New therapies for chronic hepatitis C infection: a systematic review of evidence from clinical trials

Oncoviruses: How do they hijack their host and current treatment regimes

Viruses have the ability to modulate the cellular machinery of their host to ensure their survival. While humans encounter numerous viruses daily, only a select few can lead to disease progression. Some of these viruses can amplify cancer-related traits, particularly when coupled with factors like immunosuppression and co-carcinogens. The global burden of cancer development resulting from viral infections is approximately 12%, and it arises as an unfortunate consequence of persistent infections that cause chronic inflammation, genomic instability from viral genome integration, and dysregulation of tumor suppressor genes and host oncogenes involved in normal cell growth. This review provides an in-depth discussion of oncoviruses and their strategies for hijacking the host's cellular machinery to induce cancer. It delves into how viral oncogenes drive tumorigenesis by targeting key cell signaling pathways. Additionally, the review discusses current therapeutic approaches that have been approved or are undergoing clinical trials to combat malignancies induced by oncoviruses. Understanding the intricate interactions between viruses and host cells can lead to the development of more effective treatments for virus-induced cancers.

Simmons-Smith Cyclopropanation: A Multifaceted Synthetic Protocol toward the Synthesis of Natural Products and Drugs: A Review

Simmons-Smith cyclopropanation is a widely used reaction in organic synthesis for stereospecific conversion of alkenes into cyclopropane. The utility of this reaction can be realized by the fact that the cyclopropane motif is a privileged synthetic intermediate and a core structural unit of many biologically active natural compounds such as terpenoids, alkaloids, nucleosides, amino acids, fatty acids, polyketides and drugs. The modified form of Simmons-Smith cyclopropanation involves the employment of Et2Zn and CH2I2 (Furukawa reagent) toward the total synthesis of a variety of structurally complex natural products that possess broad range of biological activities including anticancer, antimicrobial and antiviral activities. This review aims to provide an intriguing glimpse of the Furukawa-modified Simmons-Smith cyclopropanation, within the year range of 2005 to 2022.

Hepatitis C virus DAA treatment adherence patterns and SVR among people who inject drugs treated in opioid agonist therapy programs

BACKGROUND

Adequate medication adherence is critical for achieving sustained viral response (SVR) of hepatitis C virus (HCV) among people who inject drugs (PWID). However, it is less known which patterns of direct-acting antiviral (DAA) treatment adherence are associated with SVR in this population or what factors are associated with each pattern.

METHODS

The randomized three-arm PREVAIL study utilized electronic blister packs to obtain daily time frame adherence data in opiate agonist therapy program settings. Exact logistic regressions were applied to test the associations between SVR and six types of treatment adherence patterns.

RESULTS

Of the 113 participants treated with combination DAAs, 109 (96.5%) achieved SVR. SVR was significantly associated with all pattern parameters except for number of switches between adherent and missed days: total adherent daily doses (exact AOR=1.12; 95%CI=1.04-1.22), percent total doses (1.09; 1.03-1.16), days on treatment (1.16; 1.05-1.32), maximum consecutive adherent days (1.34; 1.06-2.04), maximum consecutive non-adherent days (.85; .74-.95=.003). SVR was significantly associated with total adherent doses in the first two months of treatment, it was not in the last month. Compared to White participants (30.7±11.8(se)), Black (18.4±7.8) and Hispanic participants (19.2±6.1) had significantly shorter maximum consecutive adherent days. While alcohol intoxication was significantly associated with frequent switches, drug use was not associated with any adherence pattern.

CONCLUSION

Consistent maintenance of adequate total dose adherence over the entire course of HCV treatment is important in achieving SVR among PWID. Additional integrative addiction and medical care may be warranted for treating PWID experiencing alcohol intoxication.

Facilitators of HCV treatment adherence among people who inject drugs: a systematic qualitative review and implications for scale up of direct acting antivirals

Background

While the public health benefits of new HCV treatments depend on treatment adherence, particularly among people who inject drugs (PWID), several social and medical factors can jeopardize treatment adherence. The aim of this study is to examine the qualitative literature on facilitators to HCV treatment adherence among PWID.

Methods

We searched six databases to identify qualitative research studies on HCV treatment adherence facilitators among PWID. Two reviewers independently extracted and analyzed data using PRISMA guidelines and the CASP tool to evaluate study quality.

Results

From ten studies representing data from 525 participants, three major themes emerged across studies: logistical facilitators within health systems enhanced HCV treatment adherence, positive social interactions between PWID and staff provided positive feedback during treatment, and HCV treatment may complicate the addiction recovery process.

Conclusions

Although PWID face several barriers to adherence, we identified treatment adherence facilitators that could be incorporated into clinical practice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3671-z) contains supplementary material, which is available to authorized users.

2015 Philip S. Portoghese Medicinal Chemistry Lectureship. Curing Hepatitis C Virus Infection with Direct-Acting Antiviral Agents: The Arc of a Medicinal Chemistry Triumph

The development of direct-acting antiviral agents that can cure a chronic hepatitis C virus (HCV) infection after 8-12 weeks of daily, well-tolerated therapy has revolutionized the treatment of this insidious disease. In this article, three of Bristol-Myers Squibb's HCV programs are summarized, each of which produced a clinical candidate: the NS3 protease inhibitor asunaprevir (64), marketed as Sunvepra, the NS5A replication complex inhibitor daclatasvir (117), marketed as Daklinza, and the allosteric NS5B polymerase inhibitor beclabuvir (142), which is in late stage clinical studies. A clinical study with 64 and 117 established for the first time that a chronic HCV infection could be cured by treatment with direct-acting antiviral agents alone in the absence of interferon. The development of small molecule HCV therapeutics, designed by medicinal chemists, has been hailed as "the arc of a medical triumph" but may equally well be described as "the arc of a medicinal chemistry triumph".

HCV inter-subtype 1a/1b recombinant detected by complete-genome next-generation sequencing

Next-generation sequencing (NGS) provides a practical approach to HCV complete-genome sequencing, detecting low-frequency variants and allowing analysis of viral genetic diversity (quasispecies) in the sample, and so far, it is very useful for identifying preexisting drug-resistant mutants and emerging escape mutations, as well as detecting viral recombinants containing genomic regions from different genotypes and subtypes. The aim of this study was to analyze the complete coding region of hepatitis C virus (HCV) genotype 1 (subtypes 1a and 1b) from patients with chronic infection who were direct-acting antiviral (DAA) naïve. Next-generation sequencing (Ion Torrent™ PGM) was used to determine the sequence of the complete coding region of 100 HCV-monoinfected DAA-naïve patients (51 and 49 subtypes 1a and 1b, respectively). We report the first description of nearly complete HCV genome sequences of subtype 1a and 1b isolates from a large population of Brazilian patients with chronic hepatitis C, and HCV-1a grouped in two different clades. Using this methodology, an inter-subtype 1a/1b recombinant was identified in this study.

Review article: safety and tolerability of direct-acting anti-viral agents in the new era of hepatitis C therapy

BACKGROUND

Direct-acting anti-virals (DAAs) licensed to treat chronic HCV infection have revolutionised treatment algorithms by drastically mitigating side effects while enhancing efficacy relative to interferon-based therapy.

AIM

To review adverse events (AEs) uniquely associated with DAA therapy across a broad spectrum of patient populations.

METHODS

Searches of PubMed and FDA surveillance studies were undertaken to complete an exhaustive review. Search terms included 'DAAs', 'safety', and 'tolerability'.

RESULTS

While DAAs are remarkably well tolerated, they are accompanied by unique AEs. Simeprevir, an NS3/4A protease inhibitor, has been known, albeit infrequently, to cause mild hyperbilirubinemia and photosensitivity reactions; and paritaprevir boosted with ritonavir causes bilirubin and ALT elevations. Asunaprevir, another protease inhibitor, infrequently causes elevated transaminase levels. NS5A and NS5B inhibitors are well tolerated, although sofosbuvir is contraindicated in patients with severe renal impairment. Ribavirin co-administered in certain treatment regimens has been associated with cough, rash and haemolytic anaemia.

CONCLUSIONS

With the impending reality of a more tolerable interferon-sparing regimen, the future of DAA therapy offers shorter treatment duration, simplified disease management, and a patient-centred regimen. With advantages come drawbacks, including development of resistance to therapy and accessibility to this expensive treatment. DAA therapy continues to advance at a brisk pace with a promising trend for higher tolerability, even in difficult-to-treat subgroups such as those with cirrhosis, nonresponders to prior therapy, and transplant recipients. Subgroup-specific contraindications and safety-related limitations are active areas of research. Concerted research efforts and continuing advances lend hope to the goal of rendering HCV a routinely curable disease.

In vitro investigation of the interaction between the hepatitis C virus drug sofosbuvir and human serum albumin through 1H NMR, molecular docking, and spectroscopic analyses

The qualitative and quantitative investigation of sofosbuvir and HSA interaction provides a convictive explanation for its binding mechanism.

Hepatitis C infection in hemodialysis patients: A review

Hepatitis C virus (HCV)-related liver disease is a significant cause of morbidity and mortality in patients with end-stage renal disease (ESRD) who is treated with dialysis or kidney transplantation (KT). The survival rate for HCV-infected renal transplant recipients is better than that for HCV-infected hemodialysis patients on transplant waiting lists. Early diagnosis and treatment HCV infection prior to KT prevents complications post-transplantation and reduces mortality. In addition to screening for anti-HCV antibodies and detecting HCV RNA, percutaneous liver biopsy is particularly valuable for assessing the stage of liver damage in HCV-infected patients, because the stage of fibrosis is important determining optimal treatment for HCV. Studies have been demonstrated that with conventional interferon (IFN) monotherapy or pegylated IFN monotherapy are similar efficacy and safety in HCV-infected hemodialysis patients. Sustained viral responses (SVRs) with these monotherapies have ranged approximately 30% to 40%. Limited reports support the use of IFN and ribavirin combination therapy as antiviral treatment for ESRD patients or patients on hemodialysis. Ribavirin can be started at low dose and careful monitoring for side effects. Patients that show SVR after treatment are strong candidates for KT. It is also generally accepted that ESRD patients with decompensated cirrhosis and portal hypertension should be referred to the liver transplant team for consideration of combined liver-KT.

Impact of all oral anti-hepatitis C virus therapy: A meta-analysis

AIM: To investigate the efficacy, safety, and cost of treatment of direct acting antivirals (DAAs) with and without peg interferon alfa2a (P), and/or ribavirin (R) in treating hepatitis C virus (HCV) genotype 1 patients.

METHODS: MEDLINE was searched for randomized controlled trials (RCT) using DAAs for HCV treatment. Phase 1 trials and studies with investigational drugs on genotype 2 or 3, and on human immunodeficiency virus patients were excluded. Data were pooled for sustained virologic response (SVR), serious adverse effects, and drug discontinuation rate on various treatment arms in trials: P + R; 1^st generation DAA (telaprevir or boceprevir) + P + R; 2^nd generation DAA (sofosbuvir or simeprevir) + P + R; 2^nd generation DAA + R; two 2^nd generation DAA + R; and two 2^nd gen DAA. Data were analyzed separately for each arm for treatment naive and non-responders (NR) to previous treatment. The cost of treatment with each regimen for achieving one SVR was also compared.

RESULTS: Twenty three RCTs (n = 9354, 62% male, 11% cirrhosis) were analyzed. All oral (P free) regimens with combination of 2 DAA achieved SVR above 95%. The cost of treatment to achieve an SVR with DAA based regimens was lower for NR compared to P+R regimen. However, the cost per SVR remained higher for treatment naive patients.

CONCLUSION: Second generation and emerging DAAs are promising agents in HCV treatment, with a very high level of safety and efficacy. An important drawback is their high cost. However, the present meta-analysis shows that the cost per SVR for non responders (but not for naive patients) was lower compared to P + R. This finding together with the superior safety profile and better compliance makes these drugs highly attractive. It is possible that further reduction in treatment duration may make them even more cost effective.

Cost-effectiveness of sofosbuvir in the treatment of patients with hepatitis C

In France, 190,306 patients were suffering from chronic hepatitis C in 2012. These patients have a decreased life expectancy and are susceptible to complications associated with chronic hepatitis. Current treatments are poorly tolerated and their effectiveness varies depending on the genotype of the virus. Sofosbuvir, a new class of treatment, has demonstrated in five phase III trials sustained viral response (SVR) rates of over 90% across genotypes, higher than current treatments and has a tolerance profile similar to placebo. The objective was to determine the cost-effectiveness of using sofosbuvir in the treatment of chronic HCV infection. A Markov model was used to compare treatment strategies with and without sofosbuvir. The model simulated the natural history of HCV infection. SVR rates were based on data from clinical trials. Utilities associated with different stages of disease were based on data from the literature. French direct medical costs were used. Price for sofosbuvir was the price used in the early access program for severe fibrosis stages. The incremental cost-effectiveness ratio for sofosbuvir versus current reference treatments was € 16,278/QALY and varied from 40,000 €/QALY for F0 stages to 12,080 €/QALY for F4 stages. The sensitivity analyses carried out confirmed the robustness of this result. Sofosbuvir is a cost-effective treatment option for patients with hepatitis C.

Generation of improved mouse models for the study of hepatitis C virus

Approximately 3% of the world׳s population suffers from chronic infections with hepatitis C virus (HCV). Although current treatment regimes are capable of effectively eradicating HCV infection from these patients, the cost of these combinations of direct-acting antivirals are prohibitive. Approximately 80% of untreated chronic HCV carriers will be at high risk for developing severe liver disease, including fibrosis, cirrhosis, and hepatocellular carcinoma. A vaccine is urgently needed to lessen this global burden. Besides humans, HCV infection can be experimentally transmitted to chimpanzees, and this is the best model for studies of HCV infection and related innate and adaptive immune responses. Although the chimpanzee model yielded valuable insight, limited availability, high cost and ethical considerations limit their utility. The only small animal models of robust HCV infection are highly immunodeficient mice with human chimeric livers. However, these mice cannot be used to study adaptive immune responses and therefore a more relevant animal model is needed to assist in vaccine development. Novel strains of immunodeficient mice have been developed that allow for the engraftment of human hepatopoietic stem cells, as well as functional human lymphoid cells and tissues, effectively creating human immune systems in otherwise immunodeficient mice. These humanized mice are rapidly emerging as pre-clinical bridges for numerous pathogens that, like HCV, only cause infectious disease in humans. This review highlights the potential these new models have for changing the current landscape for HCV research and vaccine development.

Deconvoluting the composition of low-frequency hepatitis C viral quasispecies: comparison of genotypes and NS3 resistance-associated variants between HCV/HIV coinfected hemophiliacs and HCV monoinfected patients in Japan

Pre-existing low-frequency resistance-associated variants (RAVs) may jeopardize successful sustained virological responses (SVR) to HCV treatment with direct-acting antivirals (DAAs). However, the potential impact of low-frequency (∼0.1%) mutations, concatenated mutations (haplotypes), and their association with genotypes (Gts) on the treatment outcome has not yet been elucidated, most probably owing to the difficulty in detecting pre-existing minor haplotypes with sufficient length and accuracy. Herein, we characterize a methodological framework based on Illumina MiSeq next-generation sequencing (NGS) coupled with bioinformatics of quasispecies reconstruction (QSR) to realize highly accurate variant calling and genotype-haplotype detection. The core-to-NS3 protease coding sequences in 10 HCV monoinfected patients, 5 of whom had a history of blood transfusion, and 11 HCV/HIV coinfected patients with hemophilia, were studied. Simulation experiments showed that, for minor variants constituting more than 1%, our framework achieved a positive predictive value (PPV) of 100% and sensitivities of 91.7–100% for genotyping and 80.6% for RAV screening. Genotyping analysis indicated the prevalence of dominant Gt1a infection in coinfected patients (6/11 vs 0/10, p = 0.01). For clinical samples, minor genotype overlapping infection was prevalent in HCV/HIV coinfected hemophiliacs (10/11) and patients who experienced whole-blood transfusion (4/5) but none in patients without exposure to blood (0/5). As for RAV screening, the Q80K/R and S122K/R variants were particularly prevalent among minor RAVs observed, detected in 12/21 and 6/21 cases, respectively. Q80K was detected only in coinfected patients, whereas Q80R was predominantly detected in monoinfected patients (1/11 vs 7/10, p < 0.01). Multivariate interdependence analysis revealed the previously unrecognized prevalence of Gt1b-Q80K, in HCV/HIV coinfected hemophiliacs [Odds ratio = 13.4 (3.48–51.9), p < 0.01]. Our study revealed the distinct characteristics of viral quasispecies between the subgroups specified above and the feasibility of NGS and QSR-based genetic deconvolution of pre-existing minor Gts, RAVs, and their interrelationships.

6-(Azaindol-2-yl)pyridine-3-sulfonamides as potent and selective inhibitors targeting hepatitis C virus NS4B

A structure-activity relationship investigation of various 6-(azaindol-2-yl)pyridine-3-sulfonamides using the HCV replicon cell culture assay led to the identification of a potent series of 7-azaindoles that target the hepatitis C virus NS4B. Compound 2ac, identified via further optimization of the series, has excellent potency against the HCV 1b replicon with an EC50 of 2nM and a selectivity index of >5000 with respect to cellular GAPDH RNA. Compound 2ac also has excellent oral plasma exposure levels in rats, dogs and monkeys and has a favorable liver to plasma distribution profile in rats.

Association between interferon use and reduced metabolic and vascular complications among patients with hepatitis C

We examined whether interferon treatment is associated with reduced metabolic/vascular complications in hepatitis C virus patients. The study had historical prospective cohort design using Maryland Medicaid administrative data (2006-2009). The end point was the incidence rate of mild, severe and combined mild/severe events from the Diabetes Complications Severity Index (DCSI). Interferon-treated and -untreated hepatitis C virus patients were matched on baseline covariates. Using multivariate counting process Cox regressions, we modeled the association between interferon receipt of at least 24 weeks and DCSI events incidence rate. Treated whites had similar rate of mild DCSI events, significantly 64% (p < 0.01) lower rate of severe DCSI events, and overall 29% (p = 0.14) lower rate of mild/severe DCSI events, compared with untreated whites. Compared with untreated blacks, treated blacks had a similar rate of DSCI events. Future studies should confirm our findings and should include important clinical variables such as viral genotype, virologic count and achieving sustained virologic response.

"Fighting an uphill battle": experience with the HCV triple therapy: a qualitative thematic analysis

Background

Hepatitis C virus (HCV) infections are a severe burden on public health worldwide, causing mortality rates triple that of the general population. Since 2011, for both therapy-naive and therapy-experienced genotype 1 patients, the first generation of direct acting antivirals (DAAs), i.e., the protease-inhibitors (PI) telaprevir and boceprevir have been added to existing dual therapies. The therapeutic effect of the resulting triple therapy is striking; however, treatment regimens are complex and commonly cause side effects. Little is known of how patients implement therapy in their daily lives, or of how they deal with these effects.

This study aims to describe HCV patients' experiences with protease-inhibitor-based triple therapy and their support needs.

Methods

A qualitative design was used. Patients from three outpatient clinics, with ongoing, completed or discontinued PI treatment experience were recruited using a maximum variation sampling approach. Open-ended interviews were conducted and analyzed using thematic analysis according to Braun & Clarke (Qual Res Psychol 3:77-101, 2006).

Results

Thirteen patients participated in the interviews. All described themselves as highly motivated to undergo treatment, since they saw the new therapy as a “real chance” for a cure. However, all later described the therapy period as a struggle. The constitutive theme–“Fighting an uphill battle”– describes the common existential experience of and negative consequences of coping with side effects. The processes that fostered this common experience followed three sub-themes: “encountering surprises”, “dealing with disruption” and “reaching the limits of systems”.

Conclusion

HCV patients undergoing outpatient protease-inhibitor-based triple therapy need systematic support in symptom management. This will require specially trained professionals to advise and support them and their families, and to provide rapid responses to their needs throughout this complex course of therapy. As the generation of DAAs for all genotypes, are expected to have less severe side effects, and many HCV patients require treatment, this knowledge can improve treatment support tremendously, especially for patients who are quite difficult to treat. Furthermore, these findings are helpful to illustrate development in HCV treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-507) contains supplementary material, which is available to authorized users.

Hepatitis C virus in the new era: Perspectives in epidemiology, prevention, diagnostics and predictors of response to therapy

Despite the great successes achieved in the fields of virology and diagnostics, several difficulties affect improvements in hepatitis C virus (HCV) infection control and eradication in the new era. New HCV infections still occur, especially in some of the poorest regions of the world, where HCV is endemic and long-term sequelae have a growing economic and health burden. An HCV vaccine is still no available, despite years of researches and discoveries about the natural history of infection and host-virus interactions: several HCV vaccine candidates have been developed in the last years, targeting different HCV antigens or using alternative delivery systems, but viral variability and adaption ability constitute major challenges for vaccine development. Many new antiviral drugs for HCV therapy are in preclinical or early clinical development, but different limitations affect treatment validity. Treatment predictors are important tools, as they provide some guidance for the management of therapy in patients with chronic HCV infection: in particular, the role of host genomics in HCV infection outcomes in the new era of direct-acting antivirals may evolve for new therapeutic targets, representing a chance for modulated and personalized treatment management, when also very potent therapies will be available. In the present review we discuss the most recent data about HCV epidemiology, the new perspectives for the prevention of HCV infection and the most recent evidence regarding HCV diagnosis, therapy and predictors of response to it.

Benzhydrylpiperazine compounds inhibit cholesterol-dependent cellular entry of hepatitis C virus

Hepatitis C virus (HCV) remains a serious global health problem that lacks an effective cure. Although the introduction of protease inhibitors to the current standard-of-care interferon/ribavirin therapy for HCV infection has improved sustained virological response of genotype 1-infected patients, these inhibitors exacerbate already problematic side effects. Thus, new HCV antivirals are urgently needed. Using a cell-protection screen previously developed in our laboratory, we evaluated 30,426 compounds for inhibitors of potentially any stage of the HCV life cycle and identified 49 new HCV inhibitors. The two most potent hits, hydroxyzine and chlorcyclizine, belong to the family of benzhydrylpiperazines and were found to inhibit the entry of cell culture-produced HCV with IC50 values of 19 and 2.3 nM, respectively, and therapeutic indices of >500 and >6500. Both compounds block HCV entry at a late stage of entry prior to viral fusion and their inhibitory activities are highly dependent on the host's cholesterol content. Both compounds are currently used in the clinic for treating allergy-related disorders and the reported peak plasma level (160 nM) and estimated liver concentration (1.7 μM) of hydroxyzine in humans are much higher than the molecule's anti-HCV IC90 in cell culture (64 nM). Further studies are therefore justified to evaluate the use of these molecules in an anti-HCV therapeutic regimen.

Targeting gap junction intercellular communication as a potential therapy for HCV-related carcinogenesis

ABSTRACT: 

Worldwide, at least 170 million people are infected with hepatitis C virus (HCV), which is associated with hepatocellular carcinoma (HCC). With the recent success of Sofosbuvir (and other agents) antiviral therapy may be used as a future early-stage HCC treatment; however, in the short term, a cost-effective solution is needed to treat patients with viral-associated HCC. Here, we emphasize the potential of targeting gap junction intercellular communication (GJIC) as a therapeutic approach for HCC as HCV perturbs GJIC, which is linked to cellular transformation. We review the ROCK inhibitor Y-27632 and structurally related compounds that may inhibit the carcinogenic properties of HCV.

A nuclear transport inhibitor that modulates the unfolded protein response and provides in vivo protection against lethal dengue virus infection

BACKGROUND

Dengue virus (DENV) is estimated to cause 390 million infections each year, but there is no licensed vaccine or therapeutic currently available.

METHODS

We describe a novel, high-throughput screen to identify compounds inhibiting the interaction between DENV nonstructural protein 5 and host nuclear transport proteins. We document the antiviral properties of a lead compound against all 4 serotypes of DENV, antibody-dependent enhanced (ADE) infection, and ex vivo and in vivo DENV infections. In addition, we use quantitative reverse-transcription polymerase chain reaction to examine cellular effects upon compound addition.

RESULTS

We identify N-(4-hydroxyphenyl) retinamide (4-HPR) as effective in protecting against DENV-1-4 and DENV-1 ADE infections, with 50% effective concentrations in the low micromolar range. 4-HPR but not the closely related N-(4-methoxyphenyl) retinamide (4-MPR) could reduce viral RNA levels and titers when applied to an established infection. 4-HPR but not 4-MPR was found to specifically upregulate the protein kinase R-like endoplasmic reticulum kinase arm of the unfolded protein response. Strikingly, 4-HPR but not 4-MPR restricted infection in peripheral blood mononuclear cells and in a lethal ADE-infection mouse model.

CONCLUSIONS

4-HPR is a novel antiviral that modulates the unfolded protein response, effective against DENV1-4 at concentrations achievable in the plasma in a clinical setting, and provides protection in a lethal mouse model.

Peg-interferon plus ribavirin with or without boceprevir or telaprevir for HCV genotype 1: a meta-analysis on the role of response predictors

Background & aim

To compare the efficacy of pegylated-interferon (Peg-IFN) α-2a or α-2b and ribavirin given as dual therapy versus triple therapy (Peg-IFN and ribavirin plus boceprevir or telaprevir) in patients with HCV-1 chronic hepatitis naïve for anti-HCV therapy or relapsers to dual therapy in relation to the presence of constitutional, clinical and virological predictors of treatment response.

Methods

Included in the meta-analysis were studies meeting these criteria: original data from randomized trials on the efficacy of dual versus triple therapy in therapy-naïve patients or relapsers; at least one primary outcome clearly defined: sustained virological response in patients with or without rapid virological response (RVR), with genotype 1a or 1b, low or high HCV load, IL28-B CC or non-CC genotype, mild or severe fibrosis; odds ratio estimates of relative risk (RR) and 95% confidence intervals; English language; and published up to the end of June 2013.

Results

Seven original studies met the inclusion criteria, allowing a meta-analysis on 3,652 patients. Triple therapy was more effective than dual, regardless of IL-28B genotype, HCV sub-genotype, liver fibrosis, and baseline HCV load. In 1,045 patients who achieved RVR, SVR was more frequently achieved with dual therapy (RR = 1.11; p = 0.002) than triple. The same results were achieved when only the therapy-naïve patients were considered.

Conclusions

Triple therapy provides a significantly higher SVR rate than dual therapy, but dual therapy obtains a significantly higher SVR rate in patients with RVR. The data stress the clinical importance of a 4-week lead-in phase in direct-acting antiviral-based treatment.

Hepatitis C virus (HCV) interaction with astrocytes: nonproductive infection and induction of IL-18

Hepatitis C virus (HCV) infection causes the central nervous system (CNS) abnormalities in more than 50 % of chronically infected subjects. However, the underlying mechanisms are largely unknown. In this study, we characterized the HCV interactions with astrocytes, one of the putative HCV target cells in the brain. We demonstrated that primary human astrocytes (PHA) were very inefficiently infected by HCV, either in the cell-free form or through cell-cell contact. We then determined the potential restriction steps of HCV infection and replication in these cells. PHA expressed all known HCV receptors but failed to support HCV entry. HCV IRES-mediated RNA translation was functional in PHA and further enhanced by miR122 expression. Nevertheless, PHA did not support HCV replication regardless of miR122 expression. To our great surprise, we found that HCV exposure induced robust IL-18 expression in PHA and exhibited direct neurotoxicity. Taken together, these results showed that astrocytes did not support productive HCV infection and replication, but HCV interactions with astrocytes and neurons alone might be sufficient to cause CNS dysfunction.

A structural biology approach enables the development of antimicrobials targeting bacterial immunophilins

Macrophage infectivity potentiators (Mips) are immunophilin proteins and essential virulence factors for a range of pathogenic organisms. We applied a structural biology approach to characterize a Mip from Burkholderia pseudomallei (BpML1), the causative agent of melioidosis. Crystal structure and nuclear magnetic resonance analyses of BpML1 in complex with known macrocyclics and other derivatives led to the identification of a key chemical scaffold. This scaffold possesses inhibitory potency for BpML1 without the immunosuppressive components of related macrocyclic agents. Biophysical characterization of a compound series with this scaffold allowed binding site specificity in solution and potency determinations for rank ordering the set. The best compounds in this series possessed a low-micromolar affinity for BpML1, bound at the site of enzymatic activity, and inhibited a panel of homologous Mip proteins from other pathogenic bacteria, without demonstrating toxicity in human macrophages. Importantly, the in vitro activity of BpML1 was reduced by these compounds, leading to decreased macrophage infectivity and intracellular growth of Burkholderia pseudomallei. These compounds offer the potential for activity against a new class of antimicrobial targets and present the utility of a structure-based approach for novel antimicrobial drug discovery.

Synthesis and evaluation of hexahydropyrimidines and diamines as novel hepatitis C virus inhibitors

In order to identify novel anti-hepatitis C virus (HCV) agents we devised cell-based strategies and screened phenotypically small molecule chemical libraries with infectious HCV particles, and identified a hit compound (1) containing a hexahydropyrimidine (HHP) core. During our cell-based SAR study, we observed a conversion of HHP 1 into a linear diamine (6), which is the active component in inhibiting HCV and exhibited comparable antiviral activity to the cyclic HHP 1. In addition, we engaged into the biological characterization of HHP and demonstrated that HHP does not interfere with HCV RNA replication, but with entry and release of viral particles. Here we report the results of the preliminary SAR and mechanism of action studies with HHP.

Protease inhibitors for hepatitis C: economic implications

Chronic hepatitis C virus (HCV) infection, a blood-borne virus, is the leading cause of chronic liver disease and liver transplantation worldwide. Chronic HCV infection is usually asymptomatic in the early stages of the disease, making an estimation of the total population affected difficult to elicit. The gold standard treatment option to date has been a combination of pegylated interferon and ribavirin. Recent developments have led to the introduction of two protease inhibitors for use in chronic HCV-boceprevir and telaprevir. Phase III studies have shown both agents have the potential to significantly increase the probability of attaining a sustained virologic response (the primary outcome of interest in chronic HCV) in genotype 1 infections. However, the added cost of these agents also presents the need for decision makers to determine their place on drug formularies. The protease inhibitors are to be administered as triple therapy with the existing gold standard. However, significant variation exists as to the proposed duration of triple therapy, use of lead-in pegylated interferon and ribavirin and subsequent pegylated interferon therapy after finishing the course of triple therapy. Treatment algorithms also exist for the use of stopping rules in the case of early non-responders.The aim of this review is to highlight the current understanding of the economic impact protease inhibitors may have on health care systems and considerations required in the treatment of HCV. Economic and health-related quality of life issues are addressed from multiple viewpoints. The major aspects of the economic evaluations, to date, that included triple therapy as an alternative in the treatment of chronic HCV are brought to light. Future economic evaluations in alternative settings would be useful. The review also emphasizes the challenges for future research. This includes the potential for new therapies to no longer require inclusion of pegylated interferon and/or ribavirin, as well as the use of protease inhibitors in non-genotype 1 patients or those with significant co-morbidities such as HIV/AIDS.

A translational study of resistance emergence using sequential direct-acting antiviral agents for hepatitis C using ultra-deep sequencing

OBJECTIVES

Direct-acting antiviral agents (DAAs) against hepatitis C virus (HCV) have recently been developed and are ultimately hoped to replace interferon-based therapy. However, DAA monotherapy results in rapid emergence of resistant strains and DAAs must be used in combinations that present a high genetic barrier to resistance, although viral kinetics of multidrug-resistant strains remain poorly characterized. The aim of this study is to track the emergence and fitness of resistance using combinations of telaprevir and NS5A or NS5B inhibitors with genotype 1b clones.

METHODS

HCV-infected chimeric mice were treated with DAAs, and resistance was monitored using direct and ultra-deep sequencing.

RESULTS

Combination therapy with telaprevir and BMS-788329 (NS5A inhibitor) reduced serum HCV RNA to undetectable levels. The presence of an NS3-V36A telaprevir resistance mutation resulted in poor response to telaprevir monotherapy but showed significant HCV reduction when telaprevir was combined with BMS-788329. However, a BMS-788329-resistant strain emerged at low frequency. Infection with a BMS-788329-resistant NS5A-L31V mutation rapidly resulted in gain of an additional NS5A-Y93A mutation that conferred telaprevir resistance during combination therapy. Infection with dual NS5AL31V/NS5AY93H mutations resulted in poor response to combination therapy and development of telaprevir resistance. Although HCV RNA became undetectable soon after the beginning of combination therapy with BMS-788329 and BMS-821095 (NS5B inhibitor), rebound with emergence of resistance against all three drugs occurred. Triple resistance also occurred following infection with the NS3V36A/NS5AL31V/NS5AY93H triple mutation.

CONCLUSIONS

Resistant strains easily develop from cloned virus strains. Sequential use of DAAs should be avoided to prevent emergence of multidrug-resistant strains.

In vitro characterization of GSK2485852, a novel hepatitis C virus polymerase inhibitor

GSK2485852 (referred to here as GSK5852) is a hepatitis C virus (HCV) NS5B polymerase inhibitor with 50% effective concentrations (EC50s) in the low nanomolar range in the genotype 1 and 2 subgenomic replicon system as well as the infectious HCV cell culture system. We have characterized the antiviral activity of GSK5852 using chimeric replicon systems with NS5B genes from additional genotypes as well as NS5B sequences from clinical isolates of patients infected with HCV of genotypes 1a and 1b. The inhibitory activity of GSK5852 remained unchanged in these intergenotypic and intragenotypic replicon systems. GSK5852 furthermore displays an excellent resistance profile and shows a <5-fold potency loss across the clinically important NS5B resistance mutations P495L, M423T, C316Y, and Y448H. Testing of a diverse mutant panel also revealed a lack of cross-resistance against known resistance mutations in other viral proteins. Data from both the newer 454 sequencing method and traditional population sequencing showed a pattern of mutations arising in the NS5B RNA-dependent RNA polymerase in replicon cells exposed to GSK5852. GSK5852 was more potent than HCV-796, an earlier inhibitor in this class, and showed greater reductions in HCV RNA during long-term treatment of replicons. GSK5852 is similar to HCV-796 in its activity against multiple genotypes, but its superior resistance profile suggests that it could be an attractive component of an all-oral regimen for treating HCV.

Treatment of children with chronic viral hepatitis: what is available and what is in store

BACKGROUND

At present, therapy of children with chronic hepatitis B and C is still based on few drugs, all burdened by a series of side-effects, unsatisfactory serum conversion rates, and/or drug-resistance. Moreover, selection of subjects to treat with conventional therapies is not univocal, especially during the pediatric age when the disease course is often mild with significant spontaneous seroconversion rate. Our review deals with pros and cons points when a physician decides to design a drug therapy for a child with chronic viral hepatitis, and different possible therapeutic opportunities.

METHODS

A literature search was performed through PubMed. The newest articles, reviews, systematic reviews, and guidelines were included in this review.

RESULTS

The management of children with viral hepatitis is still controversial over whom and when to treat and the use of drug(s). Novel therapeutic strategies have been evaluated only in clinical and preclinical trials involving, for instance, "therapeutic" vaccines. The data on safety and effectiveness of new drugs are also reviewed.

CONCLUSION

The results of reported studies confirmed that at least some of the new drugs, with greater efficacy and/or minor side-effects, will be used clinically.

HCV NS3/4a Protease Inhibitors: Simeprevir (TMC‐435350), Vaniprevir (MK‐7009) and MK‐5172

Hepatitis C virus (HCV) infection continues to represent a major health issue, with estimates of 130–170 million people infected worldwide. Recent developments in the HCV NS3/4a protease inhibitor area have significantly improved treatment options for patients. However, a more dramatic paradigm shift in the treatment of HCV infection appears all but certain in coming years, with a move to all oral combination therapy with direct‐acting antivirals (DAAs). HCV protease inhibitors have the potential to play a significant role in these DAA combination therapies. This chapter discusses in detail the design and discovery of three HCV NS3/4a protease inhibitors in clinical development: simeprevir (TMC‐435350), vaniprevir (MK‐7009) and MK‐5172.

Current and emerging antiviral treatments for hepatitis C infection

Newly licensed direct acting antivirals for hepatitis C virus HCV are able to cure up to 75% of patients chronically infected with genotype-1 infection, which is the predominant HCV strain in Europe and North America. Emerging antiviral therapies promise further increases in virological response, as well as improved tolerability, reduced duration of therapy, and will potentially eliminate the need for interferon use. This review highlights the main therapeutic agents used in current standard of care, including telaprevir and boceprevir. It goes on to evaluate the mechanisms of emerging drugs, their stage of development and response rates seen in research to date. Finally, it projects into the not too distant future to consider treatment strategies involving combinations of agents and interferon-free therapies, and in which patients they might prove most successful.

A new helicase assay based on graphene oxide for anti-viral drug development

Recently, graphene oxide (GO), one of the carbon nanomaterials, has received much attention due to its unique physical and chemical properties and high potential in many research areas, including applications as a biosensor and drug delivery vehicle. Various GO-based biosensors have been developed, largely based on its surface adsorption properties for detecting biomolecules, such as nucleotides and peptides, and real-time monitoring of enzymatic reactions. In this review, we discuss recent advances in GO-based biosensors focusing on a novel assay platform for helicase activity, which was also employed in high-throughput screening to discover selective helicase inhibitors.

Hepatitis C virus vaccines--progress and perspectives

Approximately 170 million individuals, representing 3% of the global population, are infected with hepatitis C virus (HCV). Whereas strategies for antiviral therapies have markedly improved resulting in clinical licensing of direct-acting antivirals, the development of vaccines has been hampered by the high genetic variability of the virus as well as by the lack of suitable animal models for proof-of-concept studies. Nevertheless, there are several promising vaccine candidates in preclinical and clinical development. After a brief summary of the molecular virology and immunology relevant to vaccine development, this review explains the model systems used for preclinical vaccine development, and highlights examples for most recently developed HCV vaccine candidates.

Chronic hepatitis B: what should be the goal for new therapies?

Chronic hepatitis B can currently be medically managed with either pegylated interferon-alpha (pegIFN-α) or one of the five nucleos(t)ide analog Direct Acting Antivirals (DAAs) that inhibit the hepatitis B virus (HBV) DNA polymerase. While pegIFN-α is effective in approximately one-third of the treated patients, the polymerase inhibitors significantly reduce viral load in the vast majority of those treated. However, neither pegIFN-α nor nucleosi(t)de analogs are capable of reliably eliminating the virus and achieving a cure. Moreover, the interferons and polymerase inhibitors are recommended by US, European and Asian professional society practice guidelines for use in only a subset of those infected with HBV. This subset is the population with the greatest levels of circulating viral DNA and abnormal liver function. Although this is the population at the highest risk for cirrhosis and liver cancer, those who fall outside the treatment guidelines, with low levels of viral replication and normal serum ALTs, may also benefit from antiviral therapy. The questions are thus: are new classes of drugs needed to manage chronic hepatitis B? Is a cure possible? Is a cure even necessary? It is therefore important to define the meaning of a cure and determine what the goals of new therapies should be. In this article, we address those questions and propose two operational definitions of medically attainable cures. The first is a "functional cure" based on the clinical outcome, in which the patient's life expectancy becomes the same as that of an individual who has resolved his HBV infection without therapy. Because such an outcome cannot be measured over the short term, we also define an "apparent virological cure," based on the stable off-drug suppression of HBV viremia and antigenemia and the normalization of ALTs and other laboratory tests. We suggest that such a virological cure should be the goal of future therapeutics in all patients with chronic hepatitis B. The extent to which a virological cure predicts a functional cure will only be determined by long-term follow-up.

NTP-mediated nucleotide excision activity of hepatitis C virus RNA-dependent RNA polymerase

Hepatitis C virus (HCV) RNA-dependent RNA polymerase replicates the viral genomic RNA and is a primary drug target for antiviral therapy. Previously, we described the purification of an active and stable polymerase-primer-template elongation complex. Here, we show that, unexpectedly, the polymerase elongation complex can use NTPs to excise the terminal nucleotide in nascent RNA. Mismatched ATP, UTP, or CTP could mediate excision of 3'-terminal CMP to generate the dinucleoside tetraphosphate products Ap(4)C, Up(4)C, and Cp(4)C, respectively. Pre-steady-state kinetic studies showed that the efficiency of NTP-mediated excision was highest with ATP. A chain-terminating inhibitor, 3'deoxy-CMP, could also be excised through this mechanism, suggesting important implications for nucleoside drug potency and resistance. The nucleotide excision reaction catalyzed by recombinant hepatitis C virus polymerase was 100-fold more efficient than the corresponding reaction observed with HIV reverse transcriptase.

Discovery and characterization of a novel 7-aminopyrazolo[1,5-a]pyrimidine analog as a potent hepatitis C virus inhibitor

We describe a novel 7-aminopyrazolo[1,5-a]pyrimidine (7-APP) derivative as a potent hepatitis C virus (HCV) inhibitor. A series of 7-APPs was synthesized and evaluated for inhibitory activity against HCV in different cell culture systems. The synthesis and preliminary structure-activity relationship study of 7-APP are reported.

Progressive loss of memory T cell potential and commitment to exhaustion during chronic viral infection

T cell exhaustion and loss of memory potential occur during many chronic viral infections and cancer. We investigated when during chronic viral infection virus-specific CD8 T cells lose the potential to form memory. Virus-specific CD8 T cells from established chronic infection were unable to become memory CD8 T cells if removed from infection. However, at earlier stages of chronic infection, these virus-specific CD8 T cells retained the potential to partially or fully revert to a memory differentiation program after transfer to infection-free mice. Conversely, effector CD8 T cells primed during acute infection were not protected from exhaustion if transferred to a chronic infection. We also tested whether memory and exhausted CD8 T cells arose from different subpopulations of effector CD8 T cells and found that only the KLRG1(lo) memory precursor subset gave rise to exhausted CD8 T cells. Together, these studies demonstrate that CD8 T cell exhaustion is a progressive developmental process. Early during chronic infection, the fate of virus-specific CD8 T cells remains plastic, while later, exhausted CD8 T cells become fixed in their differentiation state. Moreover, exhausted CD8 T cells arise from the memory precursor and not the terminally differentiated subset of effector CD8 T cells. These studies have implications for our understanding of senescence versus exhaustion and for therapeutic interventions during chronic infection.