitro, being inactive against a variety of other DNA and RNA viruses. A structure-activity relationship (SAR) study showed that the presence of a biphenyl ethyl moiety and the acetylation at the amino group of tryptamine are a prerequisite for anti-VZV activity. The novel compound shows the same activity against thymidine kinase (TK)-competent (TK⁺) and TK-deficient (TK⁻) VZV strains, pointing to a novel mechanism of antiviral action.

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A library of indole-based derivatives has been designed and synthesized as potential antiviral agents.

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Friedel-Crafts and Mannich reactions were used for the synthesis of different indole derivatives.

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Tryptamine derivative 17a displays significant inhibitory activity against VZV replication.

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A mechanism of action independent from the virus-encoded thymidine kinase is suggested.

Effects of 1α,25-Dihydroxyvitamin D3 on Intestinal Absorption and Disposition of Adefovir Dipivoxil and Its Metabolite, Adefovir, in Rats

The aim of this study was to investigate the effect of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), an active form of vitamin D, on the oral absorption and disposition of adefovir dipivoxil (P-glycoprotein (P-gp) substrate) and its major active metabolite, adefovir (multidrug resistance-associated protein 4 (Mrp4) substrate), in rats. The pharmacokinetics of intravenous adefovir and oral adefovir dipivoxil was evaluated in control and 1,25(OH)2D3-treated rats. The intestinal absorption of adefovir dipivoxil was investigated through an in situ closed loop study, and the tissue distribution of adefovir after oral administration of adefovir dipivoxil was evaluated in the two groups. There was no significant difference in pharmacokinetic parameters of intravenous adefovir between the two groups. Importantly, the total area under the plasma concentration-time curve from time zero to time infinity (AUC), peak plasma concentration (Cmax) and extent of absolute oral bioavailability (F) of adefovir after oral administration of adefovir dipivoxil were significantly higher in 1,25(OH)2D3-treated rats than in control rats. In the in situ closed loop study, there was no significant difference in the remaining fraction of adefovir dipivoxil in the duodenum, jejunum and ileum loops between the two groups. In the tissue distribution study after oral administration of adefovir dipivoxil, the tissue-to-plasma partition coefficients of adefovir in the liver, brain, kidney, and intestine were significantly lower in the 1,25(OH)2D3-treated rats than in control rats. The present study indicates that 1,25(OH)2D3 treatment can enhance the oral absorption of adefovir dipivoxil, likely via the induction of basolateral Mrp4 function in rat intestine. However, the impact of 1,25(OH)2D3 treatment on the pharmacokinetics of intravenous adefovir was limited. These results could lead to further studies in clinically significant P-gp and/or MRP4-mediated 1,25(OH)2D3-drug interactions.

Reduction Sensitive Lipid Conjugates of Tenofovir: Synthesis, Stability, and Antiviral Activity

The therapeutic value of numerous small molecules hinges on their ability to permeate the plasma membrane. This is particularly true for tenofovir (TFV), adefovir, and other antiviral nucleosides that demonstrate potent antiviral activity but poor bioavailability. Using TFV as a model substrate, we hybridized two disparate prodrug strategies to afford novel reduction-sensitive lipid conjugates of TFV that exhibit subnanomolar activity toward HIV-1 and are stable in human plasma for more than 24 h with a therapeutic index approaching 30000. These compounds significantly rival the clinically approved formulation of TFV and revitalize the potential of disulfide-bearing prodrugs which have seen limited in vitro and in vivo success since their debut over 20 years ago. We further demonstrate the utility of these conjugates as a tool to indirectly probe the enzymatic hydrolysis of phosphonomonoesters that may further advance the development of other prodrug strategies for nucleosides, peptides, and beyond.

Approved Antiviral Drugs over the Past 50 Years

Since the first antiviral drug, idoxuridine, was approved in 1963, 90 antiviral drugs categorized into 13 functional groups have been formally approved for the treatment of the following 9 human infectious diseases: (i) HIV infections (protease inhibitors, integrase inhibitors, entry inhibitors, nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and acyclic nucleoside phosphonate analogues), (ii) hepatitis B virus (HBV) infections (lamivudine, interferons, nucleoside analogues, and acyclic nucleoside phosphonate analogues), (iii) hepatitis C virus (HCV) infections (ribavirin, interferons, NS3/4A protease inhibitors, NS5A inhibitors, and NS5B polymerase inhibitors), (iv) herpesvirus infections (5-substituted 2'-deoxyuridine analogues, entry inhibitors, nucleoside analogues, pyrophosphate analogues, and acyclic guanosine analogues), (v) influenza virus infections (ribavirin, matrix 2 protein inhibitors, RNA polymerase inhibitors, and neuraminidase inhibitors), (vi) human cytomegalovirus infections (acyclic guanosine analogues, acyclic nucleoside phosphonate analogues, pyrophosphate analogues, and oligonucleotides), (vii) varicella-zoster virus infections (acyclic guanosine analogues, nucleoside analogues, 5-substituted 2'-deoxyuridine analogues, and antibodies), (viii) respiratory syncytial virus infections (ribavirin and antibodies), and (ix) external anogenital warts caused by human papillomavirus infections (imiquimod, sinecatechins, and podofilox). Here, we present for the first time a comprehensive overview of antiviral drugs approved over the past 50 years, shedding light on the development of effective antiviral treatments against current and emerging infectious diseases worldwide.

A 65-Year-Old Female from Connecticut with Orf Infection

The virus, which causes orf and induces acute pustular skin lesions in sheep and goats, is transmissible to humans yet is rarely observed in North America. We present a case of a 65-year-old female farmer from Connecticut who contracted orf from her sheep. The clinical and histopathologic features, important to arrive at the correct diagnosis of this uncommon yet important infection, are described. We also discuss the benign nature of this condition and emphasize that treatment is not required.

Susceptibility of porcine endogenous retrovirus to anti-retroviral inhibitors

BACKGROUND

Porcine endogenous retrovirus (PERV) is an endogenous retrovirus that poses a risk of iatrogenic transmission in the context of pig-to-human xenotransplantation. The lack of a means to control PERV infection in the context of pig-to-human xenotransplantation is a major concern in the field. In this study, we set out to evaluate the ability of currently licensed anti-HIV drugs, and other types of anti-retroviral compounds, to inhibit PERV infection in vitro.

METHODS

We used target cells stably expressing one of the known PERV viral receptors, an infectious molecular clone, PERV-A 14/220, and at least one drug from each class of anti-retroviral inhibitors as well as off-label drugs shown to have anti-viral activities. The susceptibility of PERV-A 14/220 LacZ to the anti-retroviral drugs was determined from infected cells by histochemical staining.

RESULTS

We extend the results of previous studies by showing that, in addition to raltegravir, dolutegravir is found to have a potent inhibitory activity against PERV replication (IC50 8.634 ±0.336 and IC50 3.06 ± 0.844 nM, respectively). The anti-HIV drug zidovudine (AZT) showed considerable anti-PERV activity with IC50 of 1.923 ±0.691 μM as well.

CONCLUSIONS

The study results indicate that some of the licensed anti-retroviral drugs may be useful for controlling PERV infection. However, the efficacy at nanomolar concentrations put forward integrase inhibitors as a drug that has the potential to be useful in the event that xenotransplantation recipients have evidence of PERV transmission and replication.

Novel therapeutic investigational strategies to treat severe and disseminated HSV infections suggested by a deeper understanding of in vitro virus entry processes

The global burden of herpes simplex virus (HSV) legitimates the critical need to develop new prevention strategies, such as drugs and vaccines that are able to fight either primary HSV infections or reactivations. Moreover, the ever-growing number of patients receiving transplants increases the number of severe HSV infections that are unresponsive to current therapies. Finally, the high global incidence of genital HSV-2 infection increases the risk of perinatal transmission to newborns, in which disseminated infection or central nervous system (CNS) involvement is frequent, with associated high morbidity and mortality rates. There are several key features shared by novel anti-HSV drugs, from currently available optimized drugs to small molecules able to interfere with various virus replication steps. However, several virological aspects of the disease and associated clinical needs highlight why an ideal anti-HSV drug has yet to be developed.

Functionalized lipids and surfactants for specific applications

Synthetic lipids and surfactants that do not exist in biological systems have been used for the last few decades in both basic and applied science. The most notable applications for synthetic lipids and surfactants are drug delivery, gene transfection, as reporting molecules, and as support for structural lipid biology. In this review, we describe the potential of the synergistic combination of computational and experimental methodologies to study the behavior of synthetic lipids and surfactants embedded in lipid membranes and liposomes. We focused on select cases in which molecular dynamics simulations were used to complement experimental studies aiming to understand the structure and properties of new compounds at the atomistic level. We also describe cases in which molecular dynamics simulations were used to design new synthetic lipids and surfactants, as well as emerging fields for the application of these compounds. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.

Synthesis, antiviral, cytotoxic and cytostatic evaluation of N 1-(phosphonoalkyl)uracil derivatives

Abstract

A series of N¹-(phosphonoalkyl)uracils was prepared in a two-step reaction sequence from ω-aminoalkylphosphonates and (E)-3-ethoxyacryloyl isocyanate followed by the uracil ring closure. Under standard conditions (NCS; NBS; I₂/CAN) all N¹-(phosphonoalkyl)uracils were transformed into the respective 5-halogeno derivatives to be later benzoylated at N3. All compounds were evaluated in vitro for activity against a broad variety of DNA and RNA viruses. One compound was slightly active against human cytomegalovirus in HEL cell cultures (EC₅₀ = 45 μM) while another showed weak activity against varicella-zoster virus (TK⁺ VZV strain OKA and TK⁻ VZV strain 07-1) with EC₅₀ = 43 and 53 µM, respectively. In addition, several compounds exhibited noticeable inhibitory effects on the proliferation of human cervical carcinoma cells (HeLa) at a concentration lower than 200 μM.

Graphical abstract

Applications and stereoselective syntheses of P-chirogenic phosphorus compounds

This review reports the best stereoselective or asymmetric syntheses, the most efficient P*-building blocks and functionalisation of P-chirogenic compounds, in the light of chiral phosphorus compound applications.

Pharmacokinetics and safety of intravesicular cidofovir in allogeneic HSCT recipients

OBJECTIVES

The objective of this study was to evaluate the pharmacokinetics and safety of cidofovir administered via the intravesicular route to patients with haemorrhagic cystitis following allogeneic HSCT (allo-HSCT).

METHODS

Patients with gross haematuria and confirmed BK or adenovirus viruria following allo-HSCT were prospectively enrolled in an open-label pharmacokinetic study (ClinicalTrials.gov registration: NCT01816646). Three hours after an oral probenecid dose (2 g), cidofovir (2.5-5 mg/kg in 50-100 mL of normal saline) was given via a transurethral catheter for up to 2 h of dwell time. Serial plasma samples were obtained over 24 h and assayed for cidofovir concentrations using LC-MS/MS. A custom pharmacokinetic model with a time-limited absorption compartment was fitted to the concentration-time profile of each patient. Systemic drug exposure was expressed as AUC0-24, by integrating the best-fit profile with respect to time.

RESULTS

Six subjects (mean ± SD age = 38 ± 21 years) with baseline serum creatinine <1.4 mg/dL were enrolled. Mean values for volume of distribution, clearance and elimination half-life were 19.5 L, 5.6 L/h and 2.8 h, respectively. Compared with the reported AUC0-24 for an equivalent intravenous dose, intravesicular instillation of cidofovir resulted in 1%-74% of the corresponding systemic exposure. Owing to primarily lower abdominal pain, only two patients were able to tolerate a 2 h dwell time. One patient developed a >50% increase in serum creatinine within 7 days of administration.

CONCLUSIONS

Intravesicular administration of cidofovir resulted in highly variable systemic exposures. The safety and efficacy of intravesicular cidofovir should be further evaluated before routine use.