A new standard of care for the treatment of chronic HCV infection

Natural killer KIR3DS1 is closely associated with HCV viral clearance and sustained virological response in HIV/HCV patients

Aim

To evaluate the influence of the presence of the killer cell immunoglobulin-like receptor (KIR) 3DS1 on HCV treatment response in HIV/HCV genotype 1 co-infected patients

Methods

HIV/HCV co-infected patients were included. KIR3DS1, their specific HLA-B ligands and IL28B gene were genotyped. Reductions of plasma HCV RNA levels between baseline and week 1, week 2 and week 4 were analyzed for IL28B genotype and KIR3DS1 (HLA Bw4 or Bw6). Rapid and sustained virological response (RVR and SVR) rates were also analyzed.

Results

Sixty HIV/HCV genotype 1 co-infected patients were included. Patients with KIR3DS1 and Bw4 had higher rates of HCV viral decline than those who were not carriers of KIR3DS1 (week1: p = 0.01; week2: p = 0.038; week 4: p = 0.03). Patients carrying KIR3DS1/Bw4 had higher rates of RVR and SVR than those who did not carry KIR3DS1 (RVR: 46.15% versus 17.02%, p = 0.012; SVR: 63.6% versus 13 26.5%, p = 0.031). With respect to patients carrying the IL28B-CC genotype, those with KIR3DS1/Bw4 had greater rates of HCV viral clearance (week1: p<0.001; week2: p = 0.01; week 4: p = 0.02), RVR (p = 0.015) and SVR (p = 0.029) than those not carrying KIR3DS1.

Conclusion

Our results show that the KIR3DS1 genotype has a positive effect on HCV viral clearance during the first weeks of Peg-IFN/RBV treatment in HCV/HCV co-infected patients bearing genotype 1, and higher RVR and SVR rates.

HCV infection: an enigma, recent advances and new paradigms for its treatment

HCV infection is a serious human liver health problem and has infected 200 million people worldwide. Persistent HCV infection can lead to chronic hepatitis C, which is a significant risk of serious hepatic diseases such as hepatic steatosis, hepatic fibrosis and hepatocellular carcinoma. The current standard-of-care options to treat HCV infection are limited, expensive and produce side effects in infected patients that often cause termination of the therapy. Recently, the approval of direct-acting antivirals represents a major breakthrough for the improvement of treatment strategies against chronic HCV infection. Similarly, the development of more effective, safe and well-tolerated interferon therapy is opening a new era in HCV therapeutics. Moreover, a new vaccine technology has been tested in mice for its therapeutic efficacy against the most conserved regions of the HCV genome. This review article will focus on the recent advances in HCV therapeutics and discuss new paradigms to develop the most convenient drugs and treatment strategies.

Molecular docking study of P4-Benzoxaborolesubstituted ligands as inhibitors of HCV NS3/4A protease

NS3/4A protease is an important emerging target for the cure of hepatitis C. There are many inhibitors of HCV NS3/4A protease that are passing through the clinical improvement indicating momentous reduction in the viral infection rate of patients. In this study molecular docking via MOE-Dock program was used to evaluate binding interactions of ligands with HCV NS3/4A protease. The docking and experimental results were found in good correlation. The best conformations of ligands were analyzed for binding interactions with the residues of binding cavity of NS3/4A protease. The valuable binding interactions and docking scores were observed for compounds 01, 05, 06, 07, 08 and 09.

Virologic response and characterisation of HCV genotype 2-6 in patients receiving TMC435 monotherapy (study TMC435-C202)

BACKGROUND & AIMS

TMC435 is a potent, once-daily, investigational hepatitis C virus (HCV) NS3/4A protease inhibitor in phase III clinical development. In the phase II trial TMC435-C202 (NCT00812331), TMC435 displayed potent activity in genotype 4, 5 and 6 patients and in 3/6 genotype 2 patients, whereas no activity was observed with genotype 3.

METHODS

Thirty-seven patients received TMC435 monotherapy (200 mg once daily) for 7 days. HCV RNA, NS3 protease sequences and the corresponding phenotypes were evaluated.

RESULTS

Genotype and isolate-specific baseline polymorphisms at NS3 positions known to affect HCV protease inhibitor activity were present in all genotypes. Consistent with the antiviral activity observed in genotypes 4 and 6, TMC435 was active in vitro against all genotype 4 isolates, and against most genotype 6 polymorphisms when tested as single or double mutants. In contrast, in genotype 3 where no HCV RNA decline was observed, isolates displayed >700-fold increases in EC(50) attributed to the D168Q polymorphism. In genotypes 2 and 5, HCV RNA changes from baseline to Day 3 ranged between -0.3 to -3.6 and -1.5 to -4.0 log(10)IU/ml, respectively, and isolates or site-directed mutants displayed intermediate in vitro susceptibility to TMC435 with fold changes in EC(50) between 15 and 78. Viral breakthrough in genotypes 4-6 was associated with emerging mutations including Q80R, R155K and/or D168E/V.

CONCLUSIONS

Sequence and phenotypic analyses of baseline isolates identified polymorphisms which could explain the differences in antiviral activity between genotypes. Pathways of TMC435 resistance in genotypes 2-6 were similar to those identified in genotype 1.

Safety and effectiveness of a nurse-led outreach program for assessment and treatment of chronic hepatitis C in the custodial setting

BACKGROUND

The global burden of disease attributable to chronic hepatitis C virus (HCV) is very large, yet the uptake of curative antiviral therapies remains very low, reflecting the marginalized patient population and the arduous nature of current treatments.

METHODS

The safety and effectiveness of a nurse-led model of care of inmates with chronic HCV was evaluated in 3 Australian correctional centers. The model featured protocol-driven assessment, triage, and management of antiviral therapy by specifically trained nurses, with specialist physician support utilizing telemedicine. Outcomes were evaluated qualitatively with key informant interviews, and quantitatively with patient numbers completing key clinical milestones and adverse events.

RESULTS

A total of 391 patients with chronic HCV infection were enrolled, of whom 141 (36%) completed the clinical and laboratory evaluations for eligibility for antiviral therapy over 24 months. Treatment was initiated in 108 patients (28%), including 85 (79%) triaged for specialist review conducted by telemedicine only. The demographic and clinical characteristics of the patients who entered the model and completed workup and those who initiated treatment featured a high prevalence of individuals of indigenous background, injection drug users, and those with psychiatric disorder. Serious adverse events occurred in 13 of 108 treated patients (12%) with discontinuation in 8 (7%). The sustained virologic response rate among those with complete follow-up data (n=68) was 69%, and by intention-to treat analysis was 44%.

CONCLUSIONS

This nurse-led and specialist-supported assessment and treatment model for inmates with chronic HCV offers potential to substantively increase treatment uptake and reduce the burden of disease.

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.

Patients receiving opioid maintenance treatment in primary care: successful chronic hepatitis C care in a real world setting

Background

Injection drug users (IDUs) represent a significant proportion of patients with chronic hepatitis C (CHC). The low treatment uptake among these patients results in a low treatment effectiveness and a limited public health impact. We hypothesised that a general practitioner (GP) providing an opioid maintenance treatment (OMT) for addicted patients can achieve CHC treatment and sustained virological response rates (SVR) comparable to patients without drug dependency.

Methods

Retrospective patient record analysis of 85 CHC patients who received OMT for more than 3 months in a single-handed general practice in Zurich from January 1, 2002 through May 31, 2008. CHC treatment was based on a combination with pegylated interferon and ribavirin. Treatment uptake and SVR (undetectable HCV RNA 6 months after end of treatment) were assessed. The association between treatment uptake and patient characteristics was investigated by multiple logistic regression.

Results

In 35 out of 85 CHC patients (52 males) with a median (IQR) age of 38.8 (35.0-44.4) years, antiviral therapy was started (41.2%). Median duration (IQR) of OMT in the treatment group was 55.0 (35.0-110.1) months compared to the group without therapy 24.0 (9.8-46.3) months (p<0.001). OMT duration remained a significant determinant for treatment uptake when controlled for potential confounding. SVR was achieved in 25 out of 35 patients (71%).

Conclusion

In addicted patients a high CHC treatment and viral eradication rate in a primary care setting in Switzerland is feasible. Opioid substitution seems a beneficial framework for CHC care in this “difficult to treat” population.

Safety of telaprevir for chronic hepatitis C virus infection: a meta-analysis of randomized controlled trials

BACKGROUND

Previous studies have reported telaprevir is effective for chronic hepatitis C virus infection, but the safety of a telaprevir-based regimen remains uncertain.

OBJECTIVE

A meta-analysis was performed to assess the safety of the addition of telaprevir to a standard regimen of pegylated interferon (peginterferon) plus ribavirin (combination telaprevir with peginterferon plus ribavirin, the TPR group) compared with the standard regimen group (peginterferon plus ribavirin, the PR group).

METHODS AND RESULTS

Seven randomized controlled trials involving a total of 2808 patients were included in the meta-analysis. The addition of telaprevir to the standard regimen was associated with a significantly increased risk of serious adverse events compared with the standard PR group (relative risk [RR] = 1.56; 95% confidence interval [CI] 1.21, 2.03; p = 0.0007; I2 = 0%). Telaprevir was also associated with increased risk of treatment discontinuation (RR = 2.10; 95% CI 1.56, 2.83; p < 0.0001; I2 = 42%). In addition, telaprevir was more likely to cause nausea (RR = 1.39; p < 0.0001), diarrhoea (RR = 1.32; p = 0.004), pruritus (RR = 1.56; p = 0.0006), rash (RR = 1.60; p < 0.0001) and anaemia (RR = 1.55; p = 0.007). There was no difference in the other kinds of adverse events between the two groups. Sensitivity analysis further validated the credibility of the above outcomes.

CONCLUSION

Our meta-analysis raises safety concerns about the potential for an increased risk of serious adverse events associated with the use of telaprevir among patients with chronic hepatitis C virus infection, and cautious use of telaprevir is warranted.

Hepatitis C virus NS4B protein targets STING and abrogates RIG-I-mediated type I interferon-dependent innate immunity

Hepatitis C virus (HCV) infection blocks cellular interferon (IFN)-mediated antiviral signaling through cleavage of Cardif by HCV-NS3/4A serine protease. Like NS3/4A, NS4B protein strongly blocks IFN-β production signaling mediated by retinoic acid-inducible gene I (RIG-I); however, the underlying molecular mechanisms are not well understood. Recently, the stimulator of interferon genes (STING) was identified as an activator of RIG-I signaling. STING possesses a structural homology domain with flaviviral NS4B, which suggests a direct protein-protein interaction. In the present study, we investigated the molecular mechanisms by which NS4B targets RIG-I-induced and STING-mediated IFN-β production signaling. IFN-β promoter reporter assay showed that IFN-β promoter activation induced by RIG-I or Cardif was significantly suppressed by both NS4B and NS3/4A, whereas STING-induced IFN-β activation was suppressed by NS4B but not by NS3/4A, suggesting that NS4B had a distinct point of interaction. Immunostaining showed that STING colocalized with NS4B in the endoplasmic reticulum. Immunoprecipitation and bimolecular fluorescence complementation (BiFC) assays demonstrated that NS4B specifically bound STING. Intriguingly, NS4B expression blocked the protein interaction between STING and Cardif, which is required for robust IFN-β activation. NS4B truncation assays showed that its N terminus, containing the STING homology domain, was necessary for the suppression of IFN-β promoter activation. NS4B suppressed residual IFN-β activation by an NS3/4A-cleaved Cardif (Cardif1-508), suggesting that NS3/4A and NS4B may cooperate in the blockade of IFN-β production.

CONCLUSION

NS4B suppresses RIG-I-mediated IFN-β production signaling through a direct protein interaction with STING. Disruption of that interaction may restore cellular antiviral responses and may constitute a novel therapeutic strategy for the eradication of HCV.

Vulnerability to somatic symptoms of depression during interferon-alpha therapy for hepatitis C: a 16-week prospective study

OBJECTIVE

This study evaluated the distinctive clinical and biological manifestations of depressive symptom subtypes (i.e., cognitive-affective and somatic) in Veterans with hepatitis C viral infection (HCV) before and during interferon-alpha (IFN) based antiviral therapy.

METHODS

Thirty-two Veterans with HCV and no prior history of IFN therapy were followed prospectively during the first 16weeks of therapy to evaluate depressive symptoms and to determine if baseline cytokine and serotonin levels predicted subsequent changes in depressive scores.

RESULTS

IFN therapy resulted in a significant increase in total depressive symptoms from baseline (week 0) to week 16, with neurovegetative and somatic symptoms of depression including loss of appetite, fatigue and irritability increasing within the first two weeks of therapy and continuing to increase throughout IFN therapy. When depressive symptoms were evaluated using a two-factor (i.e., Cognitive-Affective and Somatic) model, the Cognitive-Affective factor score did not change significantly following IFN therapy initiation, while the Somatic factor score showed a significant increase from week 0 to week 16. Veterans with the largest increases in somatic symptoms from week 0 to week 2 had significantly higher levels of tumor necrosis factor-alpha (TNF-α) and lower levels of serotonin at baseline, as compared to Veterans with minimal or no increase in somatic symptoms.

CONCLUSION

Somatic symptoms of depression can be significantly exacerbated during IFN therapy and may be predicted by higher TNF-α levels and lower serotonin levels at baseline.

The efficacy and safety of telaprevir-based regimens for treating chronic hepatitis C virus genotype 1 infection: a meta-analysis of randomized trials

OBJECTIVE

Previous studies have reported that telaprevir is effective for treating chronic hepatitis C virus (HCV) genotype 1 infection; however, the efficacy and safety of telaprevir-based regimens remain uncertain.

METHODS

To assess the efficacy and safety of telaprevir in patients with chronic HCV genotype 1 infection, we conducted a meta-analysis of all available randomized controlled trials (RCT) comparing the efficacy and safety of the addition of telaprevir to a standard regimen (combination of telaprevir with peginterferon and ribavirin, TPR group) with the standard regimen alone (peginterferon and ribavirin, PR group).

RESULTS

Ultimately, six RCTs involving a total of 2,759 patients with chronic HCV genotype 1 infection were included in this meta-analysis. The outcomes showed that the sustained virologic response (SVR) rate was significantly higher in the TPR group (1,284/1,932, 66.5%) than in the PR group (296/827, 35.8%) with a pooled odds ratio (OR) [3.81, 95% confidence interval (CI) 2.43-5.96, p<0.001]. The results also showed that the relapse rate was significantly lower in the TPR group (190/1,484, 12.8%) than in the PR group (140/425, 32.9%) with a pooled risk ratio (RR) (0.40; 95% CI 0.24-0.66, p<0.001). However, there was an increased risk of serious adverse events in the TPR group (RR=1.45, 95% CI 1.12-1.87, p=0.005).

CONCLUSION

Telaprevir-based regimens can significantly increase the SVR rate and reduce the relapse rate in patients with chronic HCV genotype 1 infection. However, the safety of telaprevir-based regimens still requires further study.

Pharmacokinetics, safety, and tolerability of GS-9851, a nucleotide analog polymerase inhibitor for hepatitis C virus, following single ascending doses in healthy subjects

To investigate the pharmacokinetics, safety, and tolerability of GS-9851 (formerly PSI-7851), a new nucleotide analog inhibitor of hepatitis C virus (HCV), we conducted a double-blind, parallel, placebo-controlled, randomized, single-ascending-dose study. Healthy subjects received oral doses of 25 to 800 mg GS-9851. Peak concentrations of GS-9851 in plasma were achieved more rapidly than those of the metabolites GS-566500 (formerly PSI-352707) and GS-331007 (formerly PSI-6206), with time to maximum concentration of drug in plasma (t(max)) values of 1.0 to 1.8 h, 1.5 to 3.0 h, and 3.0 to 6.0 h, respectively. The majority of systemic drug exposure was from the nucleoside GS-331007, with maximum concentration of drug in plasma (C(max)) and area under the concentration-time curve to the last measurable concentration (AUC(0-t)) values at least 7- and 41-fold higher, respectively, than those obtained for GS-9851 after adjusting for differences in molecular weight. The terminal elimination half-life (t(1/2)) of GS-331007 increased with the dose, achieving a t(1/2) of 25.7 h at 800 mg GS-9851. Dose proportionality was not observed for GS-331007. The majority of drug recovered in urine was in the form of GS-331007, with the percentage of this metabolite in urine samples ranging from 57% to 27% with increasing dose. GS-9851 was generally well tolerated, with no maximum tolerated dose identified. In conclusion, GS-9851 and its metabolites demonstrated a favorable pharmacokinetic profile consistent with once-daily dosing, and therefore, further clinical studies evaluating GS-9851 in HCV-infected patients are warranted.

Antiviral treatment to prevent chronic hepatitis B or C-related hepatocellular carcinoma

Antiviral treatment is the only option to prevent or defer the occurrence of hepatocellular carcinoma (HCC) in patients chronically infected with hepatitis B virus (HBV) or hepatitis C virus (HCV). The approved medication for the treatment of chronic HBV infection is interferon-α (IFNα) and nucleos(t)ide analogues (NAs), including lamivudine, adefovir dipivoxil, telbivudine, entecavir and tenofovir disoproxil fumarate. IFNα is the most suitable for young patients with less advanced liver diseases and those infected with HBV genotype A. IFNα treatment significantly decreases the overall incidence of HBV-related HCC in sustained responders. However, side effects may limit its long-term clinical application. Orally administered NAs are typically implemented for patients with more advanced liver diseases. NA treatment significantly reduces disease progression of cirrhosis and therefore HCC incidence, especially in HBV e antigen-positive patients. NA-resistance due to the mutations in HBV polymerase is a major limiting factor. Of the NA resistance-associated mutants, A181T mutant significantly increases the risk of HCC development during the subsequent course of NA therapy. It is important to initiate treatment with NAs that have a high genetic barrier to resistance, to counsel patients on medication adherence and to monitor virological breakthroughs. The recommended treatment for patients with chronic HCV infection is peg-IFN plus ribavirin that can decrease the occurrence of HCC in those who achieve a sustained virological response and have not yet progressed to cirrhosis. IFN-based treatment is reserved for patients with decompensated cirrhosis who are under evaluation of liver transplantation to reduce post-transplant recurrence of HCV. More effective therapeutic options such as direct acting antiviral agents will hopefully increase the response rate in difficult-to-treat patients with HCV genotype 1. However, the risk of HCC remains in cirrhotic patients (both chronic HBV and HCV infection) if treatment is initiated after cirrhosis is established. Future research should focus on investigating new agents, especially for those patients with hepatic decompensation or post-transplantation.

IL28B polymorphisms as a pretreatment predictor of response to HCV treatment

Genome-wide association studies have identified polymorphisms located near the gene encoding IL28B, which turned out to be the best predictor of response to pegylated interferon plus ribavirin for chronic hepatitis C virus (HCV) genotype 1 infection. This association was extended to spontaneous clearance of HCV, suggesting shared mechanisms of treatment and natural control of this virus. In addition to the biologic implications for innate immunity and HCV, a variety of clinical studies have suggested possible translation to a useful genetic test for practitioners. This article reviews the discovery, biology, and potential clinical applications that have stemmed from the seminal observation that IL28B polymorphisms are a main predictor of HCV clearance.

Budget impact analysis of boceprevir and telaprevir for the treatment of hepatitis C genotype 1 infection

BACKGROUND

Boceprevir and telaprevir have recently showed dramatically better treatment outcomes than conventional PEGylated interferon plus ribavirin for the treatment of hepatitis C virus genotype 1, but the average cost per patient is unknown.

METHODS

In the UK context, we performed a budget impact analysis to estimate the average per patient cost of adding boceprevir or telaprevir to PEGylated interferon plus ribavirin therapy. We considered both standard-duration therapy and response-guided therapy regimens of boceprevir and telaprevir for treatment-naïve and treatment-experienced patients. Our model utilized monthly discontinuation rates. We built a Bayesian Markov model to account for uncertainty associated with the clinical input and cost data.

RESULTS

The total average cost of response-guided therapy with boceprevir is £22,850 and £25,060 for treatment-naïve and treatment-experienced patients, respectively. By comparison, the total average cost of response-guided therapy with telaprevir was £29,930 and £31,880 for treatment-naïve and treatment-experienced patients, respectively, whereas the total average cost of standard-duration boceprevir is £34,680 and £34,350 and for telaprevir was £32,530 and £31,680 for treatment-naïve and treatment experienced patients, respectively.

CONCLUSION

Our results demonstrate that response-guided therapy with boceprevir is notably less costly than response-guided therapy with telaprevir. Our results also suggest that the standard treatment duration of boceprevir is slightly more costly than the standard treatment duration of telaprevir.

Inhibition of both protease and helicase activities of hepatitis C virus NS3 by an ethyl acetate extract of marine sponge Amphimedon sp

Combination therapy with ribavirin, interferon, and viral protease inhibitors could be expected to elicit a high level of sustained virologic response in patients infected with hepatitis C virus (HCV). However, several severe side effects of this combination therapy have been encountered in clinical trials. In order to develop more effective and safer anti-HCV compounds, we employed the replicon systems derived from several strains of HCV to screen 84 extracts from 54 organisms that were gathered from the sea surrounding Okinawa Prefecture, Japan. The ethyl acetate-soluble extract that was prepared from marine sponge Amphimedon sp. showed the highest inhibitory effect on viral replication, with EC₅₀ values of 1.5 and 24.9 µg/ml in sub-genomic replicon cell lines derived from genotypes 1b and 2a, respectively. But the extract had no effect on interferon-inducing signaling or cytotoxicity. Treatment with the extract inhibited virus production by 30% relative to the control in the JFH1-Huh7 cell culture system. The in vitro enzymological assays revealed that treatment with the extract suppressed both helicase and protease activities of NS3 with IC₅₀ values of 18.9 and 10.9 µg/ml, respectively. Treatment with the extract of Amphimedon sp. inhibited RNA-binding ability but not ATPase activity. These results suggest that the novel compound(s) included in Amphimedon sp. can target the protease and helicase activities of HCV NS3.

Hepatitis C virus and natural compounds: a new antiviral approach?

Hepatitis C is a major global health burden with an estimated 160 million infected individuals worldwide. This long-term disease evolves slowly, often leading to chronicity and potentially to liver failure. There is no anti-HCV vaccine, and, until recently, the only treatment available, based on pegylated interferon and ribavirin, was partially effective, and had considerable side effects. With recent advances in the understanding of the HCV life cycle, the development of promising direct acting antivirals (DAAs) has been achieved. Their use in combination with the current treatment has led to encouraging results for HCV genotype 1 patients. However, this therapy is quite expensive and will probably not be accessible for all patients worldwide. For this reason, constant efforts are being made to identify new antiviral molecules. Recent reports about natural compounds highlight their antiviral activity against HCV. Here, we aim to review the natural molecules that interfere with the HCV life cycle and discuss their potential use in HCV therapy.

Prevalence of amino acid mutations in hepatitis C virus core and NS5B regions among Venezuelan viral isolates and comparison with worldwide isolates

BACKGROUND

Recent reports show that R70Q and L/C91M amino acid substitutions in the core from different hepatitis C virus (HCV) genotypes have been associated with variable responses to interferon (IFN) and ribavirin (RBV) therapy, as well to an increase of hepatocellular carcinoma (HCC) risk, liver steatosis and insulin resistance (IR). Mutations in NS5B have also been associated to IFN, RBV, nucleoside and non-nucleoside inhibitors drug resistance. The prevalence of these mutations was studied in HCV RNA samples from chronically HCV-infected drug-naïve patients.

METHODS

After amplification of core and NS5B region by nested-PCR, 12 substitutions were analyzed in 266 Venezuelan HCV isolates subtype 1a, 1b, 2a, 2c, 2b, 2j (a subtype frequently found in Venezuela) and 3a (n = 127 and n = 228 for core and NS5B respectively), and compared to isolates from other countries (n = 355 and n = 646 for core and NS5B respectively).

RESULTS

R70Q and L/C91M core substitutions were present exclusively in HCV G1b. Both substitutions were more frequent in American isolates compared to Asian ones (69% versus 26%, p < 0.001 and 75% versus 45%, p < 0.001 respectively). In Venezuelan isolates NS5B D310N substitution was detected mainly in G3a (100%) and G1a (13%), this later with a significantly higher prevalence than in Brazilian isolates (p = 0.03). The NS5B mutations related to IFN/RBV treatment D244N was mainly found in G3a, and Q309R was present in all genotypes, except G2. Resistance to new NS5B inhibitors (C316N) was only detected in 18% of G1b, with a significantly lower prevalence than in Asian isolates, where this polymorphism was surprisingly frequent (p < 0.001).

CONCLUSIONS

Genotypical, geographical and regional differences were found in the prevalence of substitutions in HCV core and NS5B proteins. The substitutions found in the Venezuelan G2j type were similar to that found in G2a and G2c isolates. Our results suggest a high prevalence of the R70Q and L/C91M mutations of core protein for G1b and D310N substitution of NS5B protein for the G3a. C316N polymorphism related with resistance to new NS5B inhibitors was only found in G1b. Some of these mutations could be associated with a worse prognosis of the disease in HCV infected patients.

Boceprevir: a protease inhibitor for the treatment of hepatitis C

BACKGROUND

Boceprevir is a protease inhibitor indicated for the treatment of chronic hepatitis C virus (HCV) genotype 1 infection in combination with peginterferon and ribavirin for treatment-naive patients and those who previously failed to improve with interferon and ribavirin treatment.

OBJECTIVE

This article provides an overview of the mechanism of action, pharmacologic and pharmacokinetic properties, clinical efficacy, and tolerability of boceprevir.

METHODS

Relevant information was identified through a search of PubMed (1990-July 2012), EMBASE (1990-July 2012), International Pharmaceutical Abstracts (1970-July 2012), and Google Scholar using the key words boceprevir, SCH 503034, non-structural protein 3 (NS3) serine protease inhibitor, and direct-acting antiviral agent (DAA). Additional information was obtained from the US Food and Drug Administration's Web site, review of the reference lists of identified articles, and posters and abstracts from scientific meetings.

RESULTS

Clinical efficacy of boceprevir was assessed in 2 Phase III trials, Serine Protease Inhibitor Therapy-2 (SPRINT-2) for treatment-naive patients and Retreatment with HCV Serine Protease Inhibitor Boceprevir and PegIntron/Rebetol 2 (RESPOND-2) for treatment-experienced patients. In SPRINT-2, patients were randomized to receive peginterferon + ribavirin (PR) or peginterferon + ribavirin + boceprevir (PRB); duration of boceprevir therapy varied from 24, 32, to 44 weeks on the basis of HCV RNA results. The primary endpoint was achievement of sustained virologic response (SVR; lower limit of detection, 9.3 IU/mL). The addition of boceprevir was shown to be superior, with overall SVR rates ranging from 63% to 66% compared with 38% with PR (P < 0.001). Results of SVR in SPRINT-2 were also reorganized to monitor SVRs in black and non-black patients. Treatment-experienced patients were assessed in RESPOND-2; however, null responders were excluded. Patients were again randomized to PR or PRB; duration of boceprevir therapy varied from 32 to 44 weeks on the basis of HCV RNA results. SVR was significantly higher in patients receiving boceprevir (59%-66% vs 21% with PR; P < 0.001). This benefit was seen in both previous nonresponders (SVR, 40%-52% vs 7% with PR), as well as previous relapsers (SVR, 69%-75% vs 29% with PR). Importantly, SVR could be attained with a shortened course of therapy in almost one half of all treated patients in SPRINT-2 (44%) and RESPOND-2 (46%).

CONCLUSIONS

Boceprevir was well tolerated in clinical trials and a welcomed addition to our HCV armamentarium.

Silencing of microRNA-122 enhances interferon-α signaling in the liver through regulating SOCS3 promoter methylation

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease worldwide. Although novel drugs against HCV are under development, the current standard therapy consists principally of interferon (IFN). To improve the response to IFN treatment by enhancing interferon-stimulated response element (ISRE)-mediated gene transcription, we screened 75 microRNAs highly expressed in hepatocytes for their ability to modulate ISRE activity. Overexpression of microRNA-122 (miR122) significantly suppressed ISRE activity. Conversely, silencing of miR122 function enhanced IFN-induced ISRE activity, by decreasing expression of suppressor of cytokine signaling 3 (SOCS3). This decrease in SOCS3 level was not mediated by microRNA target gene suppression, but rather by enhanced methylation at SOCS3 gene promoter. Taken together, our data, along with the fact that antisense oligonucleotides of miR122 also directly inhibit HCV replication, suggest that a combination therapy comprising IFN and silencing of miR122 function may be a promising therapeutic option in the near future.

Interferon-γ-stimulated genes, but not USP18, are expressed in livers of patients with acute hepatitis C

BACKGROUND & AIMS

Approximately 50% of patients with chronic hepatitis C (CHC) have a sustained virologic response to treatment with pegylated interferon (pegIFN)-α and ribavirin. Nonresponse to treatment is associated with constitutively increased expression of IFN-stimulated genes (ISGs) in the liver. Treatment of patients with acute hepatitis C (AHC) is more effective, with sustained virologic response rates greater than 90%. We investigated mechanisms of the different responses of patients with CHC and AHC to pegIFN-α therapy.

METHODS

We analyzed IFN signaling and ISG expression in liver samples from patients with AHC, patients with CHC, and individuals without hepatitis C (controls) using microarray, immunohistochemical, and protein analyses. Findings were compared with those from primary human hepatocytes stimulated with IFN-α or IFN-γ, as reference sets.

RESULTS

Expression levels of hundreds of genes, primarily those regulated by IFN-γ, were altered in liver samples from patients with AHC compared with controls. Expression of IFN-γ-stimulated genes was induced in liver samples from patients with AHC, whereas expression of IFN-α-stimulated genes was induced in samples from patients with CHC. In an expression analysis of negative regulators of IFN-α signaling, we did not observe differences in expression of suppresor of cytokine signaling 1 or SOCS3 between liver samples from patients with AHC and those with CHC. However, USP18 (another negative regulator of IFN-α signaling), was up-regulated in liver samples of patients with CHC that did not respond to therapy, but not in AHC.

CONCLUSIONS

Differences in expression of ISGs might account for the greater response of patients with AHC, compared with those with CHC, to treatment with pegIFN-α and ribavirin. Specifically, USP18 is up-regulated in liver samples of patients with CHC that did not respond to therapy, but not in patients with AHC.

Hepatitis C prevalence in Denmark -an estimate based on multiple national registers

BACKGROUND

A national survey for chronic hepatitis C has not been performed in Denmark and the prevalence is unknown. Our aim was to estimate the prevalence of chronic hepatitis C from public registers and the proportion of these patients who received specialized healthcare.

METHODS

Patients with a diagnosis of chronic hepatitis C were identified from four national registers: a laboratory register, the Hospital Discharge Register, a clinical database of chronic viral hepatitis and the Register of Communicable Diseases. The total population diagnosed with hepatitis C was estimated by capture-recapture analysis. The population with undiagnosed hepatitis C was derived from the national register of drug users by comparing diagnosed and tested persons.

RESULTS

A total of 6,935 patients diagnosed with chronic hepatitis C were identified in the four registers and the estimated population diagnosed with the disease was 9,166 persons (95% C.I. interval 8,973 - 9,877), corresponding to 0.21% (95% CI 0.21%-0.23%) of the Danish population over 15 years of age. The prevalence was highest among persons 40-49 years old (0.39%) and males (0.28%). It was estimated that 40% of the diagnosed patients lived in the capital region, and 33.5% had attended specialised healthcare. It was estimated that 46% of hepatitis C patients had not been diagnosed and the total population with chronic hepatitis C in Denmark was 16,888 (95% C.I. 16,474-18,287), corresponding to 0.38% (95% CI 0.37-0.42) of the population over 15 years of age.

CONCLUSIONS

The estimated prevalence of chronic hepatitis C in Denmark was 0.38%. Less than half of the patients with chronic hepatitis C in Denmark have been identified and among these patients, one in three has attended specialised care.

Relating human genetic variation to variation in drug responses

Although sequencing a single human genome was a monumental effort a decade ago, more than 1000 genomes have now been sequenced. The task ahead lies in transforming this information into personalized treatment strategies that are tailored to the unique genetics of each individual. One important aspect of personalized medicine is patient-to-patient variation in drug response. Pharmacogenomics addresses this issue by seeking to identify genetic contributors to human variation in drug efficacy and toxicity. Here, we present a summary of the current status of this field, which has evolved from studies of single candidate genes to comprehensive genome-wide analyses. Additionally, we discuss the major challenges in translating this knowledge into a systems-level understanding of drug physiology, with the ultimate goal of developing more effective personalized clinical treatment strategies.

Liver stiffness using transient elastography is applicable to canines for hepatic disease models

Background

The objectives of this study were to evaluate the best position and best exploration probe for determining liver stiffness (LS) in dogs using transient liver elastography (TE). Thirteen dogs were used in the study.

Methodology/Principal Findings

Morphometric measurements taken were thoracic circumference, weight and height. Elastographic measurements were taken in 4 anatomical positions using two different probes: medium (M) and small (S). The exploration was considered correct when the success rate was above 60% and the interquartile range of the measurements did not exceed 30%. The best measurements were obtained in the middle of the 6th–9th intercostal spaces, with the dog in the left lateral position and using probe M for preference in adults and probe S mandatory for animals <2 years. The correlation between probes was 99%. Intra-observer variability showed an intra-class correlation of 97.6%.

Conclusions/Significance

TE is a technique that is reproducible in dogs.

Molecular study of HCV detection, genotypes and their routes of transmission in North West Frontier Province, Pakistan

OBJECTIVE

To determine hepatitis C virus (HCV) genotypes and explore the associated risk factors in chronic HCV patients.

METHODS

A total of 116 patients with chronic hepatitis C were subjected to polymerase chain reaction (PCR) based detection out of which 112 chronic HCV patients [53 male (47.32%), 59 female (52.68%); mean age (43.76±16.40) years; mean BMI (23.8±3.9) kg] were enrolled in this study. The frequency of 6 HCV genotypes and associated risk factors were evaluated from five districts of North West Frontier Province (NWFP).

RESULTS

Genotype 3 was the most prevalent in 73 samples (65.17%) followed by genotype 1 in 24 (21.42%) and genotype 2 in 13 (11.60%) samples. Genotype 3 had significantly high prevalence (P=0.000 2). The results showed that 48 (42.85%) samples were infected with HCV 3a; 25 (22.32%) with 3b; 14 (12.50%) with 1a; 10 (8.92%) with 1b; 11 (9.82%) with 2a; 2 (1.78%) with 2b; and 2 were untypable. The distribution of HCV genotypes in Mardan, Charsadda, Peshawar, Sawabi and Nowshehra districts was different. Use of unsterile equipment for medication, barbers and previous history of hospitalization were the main risk factors for HCV transmission.

CONCLUSIONS

Genotype 3a and 3b, 1a, 1b and 2a are the common genotypes in NWFP. Genotype 4, 5, and 6 can not be found in a single sample. The level of awareness about various modes of transmission of HCV among the population is found to be very low.

Mutations that alter use of hepatitis C virus cell entry factors mediate escape from neutralizing antibodies

BACKGROUND & AIMS

The development of vaccines and other strategies to prevent hepatitis C virus (HCV) infection is limited by rapid viral evasion. HCV entry is the first step of infection; this process involves several viral and host factors and is targeted by host-neutralizing responses. Although the roles of host factors in HCV entry have been well characterized, their involvement in evasion of immune responses is poorly understood. We used acute infection of liver graft as a model to investigate the molecular mechanisms of viral evasion.

METHODS

We studied factors that contribute to evasion of host immune responses using patient-derived antibodies, HCV pseudoparticles, and cell culture-derived HCV that express viral envelopes from patients who have undergone liver transplantation. These viruses were used to infect hepatoma cell lines that express different levels of HCV entry factors.

RESULTS

By using reverse genetic analyses, we identified altered use of host-cell entry factors as a mechanism by which HCV evades host immune responses. Mutations that alter use of the CD81 receptor also allowed the virus to escape neutralizing antibodies. Kinetic studies showed that these mutations affect virus-antibody interactions during postbinding steps of the HCV entry process. Functional studies with a large panel of patient-derived antibodies showed that this mechanism mediates viral escape, leading to persistent infection in general.

CONCLUSIONS

We identified a mechanism by which HCV evades host immune responses, in which use of cell entry factors evolves with escape from neutralizing antibodies. These findings advance our understanding of the pathogenesis of HCV infection and might be used to develop antiviral strategies and vaccines.

First-in-human study of the pharmacokinetics and antiviral activity of IDX375, a novel nonnucleoside hepatitis C virus polymerase inhibitor

IDX375 is a potent and selective palm-binding nonnucleoside inhibitor of the hepatitis C virus (HCV) genotype 1 polymerase. This first-in-human study evaluated the safety, tolerability, and pharmacokinetics of IDX375 in healthy volunteers, as well as its antiviral activity in HCV-infected patients. IDX375, as a choline salt, was administered for 1 day to 40 healthy male volunteers (25- to 200-mg IDX375-equivalent single ascending doses and a 200-mg twice-daily [BID] dose) and three patients chronically infected with HCV genotype 1 (200 mg BID only). IDX375 was well absorbed and well tolerated by all of the study participants. A single-day 200-mg BID dose resulted in exposure-related anti-HCV activity with maximal 0.5 to 1.1 log(10) reductions in plasma HCV RNA. These observations support further clinical investigations of IDX375.

Combined effects of different interleukin-28B gene variants on the outcome of dual combination therapy in chronic hepatitis C virus type 1 infection

In patients with chronic hepatitis C virus (HCV) infection, several variants of the interleukin-28B (IL28B) gene have been shown to correlate significantly with a sustained virologic response (SVR). Recent evidence shows that determination of one single IL28B polymorphism, rs12979860, is sufficient for predicting treatment outcome. We examined whether the combined determination of the IL28B single-nucleotide polymorphisms (SNPs), rs12979860, rs8099917, rs12980275, and rs8103142, might improve the prediction of SVR in patients with HCV. In the study cohort, 54% of 942 patients with chronic HCV type 1 infection had SVR. The IL28B SNPs, rs12979860CC and rs8099917TT, correlated significantly with SVR (68% and 62%). The SNPs, rs12980275 and rs8103142, were in strong linkage disequilibrium with rs12979860 and were not included in further analysis. In homozygous carriers of the rs12979860 responder allele C, additional genotyping of the rs8099917 SNP had no effect on response prediction, whereas in carriers of the rs12979860 nonresponder allele, the rs8099917 SNP improved the response prediction. In heterozygous carriers of the rs12979860 nonresponder T allele, SVR rates were 55% in the presence of the rs8099917TT genotype and 40% in patients carrying the rs8099917 TG or GG genotype. Analysis of an independent confirmation cohort of 377 HCV type 1-infected patients verified the significant difference in SVR rates between the combined genotypes, rs12979860CT/rs8099917TT and rs12979860CT/rs8099917TG (38% versus 21%; P = 0.018).

CONCLUSION

Treatment outcome prediction could not be improved in homozygous carriers of the IL28B rs12979860 C responder allele by the additional determination of the rs8099917 SNP. There is evidence that a significant proportion of heterozygous carriers of the rs12979860 T nonresponder allele can profit with respect to SVR prediction by further determination of the rs8099917 SNP. (HEPATOLOGY 2012;55:1700-1710).

Antiviral activity of TMC435 monotherapy in patients infected with HCV genotypes 2-6: TMC435-C202, a phase IIa, open-label study

BACKGROUND & AIMS

TMC435 is an investigational, once-daily, oral NS3/4A protease inhibitor currently in phase III development for the treatment of hepatitis C virus (HCV) infection. Phase I and II studies in patients infected with HCV genotype 1 have demonstrated that TMC435 is generally well tolerated, has a pharmacokinetic profile that supports once daily dosing, and demonstrates potent antiviral activity. This phase IIa study (TMC435-C202; NCT00812331) was conducted to investigate the antiviral activity, safety, tolerability, and pharmacokinetics of TMC435 in treatment-naїve patients infected with HCV genotypes 2-6.

METHODS

The study consisted of 7 days of monotherapy with TMC435 (200mg once daily). Patients could begin treatment with pegylated interferon/ribavirin from day 8 with a follow-up period up to days 37-42.

RESULTS

Thirty-seven patients were enrolled in Germany, Belgium and Thailand. For the primary end point at day 8, the mean (± standard error) change in plasma HCV ribonucleic acid (log(10)IU/ml) from baseline was the greatest for genotypes 6 (-4.35 ± 0.29) and 4 (-3.52 ± 0.43), followed by genotypes 2 (-2.73 ± 0.71) and 5 (-2.19 ± 0.39). No antiviral activity was evident for genotype 3. Viral breakthrough occurred in six patients during the monotherapy phase and in six additional patients during PegIFN/RBV-only period. All adverse events were mild or moderate and there were no discontinuations during the TMC435 monotherapy period.

CONCLUSIONS

The results of this phase IIa proof-of-concept trial provide evidence that TMC435 has a spectrum of activity against multiple HCV genotypes, except for genotype 3. In this study, TMC435 was generally safe and well tolerated.

Current standards in the treatment of chronic hepatitis C

BACKGROUND

In Germany, 400 000 to 500 000 people are chronically infected with the hepatitis C virus (HCV), 70% to 80% of them with HCV genotype 1. Combined treatment with peginterferon-alfa and ribavirin leads to a sustained virologic response (SVR) in 40% to 50% of patients with genotype 1 and 70% to 80% of patients with genotypes 2 and 3. The HCV protease inhibitors boceprevir and telaprevir were approved for clinical use in Germany in 2011.

METHODS

Selective literature review.

RESULTS

Treatment with peginterferon and ribavirin is recommended for a variable length of time depending on the HCV genotype (24 to 72 weeks for genotype 1, 16 to 48 weeks for genotypes 2 and 3), the baseline HCV-RNA concentration (greater or less than 600 000 to 800 000 IU/mL), and the decline in HCV-RNA concentration after 4 and 12 weeks of treatment. Either boceprevir or telaprevir is given in addition to peginterferon and ribavirin. In the approval studies, these triple combinations were shown to yield higher SVR rates than dual treatment for genotype 1 (66% to 75% versus 37% to 44%). If there is a favorable early decline in HCV-RNA, the treatment can be shortened to 24 to 28 weeks in 44% to 65% of patients with genotype 1. The SVR rates in genotype 1 patients who failed previous dual therapy were 69% to 88% for prior relapsers, 52% to 59% for partial responders, and 33% for null responders. Triple combination therapy is associated with new adverse events.

CONCLUSION

Individualized treatment durations are recommended for the treatment of chronic hepatitis C with peginterferon and ribavirin. Triple therapy in combination with either boceprevir or telaprevir leads to a higher rate of SVR both in previously untreated genotype 1 patients and in those who have failed prior antiviral treatment.\

Hepatitis C virus attachment mediated by apolipoprotein E binding to cell surface heparan sulfate

Viruses are known to use virally encoded envelope proteins for cell attachment, which is the very first step of virus infection. In the present study, we have obtained substantial evidence demonstrating that hepatitis C virus (HCV) uses the cellular protein apolipoprotein E (apoE) for its attachment to cells. An apoE-specific monoclonal antibody was able to efficiently block HCV attachment to the hepatoma cell line Huh-7.5 as well as primary human hepatocytes. After HCV bound to cells, however, anti-apoE antibody was unable to inhibit virus infection. Conversely, the HCV E2-specific monoclonal antibody CBH5 did not affect HCV attachment but potently inhibited HCV entry. Similarly, small interfering RNA-mediated knockdown of the key HCV receptor/coreceptor molecules CD81, claudin-1, low-density lipoprotein receptor (LDLr), occludin, and SR-BI did not affect HCV attachment but efficiently suppressed HCV infection, suggesting their important roles in HCV infection at postattachment steps. Strikingly, removal of heparan sulfate from the cell surface by treatment with heparinase blocked HCV attachment. Likewise, substitutions of the positively charged amino acids with neutral or negatively charged residues in the receptor-binding region of apoE resulted in a reduction of apoE-mediating HCV infection. More importantly, mutations of the arginine and lysine to alanine or glutamic acid in the receptor-binding region ablated the heparin-binding activity of apoE, as determined by an in vitro heparin pulldown assay. HCV attachment could also be inhibited by a synthetic peptide derived from the apoE receptor-binding region. Collectively, these findings demonstrate that apoE mediates HCV attachment through specific interactions with cell surface heparan sulfate.

Altered thymic function during interferon therapy in HCV-infected patients

Interferon alpha (IFNα) therapy, despite good efficacy in curing HCV infection, leads to major side effects, in particular inducement of a strong peripheral T-cell lymphocytopenia. We here analyze the early consequences of IFNα therapy on both thymic function and peripheral T-cell homeostasis in patients in the acute or chronic phase of HCV-infection as well as in HIV/HCV co-infected patients. The evolution of T-cell subsets and T-cell homeostasis were estimated by flow cytometry while thymic function was measured through quantification of T-cell receptor excision circles (TREC) and estimation of intrathymic precursor T-cell proliferation during the first four months following the initiation of IFNα therapy. Beginning with the first month of therapy, a profound lymphocytopenia was observed for all T-cell subsets, including naïve T-cells and recent thymic emigrants (RTE), associated with inhibition of intrathymic precursor T-cell proliferation. Interleukin (IL)-7 plasma concentration rapidly dropped while lymphocytopenia progressed. This was neither a consequence of higher consumption of the cytokine nor due to its neutralization by soluble CD127. Decrease in IL-7 plasma concentration under IFNα therapy correlated with the decline in HCV viral load, thymic activity and RTE concentration in blood. These data demonstrate that IFNα-based therapy rapidly impacts on thymopoiesis and, consequently, perturbs T-cell homeostasis. Such a side effect might be detrimental for the continuation of IFNα therapy and may lead to an increased level of infectious risk, in particular in HIV/HCV co-infected patients. Altogether, this study suggests the therapeutic potential of IL-7 in the maintenance of peripheral T-cell homeostasis in IFNα-treated patients.

Inhibition of hepatitis C virus replication and viral helicase by ethyl acetate extract of the marine feather star Alloeocomatella polycladia

Hepatitis C virus (HCV) is a causative agent of acute and chronic hepatitis, leading to the development of hepatic cirrhosis and hepatocellular carcinoma. We prepared extracts from 61 marine organisms and screened them by an in vitro fluorescence assay targeting the viral helicase (NS3), which plays an important role in HCV replication, to identify effective candidates for anti-HCV agents. An ethyl acetate-soluble fraction of the feather star Alloeocomatella polycladia exhibited the strongest inhibition of NS3 helicase activity, with an IC(50) of 11.7 µg/mL. The extract of A. polycladia inhibited interaction between NS3 and RNA but not ATPase of NS3. Furthermore, the replication of the replicons derived from three HCV strains of genotype 1b in cultured cells was suppressed by the extract with an EC(50) value of 23 to 44 µg/mL, which is similar to the IC(50) value of the NS3 helicase assay. The extract did not induce interferon or inhibit cell growth. These results suggest that the unknown compound(s) included in A. polycladia can inhibit HCV replication by suppressing the helicase activity of HCV NS3. This study may present a new approach toward the development of a novel therapy for chronic hepatitis C.

Boceprevir and telaprevir for the treatment of chronic hepatitis C genotype 1 infection: an indirect comparison meta-analysis

Background

The aim of this study was to examine the relative efficacy and safety of boceprevir and telaprevir, when used in combination with pegylated interferon alpha and ribavirin, using an indirect comparison meta-analysis.

Methods

Published phase II and phase III randomized placebo-controlled trials examining the efficacy of boceprevir and telaprevir in chronic hepatitis C virus genotype 1 infected adult populations were included. The primary outcomes were sustained virologic response, relapse, and discontinuation of all study drugs. Secondary outcomes included the adverse events of anemia, neutropenia, rash, and pruritus.

Results

Four boceprevir trials and six telaprevir trials were included. No significant differences were observed for sustained virologic response among either naïve (relative risk [RR] 1.14, 95% confidence interval [CI] 0.93–1.37, P = 0.20) or experienced patients (RR 0.81, 95% CI 0.52–1.23, P = 0.30). Similarly, for relapse among naïve (RR 0.80, 95% CI 0.18–3.45, P = 0.77) and experienced patients (RR 1.71, 95% CI 0.90–3.24, P = 0.10), or discontinuation of therapy for naïve (RR 0.80, 95% CI 0.28–2.29, P = 0.72) and experienced patients (RR 0.88, 95% CI 0.69–1.12, P = 0.30). Telaprevir was more likely to be associated with rash and pruritus, and boceprevir was more likely to be associated with neutropenia in certain patient populations.

Conclusion

Boceprevir and telaprevir appear comparable in terms of sustained virologic response, relapse, or discontinuation of therapy for patients treated with standard-dose therapy durations and response-guided therapy durations.

Exploitation of lipid components by viral and host proteins for hepatitis C virus infection

Hepatitis C virus (HCV), which is a major causative agent of blood-borne hepatitis, has chronically infected about 170 million individuals worldwide and leads to chronic infection, resulting in development of steatosis, cirrhosis, and eventually hepatocellular carcinoma. Hepatocellular carcinoma associated with HCV infection is not only caused by chronic inflammation, but also by the biological activity of HCV proteins. HCV core protein is known as a main component of the viral nucleocapsid. It cooperates with host factors and possesses biological activity causing lipid alteration, oxidative stress, and progression of cell growth, while other viral proteins also interact with host proteins including molecular chaperones, membrane-anchoring proteins, and enzymes associated with lipid metabolism to maintain the efficiency of viral replication and production. HCV core protein is localized on the surface of lipid droplets in infected cells. However, the role of lipid droplets in HCV infection has not yet been elucidated. Several groups recently reported that other viral proteins also support viral infection by regulation of lipid droplets and core localization in infected cells. Furthermore, lipid components are required for modification of host factors and the intracellular membrane to maintain or up-regulate viral replication. In this review, we summarize the current status of knowledge regarding the exploitation of lipid components by viral and host proteins in HCV infection.

Chronic hepatitis C treatment outcomes in low- and middle-income countries: a systematic review and meta-analysis

OBJECTIVE

To assess the effectiveness of treatment for hepatitis C virus (HCV) infection in low- and middle-income countries and identify factors associated with successful outcomes.

METHODS

We performed a systematic review and meta-analysis of studies of HCV treatment programmes in low- and middle-income countries. The primary outcome was a sustained virological response (SVR). Factors associated with treatment outcomes were identified by random-effects meta-regression analysis.

FINDINGS

The analysis involved data on 12 213 patients included in 93 studies from 17 countries. The overall SVR rate was 52% (95% confidence interval, CI: 48-56). For studies in which patients were predominantly infected with genotype 1 or 4 HCV, the pooled SVR rate was 49% (95% CI: 43-55). This was significantly lower than the rate of 59% (95% CI: 54-64) found in studies in which patients were predominantly infected with other genotypes (P = 0.012). Factors associated with successful outcomes included treatment with pegylated interferon and ribavirin, infection with an HCV genotype other than genotype 1 or 4 and the absence of liver damage or human immunodeficiency virus infection at baseline. No significant difference in the SVR rate was observed between weight-adjusted and fixed-dose ribavirin treatment. Overall, 17% (95% CI: 13-23) of adverse events resulted in treatment interruption or dose modification, but only 4% (95% CI: 3-5) resulted in treatment discontinuation.

CONCLUSION

The outcomes of treatment for HCV infection in low- and middle-income countries were similar to those reported in high-income countries.

Future of hepatitis C therapy: development of direct-acting antivirals

PURPOSE OF REVIEW

The landscape of hepatitis C virus (HCV) therapy will change considerably over the next decade with the probable licensure of many HCV direct-acting antiviral (DAA) therapy agents. This review will outline the data on the initial two DAA agents licensed (protease inhibitors telaprevir and boceprevir) and cover potential future therapeutic strategies and challenges for DAA-based therapy, including in the context of HIV/HCV coinfection.

RECENT FINDINGS

Phase III trials evaluating the addition of telaprevir or boceprevir to pegylated interferon and ribavirin in both HCV treatment naïve and experienced populations with chronic HCV genotype 1 have demonstrated considerable improvements in sustained virological response, with many patients able to shorten total treatment duration from 48 to 24-36 weeks. Although these initial DAA-based treatment results are encouraging, additional toxicity, problematic dosing schedules, and potential drug-drug interactions pose challenges for clinical management, particularly in HIV/HCV coinfection. Phase II trials with telaprevir and boceprevir in HIV/HCV populations are underway. Subsequent DAA agents appear to have improved tolerability and dosing schedules and open the door for interferon (IFN)-free DAA-based combination therapy.

SUMMARY

Development of DAA therapy will lead to a major shift in HCV clinical management, particularly with the potential for IFN-free combination therapy.

Matrigel-embedded 3D culture of Huh-7 cells as a hepatocyte-like polarized system to study hepatitis C virus cycle

Hepatocytes are highly polarized cells where intercellular junctions, including tight junctions (TJs), determine the polarity. Recently, the TJ-associated proteins claudin-1 and occludin have been implicated in hepatitis C virus (HCV) entry and spread. Nevertheless, cell line-based experimental systems that exhibit hepatocyte-like polarity and permit robust infection and virion production are not currently available. Thus, we sought to determine whether cell line-based, Matrigel-embedded cultures could be used to study hepatitis C virus (HCV) infection and virion production in a context of hepatocyte-like polarized cells. In contrast to standard bidimensional cultures, Matrigel-cultured Huh-7 cells adopted hepatocyte polarization features forming a continuous network of functional proto-bile canaliculi structures. These 3D cultures supported HCV infection by JFH-1 virus and produced infective viral particles which shifted towards lower densities with higher associated specific infectivity. In conclusion, our findings describe a novel use of Matrigel to study the entire HCV cycle in a more relevant context.

Sequence analysis of the IL28A/IL28B inverted gene duplication that contains polymorphisms associated with treatment response in hepatitis C patients

Several SNPs located in or around the IL28B gene are associated with response of patients infected with Hepatitis C virus to treatment with pegylated interferon-α ⁺/⁻ ribavirin or with spontaneous clearance of the virus. The results of such studies are so compelling that future treatment approaches are likely to involve clinical decisions being made on the basis of a patient's genotype. Since IL28B is a paralogue of IL28A with greater than 95% sequence identity, it is possible that without genotyping assay specificity, sequences in IL28A may contribute to genotype identification, and potentially confound treatment decisions. This study aimed to 1) examine DNA sequences in IL28B surrounding each of the reported associated SNPs and the corresponding regions in IL28A; and 2) develop a robust assay for rs12979860, the most 'cosmopolitan' SNP most strongly associated with treatment response across all global populations studied to date. Bioinformatic analysis of genomic regions surrounding IL28A and IL28B demonstrated that 3 SNPs were unique to IL28B, whereas the remaining 6 SNP regions shared >93% identity between IL28A and IL28B. Using a panel of DNA samples, PCR amplification followed by Sanger sequencing was used to examine IL28B SNPs and the corresponding regions in IL28A. For the overlapping SNPs, all 6 in IL28B were confirmed to be polymorphic whereas the corresponding positions in IL28A were monomorphic. Based upon IL28A and IL28B sequence data, a specific TaqMan® assay was developed for SNP rs12979860 that was 100% concordant to the sequence-derived genotypes. Analysis using a commercial assay identified one discordant result which led to a change in their genotype-calling algorithm. Where future treatment decisions are made upon the results of genotyping assays, it is very important that results are concordant with data from a sequence-based format. This is especially so in situations where designing specific PCR primers is a challenge.

Weight loss and resting energy expenditure in patients with chronic hepatitis C before and during standard treatment

OBJECTIVE

Infection with hepatitis C virus (HCV) is a serious public health problem worldwide. In clinical studies, weight loss has been reported in 11% to 29% of patients treated with pegylated interferon-α-2a/2b. Few reports have tried to explain such a weight loss. The aim of this study was to evaluate nutritional status, body composition, and resting energy expenditure (REE) in patients with chronic hepatitis C before and during treatment with pegylated interferon and ribavirin.

METHODS

This was a prospective study with the evaluation of patients with hepatitis C virus before and after 12 wk of treatment with pegylated interferon and ribavirin. The evaluation consisted of anthropometry (weight, height, body mass index, and waist circumference), and body composition was determined by bioelectrical impedance analysis. The REE of each individual was obtained by indirect calorimetry. To compare the two phases of treatment, the Wilcoxon test was used. The significance level was 5%.

RESULTS

Subjects had significant weight loss during treatment with a consequent decrease in body mass index. This weight decrease was accompanied by a significant decrease in body fat and no decrease in fat-free mass. There was a significant decrease in energy intake as assessed by 24-h recall. However, there was no change in REE and in REE corrected for fat-free mass.

CONCLUSION

Our study of patients with hepatitis C treatment showed that these patients had significant weight loss and this was not associated with changes in energy expenditure. However, we observed a significant decrease in energy intake, pointing to a possible need for intervention measures to decrease the damage.

A macrocyclic HCV NS3/4A protease inhibitor interacts with protease and helicase residues in the complex with its full-length target

Hepatitis C virus (HCV) infection is a global health burden with over 170 million people infected worldwide. In a significant portion of patients chronic hepatitis C infection leads to serious liver diseases, including fibrosis, cirrhosis, and hepatocellular carcinoma. The HCV NS3 protein is essential for viral polyprotein processing and RNA replication and hence viral replication. It is composed of an N-terminal serine protease domain and a C-terminal helicase/NTPase domain. For full activity, the protease requires the NS4A protein as a cofactor. HCV NS3/4A protease is a prime target for developing direct-acting antiviral agents. First-generation NS3/4A protease inhibitors have recently been introduced into clinical practice, markedly changing HCV treatment options. To date, crystal structures of HCV NS3/4A protease inhibitors have only been reported in complex with the protease domain alone. Here, we present a unique structure of an inhibitor bound to the full-length, bifunctional protease-helicase NS3/4A and show that parts of the P4 capping and P2 moieties of the inhibitor interact with both protease and helicase residues. The structure sheds light on inhibitor binding to the more physiologically relevant form of the enzyme and supports exploring inhibitor-helicase interactions in the design of the next generation of HCV NS3/4A protease inhibitors. In addition, small angle X-ray scattering confirmed the observed protease-helicase domain assembly in solution.

Antiviral therapy for recurrent hepatitis C reduces recurrence of hepatocellular carcinoma following liver transplantation

Recurrence of hepatocellular carcinoma (HCC) is one of the major concerns following liver transplantation (LT). With the potential antitumor properties of interferon (IFN), their role in prevention of HCC recurrence is to be defined. We retrospectively reviewed 46 patients who underwent LT for hepatitis C virus (HCV)-related HCC between January 2004 and December 2008. Twenty-four (52.2%) patients with biopsy-proven HCV recurrence received antiviral therapy (IFN group); their outcomes were compared with 22 patients (control group). There was no significant difference for tumor size, number, and type of neo-adjuvant therapy between the two groups. The 1- and 3-year overall patient survival (100% vs. 90.9% and 87.3% vs. 71.8%; P = 0.150) and tumor-free survival (100% vs. 72.7% and 83.1% vs. 67.5%; P = 0.214) between IFN and control group were comparable. HCC recurrence was the most common cause of death (n = 6 of 12, 50%), all in the control group. During follow-up, seven (15.2%) patients developed HCC recurrence: one (4.1%) in the IFN group and six (27.3%) in the control group (P < 0.05). In conclusions, HCC recurrence rate and related deaths were significantly lower in patients that received post-transplant antiviral therapy for recurrent HCV.

Mathematical model of viral kinetics in vitro estimates the number of E2-CD81 complexes necessary for hepatitis C virus entry

Interaction between the hepatitis C virus (HCV) envelope protein E2 and the host receptor CD81 is essential for HCV entry into target cells. The number of E2-CD81 complexes necessary for HCV entry has remained difficult to estimate experimentally. Using the recently developed cell culture systems that allow persistent HCV infection in vitro, the dependence of HCV entry and kinetics on CD81 expression has been measured. We reasoned that analysis of the latter experiments using a mathematical model of viral kinetics may yield estimates of the number of E2-CD81 complexes necessary for HCV entry. Here, we constructed a mathematical model of HCV viral kinetics in vitro, in which we accounted explicitly for the dependence of HCV entry on CD81 expression. Model predictions of viral kinetics are in quantitative agreement with experimental observations. Specifically, our model predicts triphasic viral kinetics in vitro, where the first phase is characterized by cell proliferation, the second by the infection of susceptible cells and the third by the growth of cells refractory to infection. By fitting model predictions to the above data, we were able to estimate the threshold number of E2-CD81 complexes necessary for HCV entry into human hepatoma-derived cells. We found that depending on the E2-CD81 binding affinity, between 1 and 13 E2-CD81 complexes are necessary for HCV entry. With this estimate, our model captured data from independent experiments that employed different HCV clones and cells with distinct CD81 expression levels, indicating that the estimate is robust. Our study thus quantifies the molecular requirements of HCV entry and suggests guidelines for intervention strategies that target the E2-CD81 interaction. Further, our model presents a framework for quantitative analyses of cell culture studies now extensively employed to investigate HCV infection.

The interaction between the hepatitis C virus (HCV) envelope protein E2 and the host cell surface receptor CD81 is critical for HCV entry into hepatocytes and presents a promising drug and vaccine target. Yet, the number of E2-CD81 complexes that must be formed between a virus and a target cell to enable viral entry remains unknown. Direct observation of the E2-CD81 complexes preceding viral entry has not been possible. We constructed a mathematical model of HCV viral kinetics in vitro and using it to analyze data from recent cell culture studies obtained estimates of the threshold number of E2-CD81 complexes necessary for HCV entry. We found that depending on the E2-CD81 binding affinity, between 1 and 13 complexes are necessary for HCV entry into human hepatoma-derived cells. Our study thus presents new, quantitative insights into the molecular requirements of HCV entry, which may serve as a guideline for intervention strategies targeting the E2-CD81 interaction. Further, our study shows that HCV viral kinetics in vitro can be described using a mathematical model, thus facilitating quantitative analyses of the wealth of data now emanating from cell culture studies of HCV infection.