Summary. During the late 1990s and early 2000s, major advances were made in the treatment of patients with chronic hepatitis C virus (HCV) infection. Interferon, combination interferon plus ribavirin (RBV) and pegylated interferon plus RBV increased sustained virologic response (SVR) rates from ~5% to ~40-80%, depending on the genotype of HCV infection. Advances in molecular biology have allowed investigators to begin to understand the mechanisms of HCV infection and replication. Advances in understanding of viral kinetics have provided tools to identify patients who are most likely to attain SVR. With the advances in the science of HCV infection, the first part of the 21st century has seen the development and early introduction of a number of direct-acting antiviral (DAA) drugs. These novel medications interfere with critical steps in HCV replication and have the potential to significantly increase SVR rates. This article will review the key elements of HCV replication and evaluate the various classes of new and investigational DAA that have the potential to create a revolution in the management of patients with chronic hepatitis C.

Treating hepatitis C: current standard of care and emerging direct‐acting antiviral agents

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 SEARCH METHODS: We searched for all published and unpublished trials in The Cochrane Hepato- Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, LILACS, and BIOSIS ; the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

Promising results have been observed with an investigational drug class for hepatitis C (HCV), the specifically targeted antiviral therapies for hepatitis C (STAT-Cs), when combined with peginterferon plus ribavirin (Peg-IFN/RBV). This class has the potential to increase sustained virological response (SVR) rates and reduce therapy duration in genotype 1 chronic HCV patients compared with Peg-IFN/RBV alone. However, because of the remarkable sequence variation in HCV (resulting from the high viral replication rate and intrinsically error-prone nature of HCV polymerase), variants with reduced susceptibility to STAT-Cs can occur naturally before treatment, usually at low levels, and can be selected in patients not responding to potent STAT-C treatment. This review first describes how resistance to a STAT-C can develop and then provides an overview of mutations that confer varying levels of resistance to STAT-Cs, which have been identified and characterized using both genotypic and phenotypic tools. We will discuss why an understanding of the selection of variants with reduced susceptibility to a treatment regimen may be important in optimizing the use of this new class of HCV therapy. Strategies for optimizing treatment regimens to increase response rates, and thereby minimize resistance, will be discussed. Finally, although resistance can be a consequence of not achieving an SVR on an initial regimen, there may be alternative treatment options for patients to achieve an SVR in the future. Future potential therapeutic strategies to address patients who do develop resistance to STAT-Cs are discussed, including combination therapy with multiple STAT-Cs with non-overlapping resistance profiles.

/pdf/viral-resistance-to-specifically-targeted-antiviral-26js736dhm.pdf

Viral resistance to specifically targeted antiviral therapies for hepatitis C (STAT-Cs)

Hepatitis C virus (HCV) causes significant morbidity and mortality worldwide with nearly 3% of the world population infected by this virus. Fortunately, this virus does not establish latency, and hence it may be possible to eradicate it. HCV is strongly associated with liver cirrhosis and hepatocellular carcinoma and is currently treated with pegylated interferon-alpha (peg-IFN-alpha) and ribavirin. Unfortunately, these limited treatment options often produce significant side effects, and currently, complete eradication of virus with combined drug modalities has not yet been achieved for the majority of chronically HCV-infected individuals. Restricted treatment options, lack of a universal cure for HCV and the link between chronic infection, liver cirrhosis and hepatocellular carcinoma necessitate design of novel drugs and treatment options. Understanding the relationship between the immune response, viral clearance and inhibition of viral replication with pharmacology-based design can ultimately allow for complete eradication of HCV. This review focuses upon significant novel preclinical and clinical specifically targeted antiviral therapy (STAT-C) drugs under development, highlights their mechanism of action, and discusses their impact on systemic viral loads and permanent clearance of infection.

HCV drug discovery aimed at viral eradication

ضدویروسها با عملکرد مستقیم برای هپاتیت مزمن c

http://www.hivandhepatitis.com/2009icr/easl/pdf/09409_MK7009.pdf

1056 mk-7009 significantly improves rapid viral response (rvr) in combination with pegylated interferon alfa-2a and ribavirin in patients with chronic hepatitis c (chc) genotype 1 infection

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1056 mk-7009 significantly improves rapid viral response (rvr) in combination with pegylated interferon alfa-2a and ribavirin in patients with chronic hepatitis c (chc) genotype 1 infection