Randomized controlled trial of danoprevir plus peginterferon alfa-2a and ribavirin in treatment-naïve patients with hepatitis C virus genotype 1 infection

Direct-acting antiviral resistance of Hepatitis C virus is promoted by epistasis

Direct-acting antiviral agents (DAAs) provide efficacious therapeutic treatments for chronic Hepatitis C virus (HCV) infection. However, emergence of drug resistance mutations (DRMs) can greatly affect treatment outcomes and impede virological cure. While multiple DRMs have been observed for all currently used DAAs, the evolutionary determinants of such mutations are not currently well understood. Here, by considering DAAs targeting the nonstructural 3 (NS3) protein of HCV, we present results suggesting that epistasis plays an important role in the evolution of DRMs. Employing a sequence-based fitness landscape model whose predictions correlate highly with experimental data, we identify specific DRMs that are associated with strong epistatic interactions, and these are found to be enriched in multiple NS3-specific DAAs. Evolutionary modelling further supports that the identified DRMs involve compensatory mutational interactions that facilitate relatively easy escape from drug-induced selection pressures. Our results indicate that accounting for epistasis is important for designing future HCV NS3-targeting DAAs.

The Costs of Hepatitis C by Liver Disease Stage: Estimates from the Veterans Health Administration

BACKGROUND

The release of highly effective but costly medications for the treatment of hepatitis C virus combined with a doubling in the incidence of hepatitis C virus have posed substantial financial challenges for many healthcare systems. We provide estimates of the cost of treating patients with hepatitis C virus that can inform the triage of pharmaceutical care in systems with limited healthcare resources.

METHODS

We conducted an observational study using a national US cohort of 206,090 veterans with laboratory-identified hepatitis C virus followed from Fiscal Year 2010 to 2014. We estimated the cost of: non-advanced Fibrosis-4; advanced Fibrosis-4; hepatocellular carcinoma; liver transplant; and post-liver transplant. The former two stages were ascertained using laboratory result data; the latter stages were ascertained using administrative data. Costs were obtained from the Veterans Health Administration's activity-based cost accounting system and more closely represent the actual costs of providing care, an improvement on the charge data that generally characterizes the hepatitis C virus cost literature. Generalized estimating equations were used to estimate and predict costs per liver disease stage. Missing data were multiply imputed.

RESULTS

Annual costs of care increased as patients progressed from non-advanced Fibrosis-4 to advanced Fibrosis-4, hepatocellular carcinoma, and liver transplant (all p < 0.001). Post-liver transplant, costs decreased significantly (p < 0.001). In simulations, patients were estimated to incur the following annual costs: US $17,556 for non-advanced Fibrosis-4; US $20,791 for advanced Fibrosis-4; US $46,089 for liver cancer; US $261,959 in the year of the liver transplant; and US $18,643 per year after the liver transplant.

CONCLUSIONS

Cost differences of treating non-advanced and advanced Fibrosis-4 are relatively small. The greatest cost savings would be realized from avoiding progression to liver cancer and transplant.

Danoprevir: First Global Approval

Ascletis has developed danoprevir (Ganovo^®), an orally-administered hepatitis C virus NS3 protease inhibitor, as a treatment for hepatitis C. Based on positive results in phase II and phase III trials in patients with hepatitis C, danoprevir, in combination with ritonavir, peginterferon alfa and ribavirin was recently approved for marketing in China for the treatment of treatment-naive patients with non-cirrhotic genotype 1b chronic hepatitis C. This article summarizes the milestones in the development of danoprevir leading to this first approval.

New Direct-Acting Antivirals for the Treatment of Patients With Hepatitis C Virus Infection: A Systematic Review of Randomized Controlled Trials

BACKGROUND

New direct-acting antiviral agents (DAAs) approved for the treatment of patients infected by Hepatitis C virus (HCV) are well tolerated and increase sustained virological response (SVR) rate. We summarize current evidence on the efficacy and safety from comparative randomized controlled trials (RCTs) of DAAs.

METHODS

We systematically searched MEDLINE, Embase, Scopus, CENTRAL, and Lilacs as well as a list of reference literature. We included RCTs comparing DAAs with placebo or active control and reporting response rates and adverse events according to antiviral regimens. Risk ratios (RRs) were pooled as appropriate. We assessed the risk of bias of included studies and graded the quality of evidence according to the GRADE method.

RESULTS

We included 28 RCTs, enrolling more than 7000 patients. The quality of evidence was generally low. Twelve-week treatment with DAAs in naïve patients significantly increased SVR12 and SVR24 compared with placebo (RR 1.4, 95% CI 1.3-1.6; RR 1.5, 95% CI 1.4-1.6, respectively). This means that for every 1000 patients, 240 or 260 more patients experienced SVR12 or SVR24 if treated with any DAAs. We could not find RCTs assessing progression of liver disease or development of hepatocellular carcinoma. DAAs were not associated with higher incidence of serious adverse events or discontinuation due to adverse events.

CONCLUSIONS

This systematic review confirms that new DAAs are more effective in inducing SVR than placebo. Outside clinical trials, in real word, HCV cure with DAA regimens occurs in less than 90% of patients, so further comparative evaluations are needed to establish their long-term effects.

GP205, a new hepatitis C virus NS3/4A protease inhibitor, displays higher metabolic stability in vitro and drug exposure in vivo

NS3/4A serine protease is a prime target for direct-acting antiviral therapies against hepatitis C virus (HCV) infection. Several NS3/4A inhibitors have been widely used in clinic, while new inhibitors with better characteristics are still urgently needed. GP205 is a new macrocyclic inhibitor of NS3/4A with low nanomolar activities against HCV replicons of genotypes 1b, 2a, 4a, and 5a, with EC₅₀ values ranging from 1.5 to 12.8 nmol/L. In resistance selection study in vitro, we found resistance-associated substitutions on D168: The activity of GP205 was significantly attenuated against 1b replicon with D168V or D168A mutation, similar as simeprevir. No cross resistance of GP205 with NS5B or NS5A inhibitor was observed. Combination of GP205 with sofosbuvir or daclatasvir displayed additive or synergistic efficacy. The pharmacokinetic profile of GP205 was characterized in rats and dogs after oral administration, which revealed good drug exposure both in plasma and in liver and long plasma half-life. The in vitro stability test showed ideal microsomal and hepatic cells stability of GP205. The preclinical profiles of GP205 support further research on this NS3/4A inhibitor to expand the existing HCV infection therapies.

Direct-acting antivirals for chronic hepatitis C

BACKGROUND

Millions of people worldwide suffer from hepatitis C, which can lead to severe liver disease, liver cancer, and death. Direct-acting antivirals (DAAs), e.g. sofosbuvir, are relatively new and expensive interventions for chronic hepatitis C, and preliminary results suggest that DAAs may eradicate hepatitis C virus (HCV) from the blood (sustained virological response). Sustained virological response (SVR) is used by investigators and regulatory agencies as a surrogate outcome for morbidity and mortality, based solely on observational evidence. However, there have been no randomised trials that have validated that usage.

OBJECTIVES

To assess the benefits and harms of DAAs in people with chronic HCV.

SEARCH METHODS

We searched for all published and unpublished trials in The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, LILACS, and BIOSIS; the Chinese Biomedical Literature Database (CBM), China Network Knowledge Information (CNKI), the Chinese Science Journal Database (VIP), Google Scholar, The Turning Research into Practice (TRIP) Database, ClinicalTrials.gov, European Medicines Agency (EMA) (www.ema.europa.eu/ema/), WHO International Clinical Trials Registry Platform (www.who.int/ictrp), the Food and Drug Administration (FDA) (www.fda.gov), and pharmaceutical company sources for ongoing or unpublished trials. Searches were last run in October 2016.

SELECTION CRITERIA

Randomised clinical trials comparing DAAs versus no intervention or placebo, alone or with co-interventions, in adults with chronic HCV. We included trials irrespective of publication type, publication status, and language.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were hepatitis C-related morbidity, serious adverse events, and health-related quality of life. Our secondary outcomes were all-cause mortality, ascites, variceal bleeding, hepato-renal syndrome, hepatic encephalopathy, hepatocellular carcinoma, non-serious adverse events (each reported separately), and SVR. We systematically assessed risks of bias, performed Trial Sequential Analysis, and followed an eight-step procedure to assess thresholds for statistical and clinical significance. We evaluated the overall quality of the evidence, using GRADE.

MAIN RESULTS

We included a total of 138 trials randomising a total of 25,232 participants. The trials were generally short-term trials and designed primarily to assess the effect of treatment on SVR. The trials evaluated 51 different DAAs. Of these, 128 trials employed matching placebo in the control group. All included trials were at high risk of bias. Eighty-four trials involved DAAs on the market or under development (13,466 participants). Fifty-seven trials administered DAAs that were discontinued or withdrawn from the market. Study populations were treatment-naive in 95 trials, had been exposed to treatment in 17 trials, and comprised both treatment-naive and treatment-experienced individuals in 24 trials. The HCV genotypes were genotype 1 (119 trials), genotype 2 (eight trials), genotype 3 (six trials), genotype 4 (nine trials), and genotype 6 (one trial). We identified two ongoing trials.We could not reliably determine the effect of DAAs on the market or under development on our primary outcome of hepatitis C-related morbidity or all-cause mortality. There were no data on hepatitis C-related morbidity and only limited data on mortality from 11 trials (DAA 15/2377 (0.63%) versus control 1/617 (0.16%); OR 3.72, 95% CI 0.53 to 26.18, very low-quality evidence). We did not perform Trial Sequential Analysis on this outcome.There is very low quality evidence that DAAs on the market or under development do not influence serious adverse events (DAA 5.2% versus control 5.6%; OR 0.93, 95% CI 0.75 to 1.15 , 15,817 participants, 43 trials). The Trial Sequential Analysis showed that there was sufficient information to rule out that DAAs reduce the relative risk of a serious adverse event by 20% when compared with placebo. The only DAA that showed a lower risk of serious adverse events when meta-analysed separately was simeprevir (OR 0.62, 95% CI 0.45 to 0.86). However, Trial Sequential Analysis showed that there was not enough information to confirm or reject a relative risk reduction of 20%, and when one trial with an extreme result was excluded, the meta-analysis result showed no evidence of a difference.DAAs on the market or under development may reduce the risk of no SVR from 54.1% in untreated people to 23.8% in people treated with DAA (RR 0.44, 95% CI 0.37 to 0.52, 6886 participants, 32 trials, low quality evidence). Trial Sequential Analysis confirmed this meta-analysis result.Only 1/84 trials on the market or under development assessed the effects of DAAs on health-related quality of life (SF-36 mental score and SF-36 physical score).There was insufficient evidence from trials on withdrawn or discontinued DAAs to determine their effect on hepatitis C-related morbidity and all-cause mortality (OR 0.64, 95% CI 0.23 to 1.79; 5 trials, very low-quality evidence). However, these DAAs seemed to increase the risk of serious adverse events (OR 1.45, 95% CI 1.22 to 1.73; 29 trials, very low-quality evidence). Trial Sequential Analysis confirmed this meta-analysis result.None of the 138 trials provided useful data to assess the effects of DAAs on the remaining secondary outcomes (ascites, variceal bleeding, hepato-renal syndrome, hepatic encephalopathy, and hepatocellular carcinoma).

AUTHORS' CONCLUSIONS

The evidence for our main outcomes of interest come from short-term trials, and we are unable to determine the effect of long-term treatment with DAAs. The rates of hepatitis C morbidity and mortality observed in the trials are relatively low and we are uncertain as to how DAAs affect this outcome. Overall, there is very low quality evidence that DAAs on the market or under development do not influence serious adverse events. There is insufficient evidence to judge if DAAs have beneficial or harmful effects on other clinical outcomes for chronic HCV. Simeprevir may have beneficial effects on risk of serious adverse event. In all remaining analyses, we could neither confirm nor reject that DAAs had any clinical effects. DAAs may reduce the number of people with detectable virus in their blood, but we do not have sufficient evidence from randomised trials that enables us to understand how SVR affects long-term clinical outcomes. SVR is still an outcome that needs proper validation in randomised clinical trials.

Direct-acting antivirals for chronic hepatitis C

BACKGROUND

Millions of people worldwide suffer from hepatitis C, which can lead to severe liver disease, liver cancer, and death. Direct-acting antivirals (DAAs) are relatively new and expensive interventions for chronic hepatitis C, and preliminary results suggest that DAAs may eradicate hepatitis C virus (HCV) from the blood (sustained virological response). However, it is still questionable if eradication of hepatitis C virus in the blood eliminates hepatitis C in the body, and improves survival and leads to fewer complications.

OBJECTIVES

To assess the benefits and harms of DAAs in people with chronic HCV.

SEARCH METHODS

We searched for all published and unpublished trials in The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, LILACS, and BIOSIS; the Chinese Biomedical Literature Database (CBM), China Network Knowledge Information (CNKI), the Chinese Science Journal Database (VIP), Google Scholar, The Turning Research into Practice (TRIP) Database, ClinicalTrials.gov, European Medicines Agency (EMA) (www.ema.europa.eu/ema/), WHO International Clinical Trials Registry Platform (www.who.int/ictrp), the Food and Drug Administration (FDA) (www.fda.gov), and pharmaceutical company sources for ongoing or unpublished trials. Searches were last run in October 2016.

SELECTION CRITERIA

Randomised clinical trials comparing DAAs versus no intervention or placebo, alone or with co-interventions, in adults with chronic HCV. We included trials irrespective of publication type, publication status, and language.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were hepatitis C-related morbidity, serious adverse events, and quality of life. Our secondary outcomes were all-cause mortality, ascites, variceal bleeding, hepato-renal syndrome, hepatic encephalopathy, hepatocellular carcinoma, non-serious adverse events (each reported separately), and sustained virological response. We systematically assessed risks of bias, performed Trial Sequential Analysis, and followed an eight-step procedure to assess thresholds for statistical and clinical significance. The overall quality of the evidence was evaluated using GRADE.

MAIN RESULTS

We included a total of 138 trials randomising a total of 25,232 participants. The 138 trials assessed the effects of 51 different DAAs. Of these, 128 trials employed matching placebo in the control group. All included trials were at high risk of bias. Eighty-four trials involved DAAs on the market or under development (13,466 participants). Fifty-seven trials administered withdrawn or discontinued DAAs. Trial participants were treatment-naive (95 trials), treatment-experienced (17 trials), or both treatment-naive and treatment-experienced (24 trials). The HCV genotypes were genotype 1 (119 trials), genotype 2 (eight trials), genotype 3 (six trials), genotype 4 (nine trials), and genotype 6 (one trial). We identified two ongoing trials.Meta-analysis of the effects of all DAAs on the market or under development showed no evidence of a difference when assessing hepatitis C-related morbidity or all-cause mortality (OR 3.72, 95% CI 0.53 to 26.18, P = 0.19, I² = 0%, 2,996 participants, 11 trials, very low-quality evidence). As there were no data on hepatitis C-related morbidity and very few data on mortality (DAA 15/2377 (0.63%) versus control 1/617 (0.16%)), it was not possible to perform Trial Sequential Analysis on hepatitis C-related morbidity or all-cause mortality.Meta-analysis of all DAAs on the market or under development showed no evidence of a difference when assessing serious adverse events (OR 0.93, 95% CI 0.75 to 1.15, P = 0.52, I² = 0%, 15,817 participants, 43 trials, very low-quality evidence). The Trial Sequential Analysis showed that the cumulative Z-score crossed the trial sequential boundary for futility, showing that there was sufficient information to rule out that DAAs compared with placebo reduced the relative risk of a serious adverse event by 20%. The only DAA that showed a significant difference on risk of serious adverse events when meta-analysed separately was simeprevir (OR 0.62, 95% CI 0.45 to 0.86). However, Trial Sequential Analysis showed that there was not enough information to confirm or reject a relative risk reduction of 20%, and when one trial with an extreme result was excluded, then the meta-analysis result showed no evidence of a difference.DAAs on the market or under development seemed to reduce the risk of no sustained virological response (RR 0.44, 95% CI 0.37 to 0.52, P < 0.00001, I² = 77%, 6886 participants, 32 trials, very low-quality evidence) and Trial Sequential Analysis confirmed this meta-analysis result.Only 1/84 trials on the market or under development assessed the effects of DAAs on health-related quality of life (SF-36 mental score and SF-36 physical score).Withdrawn or discontinued DAAs had no evidence of a difference when assessing hepatitis C-related morbidity and all-cause mortality (OR 0.64, 95% CI 0.23 to 1.79, P = 0.40, I² = 0%; 5 trials, very low-quality evidence). However, withdrawn DAAs seemed to increase the risk of serious adverse events (OR 1.45, 95% CI 1.22 to 1.73, P = 0.001, I² = 0%, 29 trials, very low-quality evidence), and Trial Sequential Analysis confirmed this meta-analysis result.Most of all outcome results were short-term results; therefore, we could neither confirm nor reject any long-term effects of DAAs. None of the 138 trials provided useful data to assess the effects of DAAs on the remaining secondary outcomes (ascites, variceal bleeding, hepato-renal syndrome, hepatic encephalopathy, and hepatocellular carcinoma).

AUTHORS' CONCLUSIONS

Overall, DAAs on the market or under development do not seem to have any effects on risk of serious adverse events. Simeprevir may have beneficial effects on risk of serious adverse event. In all remaining analyses, we could neither confirm nor reject that DAAs had any clinical effects. DAAs seemed to reduce the risk of no sustained virological response. The clinical relevance of the effects of DAAs on no sustained virological response is questionable, as it is a non-validated surrogate outcome. All trials and outcome results were at high risk of bias, so our results presumably overestimate benefit and underestimate harm. The quality of the evidence was very low.

Current therapy for chronic hepatitis C: The role of direct-acting antivirals

One of the most exciting developments in antiviral research has been the discovery of the direct-acting antivirals (DAAs) that effectively cure chronic hepatitis C virus (HCV) infections. Based on more than 100 clinical trials and real-world studies, we provide a comprehensive overview of FDA-approved therapies and newly discovered anti-HCV agents with a special focus on drug efficacy, mechanisms of action, and safety. We show that HCV drug development has advanced in multiple aspects: (i) interferon-based regimens were replaced by interferon-free regimens; (ii) genotype-specific drugs evolved to drugs for all HCV genotypes; (iii) therapies based upon multiple pills per day were simplified to a single pill per day; (iv) drug potency increased from moderate (∼60%) to high (>90%) levels of sustained virologic responses; (v) treatment durations were shortened from 48 to 12 or 8 weeks; and (vi) therapies could be administered orally regardless of prior treatment history and cirrhotic status. However, despite these remarkable achievements made in HCV drug discovery, challenges remain in the management of difficult-to-treat patients.

•

HCV genotype-specific drugs evolve to pan-genotypic drugs.

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Drug potency increases from moderate (∼60%) to high (>90%) levels of sustained virologic response.

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Treatment durations are shortened from a 48-week to 12-week or 8-week period.

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HCV therapies based upon multiple pills per day are simplified to a single pill per day.

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HCV therapies are administered orally regardless of prior treatment history and cirrhotic status.

History and future of antiviral therapy of chronic hepatitis C

Hepatitis C virus (HCV) infection often leads to chronic diseases, and antiviral therapy is an important way to prevent chronic hepatitis C from progressing to end-stage liver disease. Up to now, hepatitis C antiviral therapy has successively experienced eras of interferon monotherapy, interferon and ribavirin combination therapy, and combination therapy of pegylated-interferon (PEG-IFN) and ribavirin. Now we are entering into a new era of direct-acting antiviral agents (DAAs). Just like acquired immune deficiency syndrome (AIDS) cocktails, combination therapy consists of two or more antiviral agents. DAAs will be the primary antiviral therapy for hepatitis C in the future for their better tolerance, lower drug resistance, higher sustained virological response and shorter treatment course. In this article, we review the history and future of antiviral therapy of HCV infection.

Ritonavir-boosted danoprevir-based regimens in treatment-naive and prior null responders with HCV genotype 1 or 4 and compensated cirrhosis

BACKGROUND AND AIM

Effective and safe antiviral treatment regimens are needed for patients with chronic hepatitis C (CHC) and cirrhosis.

METHODS

An international open-label trial was conducted in CHC patients with genotype (G)1/4 infection, compensated cirrhosis, HCV RNA ≥ 50,000 IU/mL and body mass index 18-35 kg/m(2). Treatment-naive patients (Cohort 1) received a triple therapy regimen [danoprevir/r 100/100 mg twice daily (bid), ribavirin 1000/1200 mg/day and peginterferon alfa-2a 180 µg/week] for 24 weeks. Prior null responders (Cohort 2) received a quadruple therapy regimen (danoprevir/r 100/100 mg bid, mericitabine 1000 mg bid and peginterferon alfa-2a/ribavirin). The primary efficacy outcome was sustained virological response (HCV RNA < limit of quantification, target not detected) at end of the 24-week follow-up period (SVR24).

RESULTS

In Cohort 1 (n = 23), 73.9 and 65.2 % of patients had a virological response at Weeks 4 and 24, respectively; 39.1 % achieved SVR24 (G1a = 1/13; G1b = 8/9; G4 = 0/1). In Cohort 2 (n = 20), 100 % achieved virological response at Weeks 4 and 24; 65 % achieved SVR24 (G1a = 4/8; G1b = 7/10; G4 = 2/2). Treatment failure was more common in G1a than G1b-infected patients and less common in patients receiving quadruple therapy. Treatment failure was associated with emergence of resistance to danoprevir, but not mericitabine. The safety profile was typical of that associated with peginterferon alfa-2a/ribavirin. No deaths/episodes of hepatic decompensation occurred.

CONCLUSIONS

Treatment with danoprevir/r-based regimens for 24 weeks is safe and well tolerated in CHC patients with compensated cirrhosis. A quadruple therapy regimen (danoprevir/r, mericitabine, peginterferon alfa/ribavirin) produced high SVR24 rates in prior null responders, particularly among G1b patients.

Uptake and utilization of directly acting antiviral medications for hepatitis C infection in U.S. veterans

New drugs therapies have revolutionized the treatment of hepatitis C virus (HCV) infection. The objectives of this study were to evaluate uptake and utilization of boceprevir and telaprevir in the Department of Veterans Affairs (VA). We evaluated whether therapies conformed to response-guided protocols, whether they replaced standard interferon plus ribavirin treatment, and whether IL-28B was used to guide treatment. We performed an administrative data-based analysis of all patients receiving pharmacologic treatment for HCV in VA from October 2009 to July 2013. There were 12 737 new HCV prescriptions in VA during this time, with 5564 boceprevir or telaprevir prescriptions (44%) and 7173 prescriptions (56%) written for standard interferon plus ribavirin treatment. Prescriptions for the new treatments heavily favoured boceprevir vs telaprevir (83% vs 17%). Sixty-two percent (62%) of boceprevir-treated patients completed their minimum-specified protocol, while 69.2% of telaprevir-treated patients completed their minimum-specified protocol. From October 2010 to July 2012, 4090 patients had an IL-28B test; less than 16% of these tests guided subsequent HCV prescriptions. Uptake of boceprevir and telaprevir was rapid; the number of patients initiating treatment approximately doubled in the period after their introduction. While new prescriptions favor boceprevir or telaprevir over standard interferon plus ribavirin therapy, there appears to still be a strong role of interferon plus ribavirin in treating HCV patients. This work can inform our understanding of how other new effective HCV therapies will be used, their diffusion, and the timing of their diffusion in actual clinical practice.

Antifibrotic therapies in the liver

Significant progress has been made in understanding the principles underlying the development of liver fibrosis. This includes appreciating its dynamic nature, the importance of active fibrolysis in fibrosis regression, and the plasticity of cell populations endowing them with fibrogenic or fibrolytic properties. This is complemented by an increasing array of therapeutic targets with known roles in the progression or regression of fibrosis. With a key role for fibrosis in determining clinical outcomes and encouraging data from recently Food and Drug Administration-approved antifibrotics for pulmonary fibrosis, the development and validation of antifibrotic therapies has taken center stage in translational hepatology. In addition to summarizing the recent progress in antifibrotic therapies, the authors discuss some of the challenges ahead, such as achieving a better understanding of the interindividual heterogeneity of the fibrotic response, how to match interventions with the ideal patient population, and the development of better noninvasive methods to assess the dynamics of fibrogenesis and fibrolysis. Together, these advances will permit a better targeting and dose titration of individualized therapies. Finally, the authors discuss combination therapy with different antifibrotics as possibly the most potent approach for treating fibrosis in the liver.

Randomized study of danoprevir/ritonavir-based therapy for HCV genotype 1 patients with prior partial or null responses to peginterferon/ribavirin

BACKGROUND & AIMS

Chronic hepatitis C treatment for prior non-responders to peginterferon (PegIFN)/ribavirin remains suboptimal. The MATTERHORN study evaluated regimens containing ritonavir-boosted danoprevir (danoprevir/r) in prior PegIFN alfa/ribavirin non-responders.

METHODS

Prior partial responders (N=152) were randomized to 24 weeks of twice-daily danoprevir/r 100/100mg, mericitabine 1000 mg and ribavirin 1000/1200 mg (IFN-free); danoprevir/r plus PegIFN alfa-2a/ribavirin (triple); or danoprevir/r, mericitabine and PegIFN alfa-2a/ribavirin (Quad). Prior null responders (N=229) were randomized to 24 weeks of IFN-free therapy, or quad alone (Quad 24) or quad plus 24-weeks of PegIFN alfa-2a/ribavirin (Quad 48). The primary endpoint was sustained virological response (HCV RNA <25 IU/ml) 24 weeks after end-of-treatment (SVR24). Due to high relapse rates, genotype (G) 1a patients in IFN-free arms were offered additional PegIFN alfa-2a/ribavirin.

RESULTS

Among prior partial responders, SVR24 rates were 46.2%, 51.0%, and 86.0%, in the IFN-free, Triple and Quad arms, respectively; among prior null responders, SVR24 rates were 45.5%, 80.5%, and 83.8% respectively. Relapse rates were lower and SVR24 rates higher in G1b-infected than G1a-infected patients. SVR24 rates in G1a and G1b patients randomized to Quad were 75.0% and 96.2%, respectively, in the partial Quad arm, and 68.1% and 100%, respectively, in the null Quad 24 arm. Treatment failure was associated with resistance to danoprevir, but not to mericitabine, and was more common in G1a infected patients. Treatment was well-tolerated.

CONCLUSIONS

Danoprevir/r, mericitabine plus PegIFN alfa-2a/ribavirin was well-tolerated and produced high overall SVR24 rates in prior partial and null responders to PegIFN alfa/ribavirin. In contrast, IFN-free regimens were associated with unacceptably high relapse rates.

Similar prevalence of low-abundance drug-resistant variants in treatment-naive patients with genotype 1a and 1b hepatitis C virus infections as determined by ultradeep pyrosequencing

Background and Objectives

Hepatitis C virus (HCV) variants that confer resistance to direct-acting-antiviral agents (DAA) have been detected by standard sequencing technology in genotype (G) 1 viruses from DAA-naive patients. It has recently been shown that virological response rates are higher and breakthrough rates are lower in G1b infected patients than in G1a infected patients treated with certain classes of HCV DAAs. It is not known whether this corresponds to a difference in the composition of G1a and G1b HCV quasispecies in regards to the proportion of naturally occurring DAA-resistant variants before treatment.

Methods

We used ultradeep pyrosequencing to determine the prevalence of low-abundance (<25% of the sequence reads) DAA-resistant variants in 191 NS3 and 116 NS5B isolates from 208 DAA-naive G1-infected patients.

Results

A total of 3.5 million high-quality reads of ≥200 nucleotides were generated. The median coverage depth was 4150x and 4470x per NS3 and NS5B amplicon, respectively. Both G1a and G1b populations showed Shannon entropy distributions, with no difference between G1a and G1b in NS3 or NS5B region at the nucleotide level. A higher number of substitutions that confer resistance to protease inhibitors were observed in G1a isolates (mainly at amino acid 80 of the NS3 region). The prevalence of amino acid substitutions that confer resistance to NS5B non-nucleoside inhibitors was similar in G1a and G1b isolates. The NS5B S282T variant, which confers resistance to the polymerase inhibitors mericitabine and sofosbuvir, was not detected in any sample.

Conclusion

The quasispecies genetic diversity and prevalence of DAA-resistant variants was similar in G1a and G1b isolates and in both NS3 and NS5B regions, suggesting that this is not a determinant for the higher level of DAA resistance observed across G1a HCV infected patients upon treatment.

Treatment of HCV infection with the novel NS3/4A protease inhibitors

HCV NS3/4A serine protease inhibitors are the first class of direct acting antivirals (DAA) introduced in clinical practice. The first generation agents, selective against HCV genotype 1, are used in association with pegylated interferons and ribavirin allowing increased cure rates at the price of increased toxicity, significant drug interactions and high risk of selecting mutants conferring cross-resistance to the entire class. A large number of second-wave HCV protease inhibitors are currently in clinical development. Advancements include higher potency, activity against a wider number of genotypes, improved tolerability, easier dosing schedules, although their genetic barrier to resistance remains low, especially for subtype 1a, except for the most recent grazoprevir and ACH-2684. The most relevant progress regards the combination with other classes of DAA allowing construction of interferon-free regimens of short duration, good tolerability with exceptionally high cure rates.

Antiviral treatment of hepatitis C

Hepatitis C virus (HCV) infection is a substantial health problem worldwide. Most patients infected with HCV remain chronically infected, with an increased risk of cirrhosis and hepatocellular carcinoma. Although they are associated with toxicities and low sustained viral response rates, interferon alfa and ribavirin have been the mainstay of treatment until recently. New direct acting antivirals, specifically designed to inhibit three viral proteins (the NS3/4A protease, the NS5A protein, and the NS5B RNA dependent RNA polymerase) are now becoming available. The NS3/4A inhibitor simeprevir and NS5B inhibitor sofosbuvir have recently been licensed and can reduce the length of antiviral treatment, improve response rates, and allow for interferon-free regimens for some HCV genotypes. Several other newer direct acting antivirals have shown promise in clinical studies and are likely to be licensed soon. These agents seem to facilitate the use of shortened courses of combination interferon-free therapy, which are associated with high (>95%) sustained response rates and relatively few toxicities. These regimens have also been successful in patients who were previously difficult to treat, including those with cirrhosis, HIV coinfection, and those who have undergone liver transplantation. The high cost of these agents may be the biggest challenge to their implementation worldwide.

Antiviral therapy for chronic hepatitis C in 2014

An all-oral therapy for treating hepatitis C (HCV) is now available for the most common genotypes although interferon-based therapy is still recommended for interferon-eligible patients with HCV genotype 1. For most patients, a prior history of treatment or presence of cirrhosis does not appear to significantly impact eradication rates with direct acting antivirals (DAA). The promising results from the numerous clinical trials of DAA's for HCV together with their tolerability represent a tremendous advance in our management of this disease, particularly as treatment is often well-tolerated, associated with few side effects and significantly shortened in duration. We will review several of the peer-reviewed landmark studies of DAA's for the treatment HCV and conclude with an expert commentary and five year view.

Pharmacogenetics of hepatitis C: transition from interferon-based therapies to direct-acting antiviral agents

Hepatitis C virus (HCV) has emerged as a major viral pandemic over the past two decades, infecting 170 million individuals, which equates to approximately 3% of the world’s population. The prevalence of HCV varies according to geographic region, being highest in developing countries such as Egypt. HCV has a high tendency to induce chronic progressive liver damage in the form of hepatic fibrosis, cirrhosis, or liver cancer. To date, there is no vaccine against HCV infection. Combination therapy comprising PEGylated interferon-alpha and ribavirin has been the standard of care for patients with chronic hepatitis C for more than a decade. However, many patients still do not respond to therapy or develop adverse events. Recently, direct antiviral agents such as protease inhibitors, polymerase inhibitors, or NS5A inhibitors have been used to augment PEGylated interferon and ribavirin, resulting in better efficacy, better tolerance, and a shorter treatment duration. However, most clinical trials have focused on assessing the efficacy and safety of direct antiviral agents in patients with genotype 1, and the response of other HCV genotypes has not been elucidated. Moreover, the prohibitive costs of such triple therapies will limit their use in patients in developing countries where most of the HCV infection exists. Understanding the host and viral factors associated with viral clearance is necessary for individualizing therapy to maximize sustained virologic response rates, prevent progression to liver disease, and increase the overall benefits of therapy with respect to its costs. Genome wide studies have shown significant associations between a set of polymorphisms in the region of the interleukin-28B (IL28B) gene and natural clearance of HCV infection or after PEGylated interferon-alpha and ribavirin treatment with and without direct antiviral agents. This paper synthesizes the recent advances in the pharmacogenetics of HCV infection in the era of triple therapies.

Emerging therapeutic options for the management of hepatitis C infection

Until recently the traditional treatment for hepatitis C infection included pegylated interferon and ribavirin combination therapy. The sustained virological response (SVR) seen with this combination is poor and requires lengthy treatment to achieve. Additionally, significant side effects and numerous contraindications prevented many patients from being successfully treated with this therapy. In 2011, two new protease inhibitors, telaprevir and boceprevir, were approved for use with pegylated interferon and ribavirin in the United States by the United States Food and Drug Administration. These agents have significantly improved SVR rates; however significant problems with toxicity remain including severe skin rash and neutropenia. There are a wide range of compounds in late stage development for the future treatment of hepatitis C that exploit many different mechanisms of viral inhibition. Some of these compounds include additional protease inhibitors, like telaprevir and boceprevir, as well as inhibitors of other nonstructural proteins in the viral genome such as NS5A and NS5B, and compounds that target host proteins within the virus. Some of these agents are being developed for oral administration once daily and various combinations are being assessed for use without the need for pegylated interferon and ribavirin. This paper reviews agents in late phase development that may be commercially available within 1-2 years.

NS3 protease inhibitors for treatment of chronic hepatitis C: Efficacy and safety

A new treatment paradigm for hepatitis C is that the treatment must include an existing direct-acting antiviral agent, namely, a protease inhibitor (PI) combined with PEGylated interferon-α and ribavirin. The currently marketed PIs and PIs in clinical trials have different mechanisms of action. The development of new PIs aims for an improved safety profile and higher effectiveness. This article reviews NS3/4A protease inhibitors, focusing on major criteria such as their effectiveness and safety. Specific attention is paid to dosing regimens and adverse event profiles of PIs administered in clinical settings.

New hepatitis C therapies: the toolbox, strategies, and challenges

Therapy for hepatitis C is undergoing a revolution. Several new drugs against the hepatitis C virus (HCV) have reached the market and many others, including direct-acting antivirals and host-targeted agents, are in phase II or III clinical development. All-oral, interferon-free combinations of drugs are expected to cure more than 90% of infections. A vast amount of data from clinical trials are presented regularly at international conferences or released to the press before peer-review, creating confusion in the viral hepatitis field. The goal of this review is to clarify the current stage of HCV therapy and drug development. This review describes the different classes of drugs and their mechanisms and properties, as well as treatment strategies in development, including those that are interferon-based and interferon-free. HCV treatment options that will be available in 2014-2015 are presented for each genotype. A number of unanswered questions and challenges remain, such as how to treat special populations, the role of ribavirin in interferon-free regimens, the role of HCV resistance in treatment failures, and how to best re-treat patients who failed on treatment. Strategic choices, cost issues, HCV screening, and improving access to care in resource-constrained areas also are discussed.

Second-wave IFN-based triple therapy for HCV genotype 1 infection: simeprevir, faldaprevir and sofosbuvir

With the approval of second-wave direct-acting antivirals simeprevir, sofosbuvir and faldaprevir in 2014-2015, for genotype 1 hepatitis C, patients and doctors will have more treatment options. During a first period, these treatments will still be used with peginterferon and ribavirin. The second wave of IFN-based triple therapy will have benefits and risk. These treatments have the following advantages: higher efficacy with more patient candidates for a shorten treatment duration (12-24 weeks, instead of 48 weeks). These new treatments appear to have a better safety profile than first generation, with no additional increase in anaemia over peginterferon/ribavirin. Then, these treatments are to take for patients with a decrease in pill burden (these three direct-acting antivirals are given orally one pill a day). Simeprevir and sofosbuvir may be approved in the US and Europe, in 2014, at the time this manuscript will be released. Approval of faldaprevir will follow. These direct-acting antivirals with many others will hopefully be combined in future interferon-free regimens. The goal of this review to summarize the results and safety of simeprevir, faldaprevir and sofosbuvir, to advise physicians and to inform patients on the benefits and risks of these second-wave IFN-based regimens for HCV genotype infection.

Antiviral treatment of hepatitis C virus infection and factors affecting efficacy

Hepatitis C virus (HCV) infection is the leading cause of chronic liver-related diseases, including cirrhosis, liver failure, and hepatocellular carcinoma. Currently, no effective vaccine is available for HCV infection. Polyethylene glycol interferon-α (PegIFN-α) in combination with ribavirin (RBV) is the standard of care (SOC) for chronic hepatitis C. However, the efficacy of PegIFN-α and RBV combination therapy is less than 50% for genotype 1 HCV, which is the dominant virus in humans. In addition, IFN and RBV have several severe side effects. Therefore, strategies to improve sustained virological response (SVR) rates have been an important focus for clinical physicians. The serine protease inhibitors telaprevir and boceprevir were approved by the United States Food and Drug Administration in 2011. The addition of HCV protease inhibitors to the SOC has significantly improved the efficacy of treatments for HCV infection. Several direct-acting antiviral drugs currently in late-stage clinical trials, both with and without peg-IFN and RBV, have several advantages over the previous SOC, including higher specificity and efficacy, fewer side effects, and the ability to be administered orally, and might be optimal regimens in the future. Factors affecting the efficacy of anti-HCV treatments based on IFN-α include the HCV genotype, baseline viral load, virological response during treatment, host IL28B gene polymorphisms and hepatic steatosis. However, determining the effect of the above factors on DAA therapy is necessary. In this review, we summarize the development of anti-HCV agents and assess the main factors affecting the efficacy of antiviral treatments.

Efficacy and safety of danoprevir-ritonavir plus peginterferon alfa-2a-ribavirin in hepatitis C virus genotype 1 prior null responders

Danoprevir (DNV) is a hepatitis C virus (HCV) protease inhibitor that achieves high sustained virologic response (SVR) rates in combination with peginterferon alfa-2a-ribavirin in treatment-naive HCV genotype 1 (G1)-infected patients. This study explored the efficacy and safety of ritonavir-boosted DNV (DNVr) plus peginterferon alfa-2a-ribavirin in G1-infected prior peginterferon-ribavirin null responders. Null responders (<2-log10 reduction in HCV RNA level at week 12) were given an open-label combination of 100 mg of ritonavir and 100 mg of DNV (100/100 mg DNVr) every 12 h (q12h) plus peginterferon alfa-2a-ribavirin for 12 weeks. All patients achieving an early virologic response (EVR; ≥2-log10 decrease in HCV RNA by week 12) continued treatment with peginterferon alfa-2a-ribavirin; those without an EVR discontinued all study drugs. Twenty-four prior null responders were enrolled; 16 patients (67%) were infected with HCV G1b, and 8 (33%) were infected with G1a. Ninety-six percent of patients had an IL28B non-CC genotype. A sustained virologic response at 24 weeks posttreatment (SVR24) was achieved in 67% of patients, with a higher rate in G1b-infected (88%) than G1a-infected (25%) patients. Resistance-related breakthrough occurred in 4/8 G1a and 1/16 G1b patients through the DNV resistance-associated variant (RAV) NS3 R155K. NS3 R155K was also detected in 2/2 G1a patients who relapsed. Treatment was well tolerated. Two patients withdrew prematurely from study medications due to adverse events. Two serious adverse events were reported; both occurred after completion of DNVr therapy and were considered unrelated to treatment. No grade 3 or 4 alanine aminotransferase (ALT) elevations were observed. DNVr plus peginterferon alfa-2a-ribavirin demonstrated high SVR24 rates in HCV G1b-infected prior null responders and was well tolerated. (This study has been registered at ClinicalTrials.gov under registration no. NCT01185860.).