The global burden of hepatitis C

Molecular survey of hepatitis C virus in the touristic city of Mar del Plata, Argentina

The global epidemiology of Hepatitis C Virus (HCV) may be roughly described by two groups of genotypes: the worldwide distributed ones (subtypes 1a, 1b, 2a and 3a, among others) and the endemic ones (subtypes 4a, 5a, 6a, among others). Epidemiological and population dynamic studies of the worldwide distributed genotypes have shown that subtypes 1a and 3a are common among intravenous drug users (IDUs) and that they are also in expansion in some countries. The molecular survey of HCV provides some clues about the epidemiological status of the infections in a local scale and the phylogenetic and demographic reconstruction analyses complement this study by inferring whether the infections of certain subtypes are in a steady state or expanding. Here, a molecular survey of the HCV variants that circulate in the touristic city of Mar del Plata (Buenos Aires, Argentina) was performed in samples obtained from 42 patients. The subtypes detected were 1a (32 patients), 3a (8 patients) and 1b (2 patients). The demographic history of subtype 1a inferred using the sequence data showed an exponential growth in the 1990′s. The period of viral expansion was delayed compared with that observed for the same genotype in other countries where the transmission was associated with IDUs. Also, the phylogeographic analysis of HCV-1a showed a statistically significant association between the location of the samples and the phylogeny, which may be the result of the local transmission of HCV in the city. The molecular analysis helped in the description of the complex epidemiological context of a touristic city, and pointed out that some sanitary measures should be taken in order to reduce the transmission of HCV (and maybe of HIV) among IDUs.

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.

Viral hepatitis: global goals for vaccination

In countries where hepatitis A is highly endemic, exposure to hepatitis A virus (HAV) is almost universal before the age of 10 years, and large-scale immunization efforts are not required. In contrast, in areas of intermediate endemicity or in transition from high to intermediate endemicity, where transmission occurs primarily from person to person in the general community (often with periodic outbreaks), control of hepatitis A may be achieved through widespread vaccination programmes. Hepatitis B virus (HBV) is one of the world's most widespread infectious agents and the cause of millions of infections each year. Between 500,000 and 700,000 people die each year from chronic infection-related cirrhosis, hepatocellular carcinoma (HCC) or from acute hepatitis B. Hepatitis B vaccine provides protection against infection and its complications including liver cirrhosis and HCC. It is therefore, the first vaccine against a cancer, the first vaccine protecting from a sexually transmitted infection, and the first vaccine against a chronic disease ever licensed. Control and significant reduction in incidence of new HBV infections as well as hepatocellular carcinoma has repeatedly been reported in countries in East Asia (i.e. Taiwan) and Africa (i.e. The Gambia). Two experimental vaccines against hepatitis E have been developed; one of them has been recently licensed but is not yet widely available. Attempts to develop a hepatitis C vaccine were so far unsuccessful.

Test of IL28B polymorphisms in chronic hepatitis C patients treated with PegIFN and ribavirin depends on HCV genotypes: results from a meta-analysis

BACKGROUND

Many studies have been published on the association between single nucleotide polymorphisms (SNP) near the IL28B gene and response to the combined treatments of pegylated-interferon (PegIFN) and ribavirin (RBV) in chronic HCV-infected patients, but without identical conclusions. The aim of this study was to assess impact of the IL28B polymorphisms on the effect of HCV standard treatment using meta-analysis based method.

METHODS

Association studies between polymorphisms of rs12979860 or rs8099917 and response to PegIFN/RBV treatment in chronic HCV patients were retrieved from PubMed. Data of qualified studies on sustained virological response (SVR) in different genotypes were extracted and analyzed using meta-analysis method in Stata 10 software.

RESULTS

Thirty-four papers, containing 46 independent studies, were included in the analysis. In the HCV G1/4 patients without treatment history, individuals carrying rs12979860 CC genotype were more likely to achieve SVR (OR 3.97, 95%CI 3.29-4.80) compared to those carrying CT/TT genotypes. Similar results were observed in the HCV G1/4 patients with unsuccessful or unknown treatment history (OR 3.76, 95%CI 2.67-5.28) or in the patients co-infected with human immunodeficiency virus (OR 5.20, 95%CI 3.04-8.90). However, associations could not be observed in HCV G2/3 patients. For rs8099917, similar results were obtained for genotype TT compared to genotypes TG/GG, indicating that TT genotype was significantly associated with better treatment response in patients infected with genotype 1 or 4 HCV, but not genotype 2 or 3 HCV.

CONCLUSION

Polymorphisms of rs12979860 and rs8099917 near IL28B only associate with the treatment response to PegIFN/RBV in patients infected with HCV genotype 1 or 4 but not with genotype 2 or 3, irrespective of the previous treatment history or HIV co-infected status. Therefore, identification of IL28B genotypes is necessary only in patients infected with relatively difficult-to-treat genotype 1 or 4 HCV.

The p7 protein of hepatitis C virus forms structurally plastic, minimalist ion channels

Hepatitis C virus (HCV) p7 is a membrane-associated oligomeric protein harboring ion channel activity. It is essential for effective assembly and release of infectious HCV particles and an attractive target for antiviral intervention. Yet, the self-assembly and molecular mechanism of p7 ion channelling are currently only partially understood. Using molecular dynamics simulations (aggregate time 1.2 µs), we show that p7 can form stable oligomers of four to seven subunits, with a bias towards six or seven subunits, and suggest that p7 self-assembles in a sequential manner, with tetrameric and pentameric complexes forming as intermediate states leading to the final hexameric or heptameric assembly. We describe a model of a hexameric p7 complex, which forms a transiently-open channel capable of conducting ions in simulation. We investigate the ability of the hexameric model to flexibly rearrange to adapt to the local lipid environment, and demonstrate how this model can be reconciled with low-resolution electron microscopy data. In the light of these results, a view of p7 oligomerization is proposed, wherein hexameric and heptameric complexes may coexist, forming minimalist, yet robust functional ion channels. In the absence of a high-resolution p7 structure, the models presented in this paper can prove valuable as a substitute structure in future studies of p7 function, or in the search for p7-inhibiting drugs.

Neurological complications of hepatitis C infection

Though well-known as a cause of liver disease, Hepatitis C virus infection is emerging as a cause of a variety of peripheral and central nervous system disorders. The virus causes chronic persistent infection with complex immune responses in the majority of individuals. Viral infection may have the potential to generate neurological illness through direct infection of neural cells or through immune-mediated mechanisms, including enhancement of autoimmune responses. Moreover, the mainstay of antiviral treatment of hepatitis C infection, interferon-alpha, is itself associated with neurological morbidity. Thus neurologists are increasingly faced with diagnosing or even predicting a wide spectrum of neurological complications of hepatitis C infection and/or its treatment.

Amino acid residue-specific neutralization and nonneutralization of hepatitis C virus by monoclonal antibodies to the E2 protein

Antibodies to epitopes in the E2 protein of hepatitis C virus (HCV) reduce the viral infectivity in vivo and in vitro. However, the virus can persist in patients in the presence of neutralizing antibodies. In this study, we generated a panel of monoclonal antibodies that bound specifically to the region between residues 427 and 446 of the E2 protein of HCV genotype 1a, and we examined their capacity to neutralize HCV in a cell culture system. Of the four monoclonal antibodies described here, two were able to neutralize the virus in a genotype 1a-specific manner. The other two failed to neutralize the virus. Moreover, one of the nonneutralizing antibodies could interfere with the neutralizing activity of a chimpanzee polyclonal antibody at E2 residues 412 to 426, as it did with an HCV-specific immune globulin preparation, which was derived from the pooled plasma of chronic hepatitis C patients. Mapping the epitope-paratope contact interfaces revealed that these functionally distinct antibodies shared binding specificity for key amino acid residues, including W(437), L(438), L(441), and F(442), within the same epitope of the E2 protein. These data suggest that the effectiveness of antibody-mediated neutralization of HCV could be deduced from the interplay between an antibody and a specific set of amino acid residues. Further understanding of the molecular mechanisms of antibody-mediated neutralization and nonneutralization should provide insights for designing a vaccine to control HCV infection in vivo.

Too low to measure, infectious nonetheless

In this issue of Blood, Busch and colleagues examine the risk of hepatitis C virus (HCV) transmission by plasma collected before HCV is detectable by licensed clinical assays.1

Health care utilization in HIV-infected patients: assessing the burden of hepatitis C virus coinfection

Abstract Health care utilization for HIV-1-infected patients appears to be declining in the United States as a result of highly active antiviral therapy (HAART); yet the opposite appears true in the HIV/hepatitis C virus (HCV) coinfected population. The reasons for this difference are not well understood. We examined the rates and reasons for emergency department visits and hospital admissions at an academic tertiary care medical center for HIV/HCV coinfected patients as compared to HIV-1 monoinfected patients, using a retrospective matched cohort study design. HIV/HCV coinfected patients had higher rates of health care utilization (emergency department visits 43.9 versus 7.1 per 100 person-years; hospital admissions 18.2 versus 6.7 per 100 person-years, for HIV coinfected and monoinfected, respectively). This increase was not solely due to liver related events. Instead, comorbidities such as diabetes, renal disease, and psychiatric/substance abuse played a larger role in the health-care utilization in the HIV/HCV coinfected population.

Interferon-γ-stimulated genes, but not USP18, are expressed in livers of patients with acute hepatitis C

BACKGROUND & AIMS

Approximately 50% of patients with chronic hepatitis C (CHC) have a sustained virologic response to treatment with pegylated interferon (pegIFN)-α and ribavirin. Nonresponse to treatment is associated with constitutively increased expression of IFN-stimulated genes (ISGs) in the liver. Treatment of patients with acute hepatitis C (AHC) is more effective, with sustained virologic response rates greater than 90%. We investigated mechanisms of the different responses of patients with CHC and AHC to pegIFN-α therapy.

METHODS

We analyzed IFN signaling and ISG expression in liver samples from patients with AHC, patients with CHC, and individuals without hepatitis C (controls) using microarray, immunohistochemical, and protein analyses. Findings were compared with those from primary human hepatocytes stimulated with IFN-α or IFN-γ, as reference sets.

RESULTS

Expression levels of hundreds of genes, primarily those regulated by IFN-γ, were altered in liver samples from patients with AHC compared with controls. Expression of IFN-γ-stimulated genes was induced in liver samples from patients with AHC, whereas expression of IFN-α-stimulated genes was induced in samples from patients with CHC. In an expression analysis of negative regulators of IFN-α signaling, we did not observe differences in expression of suppresor of cytokine signaling 1 or SOCS3 between liver samples from patients with AHC and those with CHC. However, USP18 (another negative regulator of IFN-α signaling), was up-regulated in liver samples of patients with CHC that did not respond to therapy, but not in AHC.

CONCLUSIONS

Differences in expression of ISGs might account for the greater response of patients with AHC, compared with those with CHC, to treatment with pegIFN-α and ribavirin. Specifically, USP18 is up-regulated in liver samples of patients with CHC that did not respond to therapy, but not in patients with AHC.

Randomized trial of albinterferon alfa-2b every 4 weeks for chronic hepatitis C virus genotype 2/3

Albinterferon alfa-2b (albIFN) is a fusion protein of recombinant human albumin/recombinant interferon (IFN)-α-2b, with ∼200-h half-life. Safety/efficacy of albIFN q4wk was evaluated in 391 treatment-naive patients with chronic hepatitis C virus (HCV) genotype 2/3. Patients were randomized 3:4:4:4 to one of four open-label treatment groups: pegylated IFN (Peg-IFN)-α-2a 180 μg qwk or albIFN 900, 1200 or 1500 μg q4wk, plus oral ribavirin 800 mg/day, for 24 weeks. Primary efficacy endpoint was sustained virologic response (SVR; HCV RNA <20 IU/mL 24 weeks post-treatment). SVR rates were as follows: 85%, 76%, 76% and 78% with Peg-IFNα-2a and albIFN 900, 1200 and 1500 μg, respectively (P = NS); corresponding rapid virologic response rates (HCV RNA <43 IU/mL at week 4) were as follows: 78%, 49% (P < 0.001), 60% (P = 0.01) and 71%. SVR rates were not influenced by interleukin 28B genotype, although rapid virologic response rates were greater with interleukin 28B CC (P = NS). Serious adverse event rates were as follows: 4%, 11%, 3% and 3% with Peg-IFNα-2a and albIFN 900, 1200 and 1500 μg, respectively. No increase in serious/severe respiratory events was noted with albIFN. Fewer absolute neutrophil count reductions <750/mm(3) occurred with albIFN (P = 0.03), leading to fewer IFN dose reductions. Haemoglobin reductions <10 g/dL were less frequent with albIFN 900 and 1200 μg vs 1500 μg and Peg-IFNα-2a (P = 0.02), leading to fewer ribavirin dose reductions. albIFN administered q4wk produced fewer haematologic reductions than Peg-IFNα-2a, but had numerically lower SVR rates (P = NS) in patients with chronic HCV genotype 2/3.

Human monoclonal antibody HCV1 effectively prevents and treats HCV infection in chimpanzees

Hepatitis C virus (HCV) infection is a leading cause of liver transplantation and there is an urgent need to develop therapies to reduce rates of HCV infection of transplanted livers. Approved therapeutics for HCV are poorly tolerated and are of limited efficacy in this patient population. Human monoclonal antibody HCV1 recognizes a highly-conserved linear epitope of the HCV E2 envelope glycoprotein (amino acids 412–423) and neutralizes a broad range of HCV genotypes. In a chimpanzee model, a single dose of 250 mg/kg HCV1 delivered 30 minutes prior to infusion with genotype 1a H77 HCV provided complete protection from HCV infection, whereas a dose of 50 mg/kg HCV1 did not protect. In addition, an acutely-infected chimpanzee given 250 mg/kg HCV1 42 days following exposure to virus had a rapid reduction in viral load to below the limit of detection before rebounding 14 days later. The emergent virus displayed an E2 mutation (N415K/D) conferring resistance to HCV1 neutralization. Finally, three chronically HCV-infected chimpanzees were treated with a single dose of 40 mg/kg HCV1 and viral load was reduced to below the limit of detection for 21 days in one chimpanzee with rebounding virus displaying a resistance mutation (N417S). The other two chimpanzees had 0.5–1.0 log₁₀ reductions in viral load without evidence of viral resistance to HCV1. In vitro testing using HCV pseudovirus (HCVpp) demonstrated that the sera from the poorly-responding chimpanzees inhibited the ability of HCV1 to neutralize HCVpp. Measurement of antibody responses in the chronically-infected chimpanzees implicated endogenous antibody to E2 and interference with HCV1 neutralization although other factors may also be responsible. These data suggest that human monoclonal antibody HCV1 may be an effective therapeutic for the prevention of graft infection in HCV-infected patients undergoing liver transplantation.

The majority of individuals infected with hepatitis C virus (HCV) become chronically infected and many go on to develop liver failure requiring liver transplantation. Unfortunately, the transplanted liver becomes infected with HCV in nearly 100% of transplant patients. Current treatments for HCV are poorly tolerated after liver transplantation and graft health is compromised by infection. We have developed a monoclonal antibody called HCV1 that blocks HCV from infecting liver cells in culture. Using chimpanzees as a model for HCV infection, we demonstrate that HCV1 has the ability to prevent HCV infection. We also show that HCV1 can treat chimpanzees chronically infected with HCV and reduce plasma viral load to below the level of detection for a period of 7 to 21 days. The virus that reemerges in the treated chimpanzees was resistant to HCV1 neutralization demonstrating target engagement. Given the ability of HCV1 to protect chimpanzees from HCV infection, we speculate that HCV1 may be beneficial in HCV- infected patients undergoing liver transplant.

Curcumin inhibits HCV replication by induction of heme oxygenase-1 and suppression of AKT

Although hepatitis C virus (HCV) affects approximately 130–170 million people worldwide, no vaccines are available. HCV is an important cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma, leading to the need for liver transplantation. In this study, curcumin, a constituent used in traditional Chinese medicine, has been evaluated for its anti-HCV activity and mechanism, using a human hepatoma cell line containing the HCV genotype 1b subgenomic replicon. Below the concentration of 20% cytotoxicity, curcumin dose-dependently inhibited HCV replication by luciferase reporter gene assay, HCV RNA detection and HCV protein analysis. Under the same conditions, curcumin also dose-dependently induced heme oxygenase-1 with the highest induction at 24 h. Hemin, a heme oxygenase-1 inducer, also inhibited HCV protein expression in a dose-dependent manner. The knockdown of heme oxygenase-1 partially reversed the curcumin-inhibited HCV protein expression. In addition to the heme oxygenase-1 induction, signaling molecule activities of AKT, extracellular signal-regulated kinases (ERK) and nuclear factor-κB (NF-κB) were inhibited by curcumin. Using specific inhibitors of PI3K-AKT, MEK-ERK and NF-κB, the results suggested that only PI3K-AKT inhibition is positively involved in curcumin-inhibited HCV replication. Inhibition of ERK and NF-κB was likely to promote HCV protein expression. In summary, curcumin inhibited HCV replication by heme oxygenase-1 induction and AKT pathway inhibition. Although curcumin also inhibits ERK and NF-κB activities, it slightly increased the HCV protein expression. This result may provide information when curcumin is used as an adjuvant in anti-HCV therapy.

Is combination therapy for chronic hepatitis C toxic for cardiac function?

BACKGROUND

Many types of cardiovascular complications such as; cardiac arrhythmias, impaired cardiac function, myocardial ischemia and decreased left ventricular function, have been attributed to interferon therapy.

OBJECTIVES

The aim of this study was to evaluate the effects of combination therapy pegylated interferon and ribavirin on left ventricular systolic and diastolic functions in patients with a chronic hepatitis C infection.

PATIENTS AND METHODS

A total of 120 patients, eligible for hepatitis C virus (HCV) treatment with pegylated interferon and ribavirin, were included in this study. All patients underwent a full cardiovascular baseline examination including; detailed medical history, thorough clinical examination, 12 lead electrocardiogram (ECG), and echocardiography. A cardiac evaluation was performed at the beginning and six months after starting combination therapy.

RESULTS

No significant changes regarding cardiac symptoms including; shortness of breath, cough, palpitations, chest pain and hypertension, were found during or six months after starting the combined therapy. ECG findings showed statistically non-significant decreases in the QT interval, while corrected QT showed statistically non-significant increases six months after beginning combined therapy, when compared to their values before treatment. Also with regard to the echocardiography findings, there was no statistically significant difference found between any of the echocardiography parameters six months after starting combined therapy compared to their values before treatment.

CONCLUSIONS

The results of our study suggest that, combination therapy does not cause a significant deterioration in cardiac function in patients with a chronic hepatitis C infection, and it may be used safely in patients without cardiac disease.

Mutations in non-structural 5A and rapid viral response to pegylated interferon-α-2b plus ribavirin therapy are associated with therapeutic efficacy in patients with genotype 1b chronic hepatitis C

For patients chronically infected with hepatitis C virus (HCV), mutations in the non-structural 5A (NS5A) gene are important predictive factors for the response to interferon (IFN) therapy. In the present study, factor analysis of the therapeutic response of patients following pegylated IFN and ribavirin combination therapy was assessed in a multicenter study. Chronic HCV-infected patients with genotype 1b and high viral load (n=96, mean age 56.5 years; 59 males, 68 females) treated with pegylated IFN-α-2b and ribavirin combination therapy were enrolled. This study was conducted at Kobe University Hospital and 25 affiliated hospitals in Hyogo prefecture. Sixty-five patients (68%) completed treatment with both pegylated IFN and ribavirin at >80% of the weight-based scheduled dosages. Patients who reduced or terminated therapy were frequently aged women (mean age 60.8 years; 11 males, 17 females). Overall, a sustained viral response (SVR) was achieved in 42 (44%) patients out of 96. Based on per-protocol-based (PPB) analysis, the SVR rate in patients with ≥6 amino acid (aa) mutations in the IFN resistance-determining region (IRRDR) (75%) or ≥1 aa mutation in the IFN sensitivity-determining region (ISDR) (61%) was significantly higher than that in patients with <5 aa mutations in IRRDR (30%) or no mutation in ISDR (29%). Multivariate analysis revealed that rapid viral response (RVR) (odds ratio, 18.1) and mutations of ≥6 in IRRDR (odds ratio, 15.5) were significantly associated with SVR. In conclusion, mutations in the NS5A region, particularly in patients with ≥6 aa mutations in IRRDR were strongly associated with a therapeutic response to pegylated IFN and ribavirin combination therapy.

Efficient replication of genotype 3a and 4a hepatitis C virus replicons in human hepatoma cells

Despite recent advances in the treatment of hepatitis C, the quest for pan-genotype, effective, and well-tolerated inhibitors continues. To facilitate these efforts, it is desirable to have in vitro replication systems for all major HCV genotypes. However, cell culture replication systems exist for only genotypes 1a, 1b, and 2a. In this study, we generated G418-selectable subgenomic replicons for prototype strains of genotypes 3a (S52) and 4a (ED43). Production of G418-resistant colonies by S52 and ED43 in Huh-7.5 cells required the amino acid substitutions S2210I and R2882G, respectively, cell culture adaptive mutations originally reported for genotype 1b replicons. RNA replication was confirmed by quantitative reverse transcription-PCR and detection of viral protein. Sequencing of multiple independent replicon clones revealed the presence of additional nonsynonymous mutations. Interestingly, all potentially adaptive mutations mapped to the NS3 protein. These mutations, when introduced back into original constructs, substantially increased colony formation efficiency. To make these replicons useful for high-throughput screening and evaluation of antiviral compounds, they were modified to express a chimeric fusion protein of firefly luciferase and neomycin phosphotransferase to yield stable replicon-expressing cells. Using these constructs, the inhibitory effects of beta interferon (IFN-β), an NS3 protease inhibitor, and an NS5B nucleoside polymerase inhibitor were readily detected by monitoring luciferase activity. In conclusion, we have established functional replicons for HCV genotypes 3a and 4a, important new additions to the armamentarium required to develop inhibitors with a pan-genotype activity.

Interaction of the antiviral drug telaprevir with renal and hepatic drug transporters

Telaprevir is a new, direct-acting antiviral drug that has been approved for the treatment of chronic hepatitis C viral infection. First data on drug-drug interactions with co-medications such as cyclosporine, tacrolimus and atorvastatin have been reported recently. Drug transporting proteins have been shown to play an important role in clinically observed drug-drug interactions. The aim of this study was therefore to systematically investigate the potential of telaprevir to inhibit drug transporting proteins. The effect of telaprevir on substrate uptake mediated by drug transporters located in human kidney and liver was investigated on a functional level in HEK293 cell lines that over-express single transporter. Telaprevir was shown to exhibit significant inhibition of the human renal drug transporters OCT2 and MATE1 with IC(50) values of 6.4 μM and 23.0 μM, respectively, whereas no inhibitory effect on OAT1 and OAT3 mediated transport by telaprevir was demonstrated. Liver drug transporters were inhibited with an IC(50) of 2.2 μM for OATP1B1, 6.8 μM for OATP1B3 and 20.7 μM for OCT1. Our data show that telaprevir exhibited significant potential to inhibit human drug transporters. In view of the inhibitory potential of telaprevir, clinical co-administration of telaprevir together with drugs that are substrates of renal or hepatic transporters should be carefully monitored.

Let-7b is a novel regulator of hepatitis C virus replication

The non-coding microRNA (miRNA) is involved in the regulation of hepatitis C virus (HCV) infection and offers an alternative target for developing anti-HCV agent. In this study, we aim to identify novel cellular miRNAs that directly target the HCV genome with anti-HCV therapeutic potential. Bioinformatic analyses were performed to unveil liver-abundant miRNAs with predicted target sequences on HCV genome. Various cell-based systems confirmed that let-7b plays a negative role in HCV expression. In particular, let-7b suppressed HCV replicon activity and down-regulated HCV accumulation leading to reduced infectivity of HCVcc. Mutational analysis identified let-7b binding sites at the coding sequences of NS5B and 5'-UTR of HCV genome that were conserved among various HCV genotypes. We further demonstrated that the underlying mechanism for let-7b-mediated suppression of HCV RNA accumulation was not dependent on inhibition of HCV translation. Let-7b and IFNα-2a also elicited a synergistic inhibitory effect on HCV infection. Together, let-7b represents a novel cellular miRNA that targets the HCV genome and elicits anti-HCV activity. This study thereby sheds new insight into understanding the role of host miRNAs in HCV pathogenesis and to developing a potential anti-HCV therapeutic strategy.

Dysregulation of innate immunity in hepatitis C virus genotype 1 IL28B-unfavorable genotype patients: impaired viral kinetics and therapeutic response

Recent studies have shown that a single-nucleotide polymorphism upstream of the interleukin-28B (IL28B) gene plays a major role in predicting therapeutic response in hepatitis C virus (HCV)-infected patients treated with pegylated interferon (PEG-IFN)/ribavirin. We sought to investigate the mechanism of the IL28B polymorphism, specifically as it relates to early HCV viral kinetics, IFN pharmacokinetics, IFN pharmacodynamics, and gene expression profiles. Two prospective cohorts (human immunodeficiency virus [HIV]/HCV-coinfected and HCV-monoinfected) completing treatment with IFN/ribavirin were enrolled. Patients were genotyped at the polymorphic site rs12979860. In the HIV/HCV cohort, frequent serum sampling was completed for HCV RNA and IFN levels. DNA microarray of peripheral blood mononuclear cells and individual expression of IFN-stimulated genes (ISGs) were quantified on IFN therapy. The IL28B-favorable (CC) genotype was associated with improved therapeutic response compared with unfavorable (CT or TT) genotypes. Patients with a favorable genotype had greater first- and second-phase viral kinetics (P = 0.004 and P = 0.036, respectively), IFN maximum antiviral efficiency (P = 0.007) and infected cell death loss (P = 0.009) compared with unfavorable genotypes. Functional annotation analysis of DNA microarray data was consistent with depressed innate immune function, particularly of natural killer cells, from patients with unfavorable genotypes (P <0.004). Induction of innate immunity genes was also lower in unfavorable genotypes. ISG expression at baseline and induction with IFN was independent of IL28B genotype.

CONCLUSION

Carriers of the IL28B-favorable genotype were more likely to have superior innate immune response to IFN therapy compared with unfavorable genotypes, suggesting that the unfavorable genotype has aberrant baseline induction of innate immune response pathways resulting in impaired virologic response. IL28B genotype is associated with more rapid viral kinetics and improved treatment response outcomes independent of ISG expression.

Do hepatitis B virus and hepatitis C virus co-infections increase hepatocellular carcinoma occurrence through synergistically modulating lipogenic gene expression?

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections cause a wide range of liver diseases including hepatocellular carcinoma (HCC). Because of the similar modes of transmission, HBV HCV co-infections are found in approximately 7-20 million people globally. Compared with HBV or HCV mono-infections, co-infections are associated with more severe liver diseases and higher risk of HCC. Abnormal lipid biosynthesis and metabolism has been increasingly recognized as a cause for cancer. While HBV infection does not seem to significantly increase the risk of developing hepatic steatosis, steatosis is a prominent feature of chronic hepatitis C (CHC). In addition, steatosis in HBV or HCV mono-infections is a significant and independent risk factor for HCC. However, whether and how HBV HCV co-infections synergistically increase the risk of HCC development through modulating lipid metabolism is not well understood. Possible mechanisms by which steatosis causes HCC include: activation of sterol regulatory element-binding protein-mediated lipogenesis through the PI3K-Akt pathway, abnormal activation of peroxisome proliferator-activated receptors and endoplasmic reticulum stress. Here, we review the potential mechanisms by which HBV HCV co-infections may increase HCC risk through modulation of lipogenic gene expression. We begin with reviewing the impact of HBV and HCV on host lipogenic gene expression and carcinogenesis. We then discuss the potential mechanisms by which HBV and HCV can increase carcinogenesis through synergistically activating lipid biosynthesis and metabolism. We end by sharing our thoughts on future research directions in this emerging paradigm with an ultimate goal of developing effective therapeutics.

Peripheral blood cytopaenia limiting initiation of treatment in chronic hepatitis C patients otherwise eligible for antiviral therapy

BACKGROUND

In patients with chronic hepatitis C virus (HCV) infection, the presence of peripheral blood cytopaenia may represent an obstacle to pegylated interferon and ribavirin treatment.

AIMS

To evaluate the prevalence of anaemia, neutropaenia and thrombocytopaenia potentially limiting initiation of pegylated interferon and ribavirin treatment in patients with chronic HCV infection who were otherwise eligible for antiviral therapy.

METHODS

We studied 3059 consecutive anti-HCV and HCV-RNA positive patients referred to our centre to be evaluated for antiviral therapy from June 2002 to May 2011. The European Association for the Study of Liver HCV guidelines were applied to assess eligibility for antiviral therapy.

RESULTS

In the study cohort, 1,521 patients (49.7%) were not eligible for treatment because of reasons different from haematological abnormalities. In the remaining 1,538 patients the overall prevalence of any peripheral blood cytopaenia potentially preventing patients from being treated with antiviral therapy was 15.1%. In particular, anaemia (haemoglobin level < 12 g/dL for women, <13 g/dL for men) was a relative contraindication to treatment in 8.9% (137/1,538) of the patients, while thrombocytopaenia (platelet count cut-off, 90 × 10(9) /L) and neutropaenia (absolute neutrophil count < 1.5 × 10(9) /L) limited treatment in 6.5% (100/1358) and 3.2% (48/1358) of patients respectively. These haematological abnormalities were more prevalent in patients with older age (P < 0.004) and cirrhosis (P < 0.001).

CONCLUSIONS

The presence of peripheral blood cytopaenia may potentially limit initiation of antiviral therapy in one in every seven patients with chronic HCV infection who are otherwise eligible for treatment.

Public health issues of hepatitis C virus infection

Hepatitis C virus (HCV) is a leading cause of liver disease worldwide, as 130-170 million individuals are chronically infected and 350,000 patients die every year from HCV infection. The HCV prevalence varies widely among countries being highest in several African and Eastern Mediterranean countries. The incidence of new HCV infections may be declining in developed countries, but there is still a large reservoir of chronic infections. The most important mode of HCV transmission has been injecting drug use in developed countries with low prevalence and unsafe therapeutic injections in developing countries with moderate-high prevalence. Since there are no systematic screening policies, most patients remain undiagnosed. Even among diagnosed patients, a minority receives treatment due to several barriers to therapy. Given the high efficacy of treatment, public health authorities should recognise the importance of HCV and make resources available for the implementation of effective primary prevention, screening and management policies.

MK-5172, a selective inhibitor of hepatitis C virus NS3/4a protease with broad activity across genotypes and resistant variants

HCV NS3/4a protease inhibitors are proven therapeutic agents against chronic hepatitis C virus infection, with boceprevir and telaprevir having recently received regulatory approval as add-on therapy to pegylated interferon/ribavirin for patients harboring genotype 1 infections. Overcoming antiviral resistance, broad genotype coverage, and a convenient dosing regimen are important attributes for future agents to be used in combinations without interferon. In this communication, we report the preclinical profile of MK-5172, a novel P2-P4 quinoxaline macrocyclic NS3/4a protease inhibitor currently in clinical development. The compound demonstrates subnanomolar activity against a broad enzyme panel encompassing major hepatitis C virus (HCV) genotypes as well as variants resistant to earlier protease inhibitors. In replicon selections, MK-5172 exerted high selective pressure, which yielded few resistant colonies. In both rat and dog, MK-5172 demonstrates good plasma and liver exposures, with 24-h liver levels suggestive of once-daily dosing. When administered to HCV-infected chimpanzees harboring chronic gt1a or gt1b infections, MK-5172 suppressed viral load between 4 to 5 logs at a dose of 1 mg/kg of body weight twice daily (b.i.d.) for 7 days. Based on its preclinical profile, MK-5172 is anticipated to be broadly active against multiple HCV genotypes and clinically important resistance variants and highly suited for incorporation into newer all-oral regimens.

The molecular basis of drug resistance against hepatitis C virus NS3/4A protease inhibitors

Hepatitis C virus (HCV) infects over 170 million people worldwide and is the leading cause of chronic liver diseases, including cirrhosis, liver failure, and liver cancer. Available antiviral therapies cause severe side effects and are effective only for a subset of patients, though treatment outcomes have recently been improved by the combination therapy now including boceprevir and telaprevir, which inhibit the viral NS3/4A protease. Despite extensive efforts to develop more potent next-generation protease inhibitors, however, the long-term efficacy of this drug class is challenged by the rapid emergence of resistance. Single-site mutations at protease residues R155, A156 and D168 confer resistance to nearly all inhibitors in clinical development. Thus, developing the next-generation of drugs that retain activity against a broader spectrum of resistant viral variants requires a comprehensive understanding of the molecular basis of drug resistance. In this study, 16 high-resolution crystal structures of four representative protease inhibitors – telaprevir, danoprevir, vaniprevir and MK-5172 – in complex with the wild-type protease and three major drug-resistant variants R155K, A156T and D168A, reveal unique molecular underpinnings of resistance to each drug. The drugs exhibit differential susceptibilities to these protease variants in both enzymatic and antiviral assays. Telaprevir, danoprevir and vaniprevir interact directly with sites that confer resistance upon mutation, while MK-5172 interacts in a unique conformation with the catalytic triad. This novel mode of MK-5172 binding explains its retained potency against two multi-drug-resistant variants, R155K and D168A. These findings define the molecular basis of HCV N3/4A protease inhibitor resistance and provide potential strategies for designing robust therapies against this rapidly evolving virus.

Hepatitis C virus (HCV) infects over 170 million people worldwide and is the leading cause of chronic liver diseases, including cirrhosis, liver failure, and liver cancer. New classes of directly-acting antiviral agents that target various HCV enzymes are being developed. Two such drugs that target the essential HCV NS3/4A protease are approved by the FDA and several others are at various stages of clinical development. These drugs, when used in combination with pegylated interferon and ribavirin, significantly improve treatment outcomes. However HCV evolves very quickly and drug resistance develops against directly-acting antiviral agents. Thus, despite the therapeutic success of NS3/4A protease inhibitors, their long-term effectiveness is challenged by drug resistance. Our study explains in atomic detail how and why drug resistance occurs for four chemically representative protease inhibitors –telaprevir, danoprevir, vaniprevir and MK-5172. Potentially with this knowledge, new drugs could be developed that are less susceptible to drug resistance. More generally, understanding the underlying mechanisms by which drug resistance occurs can be incorporated in drug development to many quickly evolving diseases.

A 2'-deoxy-2'-fluoro-2'-C-methyl uridine cyclopentyl carbocyclic analog and its phosphoramidate prodrug as inhibitors of HCV NS5B polymerase

The 2 '-deoxy-2 '-fluoro-2 '-C-methyluridine nucleotide prodrug, PSI-7851 and its single diastereomer PSI-7977 have displayed potent antiviral activity against hepatitis C virus in clinical trials, and PSI-7977 is currently in Phase III studies. As part of our SAR study of the 2 '-deoxy-2 '-fluoro-2 '- C-methyl class of nucleosides, we prepared the cyclopentyl carbocyclic uridine analog 11 and its phosphoramidate prodrug 15. Both 11 and 15 were shown not to inhibit HCV replication. This lack of activity might be attributed to the inability of the monophosphate to be converted to the corresponding diphosphate or triphosphate or the inactivity of triphosphate of 11 as an inhibitor of the polymerase.

Incidence analyses and space-time cluster detection of hepatitis C in Fujian Province of China from 2006 to 2010

BACKGROUND

There is limited epidemiologic information about the incidence of hepatitis C in China, and few studies have applied space-time scan statistic to detect clusters of hepatitis C and made adjustment for temporal trend and relative risk of regions.

METHODOLOGY AND PRINCIPAL FINDINGS

We analyzed the temporal changes and characteristics of incidence of hepatitis C in Fujian Province from 2006 through 2010. The discrete Poisson model of space-time scan statistic was chosen for cluster detection. Data on new cases of hepatitis C were obtained from the Center for Disease Control and Prevention of Fujian Province. Between 2006 and 2010, there was an annualized increase in the incidence of hepatitis C of 23.0 percent, from 928 cases (2.63 per 100,000 persons) to 2,180 cases (6.01 per 100,000 persons). The incidence among women increased more rapidly. The cumulative incidence showed that people who were over 60 years had the highest risk to suffer hepatitis C (52.51 per 100,000 persons), and women had lower risk compared to men (OR=0.69). Putian had the highest cumulative incidence among all the regions (86.95 per 100,000 persons). The most likely cluster was identified in Putian during March to August in 2009 without adjustment, but it shifted to three contiguous cities with a two-month duration after adjustment for temporal trend and relative risk of regions.

CONCLUSIONS/SIGNIFICANCE

The incidence of hepatitis C is increasing in Fujian Province, and women are at a more rapid pace. The space-time scan statistic is useful as a screening tool for clusters of hepatitis C, with adjustment for temporal trend and relative risk of regions recommended.

A formula to estimate the optimal dosage of ribavirin for the treatment of chronic hepatitis C: influence of ITPA polymorphisms

BACKGROUND

Greater cumulative exposure to ribavirin increases response to interferon-ribavirin combination therapy for hepatitis C but also induces more severe anaemia. Polymorphisms in the ITPA gene protect against ribavirin-induced anaemia. The maximum dosage of ribavirin that can be tolerated by patients with different ITPA polymorphisms remains unknown.

METHODS

We developed a mathematical model of haemoglobin (Hb) decline in patients undergoing combination therapy. Using it to analyse published patient data, we estimated the average erythrocyte lifespan in patients with different ITPA polymorphisms. Coupled with a previous population pharmacokinetic study, we derived a formula for predicting the optimal ribavirin dosage, D(opt), above which anaemia becomes intolerable (Hb<10 g/dl).

RESULTS

Our model provided good fits to patient data of ribavirin accumulation in erythrocytes and the ensuing Hb decline during therapy. With the current treatment protocol, the average erythrocyte lifespan was approximately 36 days in patients with wild-type ITPA activity, and approximately 43 days and 55 days, respectively, in patients with mild and moderate ITPA deficiency. Our model yielded a facile formula for estimating D(opt) given a patient's weight, creatinine clearance, pretreatment Hb and ITPA polymorphism. Patients with moderate ITPA deficiency are predicted to tolerate twice the ribavirin dosage as patients with wild-type ITPA.

CONCLUSIONS

Our formula for D(opt) presents an avenue for personalizing ribavirin dosage. By keeping anaemia tolerable, the predicted optimal dosage may improve adherence, reduce the need for drug monitoring, and increase response rates. Response rates may be increased further by the higher dosages recommended for patients with ITPA deficiency.

Hepatitis C virus promotes expression of the 3β-hydroxysterol δ24-reductase through Sp1

Hepatitis C virus (HCV) establishes chronic infection, which often causes hepatocellular carcinoma. Overexpression of 3β-hydroxysterol Δ24-reductase (DHCR24) by HCV has been shown to impair the p53-mediated cellular response, resulting in tumorigenesis. In the present study, the molecular mechanism by which HCV promotes the expression of DHCR24 was investigated. A significant increase in DHCR24 mRNA transcription was observed in a cell line expressing complete HCV genome, whereas no significant difference in the expression of DHCR24 was seen in cell lines expressing individual viral proteins. The 5'-flanking genomic region of DHCR24 was characterized to explore the genomic region and host factor(s) involved in the transcriptional regulation of DHCR24. As a result, the HCV response element (-167/-140) was identified, which contains AP-2α, MZF-1, and Sp1 binding motifs. The binding affinity of the host factor to this response element was increased in nuclear extracts from cells infected with HCV and corresponded with augmented affinity of Sp1. Both mithramycin A (Sp1 inhibitor) and small interfering RNA targeting Sp1 prevented the binding of host factors to the response element. Silencing of Sp1 also downregulated the increased expression of DHCR24. The binding affinity of Sp1 to the response element was augmented by oxidative stress, whereas upregulation of DHCR24 in cells expressing HCV was blocked significantly by a reactive oxygen species scavenger. Elevated phosphorylation of Sp1 in response to oxidative stress was mediated by the ATM kinase. Thus, activation of Sp1 by oxidative stress is involved in the promotion of expression of DHCR24 by HCV.

Treatment Response and Tolerability of Pegylated Interferon-α Plus Ribavirin Combination Therapy in elderly Patients (≥ 65 years) With Chronic Hepatitis C in Korea

BACKGROUND

The prevalence of hepatitis C virus (HCV) infections in elderly patients has been increasing in a number of countries. A few reports concerning pegylated interferon-α (PEG-IFN-α)-based combination treatment in elderly chronic hepatitis C (CHC) patients have been published, with slightly different treatment outcomes.

OBJECTIVES

We investigated the treatment response and safety of PEG-IFN-α plus ribavirin combination therapy in elderly patients with CHC.

PATIENTS AND METHODS

Among a total of 181 treatment-naïve CHC patients (60 patients with genotype 1, 121 patients with genotype 2 or 3), 38 were aged ≥ 65 years (defined as the elderly group) and 143 were aged < 65 years (defined as the non-elderly group).

RESULTS

The overall sustained virologic response (SVR) was lower in the elderly group than in the non-elderly group, but it was not significantly different (65.8 % vs. 76.2 %, P = 0.15). In a subgroup analysis, among patients with genotype 1, the elderly group had a significantly lower SVR rate than the non-elderly group (30.8 % vs. 66.0 %, P = 0.03). However, the SVR rate in patients with HCV genotype 2 or 3 was comparable between the two groups (84.0 % vs. 81.3 %, P = 0.85). HCV genotype was significantly associated with SVR in the elderly patients (genotype 1 vs. 2 or 3, odds ratio: 0.18, 95% confidence interval: 0.000-0.869, P = 0.03). The incidence of premature discontinuation of treatment (21.1 % vs. 9.1 %, P = 0.05) and dose modification (52.6 % vs. 31.5 %; P = 0.02) due mainly to adverse events or laboratory abnormalities, were higher in the elderly group than in the non-elderly group.

CONCLUSIONS

PEG-IFN-α plus ribavirin combination therapy might be considered for elderly CHC patients, especially for genotype 2 or 3, with vigilant monitoring of adverse events.

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

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.

Pyridofuran substituted pyrimidine derivatives as HCV replication (replicase) inhibitors

Introduction of nitrogen atom into the benzene ring of a previously identified HCV replication (replicase) benzofuran inhibitor 2, resulted in the discovery of the more potent pyridofuran analogue 5. Subsequent introduction of small alkyl and alkoxy ligands into the pyridine ring resulted in further improvements in replicon potency. Replacement of the 4-chloro moiety on the pyrimidine core with a methyl group, and concomitant monoalkylation of the C-2 amino moiety resulted in the identification of several inhibitors with desirable characteristics. Inhibitor 41, from the monosubstituted pyridofuran and inhibitor 50 from the disubstituted series displayed excellent potency, selectivity (GAPDH/MTS CC(50)) and PK parameters in all species studied, while the selectivity in the thymidine incorporation assay (DNA·CC(50)) was low.

A predictive model of treatment outcome in patients with chronic HCV infection using IL28B and PD-1 genotyping

BACKGROUND & AIMS

The advent of new chronic hepatitis C virus (HCV) therapies requires characterization of patients in order to predict adequate treatment. A good candidate marker is Programmed Cell Death-1 (PD-1) which is involved in progression of HCV infection. The aim of this study was to analyse the effect of several single nucleotide polymorphisms of PD-1 gene and several previously associated factors (IL28B and KIR receptors) on treatment responses.

METHODS

407 HCV chronic infected patients treated with PEG-IFN-α and ribavirin were recruited and classified according to their response to treatment. They were genotyped for PD-1 and IL28B polymorphisms, killer immunoglobulin-like receptors (KIR) and HLA genes. A multivariate logistic regression analysis and a Chi-squared Automatic Interaction Detector (CHAID) prediction model of response included these and other clinical parameters.

RESULTS

Our results showed that PD-1.3/A allele was significantly associated with sustained virological response (SVR) in a multivariate logistic regression analysis (p<0.01, OR=2.57). Additionally, IL28B C/C genotype was the most significant predictor of an SVR to treatment in all HCV genotypes (74.5%). In IL28B C/C patients, the presence of PD-1.3/A allele increased the probability of an SVR to 93.3%. Moreover, when this analysis was made only with patients infected by HCV-1, the predictive value of IL28B C/C genotype with PD-1.3/A allele was 90%.

CONCLUSIONS

PD-1.3/A allele is associated with SVR to treatment and notably increases the predictive value of IL28B C/C genotype. Both markers in conjunction could be a useful tool, more relevant than HCV genotype in some cases, in clinical practice.

Response-guided therapy for patients with hepatitis C virus genotype 6 infection: a pilot study

The optimal duration of treatment with pegylated interferon (PEG-IFN) plus ribavirin (RBV) in patients with hepatitis C virus (HCV) genotype 6 is unknown. This study was aimed at determining treatment response on the basis of rapid virological response (RVR) of HCV genotype 6 in comparison with genotypes 1 and 3. Sixty-six treatment naïve patients were treated with PEG-IFN-α2a (180 μg/week) plus weight-based RBV (1000-1200 mg/day). Patients with genotype 1 n = 16) and genotype 3 (n = 16) were treated for a fixed duration of 48 and 24 weeks, respectively. Patients with genotype 6 (n = 34) who achieved RVR were treated for 24 weeks (response-guided therapy) and the remaining patients were treated for 48 weeks (standard therapy). The mean baseline HCV RNA levels were not statistically different between groups (6.4 ± 0.8, 6.0 ± 1.0 and 6.5 ± 0.8 Log(10) IU/mL for genotypes 1, 3 and 6, respectively). Patients with genotypes 1, 3 and 6 achieved RVR in 43.8%, 87.5% and 73.5% of cases, respectively. One patient with genotype 1 and 3 with genotype 6 were considered nonresponders and discontinued therapy. Sustained virological response (SVR) was achieved in 62.5%, 81.3% and 76.5% of patients with genotypes 1, 3 and 6, respectively. The SVR rate in patients with genotype 6 who underwent response-guided therapy was 88%. This pilot study suggested that the SVR rate of HCV genotype 6 was at an intermediate level between those of genotypes 3 and 1. Treatment with PEG-IFN plus RBV for 24 weeks may be sufficient for patients with genotype 6 who achieve RVR. Prospective randomized trials are required to evaluate this response-guided strategy in a larger number of patients with genotype 6.

Antiviral activity of TMC435 monotherapy in patients infected with HCV genotypes 2-6: TMC435-C202, a phase IIa, open-label study

BACKGROUND & AIMS

TMC435 is an investigational, once-daily, oral NS3/4A protease inhibitor currently in phase III development for the treatment of hepatitis C virus (HCV) infection. Phase I and II studies in patients infected with HCV genotype 1 have demonstrated that TMC435 is generally well tolerated, has a pharmacokinetic profile that supports once daily dosing, and demonstrates potent antiviral activity. This phase IIa study (TMC435-C202; NCT00812331) was conducted to investigate the antiviral activity, safety, tolerability, and pharmacokinetics of TMC435 in treatment-naїve patients infected with HCV genotypes 2-6.

METHODS

The study consisted of 7 days of monotherapy with TMC435 (200mg once daily). Patients could begin treatment with pegylated interferon/ribavirin from day 8 with a follow-up period up to days 37-42.

RESULTS

Thirty-seven patients were enrolled in Germany, Belgium and Thailand. For the primary end point at day 8, the mean (± standard error) change in plasma HCV ribonucleic acid (log(10)IU/ml) from baseline was the greatest for genotypes 6 (-4.35 ± 0.29) and 4 (-3.52 ± 0.43), followed by genotypes 2 (-2.73 ± 0.71) and 5 (-2.19 ± 0.39). No antiviral activity was evident for genotype 3. Viral breakthrough occurred in six patients during the monotherapy phase and in six additional patients during PegIFN/RBV-only period. All adverse events were mild or moderate and there were no discontinuations during the TMC435 monotherapy period.

CONCLUSIONS

The results of this phase IIa proof-of-concept trial provide evidence that TMC435 has a spectrum of activity against multiple HCV genotypes, except for genotype 3. In this study, TMC435 was generally safe and well tolerated.

HIV and hepatitis C virus coinfection in Canada: challenges and opportunities for reducing preventable morbidity and mortality

OBJECTIVES

Hepatitis C virus (HCV) has emerged as an important health problem in the era of effective HIV treatment. However, very few data exist on the health status and disease burden of HIV/HCV-coinfected Canadians.

METHODS

HIV/HCV-coinfected patients were enrolled prospectively in a multicentre cohort from 16 centres across Canada between 2003 and 2010 and followed every 6 months. We determined rates of a first liver fibrosis or endstage liver disease (ESLD) event and all-cause mortality since cohort enrolment and calculated standardized mortality ratios compared with the general Canadian population.

RESULTS

A total of 955 participants were enrolled in the study and followed for a median of 1.4 (interquartile range 0.5-2.3) years. Most were male (73%) with a median age of 44.5 years; 13% self-identified as aboriginal. There were high levels of current injecting drug and alcohol use and poverty. Observed event rates [per 100 person-years; 95% confidence interval (CI)] were: significant fibrosis (10.21; 8.49, 12.19), ESLD (3.16; 2.32, 4.20) and death (3.72; 2.86, 4.77). The overall standardized mortality ratio was 17.08 (95% CI 12.83, 21.34); 12.80 (95% CI 9.10, 16.50) for male patients and 28.74 (95% CI 14.66, 42.83) for female patients. The primary causes of death were ESLD (29%) and overdose (24%).

CONCLUSIONS

We observed excessive morbidity and mortality in this HIV/HCV-coinfected population in care. Over 50% of observed deaths may have been preventable. Interventions aimed at improving social circumstances, reducing harm from drug and alcohol use and increasing the delivery of HCV treatment in particular will be necessary to reduce adverse health outcomes among HIV/HCV-coinfected persons.

IL28B genetic variation is associated with spontaneous clearance of hepatitis C virus, treatment response, serum IL-28B levels in Chinese population

BACKGROUND

The interleukin-28B gene (IL28B) locus has been associated with host resistance to hepatitis C virus (HCV) infection and response to PEG-IFN/RBV treatment in western populations. This study was to determine whether this gene variant is also associated with spontaneous clearance of HCV infection, treatment response and IL-28B protein production in Chinese patients.

METHODS

We genotyped IL28B genetic variations (rs12980275, rs8103142, rs8099917 and rs12979860) by pyrosequencing DNA samples from cohorts consisting of 529 subjects with persistent HCV infection, 196 subjects who cleared the infection, 171 healthy individuals and 235 chronic HCV patients underwent IFN/RBV treatment. The expression of IL-28B were measured by ELISA and RT-PCR.

RESULTS

We found that the four IL28B variants were in complete linkage disequilibrium (r2 = 0.97-0.98). The rs12979860 CC genotype was strongly associated with spontaneously HCV clearance and successful IFN/RBV treatment compared to the CT/TT. IL-28B levels in persistent HCV patients were significantly lower than subjects who spontaneously resolved HCV and healthy controls and were also associated with high levels of ALT (alanine aminotransferase) and AST (aspartate aminotransferase). IL-28B levels were also significantly lower in individuals carrying T alleles than CC homozygous.

CONCLUSIONS

Thus, the rs12979860-CC variant upstream of IL28B gene is associated with spontaneous clearance of HCV, susceptible to IFN/RBV treatment and increased IL-28B levels in this Chinese population.

Difference in serum complement component C4a levels between hepatitis C virus carriers with persistently normal alanine aminotransferase levels or chronic hepatitis C

Certain hepatitis C virus (HCV) carriers exhibit persistently normal alanine aminotransferase (ALT) levels (PNALT) (≤30 IU/l) accompanied by normal platelet counts (≥15×10⁴/μl); these individuals show milder disease activity and slower progression to cirrhosis. This study aimed to elucidate the characteristics of HCV carriers with PNALT using serum proteomics. The first group of subjects, who underwent clinical evaluation in the hospital, consisted of 19 HCV carriers with PNALT (PNALT-1) and 20 chronic hepatitis C (CHC-1) patients. The second group of subjects was part of a cohort study on the natural history of liver disease, and included 37 PNALT (PNALT-2) and 30 CHC (CHC-2) patients. Affinity bead-purified serum protein was subjected to matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis. Serum proteomics showed that 6 protein peaks with mass-to-charge ratios ranging from 1,000 to 3,000 differed significantly between the PNALT-1 and CHC-1 groups. Among these peaks, a 1738-m/z peak protein was identified as a fragment of complement component 4 (C4) and correlated significantly with serum C4a concentrations as determined by enzyme immunoassay. Serum C4a levels were also significantly higher in the PNALT-2 group compared to the CHC-2 group and healthy volunteers. Furthermore, in the PNALT-2 group, serum C4a levels negatively correlated with transaminase levels, but not with other biochemical tests, HCV core antigen levels, peripheral blood cell counts or serum hepatic fibrosis markers. This study indicates that host factors such as C4a not only differ between HCV carriers with PNALT and CHC, but that proteomic approaches could also contribute to the elucidation of factors in PNALT as more differences are discovered.

Using decision tree learning to predict the responsiveness of hepatitis C patients to drug treatment

The recommended treatment for patients with chronic hepatitis C, pegylated interferon α (PEG-IFN-α) plus rebavirin (RBV), does not provide a sustained virologic response in all patients, especially those with hepatitis C virus (HCV) genotype 1. It is therefore important to predict whether or not a new patient with HCV genotype 1 will be cured by the recommended treatment. We propose a prediction method for a new patient using a decision tree learning model based on SNPs evaluated in a genome-wide association study. By the decision tree learning for 142 Japanese patients with HCV genotype 1 (78 with null virologic response and 64 with virologic response), we can predict with high probability (93%) whether or not a new patient with HCV will be helped by the recommended treatment.

A practical guide for the use of boceprevir and telaprevir for the treatment of hepatitis C

The aim of this study is to review clinical trial data on the newly approved protease inhibitors boceprevir and telaprevir to develop consensus recommendations on the optimal use of these agents for the treatment of patients with chronic hepatitis C virus (HCV) infection. An expert panel of seven leading authorities in viral hepatitis was convened to establish and disseminate a practical guide on best practices for incorporating boceprevir and telaprevir into therapy for HCV infection in both treatment-naive and treatment-experienced patients. The topics covered include selecting candidates for boceprevir- or telaprevir-based treatments, predictors of response and early viral kinetics, response-guided therapy approaches, on-treatment management strategies to optimize the likelihood of response and minimize the risk of drug resistance, management of adverse effects during therapy and key considerations for special populations. The expert panel incorporated the best available clinical evidence into recommendations on how boceprevir and telaprevir should be used in the clinical setting. They indicated how treatment regimens may differ according to the baseline factors, such as presence of cirrhosis and when therapy may need to be modified or stopped altogether because of adverse events or poor virologic response. This practical guide will serve as a valuable resource for clinicians embarking on the new treatment paradigm of boceprevir or telaprevir in combination with peginterferon/ribavirin for chronic genotype 1 HCV infection.

A randomized trial of 48 versus 24 weeks of combination pegylated interferon and ribavirin therapy in genotype 6 chronic hepatitis C

BACKGROUND & AIMS

Genotype 6 chronic hepatitis C (HCV) is encountered predominantly in Southeast Asia and data on optimal treatment strategy is limited. This study was aimed at assessing the rate and predictors of sustained virological response (SVR) in genotype 6 chronic HCV following 48 and 24 weeks of pegylated interferon and ribavirin therapy.

METHODS

This investigator-initiated, open-label randomized trial was conducted in Vietnam between 2008 and 2010. One hundred and five treatment-naïve HCV genotype 6 patients were randomized to either 48-week (N=70) or 24-week (N=35) duration of pegylated interferon (PEG-IFN) alfa-2a 180 mcg/week and ribavirin (RBV) 15mg/kg/day; 92 patients completed the study (63 in the 48-week and 29 in the 24-week group, respectively). Primary outcome was sustained virological response (SVR) as intention-to-treat analysis.

RESULTS

There was no statistical difference in SVR between 48-week and 24-week treated groups (71% vs. 60%, respectively; p=0.24). In the 48-week and 24-week treatment groups, 81% and 80% of cases achieved rapid virological response (RVR) (p=0.86), and 86% and 80% achieved complete early virological response (p=0.45). Among those patients with RVR, SVR was in 86% (48-weeks), and 75% (24-weeks) of cases, whereas following non-RVR, only 8% of cases had an SVR with 48-week treatment duration.

CONCLUSIONS

Overall, RVR was achieved in the majority of genotype 6 patients and, in those patients, similar and high rates of SVR were noted following 24-week and 48-week therapy. This observation, however, needs validation in a larger study to demonstrate non-inferiority of the shorter duration therapy. In non-RVR patients, even 48-week therapy achieved low SVR rates.

Management of patients coinfected with HCV and HIV: a close look at the role for direct-acting antivirals

With the development of effective therapies against human immunodeficiency virus (HIV), hepatitis C virus (HCV) infection has become a major cause of morbidity and mortality among patients with both infections (coinfection). In addition to the high prevalence of chronic HCV, particularly among HIV-infected injection drug users, the rate of incident HIV infections is increasing among HIV-infected men who have sex with men, leading to recommendations for education and screening for HCV in this population. Liver disease is the second leading and, in some cases, a preventable cause of death among coinfected patients. Those at risk for liver disease progression are usually treated with a combination of interferon (IFN) and ribavirin (RBV), which is not highly effective; it has low rates of sustained virologic response (SVR), especially for coinfected patients with HCV genotype 1 and those of African descent. Direct-acting antivirals might overcome factors such as immunodeficiency that can reduce the efficacy of IFN. However, for now it remains challenging to treat coinfected patients due to interactions among drugs, additive drug toxicities, and the continued need for combination therapies that include pegylated IFN. Recently developed HCV protease inhibitors such as telaprevir and boceprevir, given in combination with pegylated IFN and RBV, could increase the rate of SVR with manageable toxicity and drug interactions. We review the latest developments and obstacles to treating coinfected patients.

New developments in small molecular compounds for anti-hepatitis C virus (HCV) therapy

Infection with hepatitis C virus (HCV) affects approximately 170 million people worldwide. However, no vaccine or immunoglobulin is currently available for the prevention of HCV infection. The standard of care (SOC) involving pegylated interferon-α (PEG-IFN α) plus ribavirin (RBV) for 48 weeks results in a sustained virologic response in less than 50% of patients with chronic hepatitis C genotype 1, the most prevalent type of HCV in North America and Europe. Recently, reliable in vitro culture systems have been developed for accelerating antiviral therapy research, and many new specifically targeted antiviral therapies for hepatitis C (STAT-C) and treatment strategies are being evaluated in clinical trials. These new antiviral agents are expected to improve present treatment significantly and may potentially shorten treatment duration. The aim of this review is to summarize the current developments in new anti-HCV drugs.

Detection of host immune responses in acute phase sera of spontaneous resolution versus persistent hepatitis C virus infection

Prior to the identification of hepatitis C virus (HCV), transfusion-transmission was common. Viral transmission in subjects with a known date of infection allows the study of the immune responses to acute HCV infection. We analysed 39 soluble immune factors in serum samples from subjects with transfusion-transmitted HCV. Dynamic expression kinetics of interferon gamma-induced protein 10 (IP-10), tumour necrosis factor-alpha and interleukin (IL)-10 were observed during acute HCV infection. Serum IP-10 was the only analyte that was significantly elevated in HCV resolvers compared with uninfected controls. In individuals who progressed to chronic HCV elevated levels of IP-10 and IL-10 coincided with first significant alanine aminotransferase elevation and remained elevated during the first year of acute HCV infection. In addition to monitoring lack of reduction in viral load, serum levels of IP-10 and IL-10 expression during acute HCV infection may be useful biomarkers to predict the progress to chronic HCV.

Interleukin 28B Gene Polymorphism and Association with Chronic Hepatitis C Therapy Results in Latvia

Introduction. With the standard treatment of chronic hepatitis C, sustained virological response (SVR) can be achieved only in half of all patients. Interleukin-28B appears to be involved in the control of HCV infection, and the genetic polymorphism of the encoding IL-28B gene may determine the efficacy of clearance of HCV. The aim of this paper was to detect IL-28B gene polymorphism in Latvia and to analyze therapy results. This is the first study on IL-28B gene polymorphism in Latvia. Material and Methods. There were 159 chronic viral hepatitis C patients included in the study. In order to detect IL-28B gene polymorphism, we used molecular biology techniques and methods: classical DNA separation, amplification by PCR, and standard sequencing. Genotype was defined as CC, CT, TC, or TT type. 142 patients were treated with the standard of care treatment. Results were analyzed according to IL-28B polymorphism. Results. There were 53 patients (33%) with CC genotype, 84 patients (53%) with CT/TC genotype, and 22 patients (14%) with TT genotype. 34 patients (74%) in CC genotype subgroup achieved SVR versus 50 patients (52%) in non-CC subgroups. In patients with genotype 1, SVR was achieved in 16 patients (84%) in CC subgroup versus 30 patients (47.6%) in non-CC subgroups, P = 0.007. Conclusions. The most common genotype of IL28B in Latvia is CT/TC, with an incidence of 53%. Patients with CC genotype achieved SVR more often than CT or TT subgroups. IL28B gene polymorphism therefore is a strong predictor of treatment result.

Structure of hepatitis C virus polymerase in complex with primer-template RNA

The replication of the hepatitis C viral (HCV) genome is accomplished by the NS5B RNA-dependent RNA polymerase (RdRp), for which mechanistic understanding and structure-guided drug design efforts have been hampered by its propensity to crystallize in a closed, polymerization-incompetent state. The removal of an autoinhibitory β-hairpin loop from genotype 2a HCV NS5B increases de novo RNA synthesis by >100-fold, promotes RNA binding, and facilitated the determination of the first crystallographic structures of HCV polymerase in complex with RNA primer-template pairs. These crystal structures demonstrate the structural realignment required for primer-template recognition and elongation, provide new insights into HCV RNA synthesis at the molecular level, and may prove useful in the structure-based design of novel antiviral compounds. Additionally, our approach for obtaining the RNA primer-template-bound structure of HCV polymerase may be generally applicable to solving RNA-bound complexes for other viral RdRps that contain similar regulatory β-hairpin loops, including bovine viral diarrhea virus, dengue virus, and West Nile virus.

Therapy with TLR7 agonists induces lymphopenia: correlating pharmacology to mechanism in a mouse model

BACKGROUND AND OBJECTIVE

Synthetic TLR7 agonists have been proposed as oral replacements for interferonα (IFNα) therapy in the treatment of hepatitis C virus infection. However, adverse effects, such as lymphopenia and cardiovascular irregularities, have been observed in the clinical following treatment with TLR7 agonists. We wished to understand and characterise the relationship between TLR7 agonism and adverse effects.

METHODS

We compared responses to two prototypic TLR7 agonists (Resiquimod: R-848; and PF-04878691) in a mouse model and compared the responses to treatment with IFNα. We measured clinically relevant adverse effects such as lymphopenia and cardiovascular irregularities and related them to plasma drug levels and clinically relevant efficacy biomarkers such as the pro-inflammatory cytokine IP-10, 2'5'OAS and TLR7 receptor expression.

RESULTS

By 2 h post dose all agents had induced a dose-dependent transient lymphopenia. IFNα increased heart rate immediately following dosing, persisting for 5 h, whilst PF-04878691 induced significant reductions in blood pressure. Lymphopenia co-incided with maximum plasma drug levels, raised levels of IP-10 and the auto-induction of TLR7 expression in the blood and lymph nodes. Peak levels of 2'5'OAS occurred at 24 h post-dose and only at doses which also induced lymphopenia.

CONCLUSIONS

We conclude that systemic delivery of TLR7 agonists or IFNα induces similar exaggerated pharmacology, consistent with there being a narrow therapeutic window between efficacy and safety. This clinically validated mouse model will help to investigate whether more potent agonists or optimised dosing schedules, will be successful strategies for targeting TLR7 in patients.