Protease inhibitors for the treatment of chronic hepatitis C genotype-1 infection: the new standard of care. Lancet Infect Dis. 2012;12:717-728. [PMID: 22647717 DOI: 10.1016/s1473-3099(12)70060-9]

Hepatitis C virus NS3 protease genotyping and drug concentration determination during triple therapy with telaprevir or boceprevir for chronic infection with genotype 1 viruses, southeastern France

Telaprevir and boceprevir, the two first hepatitis C virus (HCV) NS3 protease inhibitors (PIs), considerably increase rates of sustained virologic response in association with pegylated interferon and ribavirin in chronic HCV genotype 1 infections. The 30 first patients treated by telaprevir or boceprevir including anti-HCV therapies since 2011 in Marseille University hospitals, France, were monitored. HCV loads and plasmatic concentrations of telaprevir and boceprevir were determined on sequential blood samples. HCV NS3 protease gene population sequencing was performed at baseline of treatment and in case of treatment failure. Fifteen patients (including 7 co-infected with HIV) received telaprevir and the other 15 patients (including 4 co-infected with HIV) received boceprevir. At baseline, HCV NS3 protease from six patients harbored amino acid substitutions associated with PI-resistance. Treatment failure occurred at week 12 for 7 patients. Amino acid substitutions associated with PI-resistance were observed in six of these cases. HCV NS3 R155K and T54A/S mutants, all of genotype 1a, were found from four patients. Median (interquartile range) plasma concentrations were 3,092 ng/ml (2,320-3,525) for telaprevir and 486 ng/ml (265-619) for boceprevir. For HIV-HCV co-infected patients, median concentrations were 3,162 ng/ml (2,270-4,232) for telaprevir and 374 ng/ml (229-519) for boceprevir. Plasma drug concentration monitoring revealed undetectable concentrations for two patients at week 4, and probable non-adherence to therapy for another patient. These findings indicate that routine HCV NS3 protease sequencing and plasma PI concentration monitoring might be helpful to characterize cases of therapy failure, at a cost dramatically low compared to that of anti-HCV therapy.

Efficacy and safety of sofosbuvir-based therapy for the treatment of chronic hepatitis C in treatment-naïve and treatment-experienced patients

Sofosbuvir, a hepatitis C virus (HCV) NS5B polymerase inhibitor, is a new direct-acting antiviral for chronic HCV infection. This systematic review and proportional meta-analysis examined the efficacy and safety of sofosbuvir-based therapy for chronic HCV infection in treatment-naïve and -experienced patients. Medline, Cochrane Database of Systematic Reviews, EMBASE and Web of Science databases were searched. Clinical trials examining sofosbuvir plus ribavirin (RBV) and pegylated interferon-α (peg-IFN) or sofosbuvir plus RBV among adults with chronic HCV infection were included. Data were extracted on virological responses including sustained virological response at post-treatment Week 12 (SVR12), relapse, treatment discontinuation due to an adverse event (AE), virological breakthrough during treatment, and AEs. One trial and 13 treatment arms/cohorts from seven studies met the criteria for analysis in treatment-naïve patients who were treated with sofosbuvir, RBV and peg-IFN; the SVR12 was 89% (95% CI 85-92%), relapse was 5% and the serious adverse event (SAE) rate was 4%. Six treatment arms/cohorts met the criteria for analysis in treatment-naïve patients who were treated with sofosbuvir and RBV; the SVR12 was 72% (95% CI 60-81%), relapse was 27% and the SAE rate was 3%. Three treatment arms/cohorts met the criteria for analysis in treatment-experienced patients who were treated with sofosbuvir and RBV; the SVR12 was 51% (95% CI 27-75%), relapse was 46% and the SAE rate was 4%. In conclusion, sofosbuvir-based treatment is effective and safe in treating chronic HCV infection, although the SVR12 of its combination with RBV, especially in treatment-experienced patients, requires improvement.

Phylogenetic analysis of hepatitis C virus strains and risk factors associated with infection and viral subtypes among Iranian patients

Hepatitis C virus (HCV) has infected approximately 170 million people worldwide. While the seroprevalence of anti-HCV antibody among Iranian blood donors is 0.13%, HCV infection is prevalent in 59-80% of Iranian injecting drug users. One hundred seventy-eight anti-HCV positive patients were referred to the Gastroenterology Department at the Taleghani Hospital (Tehran, Iran) between June 2007 and June 2012. Out of 178 samples, 142 were positive for HCV-RNA. HCV subtypes were determined using phylogenetic analysis of the NS5B or 5'UTR/core regions. Of 142 viremic patients, 71 (50%) were infected with HCV subtype 1a, 43 (30.3%) with subtype 3a, 20 (14.1%) with subtype 1b, 3 (2.1%) with subtype 4d, 2 (1.4%) with subtype 4a, 1 (0.7%) with subtype 2b, and 1 (0.7%) with subtype 6a. Interestingly, genetic analysis of a sub-genomic fragment from one patient identified a non-subtypeable HCV genotype-3 strain. There was a significant association between HCV subtype and a history of injecting drug use (P = 0.003). Subtype 3a was predominant among patients with such a history. Injecting drug use was associated with younger age (P < 0.001). HCV subtype was also significantly associated with a history of upper gastrointestinal endoscopy (P = 0.02). Subtype 1a was more frequent among patients with such a history. In addition, history of upper gastrointestinal endoscopy was significantly associated with older age (P = 0.002). In conclusion, while HCV subtype 1a is predominant among infected Iranian individuals, subtype 3a is predominant among Iranian injecting drug users.

Peg-interferon plus ribavirin with or without boceprevir or telaprevir for HCV genotype 1: a meta-analysis on the role of response predictors

Background & aim

To compare the efficacy of pegylated-interferon (Peg-IFN) α-2a or α-2b and ribavirin given as dual therapy versus triple therapy (Peg-IFN and ribavirin plus boceprevir or telaprevir) in patients with HCV-1 chronic hepatitis naïve for anti-HCV therapy or relapsers to dual therapy in relation to the presence of constitutional, clinical and virological predictors of treatment response.

Methods

Included in the meta-analysis were studies meeting these criteria: original data from randomized trials on the efficacy of dual versus triple therapy in therapy-naïve patients or relapsers; at least one primary outcome clearly defined: sustained virological response in patients with or without rapid virological response (RVR), with genotype 1a or 1b, low or high HCV load, IL28-B CC or non-CC genotype, mild or severe fibrosis; odds ratio estimates of relative risk (RR) and 95% confidence intervals; English language; and published up to the end of June 2013.

Results

Seven original studies met the inclusion criteria, allowing a meta-analysis on 3,652 patients. Triple therapy was more effective than dual, regardless of IL-28B genotype, HCV sub-genotype, liver fibrosis, and baseline HCV load. In 1,045 patients who achieved RVR, SVR was more frequently achieved with dual therapy (RR = 1.11; p = 0.002) than triple. The same results were achieved when only the therapy-naïve patients were considered.

Conclusions

Triple therapy provides a significantly higher SVR rate than dual therapy, but dual therapy obtains a significantly higher SVR rate in patients with RVR. The data stress the clinical importance of a 4-week lead-in phase in direct-acting antiviral-based treatment.

Inhibitors of the tick-borne, hemorrhagic fever-associated flaviviruses

No antiviral therapies are available for the tick-borne flaviviruses associated with hemorrhagic fevers: Kyasanur Forest disease virus (KFDV), both classical and the Alkhurma hemorrhagic fever virus (AHFV) subtype, and Omsk hemorrhagic fever virus (OHFV). We tested compounds reported to have antiviral activity against members of the Flaviviridae family for their ability to inhibit AHFV replication. 6-Azauridine (6-azaU), 2'-C-methylcytidine (2'-CMC), and interferon alpha 2a (IFN-α2a) inhibited the replication of AHFV and also KFDV, OHFV, and Powassan virus. The combination of IFN-α2a and 2'-CMC exerted an additive antiviral effect on AHFV, and the combination of IFN-α2a and 6-azaU was moderately synergistic. The combination of 2'-CMC and 6-azaU was complex, being strongly synergistic but with a moderate level of antagonism. The antiviral activity of 6-azaU was reduced by the addition of cytidine but not guanosine, suggesting that it acted by inhibiting pyrimidine biosynthesis. To investigate the mechanism of action of 2'-CMC, AHFV variants with reduced susceptibility to 2'-CMC were selected. We used a replicon system to assess the substitutions present in the selected AHFV population. A double NS5 mutant, S603T/C666S, and a triple mutant, S603T/C666S/M644V, were more resistant to 2'-CMC than the wild-type replicon. The S603T/C666S mutant had a reduced level of replication which was increased when M644V was also present, although the replication of this triple mutant was still below that of the wild type. The S603 and C666 residues were predicted to lie in the active site of the AHFV NS5 polymerase, implicating the catalytic center of the enzyme as the binding site for 2'-CMC.

Novel Peptidomimetic Hepatitis C Virus NS3/4A Protease Inhibitors Spanning the P2-P1' Region

Herein, novel hepatitis C virus NS3/4A protease inhibitors based on a P2 pyrimidinyloxyphenylglycine in combination with various regioisomers of an aryl acyl sulfonamide functionality in P1 are presented. The P1' 4-(trifluoromethyl)phenyl side chain was shown to be particularly beneficial in terms of inhibitory potency. Several inhibitors with K i-values in the nanomolar range were developed and included identification of promising P3-truncated inhibitors spanning from P2-P1'. Of several different P2 capping groups that were evaluated, a preference for the sterically congested Boc group was revealed. The inhibitors were found to retain inhibitory potencies for A156T, D168V, and R155K variants of the protease. Furthermore, in vitro pharmacokinetic profiling showed several beneficial effects on metabolic stability as well as on apparent intestinal permeability from both P3 truncation and the use of the P1' 4-(trifluoromethyl)phenyl side chain.

Discovery of Thienoimidazole-Based HCV NS5A Genotype 1a and 1b Inhibitors

The discovery of potent thienoimidazole-based HCV NS5A inhibitors is herein reported. A novel method to access the thienoimidazole [5,5]-bicyclic system is disclosed. This method gave access to a common key intermediate (6) that was engaged in Suzuki or Sonogashira reactions with coupling partners bearing different linkers. A detailed study of the structure-activity relationship (SAR) of the linkers revealed that aromatic linkers with linear topologies are required to achieve high potency for both 1a and 1b HCV genotypes. Compound 20, with a para-phenyl linker, was identified as a potential lead displaying potencies of 17 and 8 pM against genotype 1a and 1b replicons, respectively.

3.0T 31P MR spectroscopy in assessment of response to antiviral therapy for chronic hepatitis C

AIM: To investigate the utility of phosphorus-31 (31P) magnetic resonance spectroscopy (MRS) as a noninvasive test for assessment of response to interferon and ribavirin treatment in patients with different severities of hepatitis C virus infection.

METHODS: Sixty chronic hepatitis C patients undergoing antiviral therapy with interferon and ribavirin underwent 31P MRS at 3.0T before treatment, 6 mo after the start of treatment, and 1 year after the start of treatment.

RESULTS: The phosphomonoester (PME)/phosphodiester (PDE) ratio at 6 mo after the start of antiviral therapy in the Child-Pugh B and C groups were significantly higher than those before therapy, but this was not seen in the Child-Pugh A group. In the antiviral therapy group, the PME/PDE ratios had decreased on follow-up MR spectroscopy. However, in the virological nonresponder group, the PME/PDE ratios on follow-up imaging were similar to the baseline values.

CONCLUSION: 31P MRS can be used to provide biochemical information on hepatic metabolic processes. This study indicates that the PME/PDE ratio can be used as an indicator of response to antiviral treatment in chronic hepatitis C patients.

Boceprevir and telaprevir-based triple therapy for chronic hepatitis C: virological efficacy and impact on kidney function and model for end-stage liver disease score

Triple therapy using telaprevir or boceprevir [hepatitis C virus (HCV)-NS3/NS4A protease inhibitors (PI)] in association with PEG-IFN/ribavirin has recently become the new standard of care (SOC) for treatment of HCV genotype 1 patients. Our objective was to assess the efficacy and tolerance of triple therapy in routine clinical practice. A total of 186 consecutive HCV patients initiating triple therapy were enrolled in a single centre study. Clinical, biological and virological data were collected at baseline and during follow-up as well as tolerance and side effect details. Among 186 HCV patients initiating triple therapy, 69% received telaprevir and 31% boceprevir. Sixty-one per cent of patients had cirrhosis. The overall extended rapid virological response (eRVR) rate and sustained virological response (SVR) rate were 57.0% and 59.7%, respectively. IL28B CC phenotype was associated with increased probability of achieving eRVR and SVR, whereas previous non-response was associated with low eRVR and SVR rates. The SVR rate increased from 30.8% in previously non-responders to 59.1% in partial non-responders and 75% in relapsers. SVR rate in naive patients was 62.5%. Glomerular filtration rate assessed by MDRD after 12 weeks of therapy was significantly reduced for both PI (P < 0.001). The model for end-stage liver disease (MELD) score was significantly increased at W12 for telaprevir (P = 0.008) and at W24 for boceprevir (P = 0.027). PI-based triple therapy leads to high rates of virological response even in previously non-responder patients. Renal function after triple therapy is impaired as well as MELD score in all patients. Cautious clinical monitoring should focus not only on haematological and dermatological side effects but also on renal function.

Eltrombopag increases platelet numbers in thrombocytopenic patients with HCV infection and cirrhosis, allowing for effective antiviral therapy

BACKGROUND & AIMS

Thrombocytopenia is common among patients with hepatitis C virus (HCV) infection and advanced fibrosis or cirrhosis, limiting initiation and dose of peginterferon-alfa (PEG) and ribavirin (RBV) therapy. The phase 3 randomized, controlled studies, Eltrombopag to Initiate and Maintain Interferon Antiviral Treatment to Benefit Subjects with Hepatitis C-Related Liver Disease (ENABLE)-1 and ENABLE-2, investigated the ability of eltrombopag to increase the number of platelets in patients, thereby allowing them to receive initiation or maintenance therapy with PEG and RBV.

METHODS

Patients with HCV infection and thrombocytopenia (platelet count <75,000/μL) who participated in ENABLE-1 (n = 715) or ENABLE-2 (n = 805), from approximately 150 centers in 23 countries, received open-label eltrombopag (25-100 mg/day) for 9 weeks or fewer. Patients whose platelet counts reached the predefined minimal threshold for the initiation of PEG and RBV therapy (95% from ENABLE-1 and 94% from ENABLE-2) entered the antiviral treatment phase, and were assigned randomly (2:1) to groups that received eltrombopag or placebo along with antiviral therapy (24 or 48 weeks, depending on HCV genotype). The primary end point was sustained virologic response (SVR) 24 weeks after completion of antiviral therapy.

RESULTS

More patients who received eltrombopag than placebo achieved SVRs (ENABLE-1: eltrombopag, 23%; placebo, 14%; P = .0064; ENABLE-2: eltrombopag, 19%; placebo, 13%; P = .0202). PEG was administered at higher doses, with fewer dose reductions, in the eltrombopag groups of each study compared with the placebo groups. More patients who received eltrombopag than placebo maintained platelet counts of 50,000/μL or higher throughout antiviral treatment (ENABLE-1, 69% vs 15%; ENABLE-2, 81% vs 23%). Adverse events were similar between groups, with the exception of hepatic decompensation (both studies: eltrombopag, 10%; placebo, 5%) and thromboembolic events, which were more common in the eltrombopag group of ENABLE-2.

CONCLUSIONS

Eltrombopag increases platelet numbers in thrombocytopenic patients with HCV and advanced fibrosis and cirrhosis, allowing otherwise ineligible or marginal patients to begin and maintain antiviral therapy, leading to significantly increased rates of SVR. Clinical trial no: NCT00516321, NCT00529568.

Current progress in antiviral strategies

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Antiviral agents function as either viral targets or host factors.

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Virus-targeting antivirals (VTAs) function through a direct (DVTAs) or an indirect (InDVTAs) method in the viral life cycle.

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Host-targeting antivirals (HTAs) include reagents that target the host proteins that are involved in the viral life cycle.

The prevalence of chronic viral infectious diseases, such as human immunodeficiency virus (HIV), hepatitis C virus (HCV), and influenza virus; the emergence and re-emergence of new viral infections, such as picornaviruses and coronaviruses; and, particularly, resistance to currently used antiviral drugs have led to increased demand for new antiviral strategies and reagents. Increased understanding of the molecular mechanisms of viral infection has provided great potential for the discovery of new antiviral agents that target viral proteins or host factors. Virus-targeting antivirals can function directly or indirectly to inhibit the biological functions of viral proteins, mostly enzymatic activities, or to block viral replication machinery. Host-targeting antivirals target the host proteins that are involved in the viral life cycle, regulating the function of the immune system or other cellular processes in host cells. Here we review key targets and considerations for the development of both antiviral strategies.

Hepatitis C genotype 1 virus with low viral load and rapid virologic response to peginterferon/ribavirin obviates a protease inhibitor

The new standard of care for treatment-naïve patients with hepatitis C virus (HCV) genotype 1 includes triple therapy with peginterferon, ribavirin, and a protease inhibitor. However, patients who achieve a rapid virologic response after 4 weeks of peginterferon and ribavirin therapy are likely to achieve a sustained virologic response (SVR), and we hypothesized that protease inhibitor therapy may be unnecessary in these patients. Treatment-naïve, noncirrhosis patients infected with genotype-1 HCV and a low viral load at baseline were considered for inclusion (n = 233). After 4 weeks of lead-in therapy with peginterferon α-2b and ribavirin, 101 patients (48%) had a rapid virologic response (defined as undetectable levels of hepatitis C virus RNA at 4 weeks) and were eligible to participate. Patients were randomized 1:1 to 20 weeks of additional therapy with peginterferon α-2b and ribavirin (double therapy) or to 24 weeks of peginterferon α-2b, ribavirin, and boceprevir (triple therapy). There was no significant difference in rates of SVR-12 in patients treated with double versus triple therapy. This similarity persisted regardless of viral subtype (genotype 1a or 1b), interleukin (IL)-28b genotype (CC or non-CC), or ethnicity (African American versus non-Hispanic white).

CONCLUSION

Protease inhibitor therapy could be obviated in genotype 1-infected treatment-naïve patients with low viral load at baseline who achieve undetectable viremia after 4 weeks of peginterferon/ribavirin.

Defer or treat? Reasons for treatment decisions in patients with chronic hepatitis C genotype 1 in the early era of directly acting antiviral agents

BACKGROUND

In chronic genotype 1 hepatitis C, telaprevir or boceprevir plus peginterferon and ribavirin have become the new standard of care. Aim of this study was to identify factors contributing to the decision whether to defer or treat with the current triple regimens.

METHODS

Prospective assessment of eight parameters on 0-4-point scales by the attending physician at a German tertiary referral centre between 1st September 2011 and 31st December 2012.

RESULTS

307 patients were evaluated at least once by one of the 11 hepatologists involved; 267 patients were considered, but only 163 were recommended to receive triple therapy. Multivariate regression analysis revealed that a higher degree of fibrosis was most strongly associated with a recommendation for treatment (OR 2.69), followed by the patients' demand (OR 2.27), presumed efficacy (OR 1.62), and tolerability (OR 1.58). A high risk of decompensation was associated with the decision to defer (OR 0.39). Speed of progression, compliance, extrahepatic manifestation, gender and age were not significantly related to the recommendation. Treatment was finally started in 101 patients (32.9%).

CONCLUSION

In chronic genotype 1 hepatitis C, advanced fibrosis and patients' preference are the main rationales to choose treatment rather than deferral in a real-life setting.

Comparative effectiveness of the hepatitis C virus protease inhibitors boceprevir and telaprevir in a large U.S. cohort

BACKGROUND

Limited data exist on the effectiveness of boceprevir and telaprevir in routine practice.

AIM

To assess the comparative effectiveness of boceprevir and telaprevir regimens.

METHODS

In this observational, intent-to-treat cohort analysis of hepatitis C genotype 1-infected veterans initiated on peginterferon/ribavirin and boceprevir (n = 661) or telaprevir (n = 198), we determined sustained virological response (SVR), treatment discontinuation rates and adverse haematological events. Inverse probability-of-treatment weighting (IPTW) was used to estimate the effect of one drug over the other, with matched pairs and unweighted logistic regression on the entire cohort for comparison.

RESULTS

Of 835 veterans, SVR occurred in 50% and 52% receiving boceprevir- and telaprevir-based treatment, respectively (P = 0.72). No significant differences occurred among subgroups: cirrhotics (37% vs. 39%, P = 0.94), null responders (23% vs. 18%, P = 0.81), partial responders (39% vs. 58%, P = 0.15) and relapsers (60% vs. 77%, P = 0.11). Early discontinuation rates for boceprevir and telaprevir, respectively, were 31% and 28% by week 24 (P = 0.46) and 54% and 45% by 48 weeks (in those completing at least 28 weeks) (P = 0.14). Choice of telaprevir over boceprevir was significantly associated with SVR in multivariate models (IPTW OR: 1.57, 95% CI: 1.10-2.25, P = 0.01; matched-pairs OR: 1.91, 95% CI: 1.23-3.00, P = 0.004; unweighted OR: 1.50 95% CI: 1.05-2.14, P = 0.02). Rates of haematological adverse events in boceprevir- and telaprevir-treated patients were as follows: anaemia 59% vs. 51%, P = 0.30, thrombocytopenia 41% vs. 48%, P = 0.26, neutropenia 41% vs. 27%, P = 0.04.

CONCLUSIONS

Sustained virological response was more likely with telaprevir-based regimens compared with boceprevir-based regimens in routine medical practice, after accounting for patient differences. Early discontinuation and haematological events, however, were similar.

The favorable IFNL3 genotype escapes mRNA decay mediated by AU-rich elements and hepatitis C virus-induced microRNAs

IFNL3, which encodes interferon-λ3 (IFN-λ3), has received considerable attention in the hepatitis C virus (HCV) field, as many independent genome-wide association studies have identified a strong association between polymorphisms near IFNL3 and clearance of HCV. However, the mechanism underlying this association has remained elusive. In this study, we report the identification of a functional polymorphism (rs4803217) in the 3' untranslated region (UTR) of IFNL3 mRNA that dictated transcript stability. We found that this polymorphism influenced AU-rich element (ARE)-mediated decay (AMD) of IFNL3 mRNA, as well as the binding of HCV-induced microRNAs during infection. Together these pathways mediated robust repression of the unfavorable IFNL3 polymorphism. Our data reveal a previously unknown mechanism by which HCV attenuates the antiviral response and indicate new potential therapeutic targets for HCV treatment.

Allosteric inhibition of the NS2B-NS3 protease from dengue virus

Dengue virus is the flavivirus that causes dengue fever, dengue hemorrhagic disease, and dengue shock syndrome, which are currently increasing in incidence worldwide. Dengue virus protease (NS2B-NS3pro) is essential for dengue virus infection and is thus a target of therapeutic interest. To date, attention has focused on developing active-site inhibitors of NS2B-NS3pro. The flat and charged nature of the NS2B-NS3pro active site may contribute to difficulties in developing inhibitors and suggests that a strategy of identifying allosteric sites may be useful. We report an approach that allowed us to scan the NS2B-NS3pro surface by cysteine mutagenesis and use cysteine reactive probes to identify regions of the protein that are susceptible to allosteric inhibition. This method identified a new allosteric site utilizing a circumscribed panel of just eight cysteine variants and only five cysteine reactive probes. The allosterically sensitive site is centered at Ala125, between the 120s loop and the 150s loop. The crystal structures of WT and modified NS2B-NS3pro demonstrate that the 120s loop is flexible. Our work suggests that binding at this site prevents a conformational rearrangement of the NS2B region of the protein, which is required for activation. Preventing this movement locks the protein into the open, inactive conformation, suggesting that this site may be useful in the future development of therapeutic allosteric inhibitors.

Cirrhosis but not neutropenia is associated with the development of infection in patients with chronic hepatitis C undergoing treatment with pegylated interferon-alpha and ribavirin

Peginterferon-alpha (PegIFNa) frequently causes neutropenia, mainly due to bone marrow suppression. The aim of this study was to explore factors that are associated with infections during antiviral treatment. We analysed data from 275 chronic hepatitis C (CHC) patients with compensated liver disease who underwent 318 courses of PegIFNa and ribavirin. Neutropenia was defined as neutrophils <1000 cells/μL. Mean leucocytes count significantly decreased from baseline to treatment nadir (7081 ± 2182 vs 3293 ± 1331 cells/μL, P < 0.001), while neutropenia was observed in 32% during treatment. Thirty-one infections were observed. The incidence rate for infection was assessed at 1.46 infections per 100 person-months of therapy. The hazard rate for infection did not correlate with the neutrophils' nadir or the decrease in white blood cells. In multivariate Cox's regression analysis, cirrhosis was the only factor that was significantly associated with the occurrence of infection. Our data show that the development of bacterial infections during treatment with PegIFNa and ribavirin in patients with compensated CHC is not associated with reduction or the nadir of white cells or neutrophil counts. Baseline cirrhosis is the only factor related with infection during treatment. The common practice of dose adjustment or discontinuation of interferon should be revised; careful assessment of liver damage before therapy and close monitoring during therapy are essential in all patients receiving interferon-based regimes, to minimize the detrimental consequences of infections.

Inhibition of novel β coronavirus replication by a combination of interferon-α2b and ribavirin

The identification of a novel β coronavirus, nCoV, as the causative agent of severe respiratory illness in humans originating in Saudi Arabia, Qatar and Jordan has raised concerns about the possibility of a coronavirus pandemic similar to that of SARS-CoV. As a definitive treatment regimen has never been thoroughly evaluated for coronavirus infections, there is an urgent need to rapidly identify potential therapeutics to address future cases of nCoV. To determine an intervention strategy, the effect of interferon-α2b and ribavirin on nCoV isolate hCoV-EMC/2012 replication in Vero and LLC-MK2 cells was evaluated. hCoV-EMC/2012 was sensitive to both interferon-α2b and ribavirin alone in Vero and LLC-MK2 cells, but only at relatively high concentrations; however, when combined, lower concentrations of interferon-α2b and ribavirin achieved comparable endpoints. Thus, a combination of interferon-α2b and ribavirin, which are already commonly used in the clinic, may be useful for patient management in the event of future nCoV infections.

Characterization of hepatitis C virus intra- and intergenotypic chimeras reveals a role of the glycoproteins in virus envelopment

Hepatitis C virus (HCV) is highly variable and associated with chronic liver disease. Viral isolates are grouped into seven genotypes (GTs). Accumulating evidence indicates that viral determinants in the core to NS2 proteins modulate the efficiency of virus production. However, the role of the glycoproteins E1 and E2 in this process is currently poorly defined. Therefore, we constructed chimeric viral genomes to explore the role of E1 and E2 in HCV assembly. Comparison of the kinetics and efficiency of particle production by intragenotypic chimeras highlighted core and p7 as crucial determinants for efficient virion release. Glycoprotein sequences, however, had only a minimal impact on this process. In contrast, in the context of intergenotypic HCV chimeras, HCV assembly was profoundly influenced by glycoprotein genes. On the one hand, insertion of GT1a-derived (H77) E1-E2 sequences into a chimeric GT2a virus (Jc1) strongly suppressed virus production. On the other hand, replacement of H77 glycoproteins within the GT1a-GT2a chimeric genome H77/C3 by GT2a-derived (Jc1) E1-E2 increased infectious particle production. Thus, within intergenotypic chimeras, glycoprotein features strongly modulate virus production. Replacement of Jc1 glycoprotein genes by H77-derived E1-E2 did not grossly affect subcellular localization of core, E2, and NS2. However, it caused an accumulation of nonenveloped core protein and increased abundance of nonenveloped core protein structures with slow sedimentation. These findings reveal an important role for the HCV glycoproteins E1 and E2 in membrane envelopment, which likely depends on a genotype-specific interplay with additional viral factors.

Antidepressant pretreatment for the prevention of interferon alfa-associated depression: a systematic review and meta-analysis

BACKGROUND

Depression is a major complication during treatment with interferon alfa (IFN-α).

AIM

The aim of this study was to clarify whether preemptive antidepressant treatment can reduce the incidence and severity of IFN-associated depression.

METHOD

Based on a systematic review of the literature up to July 2012, a meta-analysis of the data from 8 trials investigating patients with malignant melanoma or hepatitis C was performed. The influence of antidepressants on the incidence of major depression and depression severity was defined as the primary outcome and the influence of somatic disorder, psychiatric comorbidity, type of antidepressants, type of IFN, and possible effects on treatment outcome as secondary outcome criteria.

RESULTS

Antidepressant pretreatment reduced the overall incidence of major depression during IFN treatment in all patients (odds ratio = 0.42; 95% confidence interval, 0.26-0.68; p < 0.001, n = 589) and was associated with lower mean depression scores after 12 weeks of IFN treatment (g = -0.37; 95% confidence interval -0.59 to -0.18; p < 0.001, n = 375). For patients with hepatitis C virus infection, antidepressants reduced the incidence of major depression (odds ratio = 0.38; 95% confidence interval 0.22-0.66; p < 0.001, n = 549) and the mean depression scores after 24 weeks of IFN treatment (g = -0.50; 95% confidence interval -0.70 to -0.29; p < 0.001, n = 335). The effects of selective serotonin reuptake inhibitors on the incidence and severity of depression were not dependent on pre-existing psychiatric disorders.

CONCLUSION

Antidepressant pretreatment with selective serotonin reuptake inhibitors lowers the incidence and severity of IFN-associated depression in patients with chronic hepatitis C infection or malignant melanoma.

Serotonin and interleukin-6: the role of genetic polymorphisms in IFN-induced neuropsychiatric symptoms

BACKGROUND

Cytokines and serotonin neurotransmission may play an important role on the development of psychopathological symptoms during interferon (IFN) treatment. The aim of the present study was to investigate the association between IFN-induced depression, anxiety and fatigue and functional genetic variants at the interleukin-6 gene (IL-6) and serotonin transporter gene (SERT).

METHODS

385 consecutive Caucasian outpatients with chronic hepatitis C initiating treatment with IFN-alpha and ribavirin were included. All patients were interviewed at baseline using the Structured Clinical Interview for DSM-IV (SCID-I) and those with a current major depressive disorder or anxiety disorder before starting treatment were excluded. Depression and anxiety were assessed at baseline during the treatment (at 4, 12, 24 and 48 weeks) using the Hospital Anxiety and Depression Scale and fatigue was evaluated using a visual analogue scale. The 5-HTTLPR region of SERT gene and the functional polymorphism located at the promoter region of IL-6 gene (rs1800795) were genotyped.

RESULTS

Genotypic distribution was in the Hardy-Weinberg equilibrium for SERT (p=0.41) and for IL-6 (p=0.72) polymorphisms. At baseline we found only a significant effect of IL-6 polymorphism on fatigue symptoms. During antiviral treatment we reported that subjects with CC genotype (IL-6) presented significantly lower changes from baseline in IFN-induced depression (p=0.005) and IFN-induced anxiety (p=0.004). We did not find statistically significant differences on depression (p=0.21) or anxiety (p=0.15) between SS/SL and LL genotypes of SERT.

CONCLUSIONS

Genetic variations in the IL-6 gene increase the risk of IFN-induced depression and anxiety. The IL-6 polymorphism was associated with fatigue rates in patients with chronic hepatitis C before treatment. Our study confirms the role of inflammatory mechanisms in IFN-induced psychopathological symptoms.

Early virologic responses and hematologic safety of direct-acting antiviral therapies in veterans with chronic hepatitis C

BACKGROUND & AIMS

There are limited data on the early effectiveness of direct-acting antiviral (DAA) therapies for patients with hepatitis C virus (HCV) infection in routine medical practice. We aimed to evaluate real-world experience with DAA-based regimens.

METHODS

By using the Veterans Affairs' Clinical Case Registry, we conducted a prospective observational intent-to-treat analysis of veterans infected with HCV genotype 1 who began treatment with pegylated interferon, ribavirin, and boceprevir (BOC, n = 661) or telaprevir (TVR, n = 198) before January 2012. We determined rates of virologic response at treatment weeks 4, 8, 12, and 24; futility; early discontinuation; and adverse hematologic events.

RESULTS

About one third of patients discontinued treatment by week 24 (30% BOC, 34% TVR). A higher percentage of treatment-naive, noncirrhotic patients receiving BOC had undetectable levels of virus at week 24 than patients receiving TVR (74% vs 60%; P = .03). There were no significant differences in rates of early response within subgroups of cirrhotic patients, prior relapsers, prior partial responders, or prior null responders. By week 24, treatment was determined to be futile for 14% of patients receiving BOC and 17% of those receiving TVR. No differences were observed in overall rates of anemia (50% BOC, 49% TVR) or thrombocytopenia (16% BOC, 18% TVR); higher rates of neutropenia were observed in BOC-treated patients (34% BOC, 21% TVR; P = .008).

CONCLUSIONS

HCV-infected veterans treated in routine medical practice with DAA-based regimens (BOC or TVR) had rates of early response comparable with those reported in clinical trials. However, they had higher rates of futility and early discontinuation than clinical trial participants. Further studies are needed to determine rates of sustained viral response.

Direct-acting antivirals for the treatment of chronic hepatitis C: open issues and future perspectives

Currently, two direct-acting antivirals (DAAs) show well-established efficacy against hepatitis C virus (HCV), namely, first-wave protease inhibitors telaprevir and boceprevir. Most clinical trials have examined DAAs in combination with standard of care (SOC) regimens. Future therapeutic drugs were divided into three categories. They are second-wave protease inhibitors, second-generation protease inhibitors, and polymerase inhibitors. Second-wave protease inhibitors are more improved form and can be administered once a day. Oral drug combinations can be favored because interferon (IFN) not only has to be given as intradermal injection, but also can cause several serious side effects. Combination of drugs with different mechanisms shows a good sustained virological response (SVR). But several mutations are associated with viral resistance to DAAs. Therefore, genotypic resistance data may provide insights into strategies aimed at maximizing SVR rates and minimizing resistance. Combined drug regimens are necessary to prevent the emergence of drug-resistant HCV. Many promising DAA candidates have been identified. Of these, a triple regimen containing sofosbuvir shows promise, and treatment with daclatasvir plus asunaprevir yields a high SVR rate (95%). Oral drug combinations will be standard of care in the near future.

ACH-806, an NS4A antagonist, inhibits hepatitis C virus replication by altering the composition of viral replication complexes

Treatment of hepatitis C patients with direct-acting antiviral drugs involves the combination of multiple small-molecule inhibitors of distinctive mechanisms of action. ACH-806 (or GS-9132) is a novel, small-molecule inhibitor specific for hepatitis C virus (HCV). It inhibits viral RNA replication in HCV replicon cells and was active in genotype 1 HCV-infected patients in a proof-of-concept clinical trial (1). Here, we describe a potential mechanism of action (MoA) wherein ACH-806 alters viral replication complex (RC) composition and function. We found that ACH-806 did not affect HCV polyprotein translation and processing, the early events of the formation of HCV RC. Instead, ACH-806 triggered the formation of a homodimeric form of NS4A with a size of 14 kDa (p14) both in replicon cells and in Huh-7 cells where NS4A was expressed alone. p14 production was negatively regulated by NS3, and its appearance in turn was associated with reductions in NS3 and, especially, NS4A content in RCs due to their accelerated degradation. A previously described resistance substitution near the N terminus of NS3, where NS3 interacts with NS4A, attenuated the reduction of NS3 and NS4A conferred by ACH-806 treatment. Taken together, we show that the compositional changes in viral RCs are associated with the antiviral activity of ACH-806. Small molecules, including ACH-806, with this novel MoA hold promise for further development and provide unique tools for clarifying the functions of NS4A in HCV replication.

Hepatitis C virus in American Indian/Alaskan Native and Aboriginal peoples of North America

Liver diseases, such as hepatitis C virus (HCV), are “broken spirit” diseases. The prevalence of HCV infection for American Indian/Alaskan Native (AI/AN) in the United States and Canadian Aboriginals varies; nonetheless, incidence rates of newly diagnosed HCV infection are typically higher relative to non-indigenous people. For AI/AN and Aboriginal peoples risk factors for the diagnosis of HCV can reflect that of the general population: predominately male, a history of injection drug use, in midlife years, with a connection with urban centers. However, the face of the indigenous HCV infected individual is becoming increasingly female and younger compared to non-indigenous counterparts. Epidemiology studies indicate that more effective clearance of acute HCV infection can occur for select Aboriginal populations, a phenomenon which may be linked to unique immune characteristics. For individuals progressing to chronic HCV infection treatment outcomes are comparable to other racial cohorts. Disease progression, however, is propelled by elevated rates of co-morbidities including type 2 diabetes and alcohol use, along with human immunodeficiency virus (HIV) co-infection relative to non-indigenous patients. Historical and personal trauma has a major role in the participation of high risk behaviors and associated diseases. Although emerging treatments provide hope, combating HCV related morbidity and mortality will require interventions that address the etiology of broken spirit diseases.

Validation of a solid-phase electrochemical array for genotyping hepatitis C virus

Hepatitis C viral infection is a major cause of progressive liver disease. HCV genotype is one of the most significant baseline predictors of response to HCV antiviral therapy. The objective was to evaluate an HCV genotyping method that targets the 5'-untranslated region (UTR) to detect genotypes/subtypes using the GenMark eSensor® XT-8 system. The HCV amplicon of major genotypes/subtypes from the Roche TaqMan® HCV assay served as a template for the nested PCR followed by a direct analysis on the XT-8 detection system. The assay was validated for limit of detection (LOD), specificity, accuracy and precision. The LOD determined was below 175 IU/ml for all the subtypes except 6ab. The genotypes detected using this assay were in concordance with the LiPA assay. The high performance characteristics (LOD, specificity, intra- and inter-assay precision, and accuracy), make this assay particularly well suited for clinical HCV genotyping in order to guide antiviral therapy.

Hepatitis C virus infection: looking for interferon free regimens

Recent developments of new drugs' combinations are changing the treatment paradigm in hepatitis C virus infection. Due to the side effect profile of pegylated interferons, interferon-sparing regimens have become the main target in chronic hepatitis C treatment research. Recent proofs of concept studies have suggested that cure of chronic hepatitis C can be achieved without interferon. The purpose of this paper is to provide an overview of the clinical results recently reported for the treatment of hepatitis C virus infection with interferon-free regimens, focusing on the most promising new compounds and combinations.

Sofosbuvir in combination with peginterferon alfa-2a and ribavirin for non-cirrhotic, treatment-naive patients with genotypes 1, 2, and 3 hepatitis C infection: a randomised, double-blind, phase 2 trial

BACKGROUND

Protease inhibitors have improved treatment of infection with hepatitis C virus (HCV), but dosing, a low barrier to resistance, drug interactions, and side-effects restrict their use. We assessed the safety and efficacy of sofosbuvir, a uridine nucleotide analogue, in treatment-naive patients with genotype 1-3 HCV infection.

METHODS

In this two-cohort, phase 2 trial, we recruited treatment-naive patients with HCV genotypes 1-3 from 22 centres in the USA. All patients were recruited between Aug 16, 2010, and Dec 13, 2010, and were eligible for inclusion if they were aged 18-70 years, had an HCV RNA concentration of 50,000 IU/mL or greater, and had no cirrhosis. We randomly allocated all eligible patients with HCV genotype 1 (cohort A) to receive sofosbuvir 200 mg, sofosbuvir 400 mg, or placebo (2:2:1) for 12 weeks in combination with peginterferon (180 μg per week) and ribavirin (1000-1200 mg daily), after which they continued peginterferon and ribavirin for an additional 12 weeks or 36 weeks (depending on viral response). Randomisation was done by use of a computer-generated randomisation sequence and patients and investigators were masked to treatment allocation until week 12. Patients with genotypes 2 or 3 (cohort B) received open-label sofosbuvir 400 mg plus peginterferon and ribavirin for 12 weeks. Our primary outcomes were safety and tolerability. Secondary efficacy analyses were by intention to treat and endpoints included sustained virological response, defined as undetectable HCV RNA at post-treatment weeks 12 and 24. This study is registered with ClinicalTrials.gov, number NCT01188772.

FINDINGS

In cohort A, 122 patients were assigned 200 mg sofosbuvir (48 patients), 400 mg sofosbuvir (48), or placebo (26). We enrolled 25 patients into cohort B. The most common adverse events--fatigue, headache, nausea, and chills--were consistent with those associated with peginterferon and ribavirin. Eight patients discontinued treatment due to adverse events, two (4%) receiving sofosbuvir 200 mg, three (6%) receiving sofosbuvir 400 mg, and three (12%) receiving placebo. In cohort A, HCV RNA was undetectable at post-treatment week 12 in 43 (90%; 95% CI 77-97) of 48 patients in the 200 mg sofosbuvir group; 43 (91%; 80-98) of 47 patients in the 400 mg sofosbuvir group, and 15 (58%; 37-77) of 26 patients in the placebo group. In cohort B, 23 (92%) of 25 patients had undetectable HCV RNA at post-treatment week 12.

INTERPRETATION

Our findings lend support to the further assessment, in phase 2 and 3 trials, of sofosbuvir 400 mg plus peginterferon and ribavirin for 12 weeks in treatment-naive patients with HCV genotype-1.

FUNDING

Gilead Sciences.

Glucose abnormalities in hepatitis C virus infection

Hepatitis C virus (HCV) infection is one of the most important causes of cirrhosis and hepatocellular carcinoma and has a tremendous impact on public health worldwide. HCV is both hepatotropic and lymphotropic. Replication of HCV in diseased extrahepatic organs and tissues may either trigger latent autoimmunity or induce autoimmune disorders. In addition to established liver injury, type 2 diabetes mellitus (T2DM) is an important feature of extrahepatic metabolic disorders which is attributed to HCV infection. It also has some impact on the disease activity, disease course, clinical outcomes, and treatment efficacy of antiviral therapy. Previous experimental and clinical findings have highly suggested that HCV per se is diabetogenic. The cause-effect interaction between a common endocrine disorder and an infectious disease is an important issue to elucidate. Although the precise mechanisms whereby HCV infection leads to insulin resistance (IR) and glucose abnormalities are not entirely clear, it differs from the usual pathogenesis of T2DM in those with non-HCV liver diseases. This review initially highlights epidemiological and pathophysiological studies addressing the mutual link between chronic HCV infection (CHC) and T2DM. The characteristics of glucose abnormalities in this special population are depicted from the current evidence. The mutual roles of IR and CHC with respect to the prediction of treatment efficacy, how treatment response affects IR, and the role of pancreatic beta cell function in the entire suite are discussed. With the rapid progression of antiviral therapy for CHC in the past decade, we have also listed some points of future perspective in this issue.

Small molecule inhibitors of the hepatitis C virus-encoded NS5A protein

Hepatitis C virus (HCV) is a modern-day pandemic; 2-3% of the world's population are thought to be infected with the virus and are subsequently at risk of developing end-stage liver diseases. The traditional standard of care (SOC) for HCV-infected patients has been limited to a regimen of pegylated-interferon alpha (pegIFN) and ribavirin; displaying low cure rates in a majority of patients and severe side effects. However, in 2011 the first direct-acting antivirals (DAA) were licensed to treat HCV-infected patients in combination with SOC, which served to elevate treatment response rates. The HCV drug development pipeline is currently populated with many additional and improved DAAs; primarily molecules that target the virus-encoded protease or polymerase enzymes. These molecules are being evaluated both in combination with the traditional SOC and together with other DAAs as all-oral pegIFN-free regimens with the ultimate goal of developing multiple DAA-containing HCV therapies that do not rely on an pegIFN backbone. A recent addition to the arsenal of HCV inhibitors in development is represented by an entirely new DAA class; molecules that target the HCV-encoded non-enzymatic NS5A protein. NS5A is essential for HCV propagation and, although its actual functions are largely unknown, it is likely a key regulator of viral genome replication and virion assembly. The protein is exquisitely sensitive to small molecule-mediated inhibition; NS5A-targeting molecules are probably the most potent antiviral molecules ever discovered and exhibit a number of other attractive drug-like properties, including activity against many HCV genotypes/subtypes and once-daily dosing potential. Although their mechanism of action is unclear, NS5A-targeting molecules are already proving their utility in clinical evaluation; particularly as components of pegIFN-sparring DAA combination regimens. This review will aim to amalgamate our current understanding and knowledge of NS5A-targeting molecules; their discovery, properties, applications, and insight into their future impact as components of all-oral pegIFN-free DAA combination therapies to combat HCV infection.