Refinement of stopping rules during treatment of hepatitis C genotype 1 infection with boceprevir and peginterferon/ribavirin

Current therapeutics against HCV

Hepatitis C is a positive stranded enveloped RNA virus belonging to the Flaviviridae family. HCV infection leads to severe liver diseases, cirrhosis and hepatocellular carcinoma worldwide. Although treatments have been available for a while, due to its complexity and genetic diversity, only few are reported to be effective against all HCV genotypes. Here, we review the HCV life cycle and its immunogenic potential and various mechanisms via which the virus interferes in the signalling process. A comprehensive overview of current anti-HCV therapeutics, such as, Direct Acting Antiviral (DAA) as well as Host Targeting Agents (HTA), along with their scope, known mechanism of action and limitations are presented.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-021-00697-0.

On-treatment HCV RNA in patients with varying degrees of fibrosis and cirrhosis in the SOLAR-1 trial

BACKGROUND

In the Phase II SOLAR-1 study, 12 or 24 weeks of ledipasvir/sofosbuvir and ribavirin yielded high sustained virological response rates at 12 weeks (SVR12) in patients with chronic HCV infection and advanced liver disease, including untransplanted patients with decompensated cirrhosis and liver transplant recipients with all stages of liver disease.

METHODS

We performed a post hoc analysis using data from this study to investigate associations between baseline characteristics and early on-treatment HCV RNA, and to determine the utility of early virological response (week 2 and 4) to predict SVR12. Serum HCV RNA was quantified using the Roche COBAS^® Ampliprep^®/Cobas TaqMan HCV Test, Version 2.0 with a lower limit of quantification (LLOQ) of 15 IU/ml.

RESULTS

Most patients achieved HCV RNA <LLOQ by treatment week 4 and target not detected (TND) by week 6. Baseline factors significantly associated with HCV RNA <LLOQ at week 2 were low HCV RNA (<800,000 IU/ml), absence of cirrhosis, age <60 years and no prior treatment experience. At week 4, low HCV RNA, absence of cirrhosis and IL28B CC were associated with <LLOQ, TND. No baseline factors were associated with week 6 response. There was no association between early on-treatment HCV RNA and SVR12.

CONCLUSIONS

On-treatment HCV RNA quantification is of limited clinical use in patients with advanced liver disease and/or liver transplantation and does not predict SVR12. ClinicalTrials.gov: NCT01938430.

Recent Advances in Antiviral Therapy for Chronic Hepatitis C

Hepatitis C virus (HCV) infection is a major worldwide health problem. Chronic infection induces continuous inflammation in the liver, progression of hepatic fibrosis, eventual cirrhosis, and possible hepatocellular carcinoma. Eradication of the virus is one of the most important treatment aims. A number of promising new direct-acting antivirals (DAAs) have been developed over the past 10 years. Due to their increased efficacy, safety, and tolerability, interferon-free oral therapies with DAAs have been approved for patients with HCV, including those with cirrhosis. This review introduces the characteristics and results of recent clinical trials of several DAAs: NS3/4A protease inhibitors, NS5A inhibitors, and NS5B inhibitors. DAA treatment failure and prognosis after DAA therapy are also discussed.

Importance of virological response in the early stage of telaprevir-based triple therapy for hepatitis C

AIM: To investigate the efficacy of virological response (VR) to telaprevir (TVR)-based triple therapy in predicting treatment outcome of hepatitis C.

METHODS: This prospective, multicenter study consisted of 253 Japanese patients infected with hepatitis C virus (HCV) genotype 1b. All received 12 wk of TVR in combination with 24 wk of pegylated-interferon-α (IFN-α) and ribavirin. Serum HCV RNA was tested at weeks 1, 2, 3, 4, 6, 8, 12, 16, 20, and 24. VR was defined as undetectable serum HCV RNA. Sustained virological response (SVR) was VR at 24 wk after the end of treatment and was regarded as a successful outcome.

RESULTS: Of 253 patients, 207 (81.8%) achieved SVR. The positive predictive value of VR for SVR was 100% at week 2, after which it gradually decreased, and was over 85% to week 12. The negative predictive value (NPV) gradually increased, reaching 100% at week 12. The upslope of the NPV showed a large increase from week 4 (40.6%) to week 6 (82.4%). There was a moderate concordance between the SVR and VR at week 6 (kappa coefficient = 0.44), although other VRs had poor concordance to SVR. Multiple logistic regression analysis extracted VR at week 6 (P < 0.0001, OR = 63.8) as an independent factor contributing to SVR. In addition, the interleukin-28B single nucleotide polymorphism and response to previous pegylated-IFN-α and ribavirin therapy were identified as independent factors for SVR.

CONCLUSION: VR at week 6, but not at week 4, is an efficient predictor of both SVR and non-SVR to TVR-based triple therapy.

Cost-effectiveness of non-invasive methods for assessment and monitoring of liver fibrosis and cirrhosis in patients with chronic liver disease: systematic review and economic evaluation

BACKGROUND

Liver biopsy is the reference standard for diagnosing the extent of fibrosis in chronic liver disease; however, it is invasive, with the potential for serious complications. Alternatives to biopsy include non-invasive liver tests (NILTs); however, the cost-effectiveness of these needs to be established.

OBJECTIVE

To assess the diagnostic accuracy and cost-effectiveness of NILTs in patients with chronic liver disease.

DATA SOURCES

We searched various databases from 1998 to April 2012, recent conference proceedings and reference lists.

METHODS

We included studies that assessed the diagnostic accuracy of NILTs using liver biopsy as the reference standard. Diagnostic studies were assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Meta-analysis was conducted using the bivariate random-effects model with correlation between sensitivity and specificity (whenever possible). Decision models were used to evaluate the cost-effectiveness of the NILTs. Expected costs were estimated using a NHS perspective and health outcomes were measured as quality-adjusted life-years (QALYs). Markov models were developed to estimate long-term costs and QALYs following testing, and antiviral treatment where indicated, for chronic hepatitis B (HBV) and chronic hepatitis C (HCV). NILTs were compared with each other, sequential testing strategies, biopsy and strategies including no testing. For alcoholic liver disease (ALD), we assessed the cost-effectiveness of NILTs in the context of potentially increasing abstinence from alcohol. Owing to a lack of data and treatments specifically for fibrosis in patients with non-alcoholic fatty liver disease (NAFLD), the analysis was limited to an incremental cost per correct diagnosis. An analysis of NILTs to identify patients with cirrhosis for increased monitoring was also conducted.

RESULTS

Given a cost-effectiveness threshold of £20,000 per QALY, treating everyone with HCV without prior testing was cost-effective with an incremental cost-effectiveness ratio (ICER) of £9204. This was robust in most sensitivity analyses but sensitive to the extent of treatment benefit for patients with mild fibrosis. For HBV [hepatitis B e antigen (HBeAg)-negative)] this strategy had an ICER of £28,137, which was cost-effective only if the upper bound of the standard UK cost-effectiveness threshold range (£30,000) is acceptable. For HBeAg-positive disease, two NILTs applied sequentially (hyaluronic acid and magnetic resonance elastography) were cost-effective at a £20,000 threshold (ICER: £19,612); however, the results were highly uncertain, with several test strategies having similar expected outcomes and costs. For patients with ALD, liver biopsy was the cost-effective strategy, with an ICER of £822.

LIMITATIONS

A substantial number of tests had only one study from which diagnostic accuracy was derived; therefore, there is a high risk of bias. Most NILTs did not have validated cut-offs for diagnosis of specific fibrosis stages. The findings of the ALD model were dependent on assuptions about abstinence rates assumptions and the modelling approach for NAFLD was hindered by the lack of evidence on clinically effective treatments.

CONCLUSIONS

Treating everyone without NILTs is cost-effective for patients with HCV, but only for HBeAg-negative if the higher cost-effectiveness threshold is appropriate. For HBeAg-positive, two NILTs applied sequentially were cost-effective but highly uncertain. Further evidence for treatment effectiveness is required for ALD and NAFLD.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42011001561.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

[Lead-in period and week 8 as predictive tools for response to boceprevir therapy: a retrospective study of Spanish real clinical practice]

INTRODUCTION

Most discontinuations due to lack of virological response occur during the first few weeks of hepatitis C virus (HCV) triple therapy. Improved knowledge of baseline factors and their correlation with boceprevir decision points may predict treatment success.

METHODS

An observational, retrospective study was conducted to describe the lead-in period as a clinical decision tool in HCV genotype 1 patients treated with boceprevir. Data were collected from the medical records of 186 consecutive patients distributed across 20 Spanish general hospitals.

RESULTS

This study included 171 patients. A total of 80% had fibrosis F3/F4, 74% were previously treated, and 26% were treatment-naïve. After the lead-in period, 54.5% of the patients had a reduction of ≥1 log10; this reduction occurred in 52.5% of those with advanced fibrosis. Boceprevir therapy was started in 94% of the patients. Discontinuations at week 4 were limited to null responders with cirrhosis. The baseline factors associated with virological response at week 4 were IL28B, previous response, and fibrosis score. At week 8, HCV-RNA was undetectable in 48.8% of the patients. The correlation between responses at weeks 8 and 12 was 88%.

CONCLUSION

In the Spanish clinical setting, lead-in was mainly used as a clinical decision point for non-responders with cirrhosis. The good correlation between stopping rules at weeks 8 and 12 could be used to anticipate discontinuation, thus saving adverse events and costs.

Rapid Prediction of Treatment Futility of Boceprevir with Peginterferon-Ribavirin for Taiwanese Treatment Experienced Hepatitis C Virus Genotype 1-Infected Patients

The efficacy and safety of the boceprevir (BOC)-containing triple therapy in Taiwanese treatment-experienced patients remains elusive. After 4 weeks of peginterferon/ribavirin lead-in therapy, patients with cirrhosis or previous null-response received triple therapy for 44 weeks; whereas others received 32 weeks of triple therapy followed by 12 weeks of peginterferon/ribavirin therapy. Patients with HCV RNA > 100 IU/mL at week 12 or with detectable HCV RNA at week 24 of treatment were viewed as futile. A total of 123 patients received treatment. The rates of sustained virological response (SVR) and relapse were 66.7% and 8.9%, respectively by using intention-to-treat analysis. Multivariate analysis revealed that factors associated with SVR included HCV-1b (odds ratio [OR]/ 95% confidence intervals [CI]: 19.23/1.76-525.15, P = 0.01), BOC adherence (7.69/1.55-48.78, P = 0.01), serum albumin (OR/CI:6.25/1.14-40.07, P = 0.03) levels and HCV RNA levels (OR/CI:0.34/0.12-0.79, P = 0.01). Twenty-six (21.1%) patients experienced severe adverse events (SAEs). Multivariate analysis revealed that APRI > 1.5 was the single factor associated with occurring SAEs (OR/CI: 3.77/ 0.97-14.98, P = 0.05). Merging the cut-off values of HCV RNA > 7 log IU/mL at baseline and HCV RNA > 6 log IU/mL at week 4 provided the earliest and best combing viral kinetics in predicting week 12/24 futility with the PPV of 100% and accuracy of 93.5%. HCV-1 treatment experienced Taiwanese patients treated with boceprevir-containing triple therapy in real world had comparable efficacy and safety profiles with those reported in clinical trials. Early viral kinetics before week 4 of treatment highly predicted futility at week 12 or 24 of treatment.

The Usefulness of Defining Rapid Virological Response by a Very Sensitive Assay (TMA) during Treatment of HCV Genotype 2/3 Infection

The aim of this study was to determine in patients with HCV genotype 2 or 3 the performance at week 4 of two assays with different sensitivities for HCV RNA detection, for the prediction of SVR and stratification for treatment duration (14 and 24 weeks). Recruitment was from two trials comparing 14 and 24 weeks treatment to patients with rapid virological response (RVR) (n = 550). RVR was originally defined as HCV RNA <50 IU/ml at week 4. Patients with an available frozen plasma sample drawn at week 4 and with follow-up data week 24 post-treatment were included (n = 429). HCV-RNA was prospectively measured with COBAS Amplicor V2, Roche (CA) (lower detection limit 50 IU/ml) and retrospectively assessed with VERSANT HCV-RNA Qualitative Assay, Siemens (TMA) (lower limit detection 10 IU/ml). Genotype 3 was present in 80% and genotype 2 in 20%. A SVR was achieved in 82%. At week 4 HCV-RNA was undetectable in 74.8% and 63% of serum samples tested with CA and TMA, respectively. CA undetectable/TMA positive was observed in 61/341 (18%) of the samples. In genotype 3 patients a relapse was seen in 9% of the patients with both CA and TMA undetectable and in 25% of the patients who were CA undetectable/TMA positive (p = 0.006). In patients allocated to 14 weeks treatment a relapse was observed in 11% of TMA undetectable patients and 26% of TMA positive (p = 0.031). In genotype 2 patients treated for 14 weeks relapse was observed in 6% of the patients with both CA and TMA undetectable week 4. Assays with high sensitivity for HCV RNA identifies patients at week 4 with high risk of virological relapse. We recommend that patients with genotype 3 and detectable HCV RNA at levels below 50 IU/ml do not receive truncated therapy with pegIFN and ribavirin.

Performance characteristics of the VERSANT hepatitis C virus RNA 1.0 (kPCR) assay

HCV RNA assays are of central importance for virological diagnostics and for clinical planning and monitoring of an antiviral combination treatment of chronic HCV infections. The objective of the pre-market evaluation of the VERSANT HCV RNA 1.0 Assay (kPCR) was to collect analytical performance data for this new method of HCV RNA quantification and to compare them with the high standards that exist in this context. The assay exhibited a specificity of 100%. The mean intra- and inter-assay imprecision was 14.1% and 14.6%, respectively. The detection limit was determined to be 16IU/ml (95% confidence interval: 11.9-30.6IU/ml) and consequently corresponded to the manufacturer's claims (i.e. 15IU/ml). The test exhibited linearity for all HCV genotypes in a broad range from 15 to 10(8)IU HCV RNA/ml. Hence, the kPCR assay in general is well suitable for HCV RNA determinations in clinical practice. However, in a methodological comparison, a considerable under-quantification of the concentrations of HCV genotype 2 and 3 isolates was detected. Provided that the assay's manufacturer will quickly remedy this shortcoming, the VERSANT HCV RNA 1.0 (kPCR) can be called a completely reliable technique for HCV RNA quantification in routine virological diagnostics.

Virological outcomes and treatment algorithms utilisation in observational study of patients with chronic hepatitis C treated with boceprevir or telaprevir

BACKGROUND

HCV-TARGET is a longitudinal observational study of chronic hepatitis C virus (HCV) patients treated with direct-acting anti-viral agents (DAAs) in a US consortium of 90 academic and community medical centres.

AIM

To assess utilisation of response-guided therapy (RGT) and sustained virological response (SVR) of a large cohort of patients.

METHODS

Patients received peginterferon (PEG-IFN), ribavirin and either telaprevir or boceprevir. Demographical, clinical and virological data were collected during treatment and follow-up. RGT and treatment futility stopping rules was assessed at key time points.

RESULTS

Of 2084 patients, 38% had cirrhosis and 56% had received prior treatment for HCV. SVR rates were 31% (95% CI: 24-40) and 50% (95% CI: 44-56) in boceprevir patients with and without cirrhosis, respectively. SVR rates were 46% (95% CI: 42-50) and 60% (95% CI: 57-64) in telaprevir patients with and without cirrhosis, respectively. Early clearance of virus, IL28B genotype, platelet counts and diabetes were identified as predictors of SVR among boceprevir patients, while early clearance of virus, IL28B, cirrhosis, HCV subtype, age, haemoglobin, bilirubin and albumin levels were identified as predictors of SVR for telaprevir patients.

CONCLUSIONS

In academic and community centres, triple therapy including boceprevir or telaprevir led to SVR rates somewhat lower than those noted in large phase 3 clinical trials. Response rates were consistently higher among patients without cirrhosis compared to those with cirrhosis regardless of DAA used and prior treatment response. Trial registration clinicaltrials.gov NCT01474811.

Hepatitis C

Hepatitis C virus (HCV) infection is a major health problem worldwide. The effects of chronic infection include cirrhosis, end-stage liver disease, and hepatocellular carcinoma. As a result of shared routes of transmission, co-infection with HIV is a substantial problem, and individuals infected with both viruses have poorer outcomes than do peers infected with one virus. No effective vaccine exists, although persistent HCV infection is potentially curable. The standard of care has been subcutaneous interferon alfa and oral ribavirin for 24-72 weeks. This treatment results in a sustained virological response in around 50% of individuals, and is complicated by clinically significant adverse events. In the past 10 years, advances in HCV cell culture have enabled an improved understanding of HCV virology, which has led to development of many new direct-acting antiviral drugs that target key components of virus replication. These direct-acting drugs allow for simplified and shortened treatments for HCV that can be given as oral regimens with increased tolerability and efficacy than interferon and ribavirin. Remaining obstacles include access to appropriate care and treatment, and development of a vaccine.

Performance of two HCV RNA assays during protease inhibitor-based triple therapy in patients with advanced liver fibrosis and cirrhosis

Introduction

On-treatment HCV RNA measurements are crucial for the prediction of a sustained virological response (SVR) and to determine treatment futility during protease inhibitor-based triple therapies. In patients with advanced liver disease an accurate risk/benefit calculation based on reliable HCV RNA results can reduce the number of adverse events. However, the different available HCV RNA assays vary in their diagnostic performance.

Aim

To investigate the clinical relevance of concordant and discordant results of two HCV RNA assays during triple therapy with boceprevir and telaprevir in patients with advanced liver fibrosis/cirrhosis.

Methods

We collected on-treatment samples of 191 patients with advanced liver fibrosis/cirrhosis treated at four European centers for testing with the Abbott RealTime (ART) and COBAS AmpliPrep/COBAS TaqMan HCV v2.0 (CTM) assays.

Results

Discordant test results for HCV RNA detectability were observed in 23% at week 4, 17% at week 8/12 and 9% at week 24 on-treatment. The ART detected HCV RNA in 41% of week 4 samples tested negative by the CTM. However, the positive predictive value of an undetectable week 4 result for SVR was similar for both assays (80% and 82%). Discordance was also found for application of stopping rules. In 27% of patients who met stopping rules by CTM the ART measured levels below the respective cut-offs of 100 and 1000 IU/ml, respectively, which would have resulted in treatment continuation. In contrast, in nine patients with negative HCV RNA by CTM at week 24 treatment would have been discontinued due to detectable residual HCV RNA by the ART assay. Importantly, only 4 of these patients failed to achieve SVR.

Conclusion

Application of stopping rules determined in approval studies by one assay to other HCV RNA assays in clinical practice may lead to over and undertreatment in a significant number of patients undergoing protease inhibitor-based triple therapy.

Cost-effectiveness analysis of sofosbuvir plus peginterferon/ribavirin in the treatment of chronic hepatitis C virus genotype 1 infection

BACKGROUND

Sofosbuvir, an oral NS5B nucleotide polymerase inhibitor, is indicated for the treatment of patients infected with hepatitis C virus (HCV).

AIM

To evaluate the long-term health economic outcomes of sofosbuvir + pegylated interferon alfa/ribavirin (pegIFN/RBV) compared with current treatments in patients infected with HCV genotype 1 in the US.

METHODS

A decision-analytic Markov model was developed to estimate health outcomes, number needed to treat and short-term and long-term economic outcomes, including incremental cost-effectiveness ratios and cost per sustained virological response (SVR), for several sofosbuvir-comparator regimen pairings for a cohort of 10 000 patients. It considered three patient cohorts: treatment-naïve, treatment-experienced and treatment-naïve human immunodeficiency virus (HIV) co-infected. Subgroup analyses were conducted for treatment-naïve patients with and without cirrhosis.

RESULTS

Reductions in the incidence of new cases of liver-disease complications with sofosbuvir + pegIFN/RBV compared with pegIFN/RBV, boceprevir + pegIFN/RBV, telaprevir + pegIFN/RBV and simeprevir + pegIFN/RBV were 64-82%, 50-68%, 43-58% and 33-56%, respectively. Sofosbuvir + pegIFN/RBV was typically associated with the lowest 1-year cost per SVR. When considering the lifetime incremental cost per quality-adjusted life-year gained, sofosbuvir + pegIFN/RBV was the most cost-effective treatment option assessed. Sofosbuvir + pegIFN/RBV generally dominated (less costly and more effective than) boceprevir + pegIFN/RBV, telaprevir + pegIFN/RBV and simeprevir + pegIFN/RBV.

CONCLUSION

Sofosbuvir + pegIFN/RBV yields more favourable future health and economic outcomes than current treatment regimens for patients across all levels of treatment experience and cirrhosis stage, as well as for individuals with or without HIV co-infection.

Predictors of early treatment discontinuation in a cohort of patients treated with boceprevir-based therapy for hepatitis C infection

In this real-world cohort, 49% of patients stopped boceprevir-based hepatitis C therapy early, with only 20% stopping due to treatment futility. Having more comorbidities was significantly associated with early discontinuation. Tolerability of boceprevir-based regimens may be substantially worse than reported in clinical trials, particularly for patients with comorbidities.

Advances in and the future of treatments for hepatitis C

Enormous progress has been made in the understanding of the hepatitis C virus and the development of novel therapeutic agents since the identification of the virus 25 years ago. From initial interferon monotherapy providing only 6% viral clearance rate in the 1980s, pharmacotherapeutics has now entered an exciting new era with direct-acting antiviral agents demonstrating viral clearance rates of more than 70%. We are now at the beginning of an era where combinations of direct-acting antiviral agents may pave the way for interferon-free regimens, even improving the viral clearance rate to near 100%.

Prediction of treatment week eight response & sustained virologic response in patients treated with boceprevir plus peginterferon alfa and ribavirin

AIM

Sustained virologic response (SVR) can be attained with boceprevir plus peginterferon alfa and ribavirin (PR) in up to 68% of patients, and short duration therapy is possible if plasma HCV RNA levels are undetectable at treatment week 8 (TW8 response). We have developed predictive models for SVR, and TW8 response using data from boceprevir clinical trials.

METHODS

Regression models were built to predict TW8 response and SVR. Separate models were built for TW8 and SVR using baseline variables only, and compared to models with baseline variables plus HCV RNA change after 4 weeks of PR (TW4 delta). Predictive accuracy was assessed by c-statistics, calibration curves, and decision curve analyses. Nomograms were developed to create clinical decision support tools. Models were externally validated using independent data.

RESULTS

The models that included TW4 delta produced the best discrimination ability. The predictive factors for TW8 response (n = 856) were TW4 delta, race, platelet count and ALT. The predictive factors for SVR (n = 522) were TW4 delta, HCV-subtype, gender, BMI, RBV dose and platelet count. The discrimination abilities of these models were excellent (C-statistics = 0.88, 0.80 respectively). Baseline models for TW8 response (n = 444) and SVR (n = 197) had weaker discrimination ability (C-statistic = 0.76, 0.69). External validation confirmed the predictive accuracy of the week 4 models.

CONCLUSIONS

Models incorporating baseline and treatment week 4 data provide excellent prediction of TW8 response and SVR, and support the clinical utility of the lead-in phase of PR. The nomograms are suitable for point-of-care use to inform individual patient and physician decision-making.

Use of first-generation HCV protease inhibitors in patients coinfected by HIV and HCV genotype 1

BACKGROUND

In HCV genotype 1-infected patients with HIV co-infection, tritherapy [HCV protease inhibitors (PIs) plus peg-interferon and ribavirin] has been shown to have an increased rate of sustained virological response. However, complex drug-to-drug interactions and tolerability issues remain a concern.

METHODS

Under the auspices of four French scientific societies of medicine, a committee was charged of establishing guidelines on the use of first-generation HCV PIs in these patients. This scientific committee based its work on preliminary results from tritherapy clinical trials in co-infected patients and, since data on these patients are still scarce, on the statements already made by the French Association for the Study of the Liver (AFEF) on the use of tritherapy in HCV mono-infected patients, written in May 2011 and updated in 2012. Each AFEF guideline concerning HCV monoinfection was examined to determine whether it could be used in the context of HIV/HCV coinfection.

RESULTS

These guidelines are addressed for the treatment of coinfected patients with various profiles, including treatment-naïve or patients with failure to previous bitherapy and mention those patients for whom tritherapy should start or those for whom it should be delayed. Preliminary results of triple therapy as well as factors associated to virological response are also discussed. Other issues include virological monitoring, clinical and virological criteria to stop therapy, practical treatment management, treatment adherence and the management of side effects and interactions with antiretroviral drugs. These guidelines were submitted for critical review to independent experts.

HCV RNA assay sensitivity impacts the management of patients treated with direct-acting antivirals

BACKGROUND

Application of response-guided therapy (RGT) rules to the treatment of HCV infection with pegylated interferon-α2a and ribavirin, and direct-acting antivirals (DAAs) such as the NS3/4A protease inhibitors (PIs) boceprevir and telaprevir, relies on the determination of viral genotype and on-treatment HCV RNA level. Currently there are few data available regarding the clinical impact of the analytical differences that exist between different HCV RNA quantification assays on treatment decisions such as those involved in RGT.

METHODS

We sought to ascertain the concordance between two HCV RNA quantification assays, the Roche/High-Pure-System COBAS(®) TaqMan (CTM) version 2 and Abbott RealTime HCV (ART), and to understand the impact of different assay characteristics on treatment decisions. We evaluated 1,336 specimens collected from 74 patients enrolled in the Phase II CHAMPION-2 study of the investigational DAAs ABT-450 (an acylsulfonamide NS3/4A PI), ABT-072 and ABT-333 (both non-nucleoside NS5B polymerase inhibitors).

RESULTS

HCV RNA level results were highly correlated, but CTM values were higher than those from ART by an average of 0.46 log IU/ml. Use of ART HCV RNA level results led to a higher positive predictive value of week 4 viral load for the achievement of a sustained virological response 24 weeks after the end of treatment (100% versus 87% using the lower limit of detection as the threshold).

CONCLUSIONS

This study suggests that HCV viral load assay performance characteristics need to be taken into consideration when managing HCV patients with RGT. Further studies are required to determine whether a consensus HCV RNA level threshold can be established or whether HCV viral load assays with greater sensitivity can increase cure rates with RGT.

Combination of vaniprevir with peginterferon and ribavirin significantly increases the rate of SVR in treatment-experienced patients with chronic HCV genotype 1 infection and cirrhosis

BACKGROUND & AIMS

The combination of vaniprevir (a NS3/4A protease inhibitor) with peginterferon and ribavirin was shown to increase rates of sustained virologic response (SVR) significantly, compared with peginterferon and ribavirin alone, in treatment-experienced patients with chronic hepatitis C virus (HCV) genotype 1 infection without cirrhosis. We performed a blinded, randomized, controlled trial of the effects of vaniprevir with peginterferon and ribavirin in patients with cirrhosis who did not respond to prior therapy with peginterferon and ribavirin.

METHODS

Treatment-experienced patients (88% white and 35% prior null responders) with HCV genotype 1 infection and compensated cirrhosis were assigned randomly to groups given vaniprevir (600 mg twice daily) with peginterferon and ribavirin for 24 weeks (n = 16), vaniprevir (600 mg twice daily) for 24 weeks with peginterferon and ribavirin for 48 weeks (n = 14), vaniprevir (300 mg twice daily) with peginterferon and ribavirin for 48 weeks (n = 15), vaniprevir (600 mg twice daily) with peginterferon and ribavirin for 48 weeks (n = 15), or placebo with peginterferon and ribavirin for 48 weeks (n = 14, control). Cirrhosis was documented by liver biopsy (84%) or noninvasive methods (16%). Before randomization, participants were stratified based on their historical response to peginterferon and ribavirin.

RESULTS

In the primary analysis, SVR rates among patients in the respective vaniprevir groups were 9 of 15 (60.0%), 9 of 13 (69.2%), 8 of 15 (53.3%), and 10 of 13 (76.9%), compared with 2 of 14 (14.3%) in the control group (pairwise P values ≤ .016). Cirrhotic patients with null or partial responses to prior therapy achieved SVR less often than patients with prior breakthrough or relapse, although 42.1% of prior null responders in the vaniprevir groups achieved SVRs. Patients in the vaniprevir groups more frequently experienced mild-moderate nausea, vomiting, and diarrhea than controls; 5% developed grade 2 anemia compared with none in the control group (no patient developed grade 3 or 4 anemia). Among patients in the vaniprevir groups who experienced virologic failure, resistance-associated variants were detected predominantly at positions 155, 156, and 168 in the HCV protease gene.

CONCLUSIONS

In a controlled phase 2B trial, vaniprevir with peginterferon and ribavirin significantly increased rates of SVR among treatment-experienced patients with chronic HCV genotype 1 infection, compared with re-treatment with peginterferon and ribavirin alone. Vaniprevir generally was well tolerated for up to 48 weeks in patients with compensated cirrhosis. ClinicalTrials.gov number, NCT00704405.

The Range of Uncertainty: a Tool for Efficiently Addressing Result Variability Around Clinical Decision Points for Hepatitis C Response-guided Therapy

Despite efforts to standardize molecular diagnostic tests, performance differences are not rare. Laboratories are challenged in situations where treatment rules have been established using a reference assay that is different from the assays being used in daily practice. Assessing the viral load status of patients with chronic hepatitis C under modern triple therapy is a recognized example. We demonstrate the use of the range of uncertainty as an easy and efficient tool that can provide information on the certainty of a test result’s interpretation in the context of making hepatitis C virus treatment decisions.

Individualization of chronic hepatitis C treatment according to the host characteristics

Hepatitis C virus (HCV) infection is a global health problem that affects more than 170 million people worldwide. It is a major cause of cirrhosis and hepatocellular carcinoma, making the virus the most common cause of liver failure and transplantation. The standard-of-care treatment for chronic hepatitis C (CHC) has been changed during the last decade and direct acting antiviral drugs have already been used. Besides, understanding of the pathogenesis of CHC has evolved rapidly during the last years and now several host factors are known to affect the natural history and response to treatment. Recent genome-wide association studies have shown the important role of interleukin-28B and inosine triphosphatase in HCV infection. The present review article attempts to summarize the current knowledge on the role of host factors towards individualization of HCV treatment.

How to optimize current therapy of HCV genotype 1 infection with boceprevir

Treatment with first generation protease inhibitors (PIs) is a milestone in the history of HCV therapy. Triple therapy with boceprevir (BOC) improves sustained virological response (SVR) by 30% in treatment naïve genotype 1 patients and by 50-60% in relapsers, 40-45% in partial responders and 25% in null responders compared with the Pegylated Interferon (PEG-IFN) and ribavirin regimen. To optimize BOC treatment, screening and access to treatment must be improved in genotype 1 patients. To select the ideal candidate for immediate treatment with triple therapy, an individual risk/benefit ratio must be assessed. Recent data have shown that patients with compensated cirrhosis and more advanced disease may also benefit from this regimen. Moreover, in HCV patients with extrahepatic manifestations, patients with HCV recurrence after liver transplantation and HIV-HCV co-infected patients, immediate treatment with triple therapy should be discussed. There is growing evidence that triple therapy with BOC is cost-effective in genotype 1 patients. Finally, the treatment design of BOC must be optimized in relation to baseline characteristics, so that optimal stopping rules can be followed, Drug-drug interactions (DDIs) can be prevented and AEs can be accurately prevented and managed.

Predictors of hepatitis C treatment response: what's new?

Hepatitis C virus infection is a growing, global health problem, with mortality expected to reach a peak in the next ten years in many western countries. A number of host and viral factors have been established as useful predictors of treatment response in the context of interferon and ribavirin. Several new markers have recently been identified that improve our understanding of treatment response. The addition of protease inhibitors to treatment regimens has highlighted the importance of viral kinetics on-treatment in predicting response to treatment. Many new classes of direct acting anti-virals are currently being developed and expected to be clinically available in the near future. Current predictors of treatment response will be redefined in the context of interferon free regimens.

Patterns of viral load decline with telaprevir-based therapy in patients with genotype 1 chronic HCV infection

BACKGROUND

Telaprevir-based therapy is associated with rapid decline in HCV RNA, enabling the application of early futility rules.

OBJECTIVES

To familiarize physicians with this paradigm, a comprehensive analysis of the most frequent HCV viral load profiles observed during treatment with telaprevir/Peg-IFN/RBV in Phase III trials is provided.

DESIGN

HCV RNA profiles were analyzed from 320 HCV genotype 1 treatment-naïve patients enrolled in the ADVANCE study, and 225 prior Peg-IFN/RBV treatment-experienced patients enrolled in the REALIZE study. Patients received 12 weeks of telaprevir with either 24 or 48 weeks of Peg-IFN alfa-2a/RBV. Patients with missing SVR assessments during follow-up, detectable HCV RNA at end of treatment but who did not have viral breakthrough (vBT), or with early vBT who discontinued telaprevir before time of failure were excluded.

RESULTS

All analyzed patients experienced a rapid decline in HCV RNA (>2.0 log(10)) by Day 14, irrespective of baseline characteristics and/or prior response to Peg-IFN/RBV (relapse, partial response and null response). Subsequently, HCV RNA continued to decline to undetectable levels in most patients. These patients went on to have one of the following outcomes: sustained virologic response, late vBT (after Week 12, i.e. during the Peg-IFN/RBV phase), or relapse. In the small subset of patients with early vBT or meeting a futility rule before Week 12, HCV RNA usually never became undetectable and/or increased rapidly after reaching the nadir.

CONCLUSIONS

HCV RNA profiles with telaprevir/Peg-IFN/RBV are different from those with Peg-IFN/RBV alone. It is important that clinicians understand these HCV RNA profiles and monitor patient viral load in order to apply futility rules correctly.

Impact of rural residence and health system structure on quality of liver care

Background

Specialist physician concentration in urban areas can affect access and quality of care for rural patients. As effective drug treatment for hepatitis C (HCV) becomes increasingly available, the extent to which rural patients needing HCV specialists face access or quality deficits is unknown. We sought to determine the influence of rural residency on access to HCV specialists and quality of liver care.

Methods

The study used a national cohort of 151,965 Veterans Health Administration (VHA) patients with HCV starting in 2005 and followed to 2009. The VHA’s constant national benefit structure reduces the impact of insurance as an explanation for observed disparities. Multivariate cox proportion regression models for each quality indicator were performed.

Results

Thirty percent of VHA patients with HCV reside in rural and highly rural areas. Compared to urban residents, highly rural (HR 0.70, CI 0.65-0.75) and rural (HR 0.96, CI 0.94-0.97) residents were significantly less likely to access HCV specialty care. The quality indicators were more mixed. While rural residents were less likely to receive HIV screening, there were no significant differences in hepatitis vaccinations, endoscopic variceal and hepatocellular carcinoma screening between the geographic subgroups. Of note, highly rural (HR 1.31, CI 1.14-1.50) and rural residents (HR 1.06, CI 1.02-1.10) were more likely to receive HCV therapy. Of those treated for HCV, a third received therapy from a non-specialist provider.

Conclusion

Rural patients have less access to HCV specialists, but this does not necessarily translate to quality deficits. The VHA's efforts to improve specialty care access, rural patient behavior and decentralization of HCV therapy beyond specialty providers may explain this contradiction. Lessons learned within the VHA are critical for US healthcare systems restructuring into accountable care organizations that acquire features of integrated systems.

An update on the treatment of genotype-1 chronic hepatitis C infection: lessons from recent clinical trials

The launch of first-generation protease inhibitors (PIs) was a major step forward in hepatitis C virus (HCV) treatment. However, this major advance is, up to now, restricted to genotype-1 (GT-1) patients. However, the ongoing development of new direct-acting antiviral agents (DAAs) allows new hope for the future. The development of second-wave and second-generation PIs yields higher antiviral potency through plurigenotypic activity, more convenient daily administration, fewer side effects and, for the second-generation PIs, potential activity against resistance-associated variants. NS5B inhibitors (NS5B.I) include nucleoside/nucleotide inhibitors (NIs) and nonnucleotide inhibitors (NNIs). NIs have high efficacy across all genotypes. Sofosbuvir has highly potent antiviral activity across all genotypes in association with pegylated interferon (IFN) and ribavirin (PR), thus allowing shortened treatment duration. NS5A inhibitors (NS5A.I) have highly potent antiviral activity. It has recently been shown for the first time that NS5A.I in combination with PI can cure GT-1b null-responder patients in an IFN-free regimen. In addition, several studies demonstrate that IFN-free regimens with DAA combinations are able to cure a large number of either naïve or treatment-experienced GT-1 patients. Moreover, a quadruple regimen with PR is able to cure almost all GT-1 null-responders. The development of pan-genotypic DAAs (NIs or NS5A.I) allows new combinations with or without PR that increase the rate of sustained virological response (SVR) for all patients, even for those with cirrhosis and independently of the genotype. Therefore, the near future of HCV treatment looks promising. The purpose of this article is to provide an overview of the clinical results recently reported for HCV treatment in GT-1 patients.

Optimizing DAA management in daily practice

Despite the incontestable benefits of telaprevir and boceprevir-based triple therapy in patients infected with genotype 1, the practitioner faces a number of new challenges. In daily clinical practice, a checklist approach may facilitate the management of triple therapy. Before initiation, several specific issues should be reviewed with the patient in order to optimize adherence and treatment outcome: potential drug to drug interaction, treatment duration and stopping rules, possible treatment outcomes, side effects, dose and administration with food advice, management of side effects. Because treatment failure is associated with the emergence of resistance-associated variants with reduced sensitivity to protease inhibitors, adherence is of major importance. In this setting, the role of educational nurse should be emphasized for the management of triple therapy in daily clinical practice.

Potential role of Hedgehog pathway in liver response to radiation

Radiation-induced fibrosis constitutes a major problem that is commonly observed in the patients undergoing radiotherapy; therefore, understanding its pathophysiological mechanism is important. The Hedgehog (Hh) pathway induces the proliferation of progenitors and myofibroblastic hepatic stellate cells (MF-HSCs) and promotes the epithelial-to-mesenchymal transition (EMT), thereby regulating the repair response in the damaged liver. We examined the response of normal liver to radiation injury. Male mice were sacrificed at 6 weeks and 10 weeks after exposure to a single dose of 6 Gy and the livers were collected for biochemical analysis. Irradiated (IR) and control mice were compared for progenitors, fibrosis, Hh pathway, and EMT at 6 and 10 weeks post irradiation. Fatty hepatocytes were observed and the expressions of Hh ligand, Indian Hh. were greater in the livers at 6 weeks, whereas expression of another Hh ligand, Sonic Hh, increased at 10 weeks post irradiation. Both Smoothened, Hh receptor, and Gli2, Hh-target gene, were up-regulated at 6 and 10 weeks after irradiation. Accumulation of progenitors (CD44, Pan-cytokeratin, and Sox9) was significant in IR livers at 6 and 10 weeks. RNA analysis showed enhanced expression of the EMT-stimulating factor, tgf-β, in the IR livers at 6 weeks and the upregulation of mesenchymal markers (α-SMA, collagen, N-cadherin, and s100a4), but down-regulation of EMT inhibitors, in IR mouse livers at 6 and 10 weeks. Increased fibrosis was observed in IR mouse livers at 10 weeks. Treatment of mice with Hh inhibitor, GDC-0449, suppressed Hh activity and block the proliferation of hepatic progenitor and expression of EMT-stimulating genes in irradiated mice. Therefore, those results demonstrated that the Hh pathway increased in response to liver injury by radiation and promoted a compensatory proliferation of MF-HSCs and progenitors, thereby regulating liver remodeling.

Genotype impact on HCV RNA levels determined with the VERSANT HCV RNA 1.0 assay (kPCR)

BACKGROUND

Accurate quantitation of hepatitis C virus (HCV) RNA is mandatory for the management of anti-HCV therapy.

OBJECTIVES

The genotype-dependent performance of the new commercially available VERSANT HCV RNA 1.0 Assay (kPCR) and the COBAS AmpliPrep/COBAS TaqMan HCV Quantitative Test, version 2.0 was investigated.

STUDY DESIGN

The molecular assays for quantitation of HCV RNA were performed according to the manufacturer's package insert instructions. HCV genotypes/subtypes/isolates, and mutations in the 5'NCR were detected by direct sequencing.

RESULTS

When members of a worldwide HCV performance panel including HCV subtypes 1a, 1b, 2a, 3b, and 4a were tested with the Siemens assay and the results were compared with those obtained by the Roche assay, the mean log10 unit differences for members containing HCV subtypes 1a, 1b, 3b, and 4a were found to be within ±0.5 log(10) units. For the panel member containing HCV subtype 2a, the HCV RNA concentration was found to be >0.5 log(10) units lower with the Siemens assay. When clinical samples were tested, the HCV RNA concentration of all samples containing HCV subtype 2a were found to be >0.5 log(10) units lower with the Siemens assay while that of certain HCV subtype 3a and 4a isolates were found to be >1.0 log(10) units lower.

CONCLUSION

The VERSANT HCV RNA 1.0 Assay substantially underestimates HCV RNA concentrations in HCV subtype 2a samples and in HCV subtype 3a and 4a samples containing certain isolates. This may be caused by mismatches with the target sequences due to the primer and/or probe design.

Therapy of chronic hepatitis C virus infection in the era of direct-acting and host-targeting antiviral agents

OBJECTIVES

Chronic hepatitis C virus (HCV) infection represents a leading worldwide medical and social problem. The expanding knowledge of HCV lifecycle has led to the development of novel antiviral agents that: a) specifically target a viral function (direct-acting antivirals), or b) specifically inhibit viral replication. The present review describes the novel anti-HCV drugs that have been better studied at the time of this writing and the current two types of treatment, namely interferon-based and interferon-free regimens. In addition, predictive factors, virological responses, side-effects, and resistance mechanisms of the novel agents are summarized.

CONCLUSIONS

The introduction of novel antiviral agents is remarkably changing the therapeutic combinations aimed at improving virological responses both for easy-to-cure and difficult-to-treat patients. Since additional, effective drugs are under advanced development, it seems reasonable to expect that further therapeutic and prognostic improvements will be achieved in the near future.

[To consider negative viral loads below the limit of quantification can lead to errors in the diagnosis and treatment of hepatitis C virus infection]

INTRODUCTION

For years many clinical laboratories have routinely classified undetectable and unquantifiable levels of hepatitis C virus RNA (HCV-RNA) determined by RT-PCR as below limit of quantification (BLOQ). This practice might result in erroneous clinical decisions.

AIM

To assess the frequency and clinical relevance of assuming that samples that are BLOQ are negative.

MATERIAL AND METHOD

We performed a retrospective analysis of RNA determinations performed between 2009 and 2011 (Cobas/Taqman, lower LOQ: 15 IU/ml). We distinguished between samples classified as «undetectable» and those classified as «<1.50E+01IU/mL» (BLOQ).

RESULTS

We analyzed 2.432 HCV-RNA measurements in 1.371 patients. RNA was BLOQ in 26 samples (1.07%) from 23 patients (1.68%). BLOQ results were highly prevalent among patients receiving Peg-Riba: 23 of 216 samples (10.6%) from 20 of 88 patients receiving treatment (22.7%). The clinical impact of BLOQ RNA samples was as follows: a) 2 patients initially considered to have negative results subsequently showed quantifiable RNA; b) 8 of 9 patients (88.9%) with BLOQ RNA at week 4 of treatment later showed sustained viral response; c) 3 patients with BLOQ RNA at weeks 12 and 48 of treatment relapsed; d) 4 patients with BLOQ RNA at week 24 and/or later had partial or breakthrough treatment responses, and e) in 5 patients the impact were null or could not be ascertained.

CONCLUSIONS

This study suggests that BLOQ HCV-RNA indicates viremia and that equating a BLOQ result with a negative result can lead to treatment errors. BLOQ results are highly prevalent in on-treatment patients. The results of HCV-RNA quantification should be classified clearly, distinguishing between undetectable levels and levels that are BLOQ.

Understanding the hepatitis C virus life cycle paves the way for highly effective therapies

More than two decades of intense research has provided a detailed understanding of hepatitis C virus (HCV), which chronically infects 2% of the world's population. This effort has paved the way for the development of antiviral compounds to spare patients from life-threatening liver disease. An exciting new era in HCV therapy dawned with the recent approval of two viral protease inhibitors, used in combination with pegylated interferon-α and ribavirin; however, this is just the beginning. Multiple classes of antivirals with distinct targets promise highly efficient combinations, and interferon-free regimens with short treatment duration and fewer side effects are the future of HCV therapy. Ongoing and future trials will determine the best antiviral combinations and whether the current seemingly rich pipeline is sufficient for successful treatment of all patients in the face of major challenges, such as HCV diversity, viral resistance, the influence of host genetics, advanced liver disease and other co-morbidities.

Emergence of resistance-associated variants after failed triple therapy with vaniprevir in treatment-experienced non-cirrhotic patients with hepatitis C-genotype 1 infection: a population and clonal analysis

BACKGROUND

Vaniprevir with P/R improved SVR rates over P/R alone in treatment-experienced patients with chronic HCV-genotype 1 infection, but treatment failure presents therapeutic challenges. We identified RAVs from non-cirrhotic patients failing to achieve SVR on vaniprevir-containing regimens from a dose/duration-ranging trial of triple-combination therapy.

METHODS

Using population analysis, resistance sequencing was performed on all baseline samples and on samples at virologic failure in the vaniprevir arms. Longitudinal clonal analyses were performed on viral isolates from six vaniprevir recipients experiencing breakthrough viremia.

RESULTS

Baseline RAVs were detected in two patients subsequently experiencing virologic failure. At virologic failure, the majority of RAVs had substitutions at R155, A156, or D168. Clonal analyses identified novel double/triple variants emerging with continuing vaniprevir dosing.

CONCLUSIONS

RAVs were predominantly observed at R155, A156, and/or D168 during virologic failure on vaniprevir/P/R. Double/triple RAVs were identified in patients remaining viremic on triple therapy, suggesting evolution of resistance under selective pressure.

Futility of antiviral treatments for hepatitis C: an evolving concept entering the direct antiviral agents era

Two first-generation non-specific protein 3/4A protease inhibitors (Boceprevir and Telaprevir) have been approved in the U.S. and in Europe in combination with the standard of care for treatment of both previously untreated and prior non responder genotype 1 chronic hepatitis C, based on the results of 5 large phase III trials. With these drugs, futility-stopping rules at weeks 4, 8 and 12 have been provided in order to avoid ineffective therapy and dangerous adverse events. However, despite several guidelines that have been published, a main question remains: how we can identify patients in whom triple therapy will be useless or ineffective? Based on the available data, this review proposes three algorithms to optimize triple antiviral therapy for chronic hepatitis C, to aid physicians avoid prescription of unnecessary treatment, given its substantial side effects and costs.

The Cobas AmpliPrep/Cobas TaqMan HCV test, version 2.0, real-time PCR assay accurately quantifies hepatitis C virus genotype 4 RNA

Accurate hepatitis C virus (HCV) RNA quantification is mandatory for the management of chronic hepatitis C therapy. The first-generation Cobas AmpliPrep/Cobas TaqMan HCV test (CAP/CTM HCV) underestimated HCV RNA levels by >1-log10 international units/ml in a number of patients infected with HCV genotype 4 and occasionally failed to detect it. The aim of this study was to evaluate the ability of the Cobas AmpliPrep/Cobas TaqMan HCV test, version 2.0 (CAP/CTM HCV v2.0), to accurately quantify HCV RNA in a large series of patients infected with different subtypes of HCV genotype 4. Group A comprised 122 patients with chronic HCV genotype 4 infection, and group B comprised 4 patients with HCV genotype 4 in whom HCV RNA was undetectable using the CAP/CTM HCV. Each specimen was tested with the third-generation branched DNA (bDNA) assay, CAP/CTM HCV, and CAP/CTM HCV v2.0. The HCV RNA level was lower in CAP/CTM HCV than in bDNA in 76.2% of cases, regardless of the HCV genotype 4 subtype. In contrast, the correlation between bDNA and CAP/CTM HCV v2.0 values was excellent. CAP/CTM HCV v2.0 accurately quantified HCV RNA levels in the presence of an A-to-T substitution at position 165 alone or combined with a G-to-A substitution at position 145 of the 5' untranslated region of HCV genome. In conclusion, CAP/CTM HCV v2.0 accurately quantifies HCV RNA in genotype 4 clinical specimens, regardless of the subtype, and can be confidently used in clinical trials and clinical practice with this genotype.

A new era in the treatment of chronic hepatitis C infection

Treatment of chronic hepatitis C virus (HCV) infection has evolved over the past three decades. At the start, treatment involved interferon monotherapy followed by combination therapy using interferon and ribavirin, and subsequently evolved to pegylated interferon (Peg-IFN) and ribavirin. In genotype 1 infection, rates of sustained virological response (SVR) are approximately 45 % with Peg-IFN and ribavirin, whereas SVR rates in genotypes 2 and 3 infections are as high as 70 % to 80 %. Side effects and cost related to these drugs are important concerns, particularly in countries like India where patients have to bear their health expenses. In the recent past, there has been a significant change in course with the on-going search and the development of more effective drugs in the management of HCV infection. Telaprevir and Boceprevir are two new potent protease inhibitors (direct acting antiviral or DAA agents) which, when administered with Peg-IFN and ribavirin, have shown to result significantly higher SVR rates in phase 3 studies in patients with genotype 1 infection, both in treatment naïve patients (up to 75 %) and those with previously failed therapy. Several other new antiviral agents some in combination with Peg-IFN and ribavirin and some in combination without Peg-IFN (IFN-free regimens) are currently being tested in patients with genotype 1, 2 and 3 infections and are expected to dramatically change the armamentarium of HCV therapy in the coming years.

How to optimize HCV therapy in genotype 1 patients: predictors of response

The advent of triple therapy (TT) with first-generation protease inhibitors boceprevir (BOC) and telaprevir (TVR) in addition to pegylated interferon and ribavirin (PEG-IFN/RBV) has resulted in a significant improvement in the sustained virological response (SVR) rate and potentially in life years gained compared to dual therapy (DT), when treating naïve or treatment-experienced patients with genotype 1 (G1) chronic hepatitis C (CHC). This benefit is partly offset by the increased complexity of treatment, and the increased costs and risks of therapy, making it necessary to optimize the indications for TT. Naïve patients with mild fibrosis and the IL28B CC polymorphism and/or with a rapid virological response (RVR) to DT can still benefit from DT, while TT is preferable in all others. Phase 3 trials have clearly shown that a 1 log(10) decrease in HCVRNA after 4 weeks of DT associated with a favourable IL28B genotype and a low stage of fibrosis, and a pattern of previous response to DT in treatment-experienced patients are the strongest predictors of an SVR to TT. Moreover, an extended rapid virological response (eRVR) is associated with an SVR rate >90%, so that the overall duration of treatment can be shortened in a high proportion of patients. Further efforts to optimize the current TT regimens both by increasing efficacy and improving tolerance are still needed. Most important, in the future, treatment can probably be personalized based on data from post-marketing surveillance of TT providing information about patient groups that were underrepresented in phase 3 studies such as those with cirrhosis.

Hepatitis C virus viral assays in the direct-acting antiviral era

In the direct-acting antiviral (DAA) era of hepatitis C virus (HCV) therapy, health care providers must be knowledgeable about genotype and subtype of HCV infection and interpretation of quantitative HCV viral assays to monitor treatment responses. They may also choose to assess interleukin 28B genotypes or resistance-associated variants after ineffective DAA therapy. DAA therapies require understanding of performance characteristics of quantitative HCV RNA assays and the definitions of terms used to report results. Only quantitative HCV RNA assays with a limit of detection of 10 to 15 IU/mL are appropriate for managing patients on DAA therapy.

Optimal treatment with boceprevir for chronic HCV infection

There are 160-170 million people with chronic hepatitis C virus (HCV) infection worldwide. The marketing of protease inhibitors (PIs) has been a milestone in the history of HCV therapy. In phase III studies, up to 75% of the patients achieved a sustained virological response (SVR) after triple therapy with pegylated-interferon (PEG-IFN)-α, ribavirin (RBV) and boceprevir (BOC). However, triple regimens are more expensive and associated with drug-drug interactions (DDIs) and more adverse events (AEs). According to results in 'real-world' settings, safety seems to be limited, in particular in patients with advanced liver disease. To optimize efficacy while minimizing AEs as well as costs, the optimal treatment strategy must be determined for BOC. Optimizing treatment is based on patient selection, the most efficient treatment design, management of side effects and the challenge of DDIs. Therapy-associated risks, treatment urgency and chances of SVR must all be considered for patient selection. In addition, certain differences between the two approved PIs may help identify the ideal candidates for each HCV PI. Optimal treatment design is based on the results of phase II and III studies, in which different approaches have been tested including 'lead-in' and response-guided strategies. Treatment regimens and stopping rules recommended by the FDA and EMA should normally be followed. Still, there are some cases in which more personalized strategies may be more promising. Management of side effects is a major challenge and plays a crucial role in ensuring safety and adherence.

Therapeutic algorithms for chronic hepatitis C in the DAA era during the current economic crisis: whom to treat? How to treat? When to treat?

The advent of triple therapy (TT) with first-generation protease inhibitors boceprevir (BOC) and telaprevir (TVR) in addition to pegylated interferon and ribavirin resulted in a significant gain in terms of sustained virological response (SVR) when treating naive or previous treated patients with genotype 1 (G1) chronic hepatitis C (CHC). This gain is partly balanced by the increased complexity of treatment and by the raised costs and risks of therapy, making necessary to optimize the indication to TT.Specifically, the identification of patient needing to TT over DT, the choice of the more correct therapeutic approach according to baseline and on treatment SVR predictors, and the timing of antiviral treatment, appear key issues to evaluate when considering TVR or BOC-based therapies.Along this line, further efforts aimed to optimize the current TT regimens are still needed, especially in under-represented groups of patients in phase 3 studies such as those with cirrhosis, where post-marketing data are giving interesting evidences.

Predictors of response to chronic hepatitis C treatment

Chronic hepatitis C is a growing health problem worldwide that has attracted increased attention in recent years. Treatment with peginterferon and ribavirin combination had previously been the standard of care. In 2011, a new treatment with protease inhibitors, telaprevir and boceprevir was approved, and a new standard of care was defined. Previous predictors of response have been redefined, and while IL28B, fibrosis stage and hepatitis C virus viral load testing continue to have their value, viral kinetics during treatment defining viral response have emerged as the strongest predictor for achieving sustained virologic response with the new treatment. New therapies are expected in the near future, and current treatment predictors of response may soon change.

Boceprevir and personalized medicine in hepatitis C virus infection

Boceprevir was the first agent, along with telaprevir, of a novel class of direct-acting antivirals that entered clinical practice for the treatment of chronic hepatitis C. Boceprevir is an antiprotease that directly blocks hepatitis C virus (HCV) replication. Two studies in patients with HCV genotype 1 infection have shown that addition of boceprevir to the standard of care, ie, pegylated interferon-alfa (PEG-IFN-α) and ribavirin, markedly increased the rate of sustained virological response. A sustained virological response was obtained in about 70% of patients who had never been treated, as well as in 69%-75% and 40% of previous relapsers and nonresponders to PEG-IFN-α-ribavirin, respectively. Side effects were observed in almost all treated patients. Anemia, the most frequent adverse event related to administration of boceprevir, occurred in about 50% of patients. The decision to add boceprevir to the standard of care is made on an individual basis, and takes into account the prognosis of the liver disease, the efficacy of therapy, as it could be at best predicted, and the side effects that may arise, taking into account the comorbidities of the patient. Ultimately, the treatment must be accepted by the patient, who should fully understand the benefits and risks. Boceprevir trials were designed with the concept of individualized and response-guided therapy which establishes treatment decisions on how rapidly patients respond to treatment. Individualized therapy for chronic hepatitis C is based on patient and viral characteristics to make the best choice about whether a person will benefit from therapy and to evaluate on-treatment predictors of response to shorten therapy in patients with a rapid response as well as in patients who did not respond sufficiently to expect HCV eradication. This review focuses on the main results obtained so far, their impact on the treatment of patients with chronic hepatitis C, and potential therapeutic perspectives.

The role of resistance in HCV treatment

The recent development of small molecule compounds that directly inhibit the viral life cycle represents a major milestone for the treatment of chronic hepatitis C virus (HCV) infection. These new drugs that are collectively termed direct-acting antivirals (DAA) include a range of inhibitors of the non-structural (NS) 3/4A protease, NS5B polymerase and NS5A protein. Two NS3/4A protease inhibitors (boceprevir and telaprevir) in combination with pegylated interferon and ribavirin have now been approved for the treatment of chronic HCV genotype 1 infection and cure rates could be increased by 20-30%. However, the majority of DAAs is still in early clinical development. The rapid replication rate of HCV, along with the error-prone polymerase activity leads to a high genetic diversity among HCV virions that includes mutants with reduced susceptibility to DAA-therapy. These resistance-associated variants often occur at very low frequencies. However, during DAA-based treatment, rapid selection of resistance mutations may occur, eventually leading to viral break-through. A number of variants with different levels of resistance have been described in vitro and in vivo for virtually all DAAs. We review the parameters that determine DAA resistance as well as the clinical implications of resistance testing. In addition, the most recent literature and conference data on resistance profiles of DAAs in clinical development and future strategies to avoid the emergence of viral resistance are also discussed.