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]

Protein structure-based in-silico approaches to drug discovery: Guide to COVID-19 therapeutics

With more than 5 million fatalities and close to 300 million reported cases, COVID-19 is the first documented pandemic due to a coronavirus that continues to be a major health challenge. Despite being rapid, uncontrollable, and highly infectious in its spread, it also created incentives for technology development and redefined public health needs and research agendas to fast-track innovations to be translated. Breakthroughs in computational biology peaked during the pandemic with renewed attention to making all cutting-edge technology deliver agents to combat the disease. The demand to develop effective treatments yielded surprising collaborations from previously segregated fields of science and technology. The long-standing pharmaceutical industry's aversion to repurposing existing drugs due to a lack of exponential financial gain was overrun by the health crisis and pressures created by front-line researchers and providers. Effective vaccine development even at an unprecedented pace took more than a year to develop and commence trials. Now the emergence of variants and waning protections during the booster shots is resulting in breakthrough infections that continue to strain health care systems. As of now, every protein of SARS-CoV-2 has been structurally characterized and related host pathways have been extensively mapped out. The research community has addressed the druggability of a multitude of possible targets. This has been made possible due to existing technology for virtual computer-assisted drug development as well as new tools and technologies such as artificial intelligence to deliver new leads. Here in this article, we are discussing advances in the drug discovery field related to target-based drug discovery and exploring the implications of known target-specific agents on COVID-19 therapeutic management. The current scenario calls for more personalized medicine efforts and stratifying patient populations early on for their need for different combinations of prognosis-specific therapeutics. We intend to highlight target hotspots and their potential agents, with the ultimate goal of using rational design of new therapeutics to not only end this pandemic but also uncover a generalizable platform for use in future pandemics.

Design and Synthesis of Novel Bis-Imidazolyl Phenyl Butadiyne Derivatives as HCV NS5A Inhibitors

In today’s global plan to completely eradicate hepatitis C virus (HCV), the essential list of medications used for HCV treatment are direct-acting antivirals (DAAs), as interferon-sparing regimens have become the standard-of-care (SOC) treatment. HCV nonstructural protein 5A (NS5A) inhibitors are a very common component of these regimens. Food and Drug Administration (FDA)-approved NS5A inhibitors, although very potent, do not have the same potency against all eight genotypes of HCV. Therefore, this study aims to synthesize NS5A inhibitor analogues with high potency pan-genotypic activity and high metabolic stability. Starting from an NS5A inhibitor scaffold previously identified by our research group, we made several modifications. Two series of compounds were created to test the effect of changing the length and spatial conformation (para-para vs. meta-meta-positioned bis-imidazole-proline-carbamate), replacing amide groups in the linker with imidazole groups, as well as different end-cap compositions and sizes. The frontrunner inhibits genotype 1b (Con1) replicon, with an EC50 value in the picomolar range, and showed high genotypic coverage with nanomolar range EC50 values against four more genotypes. This together with its high metabolic stability (t½ > 120 min) makes it a potential preclinical candidate.

An Experimental and Theoretical Approach to Understand Fever, DENF & its Cure

Fever is a response of a human body, due to an increase in the temperature, against certain stimuli. It may be associated with several reasons and one of the major causes of fever is a mosquito bite. Fever due to dengue virus (DENV) infection is being paid most attention out of several other fever types because of a large number of deaths reported worldwide. Dengue virus is transmitted by biting of the mosquitoes, Aedes aegypti and Aedes albopictus. DENV1, DENV2, DENV3 and DENV4 are the four serotypes of dengue virus and these serotypes have 65% similarities in their genomic structure. The genome of DENV is composed of single-stranded RNA and it encodes for the polyprotein. Structural and non-structural proteins (nsP) are the two major parts of polyprotein. Researchers have paid high attention to the non-structural protease (nsP) of DENV like nsP1, nsP2A, nsP2B, nsP3, nsP4A, nsP4B and nsP5. The NS2B-NS3 protease of DENV is the prime target of the researchers as it is responsible for the catalytic activity. In the present time, Dengvaxia (vaccine) is being recommended to patients suffering severely from DENV infection in few countries only. Till date, neither a vaccine nor an effective medicine is available to combat all four serotypes. This review describes the fever, its causes, and studies to cure the infection due to DENV using theoretical and experimental approaches.

HCV Replicon Systems: Workhorses of Drug Discovery and Resistance

The development of direct-acting antivirals (DAAs) has revolutionized the state-of-the art treatment of HCV infections, with sustained virologic response rates above 90%. However, viral variants harboring substitutions referred to as resistance-associated substitutions (RASs) may be present in baseline levels and confer resistance to DAAs, thereby posing a major challenge for HCV treatment. HCV replicons have been the primary tools for discovering and evaluating the inhibitory activity of DAAs against viral replication. Interest in replicon systems has further grown as they have become indispensable for discovering genotype-specific and cross-genotype RASs. Here, we review functional replicon systems for HCV, how these replicon systems have contributed to the development of DAAs, and the characteristics and distribution of RASs for DAAs.

A novel, potent, and orally bioavailable thiazole HCV NS5A inhibitor for the treatment of hepatitis C virus

A medicinal chemistry program based on the small-molecule HCV NS5A inhibitor daclatasvir has led to the discovery of dimeric phenylthiazole compound 8, a novel and potent HCV NS5A inhibitor. The subsequent SAR studies and optimization revealed that the cycloalkyl amide derivatives 27a-29a exhibited superior potency against GT1b with GT1b EC₅₀ values at picomolar concentration. Interestingly, high diastereospecificity for HCV inhibition was observed in this class with the (1R,2S,1'R,2'S) diastereomer displaying the highest GT1b inhibitory activity. The best inhibitor 27a was found to be 3-fold more potent (GT1b EC₅₀ = 0.003 nM) than daclatasvir (GT1b EC₅₀ = 0.009 nM) against GT1b, and no detectable in vitro cytotoxicity was observed (CC₅₀ > 50 μM). Pharmacokinetic studies demonstrated that compound 27a had an excellent pharmacokinetic profiles with a superior oral exposure and desired bioavailability after oral administration in both rats and dogs, and therefore it was selected as a developmental candidate for the treatment of HCV infection.

The Unique Cofactor Region of Zika Virus NS2B-NS3 Protease Facilitates Cleavage of Key Host Proteins

Zika virus is an emerging mosquito-borne pathogen capable of severely damaging developing fetuses as well as causing neurological abnormalities in adults. The molecular details of how Zika virus causes pathologies that are unique among the flavivirus family remain poorly understood and have contributed to the lack of Zika antiviral therapies. To elucidate how Zika virus protease (ZVP) affects host cellular pathways and consequent pathologies, we used unbiased N-terminomics to identify 31 human proteins cleaved by the NS2B-NS3 protease. In particular, autophagy-related protein 16-1 (ATG16L1) and eukaryotic translation initiation factor 4 gamma 1 (eIF4G1) are dramatically depleted during Zika virus infection. ATG16L1 and eIF4G1 mediate type-II interferon production and host-cell translation, respectively, likely aiding immune system evasion and driving the Zika life cycle. Intriguingly, the NS2B cofactor region from Zika virus protease is essential for recognition of host cell substrates. Replacing the NS2B region in another flavivirus protease enabled recognition of novel Zika-specific substrates by hybrid proteases, suggesting that the cofactor is the principal determinant in ZVP substrate selection.

First-wave protease inhibitors for hepatitis C genotype 1 treatment: a real-life experience in Brazilian patients

INTRODUCTION

Licensed for chronic hepatitis C treatment in 2011, the protease inhibitors (PIs) telaprevir (TVR) and boceprevir (BOC), which have high sustained viral responses (SVR), ushered a new era characterized by the development of direct-action drugs against the hepatitis C virus (HCV). The aim of this study was to analyze the effectiveness and safety of BOC and TVR administered with pegylated interferon and ribavirin and to share the experience of a Brazilian reference center.

METHODS

A retrospective descriptive study was conducted in patients with HCV genotype 1 infection who started treatment between July 2013 and December 2015. Data were collected using a computerized system.

RESULTS

A total of 115 subjects were included, of which 58 (50.4 %) had liver cirrhosis and 103 (89.6 %) used TVR. The overall SVR rate was 61.7 % (62.1 % for TVR and 58.3 % for BOC). The presence of cirrhosis was associated with a lower SVR rate, whereas patients who relapsed after prior therapy had a greater chance of showing SVR than did non-responders. The incidence of adverse drug reactions (ADRs) was high. Almost all patients (~100 %) presented with hematologic events. Furthermore, treatment had to be discontinued in 15 subjects (13 %) due to severe ADRs.

CONCLUSIONS

In conclusion, the SVR rates in our study were lower than those reported in pre-marketing studies but were comparable to real-life data. ADRs, particularly hematological ADRs, were more common compared to those in previous studies and resulted in a high rate of treatment discontinuity.

Outcomes for Cirrhotic Patients with Hepatitis C Virus 1b Treated with Asunaprevir and Daclatasvir Combination

BACKGROUND

The efficacy and safety of asunaprevir + daclatasvir combination therapy for treatment of hepatitis C virus (HCV) in compensated cirrhotic patients was not fully evaluated in real-world. Outcomes were assessed in cirrhotic patients with sustained viral response (SVR).

MATERIAL AND METHODS

A total of 145 patients without resistance-associated substitutions (RASs) at L31 and Y93 in the nonstructural protein 5A of HCV genotype 1b, consisting of 49 hepatic cirrhotic and 96 non-cirrhotic patients, were enrolled to the therapy. The patients were treated with 100 mg asunaprevir twice daily plus 60 mg daclatasvir once daily for 24 weeks. The primary endpoint was SVR 24 weeks after completing treatment. In addition, we evaluated the improvement of liver function and development of HCC for 1 year from the end of treatment (EOT).

RESULTS

The SVR24 rate was 96% (47/49) in the cirrhotic group and 96% (91/95) in the non-cirrhotic group (p = 0.69). During treatment, grade III/IV adverse events occurred more frequently in cirrhotic patients (10/49; 20.4%) than in non-cirrhotic patients (10/96; 10.4%) (p = 0.099). After EOT, alanine aminotransferase and AFP levels were significantly decreased in cirrhotic patients with SVR. In addition, serum levels of albumin and platelet counts were significantly increased. On the other hand, the rates of HCC recurrence (43%) and development (7.4%) were higher in cirrhotic patients than in the non-cirrhotic patients (12.5% and 1.1%, respectively).

CONCLUSION

RAS-oriented asunaprevir/daclatasvir therapy has a strong anti-HCV effect in patients with HCV genotype 1b. However, careful management is necessary in patients with cirrhosis.

The effect of the first-generation HCV-protease inhibitors boceprevir and telaprevir and the relation to baseline NS3 resistance mutations in genotype 1: experience from a small Swedish cohort

BACKGROUND

The clinical experience with protease-inhibitor (PI) triple regimen appears disappointing regarding effect, side effects, high work load, and costs. This real-world study evaluates baseline and emerging resistance-associated substitutions (RASs) and their significance for treatment outcome.

METHOD

Thirty-six genotype 1a/b patients treated according to Swedish recommendations during 2011-2013 with triple therapy including pegylated interferon and ribavirin in combination with a protease-inhibitor, either boceprevir (BOC) or telaprevir (TVR), were retrospectively evaluated. Frozen serum samples from the patients were tested for resistance with pan-genotypic population sequencing.

RESULTS

Overall, 56% (20/36) of the patients achieved sustained viral response (SVR). The SVR was comparable between BOC (64%; 9/14) and TVR (50%; 11/22) (p = 0.07), and the IL28B type non-CC (48%; 12/25) and CC (46%; 6/13) (p = 0.77). The SVR was higher in patients without cirrhosis (89.5%; 17/19) (p < 0.0005), in treatment-naïve patients (70%; 14/20) (p = 0.02), and those with low viral load (<800,000 IU/mL) (66.7%; 8/12) (p < 0.0002), compared to those with cirrhosis (17.6%; 3/17), treatment-experienced (37.5%; 6/16), and high viral load (>800,000 IU/mL) (50%; 12/24).

CONCLUSION

PI triple regimes were highly effective in treatment-naïve patients without cirrhosis, but in this real-world cohort an inferior effect was evident in cirrhotic and treatment-experienced patients. Although tested on a limited sample, the baseline resistance testing seems to have no impact on prediction of therapy outcome. The reason could be that the baseline RASs T54S and V55A have relatively low resistance towards BOC and TVR. Emerging RASs, mainly R155K, with known high resistance to BOC and TVR were frequently found in non-responders.

Efficiency and Safety of an Early Dose Adjustment of Ribavirin in Patients Infected With Hepatitis C Underexposed to the Drug and Treated With Peginterferon Ribavirin

BACKGROUND

Ribavirin exposure after the first dose (D0AUC0-4h) >1755 mcg·h·L is predictive of sustained virological response (SVR) in patients with hepatitis C treated with peginterferon and ribavirin. The aim of this study was to test the benefit of ribavirin early dose adjustment based on this target in naïve patients infected with genotype 1.

METHODS

A multicenter randomized controlled trial with two parallel groups; fixed-dose (FD) group: standard of care in 2010-2011, ie, peginterferon-α2a 180 mcg·wk and weight-based ribavirin 1000-1200 mg/d during 48 weeks; adapted-dose (AD) group: increase of ribavirin dose if D0AUC0-4h <1755 mcg·h·L.

RESULTS

A total of 221 patients were included, 110 in the AD group and 111 in the FD group with similar baseline characteristics. In the perprotocol analysis, SVR was higher in the AD group (55.1% versus 40.4%; P = 0.042), especially in patients with D0AUC0-4h <1755 mcg·h·L (54.3% versus 31.9%; P = 0.029). In the intention-to-treat analysis, the difference was not significant (50% versus 41%; P = 0.197). Ribavirin trough concentrations (C0s) at week 4 of treatment (intention-to-treat analysis) were higher in patients achieving SVR (2.06 versus 1.72 mg/L, P = 0.003). In the subgroup of patients with AUC0-4h <1755 mcg·h·L, 46% of patients with AD achieved a C0 >2.0 mg/L versus 22% of patients with FD (P = 0.013). Grade 1 anemia (but not other grades) was more frequent in the AD group (70% versus 48%, P = 0.001). The number of dose reductions or discontinuation of ribavirin was similar in both groups.

CONCLUSIONS

Early ribavirin dose adjustment increases SVR in patients underexposed to ribavirin without increasing grade II-IV anemia. Such a strategy could be useful in patients with no access to new antiviral drugs.

Multiple effects of toxins isolated from Crotalus durissus terrificus on the hepatitis C virus life cycle

Hepatitis C virus (HCV) is one of the main causes of liver disease and transplantation worldwide. Current therapy is expensive, presents additional side effects and viral resistance has been described. Therefore, studies for developing more efficient antivirals against HCV are needed. Compounds isolated from animal venoms have shown antiviral activity against some viruses such as Dengue virus, Yellow fever virus and Measles virus. In this study, we evaluated the effect of the complex crotoxin (CX) and its subunits crotapotin (CP) and phospholipase A2 (PLA2-CB) isolated from the venom of Crotalus durissus terrificus on HCV life cycle. Huh 7.5 cells were infected with HCVcc JFH-1 strain in the presence or absence of these toxins and virus was titrated by focus formation units assay or by qPCR. Toxins were added to the cells at different time points depending on the stage of virus life cycle to be evaluated. The results showed that treatment with PLA2-CB inhibited HCV entry and replication but no effect on HCV release was observed. CX reduced virus entry and release but not replication. By treating cells with CP, an antiviral effect was observed on HCV release, the only stage inhibited by this compound. Our data demonstrated the multiple antiviral effects of toxins from animal venoms on HCV life cycle.

Megamitochondria formation in hepatocytes of patient with chronic hepatitis C - a case report

Although chronic hepatitis C virus (HCV) infection affect 185 million people world-wide, pathomechanism of liver damage is still unclear. Electron microscopy can reveal liver injury in very early stage and help understanding the mechanisms that is crucial in the pathogenesis of chronic hepatitis C. We present the morphological changes in the liver of HCV infected 24-year-old female patient, using light and transmission electron microscopy. Examination by TEM revealed wide range of specific subcellular abnormalities in hepatocellular ultrastructure. The most common observed changes were ring-shaped nuclei with intranuclear inclusion, megamitochondria, and “membranous web” structures – the hallmark of RNA-viruses infection.

Efficacy and safety of boceprevir-based triple therapy in HCV cirrhotic patients awaiting liver transplantation (ANRS HC29 BOCEPRETRANSPLANT)

BACKGROUND AND AIMS

In this French multicentre, open-label study, we analyzed the efficacy, safety and patient-reported outcomes of a boceprevir-based triple therapy in HCV genotype 1 cirrhotic patients awaiting liver transplantation (LT).

METHODS

Patients received PEG-IFN/ribavirin (RBV) for 48 weeks (W) and boceprevir from W4 to W48 or until LT.

RESULTS

Fifty-one patients (80% males, median age: 56 years) were included. Fifty-seven percent had hepatocellular carcinoma and 43% end-stage liver disease. At enrolment, the median MELD score was 9 (range: 6-18); the Child-Pugh score was A in 65%, B in 35% and C in 2%. Therapy was discontinued because of severe adverse events (SAEs) in 39% of cases and virological inefficacy in 24%. 16% of patients had undetectable HCV RNA 24 weeks after the end of treatment (SVR24). LT was performed in 18 patients (35%). HCV RNA was undetectable in 16.6% at LT. Seven patients (14%) died and three deaths were attributed to treatment. SAEs (n=129) were observed in 84% of patients. Twenty-four percent of patients developed severe infections. Albumin<35g/L was independently associated with severe infection. Compared with baseline values, a significant decrease (P=0.02) of the physical dimension of health-related quality of life was observed between W4 and W24. The mean (95% CI) number of self-reported symptoms doubled during treatment (from 6.3 [4.8-7.7] to 11.8 [9.3-14.3]; P<0.001).

CONCLUSIONS

The safety of the PEG-IFN/RBV/boceprevir combination is poor in patients awaiting LT, with a high risk of severe infection. Moreover, the limited efficacy confirms the indication for IFN-free combinations in these patients.

Cell transplantation as a non-invasive strategy for treating liver fibrosis

Advancements in antiviral drugs have enabled control of viral hepatitis; yet, many patients with liver cirrhosis (LC) are awaiting liver transplants. Liver transplantation yields dramatic therapeutic effects, but problems such as shortage of donors, surgical invasiveness, immunological rejection and costs, limit the number of transplantations. Advances in liver regeneration therapy through cell transplantation as a non-invasive treatment for cirrhosis will supplement these restrictions to the number of liver transplants. Clinical trials for LC have included hematopoietic stem cell mobilization by administration of granulocyte colony-stimulating factor, infusion of autologous bone marrow cells, and administration of autologous mesenchymal stem cells derived from bone marrow or umbilical cord. Several recently reported randomized controlled studies have shown the effectiveness of these approaches. However, to promote implementation of new liver regeneration therapies, it is important to develop a system whereby cell therapies with ensured safety can be approved quickly.

Inhibition of enterovirus 71 replication by an α-hydroxy-nitrile derivative NK-1.9k

Enterovirus 71 (EV71) is one of the major etiological agents of human hand-foot-and-mouth disease (HFMD) worldwide. EV71 infection in young children and people with immunodeficiency causes severe symptoms with a high fatality rates. However, there is still no approved drugs to treat such infections. Based on our previous report of a peptide-aldehyde anti-EV71 protease, we present here a highly specific α-hydroxy-nitrile derivative NK-1.9k, which inhibited the proliferation of multiple EV71 strains and coxsackievirus A16 (CVA16) in various cells with EC₅₀ of 37.0 nM with low cytotoxicity (CC₅₀ > 200 μM). The hydroxy-nitrile covalent warhead conferred NK-1.9k high potency and selectivity to interact with the cysteine residue of the active site of the viral protease. We also documented the resistance to NK-1.9k with a N69S mutation in EV71 3C^pro. The combination of NK-1.9k and EV71 polymerase or entry inhibitors produced strong synergistic antiviral effects. Collectively, our findings suggest our compounds can potentially be developed as drugs for the treatment of HFMD.

A Potent, Selective, and Orally Bioavailable HCV NS5A Inhibitor for Treatment of Hepatitis C Virus: (S)-1-((R)-2-(Cyclopropanecarboxamido)-2-phenylacetyl)-N-(4-phenylthiazol-2-yl)pyrrolidine-2-carboxamide

Starting from the initial lead 4-phenylthiazole 18, a modest HCV inhibitor (EC₅₀ = 9440 nM), a series of structurally related thiazole derivatives has been identified as a novel chemical class of potent and selective HCV NS5A inhibitors. The introduction of a carboxamide group between the thiazole and pyrrolidine ring (42) of compound 18 resulted in a dramatic increase in activity (EC₅₀ = 0.92 nM). However, 42 showed only moderate pharmacokinetic properties and limited oral bioavalability of 18.7% in rats. Further optimization of the substituents at the 4-position of the thiazole ring and pyrrolidine nitrogen of the lead compound 42 led to the identification of compound 57, a highly potent and selective NS5A inhibitor of HCV (EC₅₀ = 4.6 nM), with greater therapeutic index (CC₅₀/EC₅₀ > 10000). Pharmacokinetic studies revealed that compound 57 had a superior oral exposure and desired bioavailability of 45% after oral administration in rats.

The NS4A Cofactor Dependent Enhancement of HCV NS3 Protease Activity Correlates with a 4D Geometrical Measure of the Catalytic Triad Region

We are developing a 4D computational methodology, based on 3D structure modeling and molecular dynamics simulation, to analyze the active site of HCV NS3 proteases, in relation to their catalytic activity. In our previous work, the 4D analyses of the interactions between the catalytic triad residues (His57, Asp81, and Ser139) yielded divergent, gradual and genotype-dependent, 4D conformational instability measures, which strongly correlate with the known disparate catalytic activities among genotypes. Here, the correlation of our 4D geometrical measure is extended to intra-genotypic alterations in NS3 protease activity, due to sequence variations in the NS4A activating cofactor. The correlation between the 4D measure and the enzymatic activity is qualitatively evident, which further validates our methodology, leading to the development of an accurate quantitative metric to predict protease activity in silico. The results suggest plausible “communication” pathways for conformational propagation from the activation subunit (the NS4A cofactor binding site) to the catalytic subunit (the catalytic triad). The results also strongly suggest that the well-sampled (via convergence quantification) structural dynamics are more connected to the divergent catalytic activity observed in HCV NS3 proteases than to rigid structures. The method could also be applicable to predict patients’ responses to interferon therapy and better understand the innate interferon activation pathway.

Randomized trial of combined triple therapy comprising two types of peginterferon with simeprevir in patients with hepatitis C virus genotype 1b

Simeprevir (SMV) is a potent, macrocyclic hepatitis C virus (HCV) non-structural 3/4 A protease inhibitor. This prospective study compared the efficacy and safety of SMV in combination with peginterferon α2a + ribavirin (P2aR) and with peginterferon α2b + ribavirin (P2bR) in Japanese patients with HCV genotype 1b infection.

METHODS

Hepatitis C virus genotype 1b patients were randomly assigned to receive SMV (100 mg QD) with P2aR for 12 weeks, then P2aR alone for 12 or 36 weeks; or SMV (100 mg QD) with P2bR for 12 weeks, then P2bR alone for 12 or 36 weeks. The primary endpoint was a sustained virologic response 24 weeks after completing treatment (SVR24).

RESULTS

In total, 151 patients were randomly assigned to the P2aR (n = 76) or P2bR group (n = 75). Six patients dropped out. Sustained virologic response 24 weeks after completing treatment was achieved in 55 (75.3%) of 73 P2aR patients and 55 (76.4%) of 72 P2bR patients. There was no difference in the rate of SVR24 between the two groups (P = 0.88). No differences in the proportion of patients who became HCV RNA-negative were detected between the P2aR and P2bR groups. The two groups had comparable numbers of adverse events, which led to the discontinuation of treatment in 9.6% and 8.3% of participants in the P2aR and P2bR groups, respectively.

CONCLUSION

Peginterferon α2a or α2b in combination with SMV + ribavirin therapy showed identical antiviral effects in patients with chronic hepatitis C. Also, the incidence of adverse events was identical for both regimens.

Hepatitis-C-virus-induced microRNAs dampen interferon-mediated antiviral signaling

Hepatitis C virus (HCV) infects 200 million people globally, and 60-80% of cases persist as a chronic infection that will progress to cirrhosis and liver cancer in 2-10% of patients. We recently demonstrated that HCV induces aberrant expression of two host microRNAs (miRNAs), miR-208b and miR-499a-5p, encoded by myosin genes in infected hepatocytes. These miRNAs, along with AU-rich-element-mediated decay, suppress IFNL2 and IFNL3, members of the type III interferon (IFN) gene family, to support viral persistence. In this study, we show that miR-208b and miR-499a-5p also dampen type I IFN signaling in HCV-infected hepatocytes by directly down-regulating expression of the type I IFN receptor chain, IFNAR1. Inhibition of these miRNAs by using miRNA inhibitors during HCV infection increased expression of IFNAR1. Additionally, inhibition rescued the antiviral response to exogenous type I IFN, as measured by a marked increase in IFN-stimulated genes and a decrease in HCV load. Treatment of HCV-infected hepatocytes with type I IFN increased expression of myosins over HCV infection alone. Since these miRNAs can suppress type III IFN family members, these data collectively define a novel cross-regulation between type I and III IFNs during HCV infection.

Pharmacokinetics and pharmacodynamics of sofosbuvir and ledipasvir for the treatment of hepatitis C

INTRODUCTION

The sofosbuvir (SOF) plus ledipasvir (LDV) fixed dose combination is the first direct action antiviral (DAA) single-treatment regimen (STR) to be commercialized. It is approved for the treatment of Hepatitis C virus (HCV) genotypes 1,3,4,5 and 6. Following approval in 2014, new pharmacokinetics and pharmacodynamics data were reported, which led to important clinical applications. Areas covered: This article reviews the pharmacokinetic and pharmacodynamic properties of the SOF/LDV fixed dose combination for the treatment of HCV. The topics covered include data regarding the drug´s absorption, distribution, metabolism and excretion and antiviral activity strategies such as the clinical dose selection and treatment duration. Expert opinion: The SOF/LDV fixed dose combination has good pharmacological properties that lead to a high sustained virological response after 12 or 24 weeks of treatment; there is minimal interference with other drugs or associated renal or hepatic impairment, such that dose adjustment is not necessary.

High-throughput screening for the identification of small-molecule inhibitors of the flaviviral protease

The mosquito-borne dengue virus serotypes 1-4 (DENV1-4) and West Nile virus (WNV) cause serious illnesses worldwide associated with considerable morbidity and mortality. According to the World Health Organization (WHO) estimates, there are about 390 million infections every year leading to ∼500,000 dengue haemorrhagic fever (DHF) cases and ∼25,000 deaths, mostly among children. Antiviral therapies could reduce the morbidity and mortality associated with flaviviral infections, but currently there are no drugs available for treatment. In this study, a high-throughput screening assay for the Dengue protease was employed to screen ∼120,000 small molecule compounds for identification of inhibitors. Eight of these inhibitors have been extensively analyzed for inhibition of the viral protease in vitro and cell-based viral replication using Renilla luciferase reporter replicon, infectivity (plaque) and cytotoxicity assays. Three of these compounds were identified as potent inhibitors of DENV and WNV proteases, and viral replication of DENV2 replicon and infectious RNA. Fluorescence quenching, kinetic analysis and molecular modeling of these inhibitors into the structure of NS2B-NS3 protease suggest a mode of inhibition for three compounds that they bind to the substrate binding pocket.

HCV-Mediated Apoptosis of Hepatocytes in Culture and Viral Pathogenesis

Chronic Hepatitis C Virus (HCV) infection is associated with progressive liver injury and subsequent development of fibrosis and cirrhosis. The death of hepatocytes results in the release of cytokines that induce inflammatory and fibrotic responses. The mechanism of liver damage is still under investigation but both apoptosis and immune-mediated processes may play roles. By observing the changes in gene expression patterns in HCV-infected cells, both markers and the causes of HCV-associated liver injury may be elucidated. HCV genotype 1b virus from persistently infected VeroE6 cells induced a strong cytopathic effect when used to infect Huh7.5 hepatoma cells. To determine if this cytopathic effect was a result of apoptosis, ultrastructural changes were observed by electron microscopy and markers of programmed cell death were surveyed. Screening of a human PCR array demonstrated a gene expression profile that contained upregulated markers of apoptosis, including tumor necrosis factor, caspases and caspase activators, Fas, Bcl2-interacting killer (BIK) and tumor suppressor protein, p53, as a result of HCV genotype 1b infection. The genes identified in this study should provide new insights into understanding viral pathogenesis in liver cells and may possibly help to identify novel antiviral and antifibrotic targets.

Retinoid and carotenoid status in serum and liver among patients at high-risk for liver cancer

Background

Approximately 2.7 million Americans are chronically infected with hepatitis C virus (HCV). HCV patients with cirrhosis form the largest group of persons at high risk for hepatocellular carcinoma (HCC). Increased oxidative stress is regarded as a major mechanism of HCV-related liver disease progression. Deficiencies in retinoid and carotenoid antioxidants may represent a major modifiable risk factor for disease progression. This study aims to identify key predictors of serum antioxidant levels in patients with HCV, to examine the relationship between retinoid/carotenoid concentrations in serum and hepatic tissue, to quantify the association between systemic measures of oxidative stress and antioxidant status, and to examine the relationship between retinoids and stellate cell activation.

Methods

Patients undergoing liver biopsy (n = 69) provided fasting blood, fresh tissue, urine and completed a diet history questionnaire. Serum and questionnaire data from healthy volunteers (n = 11), normal liver tissue from public repositories and patients without liver disease (n = 11) were also collected. Urinary isoprostanes, serum and tissue retinoid concentrations were obtained by UHPLC-MS-MS. Immunohistochemistry for αSMA was performed on FFPE sections and subsequently quantified via digital image analysis. Associations between urinary isoprostanes, αSMA levels, and retinoids were assessed using Spearman correlation coefficients and non-parametric tests were utilized to test differences among disease severity groups.

Results

There was a significant inverse association between serum retinol, lycopene, and RBP4 concentrations with fibrosis stage. Serum β-carotene and lycopene were strongly associated with their respective tissue concentrations. There was a weak downward trend of tissue retinyl palmitate with increasing fibrosis stage. Tissue retinyl palmitate was inversely and significantly correlated with hepatic αSMA expression, a marker for hepatic stellate cell activation (r = −0.31, P < 0.02). Urinary isoprostanes levels were inversely correlated with serum retinol, β-carotene, and RBP4.

Conclusions

A decrease in serum retinol, β-carotene, and RBP4 is associated with early stage HCV. Retinoid and carotenoid levels decline as disease progresses, and our data suggest that this decline occurs early in the disease process, even before fibrosis is apparent. Measures of oxidative stress are associated with fibrosis stage and concurrent antioxidant depletion. Vitamin A loss is accompanied by stellate cell activation in hepatic tissue.

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-016-0432-5) contains supplementary material, which is available to authorized users.

Recent Advances in Antiviral Therapy for Chronic Hepatitis C

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

Evaluating Andrographolide as a Potent Inhibitor of NS3-4A Protease and Its Drug-Resistant Mutants Using In Silico Approaches

Current combination therapy of PEG-INF and ribavirin against the Hepatitis C Virus (HCV) genotype-1 infections is ineffective in maintaining sustained viral response in 50% of the infection cases. New compounds in the form of protease inhibitors can complement the combination therapy. Asunaprevir is new to the drug regiment as the NS3-4A protease inhibitor, but it is susceptible to two mutations, namely, R155K and D168A in the protein. Thus, in our study, we sought to evaluate Andrographolide, a labdane-diterpenoid from the Andrographis paniculata plant as an effective compound for inhibiting the NS3-4A protease as well as its concomitant drug-resistant mutants by using molecular docking and dynamic simulations. Our study shows that Andrographolide has best docking scores of −15.0862, −15.2322, and −13.9072 compared to those of Asunaprevir −3.7159, −2.6431, and −5.4149 with wild-type R155K and D168A mutants, respectively. Also, as shown in the MD simulations, the compound was good in binding the target proteins and maintains strong bonds causing very less to negligible perturbation in the protein backbone structures. Our results validate the susceptibility of Asunaprevir to protein variants as seen from our docking studies and trajectory period analysis. Therefore, from our study, we hope to add one more option in the drug regiment to tackle drug resistance in HCV infections.

Efficacy and Tolerability of Peginterferon alpha-2a and Peginterferon alpha-2b in Iranian Patients With Chronic Hepatitis C

BACKGROUND

Nearly 0.5% of Iranians are infected with HCV. Peginterferon-alpha-2a and Peginterferon-alpha-2b are the two available types of interferon for the treatment of hepatitis C. Comparing the results of these two treatments is still a challenge.

OBJECTIVES

The aim of this study was to compare the results of Peginterferon-alpha-2a and Peginterferon-alpha-2b in Iranian patients with chronic hepatitis C.

PATIENTS AND METHODS

289 patients with chronic hepatitis C attending Tehran Hepatitis Center (THC) and Hepatitis Clinic of Tehran Blood Transfusion Organization (TBTO) from January 2008 to April 2013 and treated with combination of Peginterferon-alpha-2a or Peginterferon-alpha-2b plus Ribavirin were enrolled in this retrospective cross-sectional study. Treatment response and side effects were compared.

RESULTS

Among all naive patients, 82.0% achieved SVR, 5.4% were resistant to therapy and 11.0% withdrew the treatment. Relapse was seen in 12.2% of naive patients who finished the course of treatment. RVR and EVR were seen in 67.7% and 90.6% of naive patients, respectively. Patients divided into two groups. Group A consists of 247 patients treated with Peginterferon-alpha-2a and group B 42 patients treated with Peginterferon-alpha-2b. No significant difference in treatment response was observed between naive patients of the two groups. The rates of arthralgia/myalgia, alopecia, pruritus, insomnia, dyspnea and anorexia were higher in group A and the rates of dermal problems, coryza and bleeding were higher in group B. In a subgroup analysis, the two kinds of Peginterferon-alpha-2a available in Iran were compared. Rapid and early viral responses and relapse rates were lower in the one made in Iran and the long-term responses were not different. The rates of arthralgia/myalgia, fever, alopecia, pruritus, insomnia, dyspnea, anorexia, cough, headache and abdominal pain were higher and the rates of irritability and coryza were lower in the one made in Iran.

CONCLUSIONS

There was no significant difference in the efficacy of Peginterferon-alpha-2a and Peginterferon-alpha-2b in Iranian patients. Physicians might choose the treatment regimen for every individual concerning the differences in side effects of Peginterferons.

Role of genetic polymorphisms in hepatitis C virus chronic infection

AIM: To analyze the host genetics factors influencing the clinical course and the response to antiviral treatment in patients with chronic hepatitis C (CHC).

METHODS: We conducted an electronic search on the PubMed and MEDLINE (2000-2014) databases and Cochrane library (2000-2014). A total of 73 articles were retrieved and their data were extensively evaluated and discussed by the authors and then analyzed in this review article.

RESULTS: Several studies associated polymorphisms in the interleukin 28B gene on chromosome 19 (19q13.13) with a spontaneous viral clearance in acute hepatitis C and with the response to pegylated interferon (Peg-IFN)-based treatment in chronic hepatitis C patients. Other investigations demonstrated that inosine triphosphate pyrophosphatase genetic variants protect hepatitis C virus-genotype-1 CHC patients from ribavirin-induced anemia, and other studies that a polymorphism in the patatin-like phospholipase domain-containing protein 3 was associated with hepatic steatosis in CHC patients. Although not conclusive, some investigations suggested that the vitamin D-associated polymorphisms play an important role in the achievement of sustained virologic response in CHC patients treated with Peg-IFN-based antiviral therapy. Several other polymorphisms have been investigated to ascertain their possible impact on the natural history and on the response to treatment in patients with CHC, but the data are preliminary and warrant confirmation.

CONCLUSION: Several genetic polymorphisms seem to influence the clinical course and the response to antiviral treatment in patients with CHC, suggesting individualized follow up and treatment strategies.

The impact of an educational program on HCV patient outcomes using boceprevir in community practices (OPTIMAL trial)

OBJECTIVES

Although effective, direct acting antiviral (DAA) therapies for genotype 1 (GT 1) hepatitis C virus (HCV) have been associated with compliance challenges. Additionally, treatment at predominantly community-based centers has been associated with low retention of patients on treatment and higher dropout rates. The OPTIMAL Phase IV interventional trial (ClinicalTrials.gov Identifier: NCT01405027) was designed to evaluate the impact of an education program for community investigator (CI) sites participating in a Chronic Liver Disease Foundation study treating chronic GT 1 HCV patients.

METHODS

This physician educational program was administered by 22 Hepatology Centers of Educational Expertise (HCEE) academic sites to 33 CI sites asked to participate from December 2011 to July 2012. The HCEE mentors from DAA-experienced academic sites educated those at CI sites on therapeutic management, practice, and patient outcomes through a series of four standardized educational sequence visits regarding the use of first generation HCV protease inhibitors and the overall treatment of HCV.

RESULTS

Treatment duration compliance rates for patients treated at CI sites versus those treated at HCEE academic sites were evaluable in 77 of 84 HCEE academic site patients, 102 of 113 patients treated at CI sites, and 179 of 197 overall patients. The treatment duration compliance rates for patients treated at HCEE academic sites, CI sites and overall were 85.4 ± 25.39%, 83.8 ± 27.37%, and 84.5 ± 26.48%, respectively, and did not differ statistically between the groups (p = 0.49). Almost half (47%) of the patients in the study achieved a sustained virological response for 24 weeks (SVR24) regardless of the type of site (p = 0.64). Safety profiles were similar at both HCEE and CI sites.

CONCLUSIONS

These results demonstrated that education of CI sites unfamiliar with DAAs resulted in patient outcomes consistent with those observed at DAA-experienced academic sites.

Early virological assessment during telaprevir- or boceprevir-based triple therapy in hepatitis C cirrhotic patients who failed a previous interferon based regimen - The ANRS CO20-CUPIC study

BACKGROUND AND OBJECTIVE

To assess within the ANRS CO20-CUPIC cohort whether the viral load (VL) at week 2/week 6 for telaprevir/boceprevir-based triple therapy, respectively, was predictive of sustained virological response (SVR) in patients with hepatitis C virus (HCV) infection and to study the relevance of this measurement to early diagnose drug resistance.

METHODS

Observational study of HCV genotype 1 patients with compensated cirrhosis (Child-Pugh A), non-responders to a prior course of interferon (IFN)-based therapy and who started triple therapy. Patients received either 12 weeks of telaprevir in combination with PEG-IFN/ribavirin (RBV), then 36 weeks of PEG-IFN/RBV, or 4 weeks of PEG-IFN/RBV, then 44 weeks of PEG-IFN/RBV and boceprevir.

RESULTS

A total of 262 patients were analyzed. For telaprevir-treated patients, 28% had undetectable VL at W2 of whom 81% achieved SVR12 whereas 67% had undetectable VL at W4 of whom 67% achieved SVR12. For boceprevir-treated patients 20% had undetectable VL at W6 and 86% of them achieved SVR12 whereas 36% had undetectable VL at W8 among whom 73% achieved SVR12. Five telaprevir-treated patients had a VL increase between W2 and W4 after a decrease between D0 and W2. Four of them did not achieve SVR12. Similarly, six boceprevir-treated patients had a VL increase between W6 and W8 after a decrease between D0 and W6. Five did not reach SVR12.

CONCLUSIONS

The assessment of HCV RNA level after two weeks of triple therapy in cirrhotic non-responder patients is a good predictor of SVR. This assessment was useful to do an early diagnosis of viral breakthrough.

Preclinical Characterization and In Vivo Efficacy of GSK8853, a Small-Molecule Inhibitor of the Hepatitis C Virus NS4B Protein

The hepatitis C virus (HCV) NS4B protein is an antiviral therapeutic target for which small-molecule inhibitors have not been shown to exhibit in vivo efficacy. We describe here the in vitro and in vivo antiviral activity of GSK8853, an imidazo[1,2-a]pyrimidine inhibitor that binds NS4B protein. GSK8853 was active against multiple HCV genotypes and developed in vitro resistance mutations in both genotype 1a and genotype 1b replicons localized to the region of NS4B encoding amino acids 94 to 105. A 20-day in vitro treatment of replicons with GSK8853 resulted in a 2-log drop in replicon RNA levels, with no resistance mutation breakthrough. Chimeric replicons containing NS4B sequences matching known virus isolates showed similar responses to a compound with genotype 1a sequences but altered efficacy with genotype 1b sequences, likely corresponding to the presence of known resistance polymorphs in those isolates. In vivo efficacy was tested in a humanized-mouse model of HCV infection, and the results showed a 3-log drop in viral RNA loads over a 7-day period. Analysis of the virus remaining at the end of in vivo treatment revealed resistance mutations encoding amino acid changes that had not been identified by in vitro studies, including NS4B N56I and N99H. Our findings provide an in vivo proof of concept for HCV inhibitors targeting NS4B and demonstrate both the promise and potential pitfalls of developing NS4B inhibitors.

Effects of boceprevir and telaprevir on the pharmacokinetics of dolutegravir

AIMS

The aim was to evaluate the effect of boceprevir and telaprevir on dolutegravir pharmacokinetics (PK); the effect of dolutegravir on boceprevir and telaprevir PK was assessed through comparison with historical data for each hepatitis C virus (HCV) drug's prescribing information alone.

METHODS

This was a single-centre, randomized, open-label, two-cohort, two-period, one-way study in healthy adult subjects. Dolutegravir 50 mg once daily was administered for 5 days in Period 1, and dolutegravir 50 mg once daily was coadministered with either boceprevir 800 mg every 8 h (Cohort 1) or telaprevir 750 mg every 8 h (Cohort 2) for 10 days in Period 2.

RESULTS

No deaths or serious adverse events were reported during the study. Four subjects were withdrawn from the study because of adverse events (elevated alanine aminotransferase, cellulitis, increased serum creatinine and dizziness). One subject became pregnant during the study. Coadministration of dolutegravir with boceprevir had no effect on dolutegravir area under the plasma concentration-time curve (AUC) and maximal plasma concentration (Cmax ) and caused a small increase in concentration at the end of the dosing interval (Cτ ; 8%). Coadministration of dolutegravir with telaprevir resulted in increased dolutegravir plasma exposures compared with those after administration of dolutegravir alone; AUC0- τ , Cmax and Cτ increased by 25, 19 and 37%, respectively. Coadministration of boceprevir or telaprevir with dolutegravir had no clinically significant effect on dolutegravir PK. Plasma boceprevir and telaprevir PK data for either combined treatment were similar to historical data, indicating no effect of dolutegravir on boceprevir or telaprevir exposure.

CONCLUSIONS

Dolutegravir can be coadministered with boceprevir or telaprevir in patients coinfected with HIV and HCV with no dose adjustment.

IL28B genotype predicts response to chronic hepatitis C triple therapy with telaprevir or boceprevir in treatment naïve and treatment-experienced patients other than prior partial- and null-responders

Single nucleotide polymorphisms (SNPs) in the IL28B gene were shown to have limited utility in predicting response to telaprevir and boceprevir in treatment of chronic HCV infection in clinical trials. Data outside of the clinical trial setting are lacking. We assessed the value of single and combined IL28B SNPs rs12979860 and rs8099917 genotypes in predicting sustained virological response 12 weeks after cessation of triple therapy (SVR12) with telaprevir or boceprevir in a single-centre cohort of treatment-naïve and treatment-experienced patients with genotype 1 HCV mono-infection (n = 105). The overall SVR12 rate was 65.7%. By unadjusted bivariate logistic regression analysis, rs12979860-CC and rs8099917-TT were significantly associated with SVR12 in the subgroup of patients including all naïve patients and all treatment-experienced patients with the exception of partial- and null-responders to previous HCV therapy. The predictive value of rs12979860-CC was stronger than rs8099917-TT and only rs12979860-CC remained significantly predictive of treatment success when the two variants were assessed by adjusted logistic regression analysis in the whole study cohort. In patients presenting the rs12979860-CC variant, the additional determination of rs8099917 genotype had no value. IL28B rs12979860-CC remained significantly associated with SVR12 also in the multivariate analysis including the other baseline characteristics associated to SVR12 in the bivariate analysis (i.e., female gender, HCV genotype 1b, baseline viral load <800,000 IU/mL, advanced liver fibrosis and prior partial- or null-response to HCV therapy). Our study suggests that testing for the IL28B rs12979860 genotype may still be useful in predicting response to triple therapy with boceprevir and telaprevir in naïve patients and treatment-experienced patients other than partial and null-responders.

Antiviral Therapy in Patients with Hepatitis C Virus-Induced Cirrhosis

BACKGROUND

Opportunities to treat infection with hepatitis C virus (HCV) are evolving rapidly. From the introduction of interferon (IFN)-α monotherapy in the early 1990s to the approval of telaprevir- and boceprevir-based triple therapies with pegylated (PEG)-IFN-α and ribavirin (RBV) in 2011, the chances of curing patients infected with HCV genotype 1 have improved dramatically to reach approximately 70%. Significant further improvements that may cure virtually all HCV patients with an all-oral, IFN-free regimen are becoming progressively available. Key Messages: Historically, a PEG-IFN/RBV combination therapy of patients with liver cirrhosis was associated with lower virological rates and a worse safety profile. The advent of the first protease inhibitor-based triple therapy was long expected, but the promise fell rapidly because of the numerous side effects and the requirement for intensive clinical management in cirrhotic patients. The newer direct-acting antivirals (DAAs) target the viral polymerase with either nucleos(t)ide analogues or nonnucleosidic inhibitors, the viral protease and the viral NS5A protein. Several clinical trials have now shown that a combination of sofosbuvir (nucleosidic polymerase inhibitor) with daclatasvir or ledipasvir (NS5A inhibitors), or sofosbuvir with simeprevir (protease inhibitor), or a combination of ABT-450 (protease inhibitor) with ritonavir (ABT-450/r), the nonnucleosidic polymerase inhibitor ABT-333 and the NS5A inhibitor ABT-267, can achieve a sustained virological response in up to 95% of naive patients or previously treated patients, even in those who failed prior treatment with first-generation protease inhibitors. The best treatment regimens enable the achievement of comparable results even in cirrhotics, while other regimens still require RBV or a longer treatment duration to achieve optimal results. This improved risk/benefit ratio justifies early access programs of IFN-free regimens for cirrhotic patients. The remaining difficult-to-treat patients are cirrhotics infected with HCV genotype 3 and those with decompensated cirrhosis, for whom novel DAA combinations should be evaluated in clinical trials.

CONCLUSIONS

As new DAAs are becoming available in early access treatment programs, treatment strategy studies are being performed to optimize treatment regimens with respect to the choice of DAAs and treatment duration, based on viral genotypes, prior treatment response and the presence of liver cirrhosis. In the near future, this should allow: (i) a decrease in the complications of HCV-induced cirrhosis, (ii) liver transplantations to be performed in virally cured patients, and (iii) the rescue of patients in the worst clinical situation (decompensated cirrhosis and HCV recurrence on liver graft).

Pharmacokinetic and pharmacodynamic evaluation of telaprevir for the treatment of hepatitis C

INTRODUCTION

Telaprevir is one of the first direct-acting antiviral drugs approved for the treatment of the hepatitis C virus (HCV) genotype 1. Following its approval in 2011, new data regarding the pharmacokinetics and pharmacodynamics were reported, leading to important clinical applications.

AREAS COVERED

This article reviews the pharmacokinetic and pharmacodynamic properties of telaprevir for the treatment of the HCV. The areas covered include data regarding the drug's absorption, distribution, metabolism and excretion, in addition to the antiviral activity strategy such as the clinical dose selection and treatment duration.

EXPERT OPINION

Telaprevir presents several pharmacological properties that could limit its administration such a high-fat, high-calorie meal; the need to be administrated with pegylated IFN plus ribavirin; and the drug-drug interaction profile. As a consequence and considering the new therapeutic arsenal against the HCV, the use of telaprevir as part of HCV therapy will be limited.

Poor Sustained Virological Response in a Multicenter Real-Life Cohort of Chronic Hepatitis C Patients Treated with Pegylated Interferon and Ribavirin plus Telaprevir or Boceprevir

BACKGROUND

There are limited data analyzing the effectiveness of boceprevir (BOC) or telaprevir (TVR) in combination with pegylated interferon (PEG-IFN) plus ribavirin (RBV) in a real-life patient cohort.

AIMS

In clinical trials, patients with chronic hepatitis C (CHC) treated with BOC or TVR plus PEG-IFN and RBV achieved sustained virological response (SVR) rates of 70 %. However, it is not clear whether similar results can be realized in routine practice. Our goal is to examine SVR rates of these triple regimens for CHC in a multicenter real-life patient cohort.

METHODS

We retrospectively studied 200 consecutive CHC genotype 1 patients who were initiated on PEG-IFN, RBV, and either TVR (n = 113) or BOC (n = 87) from July 2011 to February 2014 at two US academic liver clinics, a Veterans Affairs liver clinic and a community gastroenterology clinic.

RESULTS

Both BOC and TVR treatment groups were similar in regard to comorbidities, BMI, and HCV RNA levels. BOC patients were more likely to have cirrhosis than TVR patients (47 vs. 24 %, P = 0.001). SVR rates were low in both cohorts (40 % for BOC, 53 % for TVR, P = 0.05). On multivariate logistic regression, treatment adherence by the "80/80/80 rule," diagnosis of cirrhosis, and use of erythropoietin were statistically significant predictors for SVR. Of these, treatment adherence was the strongest predictor (OR 4.43, 95 % CI 2.8-6.06, P < 0.001).

CONCLUSION

SVR was much lower in a real-life patient cohort than in clinical trials (53 % for TVR and 40 % for BOC, compared to 66-75 % in clinical trials).

HIV-hepatitis C virus co-infection in the era of direct-acting antivirals

Approximately one-third of patients infected with human immunodeficiency virus (HIV) are concomitantly infected with hepatitis C virus (HCV). As a result, liver disease remains a major source of morbidity and mortality in HIV patients. Prior to 2011, treatments of HCV lacked efficacy in clinical trials in HIV/HCV co-infected patients. Fortunately, several direct-acting antivirals (DAAs) have now entered clinical practice and others have reached advanced stages of clinical development. These therapies offer significant benefits such as improved rates of sustained virologic response (SVR), shortened durations of treatment, and compatibility with HIV antiretroviral therapies. Treatments such as sofosbuvir (SOF) have received approval for HIV/HCV co-infected patients. Moreover, interferon-free options exist for HIV/HCV co-infected patients who may be ineligible or intolerant of interferon. Despite these improvements, physicians must be aware of the differences between these DAAs, the patient characteristics that play a role on the effectiveness of these medications, and the drug-drug interactions these DAAs may have with existing HIV antiretroviral therapies. The aim of this review is to discuss the prevalence and incidence of HIV/HCV co-infection, critical factors related to patient evaluation, current treatment options, and new developments in the management of HIV/HCV co-infected patients.

Non-proteolytic functions of microbial proteases increase pathological complexity

Proteases are enzymes that catalyse hydrolysis of peptide bonds thereby controlling the shape, size, function, composition, turnover and degradation of other proteins. In microbes, proteases are often identified as important virulence factors and as such have been targets for novel drug design. It is emerging that some proteases possess additional non‐proteolytic functions that play important roles in host epithelia adhesion, tissue invasion and in modulating immune responses. These additional “moonlighting” functions have the potential to obfuscate data interpretation and have implications for therapeutic design. Moonlighting enzymes comprise a subcategory of multifunctional proteins that possess at least two distinct biological functions on a single polypeptide chain. Presently, identifying moonlighting proteins relies heavily on serendipitous empirical data with clues arising from proteins lacking signal peptides that are localised to the cell surface. Here, we describe examples of microbial proteases with additional non‐proteolytic functions, including streptococcal pyrogenic exotoxin B, PepO and C5a peptidases, mycoplasmal aminopeptidases, mycobacterial chaperones and viral papain‐like proteases. We explore how these non‐proteolytic functions contribute to host cell adhesion, modulate the coagulation pathway, assist in non‐covalent folding of proteins, participate in cell signalling, and increase substrate repertoire. We conclude by describing how proteomics has aided in moonlighting protein discovery, focusing attention on potential moonlighters in microbial exoproteomes.

Clinical course of infection and viral tissue tropism of hepatitis C virus-like nonprimate hepaciviruses in horses

Hepatitis C virus (HCV) has a very narrow species and tissue tropism and efficiently replicates only in humans and the chimpanzee. Recently, several studies identified close relatives to HCV in different animal species. Among these novel viruses, the nonprimate hepaciviruses (NPHV) that infect horses are the closest relatives of HCV described to date. In this study, we analyzed the NPHV prevalence in northern Germany and characterized the clinical course of infection and viral tissue tropism to explore the relevance of HCV-related horse viruses as a model for HCV infection. We found that approximately 31.4% of 433 horses were seropositive for antibodies (Abs) against NPHV and approximately 2.5% carried viral RNA. Liver function analyses revealed no indication for hepatic impairment in 7 of 11 horses. However, serum gamma-glutamyl transferase (GGT) concentrations were mildly elevated in 3 horses, and 1 horse displayed even highly elevated GGT levels. Furthermore, we observed that NPHV infection could be cleared in individual horses with a simultaneous emergence of nonstructural (NS)3-specific Abs and transient elevation of serum levels of liver-specific enzymes indicative for a hepatic inflammation. In other individual horses, chronic infections could be observed with the copresence of viral RNA and NS3-specific Abs for over 6 months. For the determination of viral tissue tropism, we analyzed different organs and tissues of 1 NPHV-positive horse using quantitative real-time polymerase chain reaction and fluorescent in situ hydridization and detected NPHV RNA mainly in the liver and at lower amounts in other organs.

CONCLUSION

Similar to HCV infections in humans, this work demonstrates acute and chronic stages of NPHV infection in horses with viral RNA detectable predominantly within the liver.

Prospective, observational real-life study on eligibility for and outcomes of antiviral treatment with peginterferon α plus ribavirin in chronic hepatitis C

BACKGROUND

We aimed to investigate eligibility, reasons for treatment discontinuation and characteristics of chronic hepatitis C patients with treatment failure to peginterferon/ribavirin in clinical practice.

METHODS

1128 chronic hepatitis C patients, from 45 Italian Hepatology centres, were enrolled in this phase-4, prospective, observational study from January 2009 to February 2010.

RESULTS

687/1118 patients (61.4%) were eligible for antiviral treatment, of which 598 (87.0%) agreed with the physician's decision. Outcome information was available in 500/598 patients, among whom 348 (69.6%) completed treatment. Treatment was discontinued in 152 patients due to: lack of response (28.9%), personal reasons (29.6%), adverse events (38.2%), and decompensation (1.3%). Sustained virological response was obtained in 263/500 (52.6%), 71 (14.2%) relapsed and 61 (12.2%) were non-responders. Treatment outcome was not available in 105 (21%): lost while receiving treatment (33.3%), lost during follow-up (25.7%), withdrawn for adverse events (19.1%) or for administrative reasons (21.9%).

CONCLUSION

In clinical practice, only 61% of chronic hepatitis C patients are considered eligible for peginterferon/ribavirin. Of these, 13% refuse treatment. Approximately 30% do not complete the scheduled treatment and, despite this, the sustained virological response rate is similar to that of randomized-controlled trials. In the era of new antiviral combinations, these findings have important implications for assessing eligibility and estimating drop-out rates.

Novel dengue virus NS2B/NS3 protease inhibitors

Dengue fever is a severe, widespread, and neglected disease with more than 2 million diagnosed infections per year. The dengue virus NS2B/NS3 protease (PR) represents a prime target for rational drug design. At the moment, there are no clinical PR inhibitors (PIs) available. We have identified diaryl (thio)ethers as candidates for a novel class of PIs. Here, we report the selective and noncompetitive inhibition of the serotype 2 and 3 dengue virus PR in vitro and in cells by benzothiazole derivatives exhibiting 50% inhibitory concentrations (IC50s) in the low-micromolar range. Inhibition of replication of DENV serotypes 1 to 3 was specific, since all substances influenced neither hepatitis C virus (HCV) nor HIV-1 replication. Molecular docking suggests binding at a specific allosteric binding site. In addition to the in vitro assays, a cell-based PR assay was developed to test these substances in a replication-independent way. The new compounds inhibited the DENV PR with IC50s in the low-micromolar or submicromolar range in cells. Furthermore, these novel PIs inhibit viral replication at submicromolar concentrations.

Clinical significance of pretreatment serum interferon-gamma-inducible protein 10 concentrations in chronic hepatitis C patients treated with telaprevir-based triple therapy

AIM

We aimed to determine whether pretreatment serum interferon-γ-inducible protein (IP)-10 concentration can predict response to telaprevir (TVR)-based triple therapy in patients with genotype 1 chronic hepatitis C (CHC), and to examine the effects of IP-10 concentration on liver histology.

METHODS

Baseline IP-10 concentrations were measured in 97 patients with genotype 1 CHC treated with TVR-based triple therapy, and the associations between baseline IP-10 and treatment outcome were assessed by univariate and multivariate analyses. Associations between baseline serum IP-10 concentration and laboratory data and liver histological findings were also investigated.

RESULTS

Median IP-10 concentration in these patients was 461.83 pg/mL (range, 151.35-4297.62). Multivariate analysis showed that IL28B genotype (P = 0.025) and IP-10 level (P = 0.004) were factors significantly predictive of rapid virological response (RVR), whereas in pretreatment factors only, IL28B genotype (P = 0.001) and liver fibrosis (P = 0.035) were independent predictors of sustained virological response. Using a cut-off IP-10 concentration of 460 pg/mL, patients with IL28B risk allele and low IP-10 had a significantly higher RVR rate than those with high IP-10 (P = 0.005). IP-10 concentration was significantly correlated with liver fibrosis (P = 0.001) and inflammation activity (P = 0.006) and had the highest areas under the curve for liver histological findings.

CONCLUSION

Baseline serum IP-10 level is a useful predictor of virological response in patients with genotype 1 CHC treated with TVR-based triple therapy, especially in patients with IL28B risk allele. IP-10 was well correlated with liver fibrosis and inflammation.

Pegylated interferon α-2a plus ribavirin for decompensated hepatitis C virus-related cirrhosis: relationship between efficacy and cumulative dose

BACKGROUND & AIMS

A combination of pegylated interferon alpha-2a (Peg-IFNα-2a) and ribavirin (RBV) achieves a sustained virological response (SVR) in 40-50% of patients infected with genotype 1 hepatitis C virus (HCV), but efficacy rates are significantly lower in patients with decompensated HCV-induced cirrhosis. The efficacy and tolerability of Peg-IFNα-2a and RBV, the cumulative dose effect, time to achieve planned cumulative dose and role of HCV phenotype on treatment response were determined in patients with decompensated HCV-induced cirrhosis.

METHODS

In this case-controlled study, 257 patients with decompensated HCV-induced cirrhosis were enrolled, including patients treated with partial splenic embolization for leukopaenia. Of patients with sufficient blood cell counts, 130 patients opted for antiviral therapy (treatment group) consisting of 180 μg/kg Peg-IFNα-2a for 48 weeks with 800-1200 mg/day RBV; the remaining 127 were considered the control group. Primary endpoints were SVR and absence of relapse; the secondary end point was assessment of disease progression.

RESULTS

Sustained virological response was highest and relapse rates were lowest when cumulative doses of Peg-IFNα-2a and RBV were both ≥80% of the prescribed dose. Patients achieving ≥80% of the planned cumulative doses in 48 weeks had a significantly higher SVR compared with patients achieving this in 72 weeks. Patients with HCV genotype 1 had significantly lower SVR compared with patients with HCV genotype 2 (19.7% vs. 42.9%, respectively; P = 0.008). Treatment group patients had a significantly lower rate of SVR-independent liver disease-related mortality.

CONCLUSIONS

Our findings provide additional evidence to support the use of Peg-IFNα-2a and RBV therapy for decompensated HCV-induced cirrhosis.

Uptake of hepatitis C specialist services and treatment following diagnosis by dried blood spot in Scotland

BACKGROUND

Dried blood spot (DBS) testing for hepatitis C (HCV) was introduced to Scotland in 2009. This minimally invasive specimen provides an alternative to venipuncture and can overcome barriers to testing in people who inject drugs (PWID).

OBJECTIVES

The objective of this study was to determine rates and predictors of: exposure to HCV, attendance at specialist clinics and anti-viral treatment initiation among the DBS tested population in Scotland.

STUDY DESIGN

DBS testing records were deterministically linked to the Scottish HCV Clinical database prior to logistic regression analysis.

RESULTS

In the first two years of usage in Scotland, 1322 individuals were tested by DBS of which 476 were found to have an active HCV infection. Linkage analysis showed that 32% had attended a specialist clinic within 12 months of their specimen collection date and 18% had begun anti-viral therapy within 18 months of their specimen collection date. A significantly reduced likelihood of attendance at a specialist clinic was evident amongst younger individuals (<35 years), those of unknown ethnic origin and those not reporting injecting drug use as a risk factor.

CONCLUSION

We conclude that DBS testing in non-clinical settings has the potential to increase diagnosis and, with sufficient support, treatment of HCV infection among PWID.

Hepatitis C virus treatment in the 'real-world': how well do 'real' patients respond?

BACKGROUND

Published clinical trials of the treatment of HCV are largely multicentre prospective pharmaceutical trials. Patients in clinical trials tend to have more favorable outcomes than patients in the 'real-world', due to strict patient selection and differences in treatment conditions and available resources.

OBJECTIVES

To assess the outcomes of Hepatitis C infected patients treated at the Barwon Health Liver Clinic with combination Pegylated interferon (PEG-IFN) and Ribavirin (RBV) therapy and to determine factors associated with a treatment response.

METHODS

Retrospective review of patients who received treatment for Hepatitis C at our institution's Liver Clinic from January 2001-September 2011. Patient demographics, comorbidities, treatment-related parameters and side effects were extracted from medical records and analyzed.

RESULTS

A total of 190 patients (120 male, 70 female) with a mean age of 42.8 years (range 20-68 years) commenced treatment. The most common genotype was genotype 3 (48.9%), followed by genotype 1 (42.6%). 150 of 190 patients (78.9%) completed treatment and had end of treatment data available. 107 of 182 patients, (58.8%) for whom sustained virologic response (SVR) rate data was available achieved an SVR. Overall response rates were; 46.9%, 68.8% and 62.4% in genotypes 1, 2 and 3 respectively. The response rate was significantly lower in 29 patients with documented cirrhosis (20.7%). Age, diabetes and alcohol abuse did not predict treatment response in our cohort. Side effects reported in 81.6% of patients included general malaise, hematological disturbance and psychiatric issues, and necessitated cessation of therapy in 16 patients (8.4%) and dose reduction in 26 patients (13.7%).

CONCLUSIONS

Response rates to combination PEG-IFN and RBV therapy at our institution are comparable to other 'real-world' and pharmaceutical registration trials. Side effects of combination therapy were prominent but resulted in fewer discontinuations of therapy compared to pharmaceutical trials.

Using pharmacokinetic and viral kinetic modeling to estimate the antiviral effectiveness of telaprevir, boceprevir, and pegylated interferon during triple therapy in treatment-experienced hepatitis C virus-infected cirrhotic patients

Triple therapy combining a protease inhibitor (PI) (telaprevir or boceprevir), pegylated interferon (PEG-IFN), and ribavirin (RBV) has dramatically increased the chance of eradicating hepatitis C virus (HCV). However, the efficacy of this treatment remains suboptimal in cirrhotic treatment-experienced patients. Here, we aimed to better understand the origin of this impaired response by estimating the antiviral effectiveness of each drug. Fifteen HCV genotype 1-infected patients with compensated cirrhosis, who were nonresponders to prior PEG-IFN/RBV therapy, were enrolled in a nonrandomized study. HCV RNA and concentrations of PIs, PEG-IFN, and RBV were frequently assessed in the first 12 weeks of treatment and were analyzed using a pharmacokinetic/viral kinetic model. The two PIs achieved similar levels of molar concentrations (P=0.5), but there was a significant difference in the 50% effective concentrations (EC50) (P=0.008), leading to greater effectiveness for telaprevir than for boceprevir in blocking viral production (99.8% versus 99.0%, respectively, P=0.002). In all patients, the antiviral effectiveness of PEG-IFN was modest (43.4%), and there was no significant contribution of RBV exposure to the total antiviral effectiveness. The second phase of viral decline, which is attributed to the loss rate of infected cells, was slow (0.19 day(-1)) and was higher in patients who subsequently eradicated HCV (P=0.03). The two PIs achieved high levels of antiviral effectiveness. However, the suboptimal antiviral effectiveness of PEG-IFN/RBV and the low loss of infected cells suggest that a longer treatment duration might be needed in cirrhotic treatment-experienced patients and that a future IFN-free regimen may be particularly beneficial in these patients.

Specific serotonin reuptake inhibitors prevent interferon-α-induced depression in patients with hepatitis C: a meta-analysis

BACKGROUND & AIMS

Interferon-α (IFN-α)-induced depression is a major complication to treatment of chronic hepatitis C virus (HCV) infection. Specific serotonin reuptake inhibitors (SSRIs) can be used to treat depression, but it is not clear whether they can prevent depression in patients receiving IFN therapy for chronic HCV infection.

METHODS

We performed a meta-analysis by searching the Cochrane Library, PubMed, and EMBASE databases through 2013 for published results from randomized, placebo-controlled trials evaluating the utility of SSRIs in preventing IFN-induced depression in HCV patients. We analyzed data from 7 studies with a total of 662 patients. The incidence of IFN-induced major depression and depression severity were defined as primary outcomes. Sustained virologic response, completion of antiviral therapy, and tolerability were considered secondary outcomes.

RESULTS

A meta-analysis of IFN-induced major depression revealed that prophylactic SSRIs reduced the risk of depression, compared with placebo (relative risk [RR], 0.56; 95% confidence interval [CI], 0.37-0.84; P = .005). Proportions of patients achieving a sustained virologic response (RR, 1.02; 95% CI, 0.79-1.32; P = .87) and completing antiviral therapy (RR, 0.98; 95% CI, 0.66-1.44; P = .91) were similar between patients given SSRIs and controls. Prophylactic SSRIs were tolerated in patients with HCV during treatment.

CONCLUSIONS

On the basis of a meta-analysis of 7 randomized controlled trials, prophylactic administration of SSRIs to patients with HCV significantly lowered the incidence of IFN-induced major depression, compared with placebo, and the SSRIs were well tolerated.

Response-guided therapy in patients with genotype 1 hepatitis C virus: current status and future prospects

On-treatment responses to antiviral therapy are used to determine duration of therapy in patients being treated for genotype 1 hepatitis C virus infection. Such use of response-guided therapy has successfully reduced exposure of patients to the side-effects of pegylated interferon and ribavirin without jeopardizing overall treatment success. Response-guided therapy is an integral part of treatment using the current standard treatments involving the direct-acting antiviral (DAA) agents--boceprevir or telaprevir--combined with pegylated interferon/ribavirin. Improvements in our understanding of the kinetics of viral load during antiviral therapy have shown us that more potent suppression of viral replication increases the rate of viral eradication, providing impetus for the development of more potent DAAs. Emerging results from clinical trials of these agents--including trials of interferon-free DAA combinations--suggest that very high rates of viral eradication are achievable, even in patients who failed to respond to previous courses of interferon-based therapy. Furthermore, because of these high rates of treatment success, on-treatment assessment of viral response may become unnecessary. The field of hepatitis C virus therapy is evolving rapidly and current trends indicate that the era of simple treatment regimens with high rates of success and good tolerability are near.