Review article: predicting response in hepatitis C virus therapy

Treatment of hepatitis C virus infection

Hepatitis C virus infection affects 71 million people worldwide. It is at the origin of a multi-organ disease associating hepatic manifestations, cryoglobulinemic vasculitis and general manifestations linked to chronic inflammation (diabetes, cardio-, reno- or cerebrovascular manifestations, extra-hepatic cancers including non-Hodgkin's lymphoma). The significant morbidity and mortality linked to the hepatitis C virus therefore justify its screening and access to treatments which have increased considerably over the past two decades. Understanding the replicative cycle of the hepatitis C virus has enabled the development of direct HCV-specific antivirals targeting viral proteins (NS3/4A protease, NS5B polymerase and the multifunctional NS5A replication complex). The combination of two to three specific inhibitors often co-formulated in a capsule, without pegylated interferon and most often without ribavirin, allows high antiviral efficacy (more than 97% cure) for a treatment duration of 8-12 weeks with satisfactory tolerance. HCV infection is the only chronic viral infection that can be cured and the hepatic or extrahepatic manifestations are mainly reversible. This underlines the importance of strengthening screening and access to care policies in order to achieve the elimination of viral infection C in the short term, in 2030, as expected from the program of the World Health Organization. If this elimination is possible in some countries (Iceland, France, Germany …), it seems compromised in others where prevention (USA), screening and/or access to care are still insufficient (Sub-Saharan Africa, Russia…).

Cell viability assay as a tool to study activity and inhibition of hepatitis C p7 channels

The p7 viroporin of the hepatitis C virus (HCV) forms an intracellular proton-conducting transmembrane channel in virus-infected cells, shunting the pH of intracellular compartments and thus helping virus assembly and release. This activity is essential for virus infectivity, making viroporins an attractive target for drug development. The protein sequence and drug sensitivity of p7 vary between the seven major genotypes of the hepatitis C virus, but the essential channel activity is preserved. Here, we investigated the effect of several inhibitors on recombinant HCV p7 channels corresponding to genotypes 1a-b, 2a-b, 3a and 4a using patch-clamp electrophysiology and cell-based assays. We established a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-based cell viability assay for recombinant p7 expressed in HEK293 cells to assess channel activity and its sensitivity to inhibitors. The results from the cell viability assay were consistent with control measurements using established assays of haemadsorption and intracellular pH, and agreed with data from patch-clamp electrophysiology. Hexamethylene amiloride (HMA) was the most potent inhibitor of p7 activity, but possessed cytotoxic activity at higher concentrations. Rimantadine was active against p7 of all genotypes, while amantadine activity was genotype-dependent. The alkyl-chain iminosugars NB-DNJ, NN-DNJ and NN-DGJ were tested and their activity was found to be genotype-specific. In the current study, we introduce cell viability assays as a rapid and cost-efficient technique to assess viroporin activity and identify channel inhibitors as potential novel antiviral drugs.

A Protease Inhibitor with Induction Therapy with Natural Interferon-β in Patients with HCV Genotype 1b Infection

The restoration of innate immune responses has potential as a novel therapeutic strategy for chronic hepatitis C (CHC). We compared the efficacy and safety of induction therapy (IT) with natural interferon-β (n-IFN-β) followed by pegylated-IFN-α/ribavirin (PR) alone (group A, n = 30) and IT with a protease inhibitor (PI) (simeprevir or vaniprevir)/PR (group B, n = 13) in CHC patients with genotype 1b and high viral loads. During IT with nIFN-β, virologic response rates in group A and group B were 10% and 8% (p = 0.6792) at week 4, 30% and 16% (p = 0.6989) at week 12 and 47% and 20% (p = 0.0887) at week 24 respectively. During and after the treatment with PR alone or PI/PR, virologic response rates in groups A and B were 50% and 82% (p = 0.01535) at week 4, 53% and 91% (p = 0.006745) at week 8, 57% and 91% (p = 0.001126) at week 12, 57% and 100% (p < 0.001845) at the end of the treatment and 57% and 80% (p < 0.005166) after treatment cessation. IT with PI/PR linked to the restoration of innate immune response was tolerated well, overcame virological breakthrough, enhanced early virologic responses, and resulted in a sustained virologic response in difficult-to-treat CHC patients. IT with PI/PR is beneficial for treating difficult-to-treat CHC patients.

Modelling hepatitis C therapy--predicting effects of treatment

Mathematically modelling changes in HCV RNA levels measured in patients who receive antiviral therapy has yielded many insights into the pathogenesis and effects of treatment on the virus. By determining how rapidly HCV is cleared when viral replication is interrupted by a therapy, one can deduce how rapidly the virus is produced in patients before treatment. This knowledge, coupled with estimates of the HCV mutation rate, enables one to estimate the frequency with which drug resistant variants arise. Modelling HCV also permits the deduction of the effectiveness of an antiviral agent at blocking HCV replication from the magnitude of the initial viral decline. One can also estimate the lifespan of an HCV-infected cell from the slope of the subsequent viral decline and determine the duration of therapy needed to cure infection. The original understanding of HCV RNA decline under interferon-based therapies obtained by modelling needed to be revised in order to interpret the HCV RNA decline kinetics seen when using direct-acting antiviral agents (DAAs). There also exist unresolved issues involving understanding therapies with combinations of DAAs, such as the presence of detectable HCV RNA at the end of therapy in patients who nonetheless have a sustained virologic response.

Understanding early serum hepatitis D virus and hepatitis B surface antigen kinetics during pegylated interferon-alpha therapy via mathematical modeling

There is little information on the early kinetics of hepatitis delta virus (HDV) and hepatitis B surface antigen (HBsAg) during interferon-α therapy. Here a mathematical model was developed and fitted to frequent HDV and HBsAg kinetic data from 10 patients during the first 28 weeks of pegylated-interferon-α2a (peg-IFN) therapy. Three patients achieved a complete virological response (CVR), defined as undetectable HDV 6 months after treatment stopped with loss of HBsAg and anti-HBsAg seroconversion. After initiation of therapy, a median delay of 9 days (interquartile range [IQR]: 5-15) was observed with no significant changes in HDV level. Thereafter, HDV declined in a biphasic manner, where a rapid first phase lasting for 25 days (IQR: 23-58) was followed by a slower or plateau second phase. The model predicts that the main effect of peg-IFN is to reduce HDV production/release with a median effectiveness of 96% (IQR: 93-99.8). Median serum HDV half-life (t1/2 ) was estimated as 2.9 days (IQR: 1.5-5.3) corresponding to a pretreatment production and clearance of about 10(10) (IQR: 10(9.7) -10(10.7) ) virions/day. None of the patients with flat second phase in HDV achieved CVR. HBsAg kinetics of decline paralleled the second phase of HDV decline consistent with HBsAg-productive-infected cells being the main source of production of HDV, with a median t1/2 of 135 days (IQR: 20-460). The interferon lambda-3 polymorphism (rs12979860) was not associated with kinetic parameters.

CONCLUSION

Modeling results provide insights into HDV-host dynamics, the relationship between serum HBsAg levels and HBsAg-infected cells, IFN's mode of action, and its effectiveness. The observation that a flat second phase in HDV and HBsAg kinetics was associated with failure to achieve CVR provides the basis to develop early stopping rules during peg-IFN treatment in HDV-infected patients.

A pharmacokinetic-viral kinetic model describes the effect of alisporivir as monotherapy or in combination with peg-IFN on hepatitis C virologic response

Alisporivir is a cyclophilin inhibitor with demonstrated in vitro and in vivo activity against hepatitis C virus (HCV). We estimated the antiviral effectiveness of alisporivir alone or in combination with pegylated interferon (peg-IFN) in 88 patients infected with different HCV genotypes treated for 4 weeks. The pharmacokinetics of the two drugs were modeled and used as driving functions for the viral kinetic model. Genotype was found to significantly affect peg-IFN effectiveness (ɛ = 86.3 and 99.1% for genotypes 1/4 and genotypes 2/3, respectively, P < 10(-7)) and the loss rate of infected cells (δ = 0.22 vs. 0.39 per day in genotype 1/4 and genotype 2/3 patients, respectively, P < 10(-6)). Alisporivir effectiveness was not significantly different across genotypes and was high for doses ≥600 mg q.d. We simulated virologic responses with other alisporivir dosing regimens in HCV genotype 2/3 patients using the model. Our predictions consistently matched the observed responses, demonstrating that this model could be a useful tool for anticipating virologic response and optimizing alisporivir-based therapies.

Emergent properties of the interferon-signalling network may underlie the success of hepatitis C treatment

Current interferon alpha-based treatment of hepatitis C virus (HCV) infection fails to cure a sizeable fraction of patients treated. The cause of this treatment failure remains unknown. Here using mathematical modelling, we predict treatment failure to be a consequence of the emergent properties of the interferon-signalling network. HCV induces bistability in the network, creating a new steady state where it can persist. Cells that admit the new steady state alone are refractory to interferon. Using a model of viral kinetics, we show that when the fraction of cells refractory to interferon in a patient exceeds a critical value, treatment fails. Direct-acting antivirals that suppress HCV replication can eliminate the new steady state, restoring interferon sensitivity and improving treatment response. Our study thus presents a new conceptual basis of HCV persistence and treatment response, elucidates the origin of the synergy between interferon and direct-acting antivirals, and facilitates rational treatment optimization.

Impact of hepatitis C treatment initiation on adherence to concomitant medications

Our study investigated whether initiating hepatitis C virus (HCV) treatment affected adherence to concomitant medications. Mixed-effects linear regression was used to analyze data from 57 patients (29 co-infected with HIV) in a prospective study of HCV treatment-naïve patients initiating HCV treatment. Adherence was assessed using structured self-report at the time of treatment initiation, and at 12 weeks and 24 weeks into treatment. There was no change in adherence to concomitant medications over the first 24 weeks of HCV treatment. There was a significant interaction effect such that the change in adherence to concomitant medications between baseline and 12 weeks differed between the HIV-infected and HIV-uninfected patients. Adherence to concomitant medications in the HIV-infected patients was found to decrease, whereas adherence in the HIV-uninfected patients was found to increase. HIV-infected patients may be more at risk for adherence problems in the first 12 weeks of HCV treatment as compared to HIV-uninfected patients.

Hepatitis C virus kinetics by administration of pegylated interferon-α in human and chimeric mice carrying human hepatocytes with variants of the IL28B gene

OBJECTIVE

Recent studies have demonstrated that genetic polymorphisms near the IL28B gene are associated with the clinical outcome of pegylated interferon α (peg-IFN-α) plus ribavirin therapy for patients with chronic hepatitis C virus (HCV). However, it is unclear whether genetic variations near the IL28B gene influence hepatic interferon (IFN)-stimulated gene (ISG) induction or cellular immune responses, lead to the viral reduction during IFN treatment.

DESIGN

Changes in HCV-RNA levels before therapy, at day 1 and weeks 1, 2, 4, 8 and 12 after administering peg-IFN-α plus ribavirin were measured in 54 patients infected with HCV genotype 1. Furthermore, we prepared four lines of chimeric mice having four different lots of human hepatocytes containing various single nucleotide polymorphisms (SNP) around the IL28B gene. HCV infecting chimeric mice were subcutaneously administered with peg-IFN-α for 2 weeks.

RESULTS

There were significant differences in the reduction of HCV-RNA levels after peg-IFN-α plus ribavirin therapy based on the IL28B SNP rs8099917 between TT (favourable) and TG/GG (unfavourable) genotypes in patients; the first-phase viral decline slope per day and second-phase slope per week in TT genotype were significantly higher than in TG/GG genotype. On peg-IFN-α administration to chimeric mice, however, no significant difference in the median reduction of HCV-RNA levels and the induction of antiviral ISG was observed between favourable and unfavourable human hepatocyte genotypes.

CONCLUSIONS

As chimeric mice have the characteristic of immunodeficiency, the response to peg-IFN-α associated with the variation in IL28B alleles in chronic HCV patients would be composed of the intact immune system.

Long-term response to peginterferon in hepatitis C virus-associated nephrotic syndrome from focal segmental glomerulosclerosis

Hepatitis C virus (HCV) infection is a global public health problem. Chronic HCV infection is an important cause of chronic liver disease. Since the first reported association between HCV and membranoproliferative glomerulonephritis (MPGN) in 1993, HCV has been described with other types of glomerular diseases, although less frequently. Focal segmental glomerulosclerosis (FSGS) is one such glomerular disease that has been rarely reported in association with HCV. Antiviral therapy with interferon and ribavirin has been shown to be beneficial in HCV-associated MPGN. The optimal therapy of HCV-associated FSGS is not currently known. To our knowledge, long-term response to pegylated interferon monotherapy in treatment of HCV-associated FSGS has not been reported. We report an adult patient with HCV-associated FSGS who presented with nephrotic syndrome and renal failure. Treatment with pegylated interferon alfa-2a monotherapy resulted in sustained virological response with a clinical remission of nephrotic syndrome and stabilization of renal function. Patient continued to remain in clinical remission of nephrotic syndrome with stable renal function, 5 years after treatment. We also briefly review the literature on HCV-associated glomerular diseases, particularly HCV-associated FSGS.

Influence of a priori Information, Designs, and Undetectable Data on Individual Parameters Estimation and Prediction of Hepatitis C Treatment Outcome

Hepatitis C viral kinetic analysis based on nonlinear mixed effect models can be used to individualize treatment. For that purpose, it is necessary to obtain precise estimation of individual parameters. Here, we evaluated by simulation the influence on Bayesian individual parameter estimation and outcome prediction of a priori information on population parameters, viral load sampling designs, and methods for handling data below detection limit (BDL). We found that a precise estimation of both individual parameters and treatment outcome could be obtained using as few as six measurements in the first month of therapy. This result remained valid even when incorrect a priori information on population parameters was set as long as the parameters were identifiable and BDL data were properly handled. However, setting wrong values for a priori population parameters could lead to severe estimation/prediction errors if BDL data were ignored and not properly accounted in the likelihood function.

Hepatitis C infection and chronic renal diseases

Hepatitis C virus (HCV) infection and chronic renal diseases can be linked in two different ways. Some forms of renal disease are precipitated by HCV infection, while patients with end-stage renal disease are at increased risk for acquiring HCV infection. Patients with chronic HCV infection and renal disease have a poor prognosis. Most studies on treatment of HCV and renal diseases have been uncontrolled trials with small number of subjects. So, there is a lack of evidence-based recommendations and guidelines on the management of this condition. In this review, we will attempt to provide the most recent insights on HCV infection both as a extrahepatic manifestations and as a complication of end-stage renal patients.

Mathematical modelling of HCV infection: what can it teach us in the era of direct-acting antiviral agents?

HCV infection is a major cause of chronic liver disease and affects nearly 170 million people worldwide. Whereas the previous standard of care with pegylated interferon and ribavirin had a modest effectiveness, the recent approval of two highly potent protease inhibitors and the ongoing development of dozens of direct-acting antiviral agents (DAAs) constitute a major milestone for HCV therapy. Mathematical modelling of viral kinetics under treatment has played an instrumental role in improving our understanding of virus pathogenesis and in guiding drug development. Here, we review the current state of HCV kinetic modelling, and challenges to the standard biphasic viral decline model that arise when fitting viral kinetic models to data obtained with DAAs.

Efficacy of peginterferon alpha-2A and ribavirin combination therapy in treatment-naive Estonian patients with chronic hepatitis C

AIM

The aim of the study was to assess the efficacy of pegylated interferon (Peg-IFN) alpha-2a and ribavirin (RBV) combination therapy in treatment-naive patients with chronic hepatitis C in Estonia.

METHODS

Out of 121 outpatients with chronic hepatitis C (73 males, 48 females, aged 19-63) enrolled in the study, 76 were infected with HCV genotype 1b and 45 with genotype 3a. At baseline, the viral load in 75.2% of patients was higher than 600,000 IU/mL. Histologically, 88.4% of patients had fibrosis score F0-2. Patients received 180 microg of Peg-IFN alpha-2a weekly plus daily ribavirin 1,000 or 1,200 mg, depending on body weight, in HCV genotype 1b, or 800 mg/day in genotype 3a infection.

RESULTS

The overall sustained virologic response (SVR) rate in our study was 60.3%, being statistically lower for patients with HCV genotype 1b as compared to patients with genotype 3a (46.1% vs. 84.4%, p < 0.05). The non-response and relapse rates were significantly higher in patients infected with HCV genotype 1b compared with patients infected with genotype 3a (19.7% vs. 2.2%, p = 0.01; and 17.1% vs. 4.4%, p = 0.04; respectively). The SVR rate was higher in patients younger than 40 years compared with older patients (76.4% vs. 47.0%, p < 0.01), regardless of the genotype. Thirteen patients infected with HCV genotype 1b required dose reduction of PegIFN and/or RBV because of adverse side effects. Nine of them achieved SVR.

CONCLUSION

HCV genotype and age younger than 40 years predetermined SVR rate in treatment-naive Estonian patients with chronic hepatitis C treated with Peg-IFN alpha-2a plus ribavirin.

Real response to therapy in chronic hepatitis C virus patients: a study from iran

BACKGROUND

Despite significant advances in the treatment of chronic hepatitis C in the past decades, factors which can affect response rates to combination therapy; peginterferon and ribavirin, are still under study and reaching sustained virological response (SVR) is affected by several different factors.

OBJECTIVES

To investigate predictor factors contributing to SVR in Iranian patients.

PATIENTS AND METHODS

The present non-randomized, clinical trial was conducted on 100 patients referred to the Tehran Hepatitis Center in 2009-2011. The patients were administered combined peginterferon α-2a-ribavirin treatment, based on the standard protocol of the Iranian Ministry of Health. At the end of the treatment, the SVR rate and predictors were evaluated.

RESULTS

The mean age of the patients was 42 and 78% were male. Genotype 1a was the most common (70%) and 55% of patients were treatment naïve. The outcomes showed that 12%, 16% and 22% patients were; non-responders, breakthroughs and relapsers, respectively, while 50% of the patients reached SVR. Patients reaching SVR were aged 40 years or lower, they were less likely to have been a non-responder in prior treatments, more likely to have a non-1a genotype and a higher number had an HCV RNA of less than 600 000 IU/ml. The multivariate analysis showed that an age of 40 or lower (OR = 3.74, CI95% = 1.52-9.22), a non-1a genotype (OR = 3.71, CI 95% = 1.40-9.81) and an HCV RNA less than 600 000 IU/ml (OR = 2.52, CI 95% = 1.03-6.15) may be useful SVR predictors.

CONCLUSIONS

The findings of the present study showed that half of the patients reached SVR through combined peginterferon α-2a and ribavirin treatment, the majority of whom had genotype 3a and a minority had genotype 1a. In addition, an age of 40 or lower, non-1a genotype and a viral load less than 600 000 IU/ml were strong SVR predictors.

The impact of fibrosis and steatosis on early viral kinetics in HCV genotype 1-infected patients treated with Peg-IFN-alfa-2a and ribavirin

Hepatitis C viral (HCV) kinetics after initiation of interferon-based therapy provide valuable insights for understanding virus pathogenesis, evaluating treatment antiviral effectiveness and predicting treatment outcome. Adverse effects of liver fibrosis and steatosis on sustained virological response have been frequently reported, yet their impacts on the early viral kinetics remain unclear. In this study, associations between histology status and early viral kinetics were assessed in 149 HCV genotype 1-infected patients treated with pegylated interferon alfa-2a and ribavirin (DITTO trial). In multivariate analyses adjusted for critical factors such as IL28B genotype and baseline viral load, presence of significant fibrosis (Ishak stage > 2) was found to independently reduce the odds of achieving an initial reduction (calculated from day 0 to day 4) in HCV RNA of ≥2 logIU/mL (adjusted OR 0.03, P = 0.004) but was not associated with the second-phase slope of viral decline (calculated from day 8 to day 29). On the contrary, presence of liver steatosis was an independent risk factor for not having a rapid second-phase slope, that is, ≥0.3 logIU/mL/week (adjusted OR 0.22, P = 0.012) but was not associated with the first-phase decline. Viral kinetic modelling theory suggests that significant fibrosis primarily impairs the treatment antiviral effectiveness in blocking viral production by infected cells, whereas the presence of steatosis is associated with a lower net loss of infected cells. Further studies will be necessary to identify the biological mechanisms underlain by these findings.

Lipid profiling of pre-treatment liver biopsy tissue predicts sustained virological response in patients with chronic hepatitis C

AIM

  Hepatic lipid is important in the pathogenesis and progression of hepatitis C-related liver disease. Polyunsaturated fatty acids have been shown to reduce viral replication in cell culture. Proton magic angle spinning magnetic resonance spectroscopy ((1) H MAS MRS) enables metabolic analysis of intact tissue. The aim was to examine the relationship between hepatic lipid composition by metabolic profiling of liver tissue at baseline and treatment response to pegylated-Interferon alfa2 and Ribavirin.

METHODS

  Baseline liver biopsy samples from 31 patients with chronic hepatitis C were analyzed histologically and by (1) H MAS MRS. Indices of lipid composition were derived and partial least squares discriminant analysis with cross-validation was used to predict treatment outcome.

RESULTS

  Of 31 patients, 14 achieved sustained virological response (SVR). Lipid polyunsaturation (median (IQR)) was higher in SVR (3.41% (2.31)) than in treatment failure (TF) (2.15% (1.51)), P = 0.02. Lipid saturation was lower in SVR (85.9% (3.39)) than TF (86.7% (2.17)), P = 0.04. The total lipid content was lower in SVR (1.54% (0.81)) than TF (2.72% (3.47)), P = 0.004. Total choline to lipid ratio was higher in SVR (11.51% (9.99)) than TF (7.5% (6.82)), P = 0.007. Cross-validation correctly predicted the SVR group in 13 of 14 samples with 1 sample misclassified, and the TF group in all 17 samples.

CONCLUSIONS

  Lipid polyunsaturation was greater and total lipid lower in those with SVR, compared with TF. Metabolic profiling of intact liver biopsy samples predicted SVR with high accuracy. Hepatic lipid composition may impact on treatment success.

IL28B genetic polymorphism testing in the era of direct acting antivirals therapy for chronic hepatitis C: ten years too late?

An association between variations at the IL28B gene locus and HCV clearance (spontaneous recovery or sustained virological response under pegylated interferon (PEG-IFN) and ribavirin (RBV) has been extensively described. In genotype 1-infected patients, the new direct antiviral agents (DAA) including the two approved protease inhibitors boceprevir and telaprevir, in association with the PEG-IFN/RBV combination is the new standard of care making it necessary to redefine the interest of the IL28B genotype in the decision to treat and how to treat genotype 1-infected patients. In treatment-naïve patients, IL28B status can certainly identify those with a high probability of achieving SVR with response guided therapy and probably in whom the duration of treatment can be markedly reduced. In experienced patients, the impact of IL28B genotypes is limited and cancelled by early viral kinetics. However, the decision to initiate or withhold therapy remains a clinical one. In summary, although it was a major milestone in the treatment of patients with PEG-IFN/RBV, IL28B polymorphism testing entered the clinical arena almost 10 years too late.

IL28B alleles associated with poor hepatitis C virus (HCV) clearance protect against inflammation and fibrosis in patients infected with non-1 HCV genotypes

Genetic polymorphisms near IL28B are associated with spontaneous and treatment-induced clearance of hepatitis C virus (HCV), two processes that require the appropriate activation of the host immune responses. Intrahepatic inflammation is believed to mirror such activation, but its relationship with IL28B polymorphisms has yet to be fully appreciated. We analyzed the association of IL28B polymorphisms with histological and follow-up features in 2335 chronically HCV-infected Caucasian patients. Assessable phenotypes before any antiviral treatment included necroinflammatory activity (n = 1,098), fibrosis (n = 1,527), fibrosis progression rate (n = 1,312), and hepatocellular carcinoma development (n = 1,915). Associations of alleles with the phenotypes were evaluated by univariate analysis and multivariate logistic regression, accounting for all relevant covariates. The rare G allele at IL28B marker rs8099917-previously shown to be at risk of treatment failure-was associated with lower activity (P = 0.04), lower fibrosis (P = 0.02) with a trend toward lower fibrosis progression rate (P = 0.06). When stratified according to HCV genotype, most significant associations were observed in patients infected with non-1 genotypes (P = 0.003 for activity, P = 0.001 for fibrosis, and P = 0.02 for fibrosis progression rate), where the odds ratio of having necroinflammation or rapid fibrosis progression for patients with IL28B genotypes TG or GG versus TT were 0.48 (95% confidence intervals 0.30-0.78) and 0.56 (0.35-0.92), respectively. IL28B polymorphisms were not predictive of the development of hepatocellular carcinoma.

CONCLUSION

In chronic hepatitis C, IL28B variants associated with poor response to interferon therapy may predict slower fibrosis progression, especially in patients infected with non-1 HCV genotypes.

Liver protein profiling in chronic hepatitis C: identification of potential predictive markers for interferon therapy outcome

The current anti-hepatitis C virus (HCV) therapy, based on pegylated-interferon alpha and ribavirin, has limited success rate and is accompanied by several side effects. The aim of this study was to identify protein profiles in pretreatment liver biopsies of HCV patients correlating with the outcome of antiviral therapy. Cytosolic or membrane/organelle-enriched protein extracts from liver biopsies of eight HCV patients were analyzed by two-dimensional fluorescence difference gel electrophoresis and mass spectrometry. Overall, this analysis identified 21 proteins whose expression levels correlate with therapy response. These factors are involved in interferon-mediated antiviral activity, stress response, and energy metabolism. Moreover, we found that post-translational modifications of dihydroxyacetone kinase were also associated with therapy outcome. Differential expression of the five best performing markers (STAT1, Mx1, DD4, DAK, and PD-ECGF) was confirmed by immunoblotting assays in an independent group of HCV patients. Finally, we showed that a prediction model based on the expression levels of these markers classifies responder and nonresponder patients with an accuracy of 85.7%. These results provide evidence that the analysis of pretreatment liver protein profiles is valuable for discriminating between responder and nonresponder HCV patients, and may contribute to reduce the number of nonresponder patients exposed to therapy-associated risks.

Anti-viral therapy in haemodialysed HCV patients: efficacy, tolerance and treatment strategy

BACKGROUND

In end-stage renal disease (ESRD) patients, hepatitis C virus (HCV) eradication improves patient and graft survival.

AIM

To determine optimal use of erythropoietin (EPO) and ribavirin, to compare ribavirin concentrations with those of HCV patients having normal renal function and to evaluate sustained virological response (SVR) in a prospective observatory of ESRD candidates for renal transplantation.

METHODS

Thirty-two naïve patients were treated with Peg-IFN-α2a and ribavirin. Two different schedules of ribavirin and EPO administration were used: starting ribavirin at 600mg per week and adapting EPO when haemoglobin (Hb) fell below 10g/dL (adaptive strategy) or starting ribavirin at 1000mg per week while increasing EPO from the start of treatment (preventive strategy).

RESULTS

Patients treated with the adaptive strategy had lower median Hb levels (9.6 vs. 10.9g/dL, P=0.02) and more frequent median Hb levels below 10g/dL (58 vs. 5%, P=0.0007) despite lower median ribavirin doses (105 vs. 142mg/day, P<0.0001) than patients treated with the preventive strategy. There was a trend for more frequent transfusion in patients treated with the adaptive strategy than in patients treated with preventive strategy (50 vs. 20%, P=0.08). Compared to patients with normal renal function, ESRD patients had lower ribavirin concentrations during the first month (0.81 vs. 1.7mg/L, P=0.007) and similar concentrations thereafter. SVR was reached in 50%.

CONCLUSIONS

Pegylated interferon (Peg-IFN) and an adapted schedule of ribavirin are effective in ESRD patients. Increasing EPO from the start of treatment provides better haematological tolerance. The optimal dosage of ribavirin remains unresolved, in light of frequent side effects.

Soluble inflammatory markers as predictors of virological response in patients with chronic hepatitis C virus infection treated with interferon-α plus ribavirin

The host immune response plays an important role in viral clearance in patients who are chronically infected with hepatitis C virus (HCV) and are treated with interferon and ribavirin. Activation of the immune system involves the release of pro and anti-inflammatory molecules that can be measured in plasma samples. The present study aimed to evaluate the association between pretreatment plasma levels of chemokines and soluble tumor necrosis factor receptors (sTNF-R) and the virological response in treated patients with chronic hepatitis C infection. Forty-one chronically-infected HCV patients that were being treated with interferon-α (IFN-α) plus ribavirin were included in the study. Socio-demographic, clinical and laboratory data were collected and pretreatment plasma levels of chemokine CCL2, CCL3, CCL11, CCL24, chemokine CXCL9, CXCL10, sTNF-R1 and sTNF-R2 were measured. The virological response was assessed at treatment week 12, at the end of treatment and 24 weeks after treatment. Pretreatment CXCL10 levels were significantly higher in patients without an early virological response (EVR) or sustained virological response (SVR) compared to responders [512.9 pg/mL vs. 179.1 pg/mL (p = 0.011) and 289.9 pg/mL vs. 142.7 pg/mL (p = 0.045), respectively]. The accuracy of CXCL10 as a predictor of the absence of EVR and SVR was 0.79 [confidence interval (CI) 95%: 0.59-0.99] and 0.69 (CI 95%: 0.51-0.87), respectively. Pretreatment plasma levels of the other soluble inflammatory markers evaluated were not associated with a treatment response. Pretreatment CXCL10 levels were predictive of both EVR and SVR to IFN-α and ribavirin and may be useful in the evaluation of candidates for therapy.

Second-phase hepatitis C virus RNA decline during telaprevir-based therapy increases with drug effectiveness: implications for treatment duration

Hepatitis C virus (HCV) RNA decay during antiviral therapy is characterized by a rapid first phase, followed by a slower second phase. The current understanding of viral kinetics attributes the magnitude of the first phase of decay to treatment effectiveness, whereas the second phase of decay is attributed to the progressive loss of infected cells. Here, we analyzed data from 44 patients treated with telaprevir, a potent HCV protease inhibitor. Using a viral kinetic model that accounts for the pharmacokinetics of telaprevir, we found the second-phase slope of viral decline to be strongly correlated with treatment effectiveness and to be roughly four-fold more rapid than has been reported with interferon-based therapies. Because telaprevir is not known to increase the death rate of infected cells, our results suggest that the second-phase slope of viral decline is driven not only by the death of infected cells, but may also involve other mechanisms, such as a treatment-effectiveness-dependent degradation of intracellular viral RNA. As a result of the enhanced viral decay caused by the high antiviral effectiveness of telaprevir, we predict that if drug resistance could be avoided by using an appropriate combination of antiviral agents, treatment duration needed to clear HCV might be dramatically shortened. Indeed, we predict that in 95% of fully compliant patients, the last virus particle should be eliminated by week 7 of therapy. If the remaining infected hepatocytes act as a potential reservoir for the renewal of infection, no more than 10 weeks of treatment should be sufficient to clear the infection in 95% of fully compliant patients. However, if patients miss doses, treatment duration would need to be extended.

Genetic and biochemical diversity in the HCV NS5B RNA polymerase in the context of interferon α plus ribavirin therapy

The hepatitis C virus (HCV) RNA polymerase (RdRp) may be a target of the drug ribavirin, and it is an object of drug development. Independent isolates of any HCV subtype differ genetically by approximately 10%, but the effects of this variation on enzymatic activity and drug sensitivity are poorly understood. We proposed that nucleotide use profiles (G/U ratio) among subtype 1b RdRps may reflect their use of ribavirin. Here, we characterized how subtype 1b genetic variation affects RNA polymerase activity and evaluated the G/U ratio as a surrogate for ribavirin use during pegylated interferon α and ribavirin therapy. Genetic and biochemical variation in the RdRp was compared between responders who would be largely sensitive to ribavirin and relapsers who would be mostly resistant. There were no consistent genetic differences between responder and relapser RdRps. RNA polymerization, RNA binding and primer usage varied widely among the RdRps, but these parameters did not differ significantly between the response groups. The G/U ratio among a set of subtype 1a RdRps increased rather than decreased following failed therapy, as would be expected if it reflected ribavirin use. Finally, RdRp activity was significantly associated with ALT levels. These data indicate that (i) current genetic approaches cannot predict RNA polymerase behaviour, (ii) the G/U ratio is not a surrogate for ribavirin use, (iii) RdRp activity may contribute to liver disease by modulating viral mRNA and antigen levels, and (iv) drug candidates should be tested against multiple patient-derived enzymes to ensure widespread efficacy even within a viral subtype.

Differences in the factors associated with serum viral load between genotypes 1 and 2 in patients with chronic hepatitis C

PURPOSE

The serum hepatitis C virus (HCV) load is persistently stable in patients with untreated chronic hepatitis C, but its differences between individuals vary widely (above 4 logU/mL). Because serum viral load is an important factor for predicting clinical outcome of interferon-based antiviral therapy, this study was performed to clarify the factors associated with serum viral load in chronic hepatitis C patients.

METHODS

We retrospectively analyzed data from 669 chronic hepatitis C patients with HCV genotype 1 or 2 infection. Stepwise regression analysis was used to estimate the relationship between demographic, viral, or biochemical variables and serum viral load.

RESULTS

In univariate analysis, serum lipid profiles, such as total cholesterol, low-density lipoprotein (LDL) and triglyceride levels, and hemoglobin A1c (HbA1c) were correlated with the serum HCV viral load. In multivariate analysis, HCV genotype 1 infection and higher total cholesterol levels were associated with higher viral load. After stratification by HCV genotype, the serum viral load was associated with triglyceride and HbA1c in genotype 1 and with platelet counts and LDL in genotype 2. Histological data (413 patients) showed correlation between severe liver fibrosis and decreased serum viral load in patients with HCV genotype 2 but not genotype 1 infection.

CONCLUSIONS

These results suggest that viral kinetics is affected by different host factors for genotypes 1 and 2.

Design evaluation and optimization for models of hepatitis C viral dynamics

Mathematical modeling of hepatitis C viral (HCV) kinetics is widely used for understanding viral pathogenesis and predicting treatment outcome. The standard model is based on a system of five non-linear ordinary differential equations (ODE) that describe both viral kinetics and changes in drug concentration after treatment initiation. In such complex models parameter estimation is challenging and requires frequent sampling measurements on each individual. By borrowing information between study subjects, non-linear mixed effect models can deal with sparser sampling from each individual. However, the search for optimal designs in this context has been limited by the numerical difficulty of evaluating the Fisher information matrix (FIM). Using the software PFIM, we show that a linearization of the statistical model avoids most of the computational burden, while providing a good approximation to the FIM. We then compare the precision of the parameters that can be expected using five study designs from the literature. We illustrate the usefulness of rationalizing data sampling by showing that, for a given level of precision, optimal design could reduce the total number of measurements by up 50 per cent. Our approach can be used by a statistician or a clinician aiming at designing an HCV viral kinetics study.

A perspective on modelling hepatitis C virus infection

By mathematically describing early hepatitis C virus (HCV) RNA decay after initiation of interferon (IFN)-based antiviral therapy, crucial parameters of the in vivo viral kinetics have been estimated, such as the rate of production and clearance of free virus, and the rate of loss of infected cells. Furthermore, by suggesting mechanisms of action for IFN and ribavirin mathematical modelling has provided a means for evaluating and optimizing treatment strategies. Here, we review recent modelling developments for understanding complex viral kinetics patterns, such as triphasic HCV RNA declines and viral rebounds observed in patients treated with pegylated interferon and ribavirin. Moreover, we discuss new modelling approaches developed to interpret the viral kinetics observed in clinical trials with direct-acting antiviral agents, which induce a rapid decline of wild-type virus but also engender a higher risk for emergence of drug-resistant variants. Lastly, as in vitro systems have allowed a better characterization of the virus lifecycle, we discuss new modelling approaches that combine the intracellular and the extracellular viral dynamics.

Prediction of prognostic biomarkers for interferon-based therapy to hepatitis C virus patients: a meta-analysis of the NS5A protein in subtypes 1a, 1b, and 3a

Background

Hepatitis C virus (HCV) is a worldwide health problem with no vaccine and the only approved therapy is Interferon-based plus Ribavarin. Response prediction to treatment has health and economic impacts, and is a multi-factorial problem including both host and viral factors (e.g: age, sex, ethnicity, pre-treatment viral load, and dynamics of the HCV non-structural protein NS5A quasispecies). We implement a novel approach for extracting features including informative markers from mutations in the non-structural 5A protein (NS5A), specifically its Interferon sensitivity determining region (ISDR) and V3 regions, and use a novel bioinformatics approach for pattern recognition on the NS5A protein and its motifs to find biomarkers for response prediction using class association rules and comparing the predictability of the different features.

Results

A total of 58 sequences from sustained responders and 94 from non-responders were downloaded from the HCV LANL database. Site-specific signatures for response prediction from the NS5A protein were extracted from the alignments. Class association rules were generated (e.g.: sustained response is associated with position A2368T in subtype 1a (support 100% and confidence 52.19%); in subtype 1b, response is associated with E2356G/D/K (support 76.3% and confidence 67.3%).

Conclusion

The V3 region was a more accurate biomarker than the ISDR region. Subtype-specific class association rules gave better support and confidence than profile hidden Markov models HMMs scores, genetic distances or number of variable sites, and would thus aid in the prediction of prognostic biomarkers and improve the accuracy of prognosis. Sites-specific class association rules in the V3 region of the NS5A protein have given the best support and confidence.

High diversity of hepatitis C viral quasispecies is associated with early virological response in patients undergoing antiviral therapy

Differential response patterns to optimal antiviral therapy, peginterferon alpha plus ribavirin, are well documented in patients with chronic hepatitis C virus (HCV) infection. Among many factors that may affect therapeutic efficiency, HCV quasispecies (QS) characteristics have been a major focus of previous studies, yielding conflicting results. To obtain a comprehensive understanding of the role of HCV QS in antiviral therapy, we performed the largest-ever HCV QS analysis in 153 patients infected with HCV genotype 1 strains. A total of 4,314 viral clones spanning hypervarible region 1 were produced from these patients during the first 12 weeks of therapy, followed by detailed genetic analyses. Our data show an exponential distribution pattern of intrapatient QS diversity in this study population in which most patients (63%) had small QS diversity with genetic distance (d) less than 0.2. The group of patients with genetic distance located in the decay region (d>0.53) had a significantly higher early virologic response (EVR) rate (89.5%), which contributed substantially to the overall association between EVR and increased baseline QS diversity. In addition, EVR was linked to a clustered evolutionary pattern in terms of QS dynamic changes.

CONCLUSION

EVR is associated with elevated HCV QS diversity and complexity, especially in patients with significantly higher HCV genetic heterogeneity.

Mathematical modeling of HCV infection and treatment

In the last decade, viral kinetic modeling has played an important role in the analysis of HCV RNA decay after the initiation of antiviral therapy. Models have provided a means of evaluating the antiviral effectiveness of therapy and of estimating parameters, such as the rate of virion clearance and the rate of loss of HCV-infected cells, and they have suggested mechanisms of action for both interferon-alpha and ribavirin. The inclusion of homeostatic proliferation of infected and uninfected hepatocytes in existing viral kinetic models has allowed prediction of most observed HCV RNA profiles under treatment, for example, biphasic and triphasic viral decay and viral rebound to baseline values after the cessation of therapy. In addition, new kinetic models have taken into consideration the different pharmacokinetics of standard and pegylated forms of interferon and have incorporated alanine aminotransferase kinetics and aspects of immune responses to provide a more comprehensive picture of the biology underlying changes in HCV RNA during therapy. Here, we describe our current understanding of the kinetics of HCV infection and treatment.

Virological relapse in chronic hepatitis C

Approximately one-third of all patients infected with hepatitis C virus (HCV) genotype 1 who complete pegylated interferon α-based therapy and have undetectable serum HCV RNA at the end of treatment will experience relapse. Although relapse is a common outcome of therapy, its pathology and strategies for optimal management are poorly understood; however, optimized ribavirin dosing is recognized as pivotal in mitigating relapse. Recent data also suggest that early viral kinetics might help identify particular patient groups, such as slow responders, who are predisposed to relapse. This review provides a comprehensive overview of the importance of relapse in patients with chronic hepatitis C, including its underlying pathobiology, potential predictors and strategies to optimize the retreatment of previous relapsers.

A mathematical model of hepatitis C virus dynamics in patients with high baseline viral loads or advanced liver disease

BACKGROUND & AIMS

Patients with baseline hepatitis C virus-RNA levels (bHCV-RNA)>6 log IU/mL or cirrhosis have a reduced probability of a sustained-virologic response (SVR). We examined the relation between bHCV-RNA, cirrhosis, and SVR with a mathematical model that includes the critical-drug efficacy (epsilonc; the efficacy required for a drug to clear HCV), the infection-rate constant (beta), and the percentage of HCV-infected hepatocytes (pi).

METHODS

The relation between baseline factors and SVR was evaluated in 1000 in silico HCV-infected patients, generated by random assignment of realistic host and viral kinetic parameters. Model predictions were compared with clinical data from 170 noncirrhotic and 75 cirrhotic patients.

RESULTS

The ranges chosen for beta and the viral production rate (p) resulted in bHCV-RNA levels that were in agreement with the distribution observed in US patients. With these beta and p values, higher bHCV-RNA levels led to higher epsilonc, resulting in lower SVR rates. However, higher beta values resulted in lower bHCV-RNA levels but higher pi and (epsilonc), predicting lower rates of SVR. Cirrhotic patients had lower bHCV-RNA levels than noncirrhotic patients (P=.013), and more had bHCV-RNA levels<6 log IU/mL (P<.001). Even cirrhotic patients with lower bHCV-RNA levels had lower SVR rates. An increase in beta could explain the results observed in cirrhotic patients.

CONCLUSIONS

Our model predicts that higher bHCV-RNA levels lead to higher epsilonc, reducing the chance of achieving SVR; cirrhotic patients have lower SVR rates because of large pi values, caused by increased rates of hepatocyte infection.

Trends in the Treatment of Chronic Hepatitis C Virus Infection

Despite reductions in the incidence of new hepatitis C virus infections, infections from previous decades continue to place a substantial burden on our health care system. Although the course of the disease is highly variable, approximately 20% to 30% of patients develop cirrhosis, end-stage liver disease, or hepatocellular carcinoma. Fortunately, treatment with our current standard of care, peginterferon a and ribavirin, can reduce the complications of chronic liver disease. However, these drugs are associated with significant adverse effects, many patients are ineligible for treatment, and only 50% are cured. Thus, there is a tremendous need to improve our current therapies and develop new compounds for this disease. This review highlights the transmission, pathophysiology, and course of illness; the pharmacokinetics, proposed mechanisms of action, adverse events, and potential drug interactions with peginterferon a and ribavirin; current treatment trends; the role of the pharmacist in the treatment of this disease; and investigational drugs in later stages of clinical development. Despite the initial hope that these new drugs would replace our current standard of care, it has become clear that ribavirin and peginterferon a will continue to play an important role in the treatment of chronic hepatitis C virus in the years to come.

Optimal therapy in genotype 1 patients

Most infections with hepatitis C virus (HCV) fail to resolve spontaneously and progress to chronic hepatitis C. Genotype 1 HCV accounts for most hepatitis C infections in North America, Western Europe, and Japan. Patients infected with HCV genotype 1 are the most resistant to treatment, which results in poor treatment outcomes. Although sustained virologic response (SVR) rates have significantly improved with introduction of combination therapy with pegylated interferon alfa and ribavirin, the rates are still lower than those in genotype 2 or 3 infections. This review discusses how treatment outcomes in patients with HCV genotype 1 infection can be optimized by using the drugs currently licensed for treatment of hepatitis C: pegylated interferon alfa-2a/b and ribavirin. Dose modifications and variations of treatment duration are the two strategies that have been investigated best, so far. Treatment--naïve patients and non-responders and relapsers to prior antiviral therapy are discussed separately.

Antiviral combination therapy for treatment of chronic hepatitis B, hepatitis C, and human immunodeficiency virus infection

This chapter reviews the main chemotherapeutic strategies used against human infections caused by agents responsible for the most important chronic viral illnesses, namely hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). There is no doubt that most current knowledge about combination antiviral therapy has been developed in the battle against HIV. The availability of more than 20 antiretroviral drugs has permitted to explore their efficacy when given in combination, an opportunity that unfortunately has only been possible since recent years for chronic hepatitis C and still is in the early stages for chronic hepatitis B. However, new antiviral compounds targeting each of these viruses are developed rapidly and will provide further opportunities to explore the efficacy of combination antiviral therapy. While sufficient suppression of HIV RNA and HBV DNA can only be achieved by long-term administration of potent antiviral drugs, HCV RNA may be completely eradicated from the infected individual after a limited duration of treatment.

"12 weeks' stopping rule" in the treatment of genotype 1 chronic hepatitis C: two prognostic categories under the same label?

OBJECTIVE

The current guidelines recommend maintenance of combined therapy for hepatitis C virus (HCV) genotype-1 chronic hepatitis when HCV-RNA is undetectable or < or = 2 log10 of baseline after 12 weeks of therapy. The aim of this study was to investigate whether the probability of obtaining sustained viral (SVR) response is similar when HCV-RNA is undetectable or is present at < or = 2 log10 level after 12 weeks of therapy.

MATERIAL AND METHODS

Retrospective analysis was carried out in 208 HCV genotype-1 chronic hepatitis patients treated with pegylated interferon and ribavirin with available data on HCV viral load after 12 weeks of therapy and definite data on the results of therapy.

RESULTS

Seventy-six (68.5%) out of 111 patients with undetectable HCV-RNA and 4 (11.8%) out of 34 patients with HCV-RNA < or = 2 log10 from baseline at week 12 reached SVR (odds ratio 16.29, 95% CI 5.08-67.12; p < 0.001). Sixty-three patients did not meet any of these criteria and therapy was discontinued.

CONCLUSIONS

The "12-week stopping rule" includes two different categories of responders considered candidates for maintained therapy, but the probability of obtaining SVR is very low in patients with HCV-RNA that is still detectable at this time of treatment. We suggest that, in these partial responders, the prolongation of therapy should be decided on an individual basis.

Baseline serum low-density lipoprotein cholesterol levels predict response to hepatitis C virus therapy in HIV/hepatitis C virus coinfected patients

BACKGROUND

High levels of serum low-density lipoprotein cholesterol are associated with better response to pegylated interferon and ribavirin in hepatitis C virus monoinfected patients. There are no data concerning this topic in HIV/hepatitis C virus coinfected patients in whom lipid disorders are particularly common.

OBJECTIVE

To assess the association between baseline lipid levels and sustained virologic response to pegylated interferon and ribavirin in coinfected patients.

METHODS

A total of 260 HIV/hepatitis C virus coinfected patients under treatment with pegylated interferon and ribavirin and who had a baseline serum lipid profile were included in this retrospective study.

RESULTS

Thirty-eight (24%) patients with genotypes 1-4 and 64 (63%) with genotypes 2-3 achieved sustained virologic response. Forty-nine (44%) patients with serum low-density lipoprotein cholesterol levels 100 mg/dl or more showed sustained virologic response compared with 53 (36%) with lower values [adjusted odds ratio: 2.51; 95% confidence interval: 1.40-4.87; P = 0.003]. This association was independent of the remaining predictors of sustained virologic response which were genotypes 2-3, plasma hepatitis C virus RNA 600,000 IU/ml or less, exposure to at least 80% of the planned therapy and lack of concomitant antiretroviral therapy. The rate of sustained virologic response in patients with genotype 1 and low-density lipoprotein cholesterol at least 100 mg/ml was 31% compared with 17% in those with lower values (adjusted odds ratio: 2.19; 95% confidence interval: 1.04-4.66; P = 0.040). The corresponding figures in subjects with genotypes 2-3 were 73 and 58% [2.71 (0.99-7.46); P = 0.054]. No other lipid was associated with response.

CONCLUSION

Higher low-density lipoprotein cholesterol levels predict sustained virologic response to pegylated interferon and ribavirin in HIV/hepatitis C virus coinfected patients. This might be used to improve the rate of sustained virologic response in this setting.

Prediction of efficient virological response to pegylated interferon/ribavirin combination therapy by NS5A sequences of hepatitis C virus and anti-NS5A antibodies in pre-treatment sera

A considerable number of patients infected with Hepatitis C virus subtype 1b (HCV-1b) do not respond to pegylated interferon/ribavirin combination therapy. In this study we explored a useful factor(s) to predict treatment outcome. A total of 47 HCV-1b-infected patients were treated with pegylated interferon/ ribavirin for 48 weeks. Sera of the patients were examined for the entire NS5A sequence of the HCV genome, HCV RNA titers and anti-NS5A antibodies. According to their responses, the patients were divided into two groups, early viral responders who cleared the virus by week 16 (EVR[16w]) and those who did not (Non-EVR[16w]). The mean number of mutations in the V3 region (aa 2356 to 2379) or that in the V3 region plus its N-terminally flanking region, which we refer to as interferon/ribavirin resistancedetermining region (IRRDR; aa 2334 to 2379), of NS5A obtained from the pretreatment sera was signifi-cantly larger for EVR(16w) compared with Non-EVR(16w). Moreover, HCV-1b isolates with > or =5 mutations in V3 or those with > or =6 mutations in IRRDR were almost exclusively found in EVR(16w). Also, the presence of detectable levels of anti-NS5A antibodies in the pretreatment sera was closely associated with EVR(16w). In conclusion, a high degree of sequence variation in V3 (> or =5) or IRRDR (> or =6) and the presence of detectable levels of anti-NS5A antibodies in the pretreatment sera would be useful factors to predict EVR(16w). On the other hand, a less diverse sequence in V3 (< or =4) or IRRDR (< or =5) together with the absence of detectable anti-NS5A antibodies could be a predictive factor for Non-EVR(16w).

Defining Optimal Therapeutic Outcomes in Chronic Hepatitis

The definition of optimal therapeutic response has been evolving concurrent with the advancement of diagnostic tests. What once was considered "therapeutic success" is considered now disease persistence or relapse. As the laboratory tools become increasingly sensitive, it follows that the criteria of successful therapeutic response are becoming more stringent. The main objectives of chronic hepatitis B and C treatment are to achieve eradication of the virus and, with this, reduction or prevention of hepatic injury and disease progression. However, in the case of hepatitis B, viral suppression is for the moment a more realistic therapeutic objective, although eradication still remains the ultimate goal. In chronic hepatitis C, sustained virologic response, defined as the absence of HCV RNA 6 months post-antiviral treatment completion, is within reach. Better test sensitivity allows for additional levels of confidence in the achievements of virus eradication in patients with hepatitis C. Challenges persist despite great advances in the treatment of chronic viral hepatitis. Now that clearer therapeutic outcomes have been refined, more efficacious, and better-tolerated drugs may change the current therapeutic landscape of chronic viral hepatitis B and C.

Pretreatment sequence diversity differences in the full-length hepatitis C virus open reading frame correlate with early response to therapy

Pegylated alpha interferon and ribavirin therapy for hepatitis C virus (HCV) genotype 1 infection fails for half of Caucasian American patients (CA) and more often for African Americans (AA). The reasons for these low response rates are unknown. HCV is highly genetically variable, but it is unknown how this variability affects response to therapy. To assess effects of viral diversity on response to therapy, the complete pretreatment genotype 1 HCV open reading frame was sequenced using samples from 94 participants in the Virahep-C study. Sequences from patients with >3.5 log declines in viral RNA levels by day 28 (marked responders) were more variable than those from patients with declines of <1.4 log (poor responders) in NS3 and NS5A for genotype 1a and in core and NS3 for genotype 1b. These correlations remained when all T-cell epitopes were excluded, indicating that these differences were not due to differential immune selection. When the sequences were compared by race of the patients, higher diversity in CA patients was found in E2 and NS2 but only for genotype 1b. Core, NS3, and NS5A can block the action of alpha interferon in vitro; hence, these genetic patterns are consistent with multiple amino acid variations independently impairing the function of HCV proteins that counteract interferon responses in humans, resulting in HCV strains with variable sensitivity to therapy. No evidence was found for novel HCV strains in the AA population, implying that AA patients may be infected with a higher proportion of the same resistant strains that are found in CA patients.

Hepatitis C: a challenge to hepatologists and to the liver transplantation team

Hepatitis C is the main cause of cirrhosis and hepatocellular carcinoma and the leading indication of liver transplantation. The aim of this article was to review specific epidemiological, clinical and therapeutic aspects of hepatitis C and their implication for the hepatologists belonging to liver transplantation services. These specific aspects were reviewed in the literature mainly using Medline. Data regarding the epidemiological, clinical and therapeutic aspects of hepatitis C are discussed, with emphasis on their consequences for the liver transplantation team. Hepatitis C is a challenge for hepatologists and for the liver transplantation team. The burden we observe today is the late consequence of infection that occurred in the past. Measures for early recognition of complications of liver disease are recommended. HCV treatment should always be performed before liver transplantation if possible, but if not, HCV recurrence should be recognized and treated early after transplantation.