Current prospects for interferon-free treatment of hepatitis C in 2012

Chronic Hepatitis C Infection Treated with Direct-Acting Antiviral Agents and Occurrence/Recurrence of Hepatocellular Carcinoma: Does It Still Matter?

Hepatitis C virus (HCV) infection is a significant risk factor for liver cirrhosis and hepatocellular carcinoma (HCC). Traditionally, the primary prevention strategy for HCV-associated HCC has focused on removing infection through antiviral regimes. Currently, highly effective direct-acting antivirals (DAAs) offer extraordinary success across all patient categories, including cirrhotics. Despite these advancements, recent studies have reported that even after sustained virologic response (SVR), individuals with advanced liver disease/cirrhosis at the time of DAA treatment may still face risks of HCC occurrence or recurrence. Based on this premise, this review tries to shed light on the multiple mechanisms that establish a tumorigenic environment, first, during chronic HCV infection and then, after eventual viral eradication by DAAs. Furthermore, it reviews evidence reported by recent observational studies stating that the use of DAAs is not associated with an increased risk of HCC development but rather, with a significantly lower chance of liver cancer compared with DAA-untreated patients. In addition, it seeks to provide some practical guidance for clinicians, helping them to manage HCC surveillance of patients who have achieved SVR with DAAs.

Synthesis and biological evaluation of Ribo 7-N/O/S pyrimidine 9-deaza C-nucleoside analogs as new antiviral agents for inhibiting HCV RNA-dependent RNA polymerases

Hepatitis C infection is caused by the bloodborne pathogen hepatitis C virus (HCV) and can lead to serious liver diseases and, ultimately, death if the treatment is ineffective. This work reports the synthesis and preclinical evaluation of 7 novel 9-O/N/S pyrimidine nucleosides, including compound 12, the triphosphate of known compound 7b. The nucleosides are 9-deaza modifications of adenosine and guanosine with β-2'-C-methyl substituent on the ribose. Within this series of compounds, a 9-deaza furopyrimidine analog of adenosine, compound 7b, showed high anti-HCV activity in vitro, good stability, low toxicity, and low genotoxicity when administrated in low doses, and an adequate pharmacokinetics profile. An improved synthesis of compound 7b compared to a previous study is also reported. Compound 12 was synthesized as a control to verify phosphorylation of 7b occurred in vivo.

Effect of Lipopolysaccharides on Liver Tumor Metastasis of twist1a/krasV12 Double Transgenic Zebrafish

The poor prognosis of patients diagnosed with hepatocellular carcinoma (HCC) is directly associated with the multi-step process of tumor metastasis. TWIST1, a basic helix-loop-helix (bHLH) transcription factor, is the most important epithelial-mesenchymal transition (EMT) gene involved in embryonic development, tumor progression, and metastasis. However, the role that TWIST1 gene plays in the process of liver tumor metastasis in vivo is still not well understood. Zebrafish can serve as a powerful model for cancer research. Thus, in this study, we crossed twist1a+ and kras+ transgenic zebrafish, which, respectively, express hepatocyte-specific mCherry and enhanced green fluorescent protein (EGFP); they also drive overexpression of their respective transcription factors. This was found to exacerbate the development of metastatic HCC. Fluorescence of mCherry and EGFP-labeled hepatocytes revealed that approximately 37.5% to 45.5% of the twist1a+/kras+ double transgenic zebrafish exhibited spontaneous tumor metastasis from the liver to the abdomen and tail areas, respectively. We also investigated the inflammatory effects of lipopolysaccharides (LPS) on the hepatocyte-specific co-expression of twist1a+ and kras+ in double transgenic zebrafish. Following LPS exposure, co-expression of twist1a+ and kras+ was found to increase tumor metastasis by 57.8%, likely due to crosstalk with the EMT pathway. Our results confirm that twist1a and kras are important mediators in the development of metastatic HCC. Taken together, our in-vivo model demonstrated that co-expression of twist1a+/kras+ in conjunction with exposure to LPS enhanced metastatic HCC offers a useful platform for the study of tumor initiation and metastasis in liver cancer.

Past and Future Perspectives for Hepatitis B and C in Pakistan

Background

Hepatitis B and C are viral infections of the liver transmitted by blood contamination. These infections are endemic in Pakistan and put a tremendous burden on its healthcare system. We conducted this study to assess the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections in Gujranwala, Pakistan, from 2010 to 2015 and determine the trend of future infections for a prediction of the disease burden by 2030 so policymakers can make informed decisions.

Methods

We conducted a retrospective cross-sectional study of 66,308 healthy blood donor samples at District Headquarters Teaching Hospital in Gujranwala from January 2010 to December 2015. Samples were screened for HBV and HCV using the kit method, and data were analyzed using IBM SPSS Statistics for Windows, version 20.0 (IBM Corp., Armonk, NY). We applied a least squares regression to our results to predict HBV and HCV incidence in 2030.

Results

A total of 715 samples (1.08%) were positive for HBV and 1,846 samples (2.78%) were positive for HCV. Our projections indicate that 3.25% of patients in Pakistan will be positive for HBV, and 6.36% will be positive for HBC by 2030.

Conclusion

We found an unexpectedly greater burden of HBV and HCV in the recent past than at current levels. The predicted percentages of future burden over the next decade were alarmingly high. These data necessitate implementing preventive and therapeutic measures by policymakers to reduce the disease burden and mortality in Pakistan.

Efficacy and safety of a fixed dose combination tablet of asunaprevir + beclabuvir + daclatasvir for the treatment of Hepatitis C

Introduction: Hepatitis C virus (HCV) is estimated to infect approximately 70 million people worldwide. If left untreated, chronic infection can progress to cirrhosis, liver failure or hepatocellular carcinoma. The advent of new direct-acting antivirals (DAA) has revolutionized patients' chances of treatment and viral elimination. Currently, several DAA options are available on the market.Areas covered: This review focuses on the pharmacokinetics, efficacy, tolerability and safety profile of DCV-TRIO, a twice-daily fixed-dose combination of daclatasvir, asunaprevir and beclabuvir approved in Japan for the treatment of genotype 1 HCV infection.Expert opinion: The DCV-TRIO combination achieved good response rates in genotype 1 patients (SVR12 ≥ 95% in naïve subtype 1b), independently from IL28B genotype, cirrhotic status and prior interferon exposure. On the other hand, unsatisfying response rates were reported in DAA-experienced patients and the risk of RAS selection should not be underestimated. Moreover, DCV-TRIO lacks differentiation from its earlier-launched DAA rivals, presents an inconvenient twice-daily dosing schedule and is not recommended in patients with advanced liver and kidney disease. All these drawbacks considerably limit its effective commercial potential. However, it can be a therapeutic option against HCV in tailored approaches according to the needs of different markets across the world.Abbreviations AE: adverse event; ALT: alanine aminotransferase; AST: aspartate aminotransferase; ASV: asunaprevir; AUC: area under the curve; BCRP: Breast Cancer Resistance Protein; BCV: boceprevir; BID: bis in die; CI: confidence intervals; CLcr: creatinine clearance; DAA: direct acting antivirals; DCV: daclatasvir; EC50: Half maximal effective concentration; GT: genotype; HCV: Hepatitis C virus; IFN: Interferon; NHL: non-Hodgkin lymphoma; OATP: Organic anion transporting polypeptides; OR: odds ratio; P-gp: P-glycoprotein; PK: pharmacokinetics; QD: quo die; RAS: resistance-associated substitutions; SVR: sustained virological response; USD: Unites States dollar.

Ledipasvir/Sofosbuvir versus Daclatasvir/Sofosbuvir for the Treatment of Chronic Hepatitis C Genotype 4 Patients

BACKGROUND

Chronic Hepatitis C (CHC) is a common progressive healthcare challenge that leads to liver cirrhosis, liver failure, and hepatocellular carcinoma. The optimum therapy was a combination of pegylated interferon and ribavirin, which was associated with moderate response and severe side effects. Sofosbuvir revolutionized CHC treatment, especially in combination with other antiviral agents.

OBJECTIVE

The aim of this study was to compare and evaluate the safety and efficacy of sofosbuvir/ daclatasvir versus sofosbuvir/ledipasvir for the treatment of non-cirrhotic naïve patients with chronic Hepatitis C Virus (HCV) genotype 4 infection for 12 weeks.

METHODS

One hundred CHC genotype 4 patients (70 females, 30 males) were recruited from the hepatology clinic at the Beni-Suef general hospital. Patients were randomly allocated into two groups that received a 12 weeks treatment of either sofosbuvir 400 mg/daclatasvir 60 mg or sofosbuvir 400 mg/ledipasvir 90 mg. The sustained virological response 12 weeks post-treatment (SVR12) (HCV RNA < Lower Limit of Quantification (LLOQ)) was determined to evaluate efficacy. The clinical laboratory tests and any reported adverse effects starting from the administration of the first dose till 30 days after the last dose were assessed to evaluate safety. The main outcome measure was the assessment of the safety, efficacy and compliance of sofosbuvir/ daclatasvir versus sofosbuvir/ledipasvir for the treatment of non-cirrhotic naïve CHC genotype 4 patients for 12 weeks.

RESULTS

SVR12 was achieved by 98% and 96% of patients receiving sofosbuvir plus ledipasvir and sofosbuvir plus daclatasvir, respectively. The most common adverse events reported were headache, and fatigue. No patients discontinued treatment due to adverse events.

CONCLUSION

The findings from this study suggest that the 12 weeks treatment regimens of sofosbuvir plus daclatasvir and sofosbuvir plus ledipasvir were both efficacious and well-tolerated in patients with HCV genotype 4 infection. Impact on Practice: In this paper, we report on the most recent approaches in the treatment of Hepatitis C genotype 4 patients in Egypt. This is significant because this article focuses on comparing the efficacy and tolerability of the most commonly used antiviral drugs in Egypt.

Daclatasvir combined with asunaprevir is a cost-effective and cost-saving treatment for hepatitis C infection in China

Aim: To evaluate the cost-effectiveness of the novel all-oral direct-acting antiviral regimen daclatasvir + asunaprevir (DUAL), versus interferon-based regimens for the treatment of chronic hepatitis C virus genotype 1b infection. Methods: Inputs for a lifetime Markov model were sourced from clinical trials and published literature. Outputs include disease management costs, life expectancy, quality-adjusted life-years and cost-effectiveness. Sensitivity analyses assessed the drivers of cost-effectiveness and sustained virologic response thresholds at which DUAL is cost-saving. Results: DUAL was associated with discounted incremental quality-adjusted life-years of 1.29-3.85 and incremental life-years of 0.85-2.59 per patient, with discounted lifetime cost savings of USD$1415-8525. Associated sustained virologic response rates could fall to 45.1-84.8%, while remaining dominant. Conclusion: Treatment with DUAL provides significant clinical benefit, while accruing lower lifetime costs.

IL28B genotyping and treatment of HCV infected subjects

Background: Chronic hepatitis C is a common cause of advanced liver disease and appropriate treatment has been complex and a challenge. Reaction of individual genotypes to classical pegylated interferon-ribavirin therapy differs and no success has been achieved in some even after repeated therapy cycles. New types of so called directly acting antivirals (DAAs) are hopeful, as shown in many recent clinical studies, and triple therapy regimens involving DAA are becoming the new standard of care.

Objective: To summarize knowledge about the relationship between HCV therapeutic regimens and the genetic background of the host represented by interleukin 28B (IL28B) gene polymorphisms. In the first part, the host basic mechanisms in specific and innate immunity are introduced. The IL28B genotype and its role in the course of HCV treatment are described in the second part.

Methods: We searched and summarized publications on HCV therapeutic regimens and host IL28B polymorphisms.

Results: Compared to classical regimens, the association between IL28B polymorphism and treatment outcome of HCV infected patients is weaker in triple therapy using first generation DAAs boceprevir and telaprevir.

Conclusions: The association between IL28B polymorphism and treatment outcome is lessened with availability of new therapeutic regimens. Nevertheless, IL28B genotyping may still be useful for individualization of treatment strategies.

Assessing the Budget Impact and Economic Outcomes of the Introduction of Daclatasvir + Asunaprevir and Sofosbuvir/Ledipasvir for the Treatment of Chronic Hepatitis C Virus Infection in Japan

BACKGROUND

The advent of highly efficacious, well-tolerated, all-oral direct-acting antiviral regimens has revolutionized the standard of care for patients chronically infected with hepatitis C virus. As efficacy and safety rates converge, prescribers and payers need to consider value for money.

OBJECTIVES

To evaluate the health economic value of daclatasvir + asunaprevir versus sofosbuvir/ledipasvir via a cost-effectiveness analysis, and determine the optimal treatment considering both costs and health outcomes in Japan.

METHODS

A previously published Markov model was used to estimate the cost-effectiveness of daclatasvir + asunaprevir compared with sofosbuvir/ledipasvir on the basis of a matching-adjusted indirect comparison of pivotal trials and modeling inputs specific to the Japanese setting. A de novo budget impact model was developed and used to predict the cost implications of differing treatment sequences.

RESULTS

Cost-effectiveness results demonstrated minimal difference in terms of benefit (0.037 fewer QALYs and 0.014 fewer life-years with daclatasvir + asunaprevir); nevertheless, a significant difference in cost was predicted (estimated ¥2,299,700 [US $21,695] reduction with daclatasvir + asunaprevir). The budget impact analysis estimated that treatment with daclatasvir + asunaprevir is expected to be less expensive than treatment with sofosbuvir/ledipasvir (as the proportion of patients initially treated with sofosbuvir/ledipasvir increased from 0% to 100%, total costs increased from ¥206 to ¥403 billion [US $1.94 billion to US $3.80 billion]).

CONCLUSIONS

On the basis of results from an established cost-effectiveness model and a conventional budget impact analysis, treatment with daclatasvir + asunaprevir is expected to be cost-saving compared with treatment with sofosbuvir/ledipasvir in Japan with similar health outcomes, regardless of treatment sequence.

Treatment rate and factors related to interferon-based treatment initiation for chronic hepatitis C in South Korea

Under-recognition and under-treatment of chronic hepatitis C virus (HCV) infection is an important determinant of the disease outcome. The aim of this study was to investigate the treatment rate and factor of initiation of interferon-based antiviral treatment for chronic hepatitis C patients in a prospective, multicenter Korean HCV cohort. Treatment-naïve 759 patients with chronic HCV infection were prospectively followed from January 2007-2013 at six university hospitals during a median (interquartile range) follow-up of 769 (76-1,427) days. The subjects consisted of patients with chronic hepatitis C (n = 553, 72.9%), liver cirrhosis (n = 127, 16.7%), and hepatocellular carcinoma (n = 79, 10.4%), and were treated usually using pegylated interferon alpha and ribavirin. Treatment initiation rate and its related factors were analysed. The initiation rate of antiviral treatment was 37.3% (n = 273), and the cumulative probability of treatment initiation over 5 years was 39.4%. Multivariate analysis showed that age <58 years (hazard ratio [HR] = 1.588, 95% CI = 1.151-2.193), job employment (HR = 1.737, 95% CI = 1.279-2.363), absence of HCC (chronic hepatitis, HR = 2.534, 95% CI = 1.003-6.400; liver cirrhosis, HR = 2.873, 95% CI = 1.101-7.494), alanine transaminase (ALT) >40 IU/L (HR = 1.682, 95% CI = 1.228-2.303), and genotype 2 (HR = 1.364, 95% CI = 1.034-1.798) were independent factors related to treatment initiation. Interferon-based antiviral treatment was initiated in more than one third of chronic HCV infected patients visiting university hospitals, who were young, employed, HCV genotype 2, and with abnormal ALT without HCC, in Korea.

Cost-effectiveness of daclatasvir plus sofosbuvir-based regimen for treatment of hepatitis C virus genotype 3 infection in Canada

OBJECTIVE

New regimens for the treatment of chronic hepatitis C virus (HCV) genotype 3 have demonstrated substantial improvement in sustained virologic response (SVR) compared with existing therapies, but are considerably more expensive. The objective of this study was to evaluate the cost-effectiveness of two novel all-oral, interferon-free regimens for the treatment of patients with HCV genotype 3: daclatasvir plus sofosbuvir (DCV + SOF) and sofosbuvir plus ribavirin (SOF + RBV), from a Canadian health-system perspective.

METHODS

A decision analytic Markov model was developed to compare the effect of various treatment strategies on the natural history of the disease and their associated costs in treatment-naïve and treatment-experienced patients. Patients were initially distributed across fibrosis stages F0-F4, and may incur disease progression through fibrosis stages and on to end-stage liver disease complications and death; or may achieve SVR. Clinical efficacy, health-related quality-of-life, costs, and transition probabilities were based on published literature. Probabilistic sensitivity analysis was performed to assess parameter uncertainty associated with the analysis.

RESULTS

In treatment-naive patients, the expected quality-adjusted life years (QALYs) for interferon-free regimens were higher for DCV + SOF (12.37) and SOF + RBV (12.48) compared to that of pINF + RBV (11.71) over a lifetime horizon, applying their clinical trial treatment durations. The expected costs were higher for DCV + SOF ($170,371) and SOF + RBV ($194,776) vs pINF + RBV regimen ($90,905). Compared to pINF + RBV, the incremental cost-effectiveness ratios (ICER) were $120,671 and $135,398 per QALYs for DCV + SOF and SOF + RBV, respectively. In treatment-experienced patients, DCV + SOF regimen dominated the SOF + RBV regimen. Probabilistic sensitivity analysis indicated a 100% probability that a DCV + SOF regimen was cost saving in treatment-experienced patients.

CONCLUSION

Daclatasvir plus sofosbuvir is a safe and effective option for the treatment of chronic HCV genotype 3 patients. This regimen could be considered a cost-effective option following a first-line treatment of peg-interferon/ribavirin treatment experienced patients with HCV genotype-3 infection.

Increased expression and dysregulated association of restriction factors and type I interferon in HIV, HCV mono- and co-infected patients

Host restriction factors and type I interferon are important in limiting HIV and HCV infections, yet the role of HIV, HCV mono- and co-infection in regulating these antiviral genes expression is not clear. In this study, we measured the levels of TRIM5α, TRIM22, APOBEC3G, and IFN-α, -β mRNA expression in peripheral blood mononuclear cells of 43 HIV mono-infected, 70 HCV mono-infected and 64 HIV/HCV co-infected patients along with 98 healthy controls. We also quantified HIV and HCV viral loads in mono- and co-infected patients. The results showed that HCV, HIV mono- and co-infection differentially increased TRIM22, APOBEC3G, and IFN-α, -β mRNA expression while the mRNA expression of TRIMα was upregulated only by HCV-mono infection. HIV/HCV co-infection was associated with higher viral load, compared to either HIV or HCV mono-infection. Additionally, we showed TRIMα and TRIM22 positively correlated with IFN-α, -β, which could be dysregulated by HIV, HCV mono- and co-infection. Furthermore, we found TRIM22 negatively correlated with HCV viral load in mono-infected patients and APOBEC3G positively correlated with HCV viral load in co-infected patients. Collectively, our findings suggest the potential role of restriction factors in restricting HIV, HCV mono- and co-infection in vivo, which appears to be a therapeutic target for potential drug discovery.

Discovery of Imidazo[1,2-α][1,8]naphthyridine Derivatives as Potential HCV Entry Inhibitor

RO8191 represents a newly discovered small-molecule IFN-like agent that displays potent anti-HCV activity. With it as lead, a series of compounds bearing an imidazo[1,2-α][1,8]naphthyridine core and an amide bond-linked side chain were designed and synthesized. These compounds were evaluated on HCV cell culture system (HCVcc-hRluc-JFH1), and some of them exhibited remarkable anti-HCV activity (EC50 = 0.017-0.159 μM) and low toxicity (CC50 > 25 μM). Moreover, it was revealed that these newly identified anti-HCV agents exert their antiviral effect through a distinct mechanism of action from that of RO8191 by targeting the viral entry process. Thus, our study provides a starting point for the development of potential HCV entry inhibitor.

Asunaprevir for hepatitis C: a safety evaluation

INTRODUCTION

The introduction of direct-acting antiviral (DAA) agents has revolutionized the treatment of hepatitis C virus (HCV) chronic infection. Non-structural 3 protease inhibitors are currently the most numerous class of DAAs on the market.

AREAS COVERED

This review mainly focuses on the tolerability and safety profile of asunaprevir (ASV)-containing DAA regimens. ASV is a second-wave protease inhibitor currently in Phase III clinical development in most countries and already available in Japan.

EXPERT OPINION

ASV shows potent antiviral effect and clinical efficacy on HCV genotypes 1 and 4. The all-oral combination daclatasvir/ASV reached high eradication rates in HCV genotype 1b and 4 infection, and a lower efficacy in genotype 1a infection. ASV presents a low potential for drug-drug interaction and a good tolerability as part of multiple, including all-oral, regimens. ASV is associated with a transient and usually mild increase in aminotransferase levels in a low percentage of cases. Due to the impaired pharmacokinetic profile observed in advanced liver disease, ASV use in patients with moderate or severe hepatic impairment is not allowed. In conclusion, ASV represents a powerful weapon against HCV infection and has to be considered an optimal option as a component of genotype tailored interferon-free combinations.

Serotonin gene polymorphisms and lifetime mood disorders in predicting interferon-induced depression in chronic hepatitis C

BACKGROUND

IFN-induced depression is a suitable model for investigating vulnerability to depression. We aimed at investigating the role of two vulnerability factors, lifetime mood disorder (LMD) and 5-HT-related gene polymorphisms in treated patients with infection by Hepatitis C Virus (HCV).

METHODS

Depressive symptoms of 130 consecutive HCV patients with no current psychopathology were measured during treatment with interferon and ribavirin. At baseline, LMD and 3 genotypes (5-HTTLPR, HTR1A, and TPH2) were also assessed.

RESULTS

Subgroups of 43 patients with LMD, 96 with HTR1A-G allele, and 12 with both LMD and HTR1A-G homozigosity scored significantly higher to depression compared to the remaining patients during antiviral therapy. At the multiple regression analysis, LMD and HTR1A-G, whether separately or combined together, explained a similar amount of 10-22% of depression score variance, after controlling for the associated variables (age and gender).

LIMITATIONS

HCV patients referred to a tertiary care center are not representative of all patients with chronic hepatitis C. Mediating factors, including proinflammatory cytokines and other potentially relevant gene polymorphisms, could not be evaluated. Patients were not stratified by degree of liver inflammation. LMD diagnoses were not cross-checked with medical records and IFN-induced depression was measured with a self-report scale only.

CONCLUSIONS

History of mood disorders and HTR1A G allele variation, the C-1019G polymorphism of the transcriptional control region of the 5-HT1A receptor, independently predicted the incidence of IFN-induced depression in HCV patients, whether separately or jointly considered and although not reciprocally associated.

ABT-450/ ritonavir and ABT-267 in combination with ABT-333 for the treatment of hepatitis C virus

INTRODUCTION

The global prevalence of chronic hepatitis C virus (HCV) is estimated to be 80 - 115 million and currently viremic infections account for 350,000 deaths annually. As the knowledge about HCV evolves, new anti-viral treatments have been developed. The primary goal of antiviral therapies has been to eradicate HCV virus from serum and achieve sustained virologic response (SVR). Historically, interferon has been a staple of nearly all HCV treatment regimens, despite significant toxic effects.

AREAS COVERED

In recent years, HCV treatment has changed rapidly and significantly. All-oral treatment regimens show promise for treatment with shorter duration and more manageable side effects. New antivirals aimed at improving SVR may provide a cure to nearly all HCV-infected patients. The unique combination of ABT-450 (paritaprevir) and ABT-267 (ombitasvir) provides highly effective treatment for patients with genotype 1 HCV. This review will examine the antiviral properties, pharmacokinetics, pharmacodynamics, and side effects of these agents.

EXPERT OPINION

The combination of ABT-450/r and ABT-267 has improved potency, favorable side effect profile, and low risk of resistance compared to the first-generation protease inhibitors. This combination is likely to be a major part of novel upcoming HCV treatment regimens and is likely to be widely used by clinicians. Additional data is awaited in additional patient populations, and with possible shorter treatment durations.

Recent advances on the synthesis of hepatitis C virus NS5B RNA-dependent RNA-polymerase inhibitors

Hepatitis C is a viral liver infection considered as the major cause of cirrhosis and hepatocellular carcinoma (HCC). The HCV NS5B polymerase, an RNA-dependent RNA polymerase, is essential for HCV replication, which is able to catalyze the synthesis of positive (genomic) and negative (template) strand HCV RNA, but has no functional equivalent in mammalian cells. Therefore, the NS5B polymerase has emerged as an attractive target for the development of specifically targeted antiviral therapy for HCV (DAA, for direct-acting antivirals). Recently, a growing number of compounds have been reported as the NS5B polymerase inhibitors, some of which especially have been licensed in clinical trials. This review describes recent advances on the synthesis of the NS5B polymerase inhibitors, focusing on the merits and demerits of their synthetic methods. In particular, inspiration from the synthesis and the future direction of the NS5B polymerase inhibitors are highlighted.

Dual antiviral therapy for HIV and hepatitis C - drug interactions and side effects

INTRODUCTION

Roughly 20% of HIV-positive persons worldwide are coinfected with hepatitis C virus (HCV). The recent advent of direct-acting antivirals (DAA) that cure most hepatitis C patients has attracted much attention. Knowledge on drug interactions between DAA and antiretrovirals (ARV) may allow maximizing antiviral efficacy while minimizing drug-related toxicities.

AREAS COVERED

We review the most frequent side effects and clinically significant drug interactions between DAA and ARV. We further discuss how they can be prevented and managed in HIV/HCV-coinfected patients.

EXPERT OPINION

The safety profile of current DAA and the most recently approved ARV is quite favorable. Interactions between DAA and ARV could be frequent in clinical practice. The most common drug interactions affect drug metabolism by inducing or inhibiting the cytochrome P450 system, leading to abnormal drug exposures. Throughout this mechanism HCV and HIV protease inhibitors interact, especially when co-formulated with ritonavir as a pharmacoenhancer, and non-nucleoside HCV and HIV polymerase inhibitors. In contrast, HIV and HCV nucleos(t)ide polymerase inhibitors, and most HCV NS5A inhibitors (i.e., ledipasvir) and HIV integrase inhibitors (i.e., dolutegravir), do not or only marginally affect CYP450, and therefore are free of significant drug interactions. Exposure to HIV and HCV nucleos(t)ide analogues (i.e., tenofovir and sofosbuvir, respectively) is subject to induction/inhibition of drug transporters (i.e., P-glycoprotein).

Beclabuvir for the treatment of hepatitis C

INTRODUCTION

About 185,000,000 people worldwide are chronically infected with hepatitis C virus (HCV). Currently, the most successful HCV infection antiviral therapies reduce the chance of progression towards the advanced phases of the hepatopathy (liver cirrhosis, hepatocellular carcinoma and death). Recently, however, several new direct-acting antivirals against HCV are available or are in an advanced phase of clinical development.

AREAS COVERED

This review focuses on beclabuvir , an allosteric non-nucleotide inhibitor of HCV polymerase. The article covers its pharmacokinetics, mechanism of action, in addition to its tolerability and safety profile as well as its resistance pattern.

EXPERT OPINION

The pharmacokinetic, efficacy and tolerability profile of beclabuvir, as well as its barrier to resistance, are very favorable. In particular, the combination of beclabuvir with asunaprevir and daclatasvir achieves very high rates of viral eradication (about 90%) in patients infected with HCV genotype 1, which is the most common genotype worldwide. Therefore, beclabuvir represents a powerful weapon against HCV infection and has to be considered an optimal option in tailored IFN-free combinations.

The role of alexithymia in quality of life impairment in patients with chronic hepatitis C during antiviral treatment

This study aimed to investigate the role of alexithymia in the quality of life of patients with chronic hepatitis C treated with antiviral therapy. A consecutive sample of 124 patients were evaluated at baseline, during, and 6months after treatment with interferon and ribavirin. At baseline past mood disorders and alexithymia and, at each index visit, adverse events, psychological distress, and disease-specific quality of life were assessed with validated instruments. Patients with past mood disorders and alexithymia had impaired levels of quality of life, psychological distress, and treatment-related adverse events. However, after controlling for covariates, poor quality of life was independently predicted by alexithymia and psychological distress before (R(2)=0.60) and 6months after (R(2)=0.69) the antiviral treatment while during treatment (at 3months and the end of therapy) by depression and somatic adverse events (R(2)=0.67 and 0.69, respectively). Alexithymia rather than history of mood disorders resulted to be an independent predictor of impaired quality of life not only before but also 6months after the end of treatment. Given the association with proneness to health-compromising behaviors, clinicians are encouraged to pay closer attention to long-term psychological and somatic effects of antiviral treatment in patients with alexithymic characteristics.

Sofosbuvir: a review of its use in patients with chronic hepatitis C

Sofosbuvir (Sovaldi(®)) is a nucleotide hepatitis C virus (HCV) NS5B polymerase inhibitor that has pangenotypic antiviral activity and a high genetic barrier to resistance. This article reviews the clinical efficacy and tolerability of sofosbuvir in patients with chronic hepatitis C and summarizes its pharmacological properties. Interferon-free treatment with sofosbuvir plus ribavirin achieved high sustained virological response (SVR) rates in treatment-naïve and treatment-experienced patients with HCV genotype 2 or 3 infection, and also had efficacy in patients with HCV genotype 1 infection. Sofosbuvir plus ribavirin was also effective in patients co-infected with HCV and HIV, and sofosbuvir plus ribavirin administered prior to liver transplantation prevented recurrent HCV infection in the majority of patients who had HCV RNA levels below the limit of quantification at the time of transplantation. Sofosbuvir plus peginterferon-α-2a and ribavirin achieved high SVR rates in patients with HCV genotype 1 infection, and also appeared effective in patients with HCV genotype 4, 5 or 6 infection. Oral sofosbuvir was generally well tolerated in patients with chronic hepatitis C. The most commonly reported adverse events and laboratory abnormalities were consistent with those expected with ribavirin and peginterferon-α. In conclusion, sofosbuvir represents an important advance in the treatment of chronic hepatitis C.

Humanized-VHH transbodies that inhibit HCV protease and replication

There is a need for safe and broadly effective anti-HCV agents that can cope with genetic multiplicity and mutations of the virus. In this study, humanized-camel VHHs to genotype 3a HCV serine protease were produced and were linked molecularly to a cell penetrating peptide, penetratin (PEN). Human hepatic (Huh7) cells transfected with the JFH-1 RNA of HCV genotype 2a and treated with the cell penetrable nanobodies (transbodies) had a marked reduction of the HCV RNA intracellularly and in their culture fluids, less HCV foci inside the cells and less amounts of HCV core antigen in culture supernatants compared with the infected cells cultured in the medium alone. The PEN-VHH-treated-transfected cells also had up-regulation of the genes coding for the host innate immune response (TRIF, TRAF3, IRF3, IL-28B and IFN-β), indicating that the cell penetrable nanobodies rescued the host innate immune response from the HCV mediated-suppression. Computerized intermolecular docking revealed that the VHHs bound to residues of the protease catalytic triad, oxyanion loop and/or the NS3 N-terminal portion important for non-covalent binding of the NS4A protease cofactor protein. The so-produced transbodies have high potential for testing further as a candidate for safe, broadly effective and virus mutation tolerable anti-HCV agents.

Daclatasvir + asunaprevir: first global approval

The combination of daclatasvir + asunaprevir [Daklinza(®) + Sunvepra(®) (Japan)], two direct-acting antiviral agents, has been developed by Bristol-Myers Squibb for the treatment of patients with chronic hepatitis C virus (HCV) genotype 1 infections, including those with compensated cirrhosis. Daclatasvir + asunaprevir has received its first global approval in this indication in Japan. Daclatasvir + asunaprevir is the first all-oral, interferon- and ribavirin-free regimen for this indication. This article summarizes the milestones in the development of daclatasvir + asunaprevir leading to this first approval for the treatment of chronic HCV genotype 1 infections.

Enhancing our understanding of current therapies for hepatitis C virus (HCV)

Great progress has been made in understanding the HCV genome and its molecular virology. This understanding has culminated in the development of direct-acting antiviral (DAA) agents targeting HCV viral proteins. Telaprevir (TVR) and boceprevir (BOC) were the first DAAs introduced for treatment of genotype 1 HCV in 2011; when used in combination with pegylated interferon (pegIFN) and ribavirin (RBV), these protease inhibitors improved efficacy in patients with chronic HCV infection compared to the traditional dual therapy. However, this combination was associated with adverse events that often led to early termination of therapy. In late 2013, the FDA approved a second wave of DAAs, sofosbuvir (SOF) and simeprevir (SMV). The use of SOF with SMV opened the door for IFN-free combination regimens. This combination was highly efficacious and well tolerated in patients with HCV genotype 1. Sofosbuvir and ledipasvir (LDV) fixed-dose oral combination (FDC) therapy, and paritaprevir/ritonavir, ombitasvir and dasabuvir ± RBV were recently approved, elevating sustained virologic response (SVR) rates to over 95 %. We are anticipating the approval of additional IFN-free regimens with comparable efficacy and tolerability but with the addition of pangenotypic coverage, fewer drug-drug interactions, and a high barrier to resistance. This review will summarize current management for chronic HCV infection.

A longitudinal study evaluating the effects of interferon-alpha therapy on cognitive and psychiatric function in adults with chronic hepatitis C

OBJECTIVE

To prospectively evaluate for changes in objective cognitive performance (attention, memory, and executive function) and psychiatric symptom severity (depression, anxiety, fatigue, and pain) in patients before, during and after interferon-alpha based therapy (IFN) for chronic hepatitis C virus infection (HCV).

METHODS

33 HCV+ adults were evaluated two months before IFN initiation (baseline), three months into IFN, and six months following IFN termination (IFN+ Group). 31 HCV+ adults who did not undergo IFN therapy were evaluated at baseline and six months later (IFN- Group). At each evaluation, participants completed the Neuropsychological Assessment Battery (NAB) Attention, Memory and Executive Functions Modules, the Beck Depression Inventory, Second Edition (BDI), Generalized Anxiety Disorder Inventory (GADI), Fatigue Severity Scale (FSS), and Brief Pain Inventory (BPI).

RESULTS

Compared with the IFN- Group, the IFN+ Group experienced significantly (p<0.050) increased symptoms of depression, anxiety, fatigue and pain during IFN therapy relative to baseline. In the IFN+ Group, psychiatric symptoms generally returned to baseline levels following IFN termination. Sustained viral response was associated with significantly lower depression and fatigue. No significant changes in cognitive performance were observed.

CONCLUSIONS

During IFN, patients with HCV evidence significantly increased psychiatric symptoms, including symptoms of depression, anxiety, fatigue and pain. These psychiatric symptoms are generally short-term and remit following IFN termination, with increased benefit if viral clearance is achieved. However, IFN is not associated with significant declines in objective cognitive performance during or following IFN.

Sofosbuvir: first global approval

Sofosbuvir (Solvadi™), a nucleotide analogue hepatitis C virus NS5B polymerase inhibitor, is under development with Gilead Sciences for the once-daily, oral treatment of chronic hepatitis C. Oral sofosbuvir has been approved in the US for the treatment of chronic hepatitis C as a component of a combination antiviral regimen. In addition, the European Medicines Agency's Committee for Medicinal Products for Human Use has recommended the approval of sofosbuvir for the treatment of chronic hepatitis C. This article summarizes the milestones in the development of sofosbuvir leading to this first approval for chronic hepatitis C.

Drug interactions with new hepatitis C oral drugs

INTRODUCTION

Chronic hepatitis C virus (HCV) infection has recently become a curable disease with antiviral therapy. The knowledge of drug interactions using direct-acting antivirals (DAA) may permit maximizing antiviral efficacy and avoiding drug-related toxicities. Ageing in the chronic hepatitis C population, along with added co-morbidities that require other medications, has increased the attention on drug interactions using DAA.

AREAS COVERED

This review provides an update of the most clinically significant pharmacokinetic and pharmacodynamic drug interactions occurring between currently available DAA and other medications. The review also revisits how drug interactions with DAA can be prevented and managed.

EXPERT OPINION

Interactions between DAA and other drugs are frequent in clinical practice. The most frequent drug interactions modify drug metabolism by inducing or inhibiting the cytochrome P450, leading to abnormal drug exposures. Through this mechanism HCV protease inhibitors, especially when co-formulated with ritonavir as pharmacoenhancer, and non-nucleoside HCV polymerase inhibitors interact with other medications. In contrast, NS5B nucleos(t)ide analog inhibitors (i.e., sofosbuvir) and some HCV NS5A inhibitors (i.e., ledipasvir), which do not or only marginally affect CYP450, are relatively free of significant pharmacokinetic interactions. However, exposure to HCV nucleos(t)ide analogs may be influenced by induction/inhibition of drug transporters (i.e., P-glycoprotein) as well as by pharmacodynamic interference with other nucleos(t)ide analogs used as antivirals or cancer drugs. Drug interactions for some NS5A inhibitors (i.e., daclatasvir) are generally moderate and can be managed with dose adjustments.

Asunaprevir-containing regimens for the treatment of hepatitis C virus infection

Chronic hepatitis C virus (HCV) infection has been a tremendous health burden worldwide with an annual mortality of 300,000 people due to decompensated cirrhosis or hepatocellular carcinoma. A combination of interferon (IFN), ribavirin (RBV), and/or direct-acting antivirals (DAAs) can eradicate HCV in a various proportion of infected patients. Unfortunately, IFN-based therapy is associated with significant adverse effects, contraindications, and limited tolerability, leading to lower adherence or even treatment discontinuation. With the rapid evolution of newer DAAs or host-targeting agents, emerging HCV therapy is moving towards an IFN- and RBV-free strategy. To this end, a recently developed NS3 protease inhibitor, asunaprevir (ASV), in combination with other DAAs as IFN/RBV-containing or -free regimen, has shown promising results with fewer adverse effects. In this review, preclinical profiles and clinical proof-of-concept studies of ASV, including viral resistance, host polymorphism, and role of ASV in future HCV therapy are reviewed and discussed.

New treatments for chronic hepatitis C: an overview for paediatricians

Pegylated interferon (IFN) α-2a or 2b in combination with ribavirin for children aged 3 years and older is the standard treatment for paediatric chronic hepatitis C. This treatment regimen was developed firstly in adults. In recent years, a number of direct-acting antiviral agents (DAAs) are under development for treatment of chronic hepatitis C virus (HCV) infection. These agents block viral replication inhibiting directly one of the several steps of HCV lifecycle. DAAs are classified into several categories based on their molecular target: HCV NS3/4A protease inhibitors, HCV NS5B polymerase inhibitors and HCV NS5A inhibitors. Other promising compounds are cyclophilin A inhibitors, mi-RNA122 and IFN-λ. Several new drugs associations will be developed in the near future starting from the actual standard of care. IFN-based and IFN-free regimens are being studied in adults. In this constantly evolving scenario new drug regimens targeted and suitable for children would be possible in the next future. Especially for children, it is crucial to identify the right combination of drugs with the highest potency, barrier to resistance and the best safety profile.

Hepatitis C drugs: the end of the pegylated interferon era and the emergence of all-oral interferon-free antiviral regimens: a concise review

Between 2001 and 2011, the standard of care for chronic hepatitis C virus (HCV) infection was a combination of pegylated interferon (PEG-IFN) and ribavirin (RBV). In May 2011, boceprevir and telaprevir, two first-generation NS3/4A protease inhibitors, were approved in combination with PEG-IFN and RBV for 24 to 48 weeks in hepatitis C virus genotype 1 infections. In December 2013, simeprevir, a second-generation NS3/4A protease inhibitor, was approved for use with PEG-IFN and RBV for 12 weeks in genotype 1, while sofosbuvir, a NS5B nucleotide polymerase inhibitor, was approved for use with PEG-IFN and RBV for 12 weeks in genotypes 1 and 4, as well as with RBV alone for 12 weeks in genotype 2 and for 24 weeks in genotype 3. Sofosbuvir combined with simeprevir or an NS5A replication complex inhibitor (ledipasvir or daclatasvir) with or without RBV for 12 weeks in genotype 1 resulted in a sustained virological response >90%, irrespective of previous treatment history or presence of cirrhosis. Similarly impressive sustained virological response rates have been shown with ABT-450/r (ritonavir-boosted NS3/4A protease inhibitor)-based regimens in combination with other direct-acting antiviral agent(s) with or without RBV for 12 weeks in genotype 1. The optimal all-oral interferon-free antiviral regimen likely entails a combination of an NS5B nucleotide polymerase inhibitor with either a second-generation NS3/4A protease inhibitor or an NS5A replication complex inhibitor with or without RBV. Further research is needed to determine the role of resistance testing, clarify the optimal follow-up duration post-treatment, and evaluate the antiviral efficacy and safety in difficult-to-cure patient populations.

Increased uptake and new therapies are needed to avert rising hepatitis C-related end stage liver disease in England: modelling the predicted impact of treatment under different scenarios

BACKGROUND & AIMS

Hepatitis C (HCV) related disease in England is predicted to rise, and it is unclear whether treatment at current levels will be able to avert this. The aim of this study was to estimate the number of people with chronic HCV infection in England that are treated and assess the impact and costs of increasing treatment uptake.

METHODS

Numbers treated were estimated using national data sources for pegylated interferon supplied, dispensed, or purchased from 2006 to 2011. A back-calculation approach was used to project disease burden over the next 30 years and determine outcomes under various scenarios of treatment uptake.

RESULTS

5000 patients were estimated to have been treated in 2011 and 28,000 in total from 2006 to 2011; approximately 3.1% and 17% respectively of estimated chronic infections. Without treatment, incident cases of decompensated cirrhosis and hepatocellular carcinoma were predicted to increase until 2035 and reach 2290 cases per year. Treatment at current levels should reduce incidence by 600 cases per year, with a peak around 2030. Large increases in treatment are needed to halt the rise; and with more effective treatment the best case scenario predicts incidence of around 500 cases in 2030, although treatment uptake must still be increased considerably to achieve this.

CONCLUSIONS

If the infected population is left untreated, the number of patients with severe HCV-related disease will continue to increase and represent a substantial future burden on healthcare resources. This can be mitigated by increasing treatment uptake, which will have the greatest impact if implemented quickly.

Asunaprevir, a protease inhibitor for the treatment of hepatitis C infection

According to the World Health Organization, approximately 150 million people worldwide are chronic carriers of hepatitis C virus (HCV). HCV infection can evolve into cirrhosis of the liver and its complications, which are ultimately responsible for more than 350,000 deaths every year. Antiviral therapy, when successful, is able to decrease the rate of progression and increase survival. Two types of therapies are currently available, ie, interferon-based therapies and interferon-free ones. The latter have several advantages in terms of safety and tolerability, and could be used even in the most advanced stages of the disease. However, their use is restricted to some viral genotypes (genotype 2 and 3) and they are expensive. Several molecules are in an advanced phase of development. This review deals with the pharmacokinetics, pharmacodynamics, tolerability, and safety of asunaprevir, an inhibitor of HCV nonstructural 3 protease. Asunaprevir exerts optimal in vitro activity particularly against HCV genotypes 1 and 4, and its pharmacokinetic profile enables twice daily administration. The drawback of asunaprevir, and of all protease inhibitors, is its low barrier to resistance. Consequently, it is used in association with other drugs to prevent resistance. Specifically, when combined with daclatasvir, an NS5A inhibitor, asunaprevir results in a very high rate of viral eradication in both treatment-naïve and treatment-experienced patients, with a sustained virological response rate of 80%-90%. Tolerability is fair; in fact, asunaprevir is associated with a transient increase in aminotransferase levels, which is mild in most cases. In conclusion, asunaprevir is a good candidate component of interferon-free combinations and may revolutionize the treatment of chronic HCV infection in the near future.

HCV RNA assay sensitivity impacts the management of patients treated with direct-acting antivirals

BACKGROUND

Application of response-guided therapy (RGT) rules to the treatment of HCV infection with pegylated interferon-α2a and ribavirin, and direct-acting antivirals (DAAs) such as the NS3/4A protease inhibitors (PIs) boceprevir and telaprevir, relies on the determination of viral genotype and on-treatment HCV RNA level. Currently there are few data available regarding the clinical impact of the analytical differences that exist between different HCV RNA quantification assays on treatment decisions such as those involved in RGT.

METHODS

We sought to ascertain the concordance between two HCV RNA quantification assays, the Roche/High-Pure-System COBAS(®) TaqMan (CTM) version 2 and Abbott RealTime HCV (ART), and to understand the impact of different assay characteristics on treatment decisions. We evaluated 1,336 specimens collected from 74 patients enrolled in the Phase II CHAMPION-2 study of the investigational DAAs ABT-450 (an acylsulfonamide NS3/4A PI), ABT-072 and ABT-333 (both non-nucleoside NS5B polymerase inhibitors).

RESULTS

HCV RNA level results were highly correlated, but CTM values were higher than those from ART by an average of 0.46 log IU/ml. Use of ART HCV RNA level results led to a higher positive predictive value of week 4 viral load for the achievement of a sustained virological response 24 weeks after the end of treatment (100% versus 87% using the lower limit of detection as the threshold).

CONCLUSIONS

This study suggests that HCV viral load assay performance characteristics need to be taken into consideration when managing HCV patients with RGT. Further studies are required to determine whether a consensus HCV RNA level threshold can be established or whether HCV viral load assays with greater sensitivity can increase cure rates with RGT.

Vertical transmission of hepatitis B virus: challenges and solutions

More than 240 million people worldwide are chronically infected with hepatitis B virus (HBV). Mother-to-child transmission remains the most important mechanism of infection in countries with a high prevalence of HBV. Universal screening of all pregnant women, at-birth prophylaxis with specific anti-HBV immune globulin, as well as HBV vaccination for newborns of infected mothers are effective in reducing the risk of vertical transmission. However, in cases of a high viral load and hepatitis B e antigen positivity, there is a residual risk of HBV transmission to the newborn despite prophylaxis. This review focuses on the above-indicated strategies and on the efficacy and safety of antiviral drugs administered during the third trimester of pregnancy.

Μanagement of patients with hepatitis B and C before and after liver and kidney transplantation

New nucleos(t)ide analogues (NAs) with high genetic barrier to hepatitis B virus (HBV) resistance (such as entecavir, tenofovir) have improved the prognosis of patients with HBV decompensated cirrhosis and have prevented HBV recurrence after liver transplantation (LT). NAs are considered the most proper approach for HBV infection in patients under renal replacement therapy but their doses should be adjusted according to the patient's creatinine clearance. In addition, physicians should be aware of the potential nephrotoxicity. However, patients with chronic hepatitis C and decompensated cirrhosis can receive only one therapeutic option before LT, as well as for Hepatitis C virus (HCV) recurrence after LT, which is the combination of subcutaneous Peg-IFN and ribavirin. Generally, therapy for HCV after renal transplantation should be avoided. Although the optimal antiviral therapy for HCV infection has not been established, attention has turned to a new, oral direct acting antiviral treatment which marks a promising strategy in prognosis and in amelioration of these diseases.

Predicting Discontinuation of Pegylated Interferon as a Result of Lack of Efficacy in United States Veterans With Chronic Hepatitis C on Dual Therapy

BACKGROUND

Many patients with chronic hepatitis C virus (HCV) being treated with pegylated interferon (peg-IFN) plus ribavirin (RBV) do not respond to therapy and do not clear the virus. Standard of care during the era of dual therapy was to discontinue the patient's therapy based on insufficient decreases in viral load after 12 and/or 24 weeks on therapy.

OBJECTIVES

We identified patient characteristics that were significant predictors of discontinuation as a result of lack of efficacy (LOE) in a national database of US veterans with genotypes 1 and 4.

METHODS

We identified US veterans who received care at Veterans Affairs medical centers in 2004-2009 and who had lab-confirmed HCV diagnoses and initiated therapy with peg-IFN plus RBV. Patients who discontinued therapy early were classified as either LOE or non-LOE discontinuers based on pharmacy refill patterns and laboratory response data. Predictors of LOE discontinuation were identified using univariate and multivariable Cox proportional hazards modeling.

RESULTS

Of 321 238 HCV patients with an ICD-9 diagnosis code, 31 215 (9.7%) initiated dual therapy with peg-IFN plus RBV, and 10 333 (3.2%) met all inclusion criteria and were included in the analysis. Overall, 13.6% of the cohort was classified as LOE. Significant predictors of LOE discontinuation included treatment for drug abuse (hazard ratio [HR] = 2.18), age >65 years (HR = 1.75), antiretroviral therapy for HIV (HR = 1.48), black race (HR = 1.47), platelet count >100/mm³ (HR = 1.46), and drug therapy for insomnia (HR = 1.40).

CONCLUSIONS

We identified risk factors for discontinuation caused by LOE. Future work should focus on determining whether these characteristics are also predictive of triple-therapy LOE discontinuations.

Hepatitis B and C

Hepatitis B and C present clinicians with many challenges. This article reviews the epidemiology of hepatitis, along with its prevention through vaccination, diagnosis and treatment, especially in relation to approaching the exposure of healthcare workers to at-risk patients. The role of prevention, diagnosis and treatment with interferon agents and protease inhibitors is discussed. The treatment of hepatitis B and C is advancing and the intensivist should be aware of the options for healthcare workers exposed to its risk on the intensive care unit.

A double-blind randomized controlled study to evaluate the efficacy of low-dose oral interferon-alpha in preventing hepatitis C relapse

Low-dose oral interferon could exert immune-modulating effects in human. We conducted a clinical trial to investigate the efficacy of oral interferon-alpha in preventing hepatitis C relapse. Totally 169 genotype 1b chronic hepatitis C patients having achieved end-of-therapy virological clearance were randomized to receive interferon-alpha lozenge 500 IU/day (n=59), 1,500 IU/day (n=53), or placebo (n=57) for 24 weeks. Overall, no significant differences were found for the relapse rates in the 3 groups (P>0.05). However, in patients with fibroindex 1.4-1.7, relapse occurred in 1/12 (8.3%) 500 IU-group patients versus 9/21 (42.9%) patients of the other groups (P=0.05). In 158 patients receiving at least 4 weeks of oral interferon, significantly higher platelet count was found at the end of trial in the 500 IU group (P=0.003). In thrombocytopenic patients, a significantly expedited recovery of platelet count was found in the 500 IU group (P=0.002). No drug-related severe adverse events were reported. In conclusion, at 500 IU/day, oral interferon exerted a borderline suppression effect of virological relapse in chronic hepatitis C patients with mild liver fibrosis. Additionally, it significantly expedited platelet count recovery after the end of peginterferon therapy.

Prediction of drug-drug interactions between various antidepressants and efavirenz or boosted protease inhibitors using a physiologically based pharmacokinetic modelling approach

BACKGROUND AND OBJECTIVE

The rate of depression in patients with HIV is higher than in the general population. The use of antidepressants can have a beneficial effect, improving antiretroviral therapy adherence and consequently their efficacy and safety. Efavirenz and protease inhibitor boosted with ritonavir are major components of the antiretroviral therapy and are inducers and/or inhibitors of several cytochrome P450 (CYP) isoforms. Although antidepressants are prescribed to a significant proportion of patients treated with antiretrovirals, there are limited clinical data on drug-drug interactions. The aim of this study was to predict the magnitude of drug-drug interactions among efavirenz, boosted protease inhibitors and the most commonly prescribed antidepressants using an in vitro-in vivo extrapolation (IVIVE) model simulating virtual clinical trials.

METHODS

In vitro data describing the chemical characteristics, and absorption, distribution, metabolism and elimination (ADME) properties of efavirenz, boosted protease inhibitors and the most commonly prescribed antidepressants were obtained from published literature or generated by standard methods. Pharmacokinetics and drug-drug interaction were simulated using the full physiologically based pharmacokinetic model implemented in the Simcyp™ ADME simulator. The robustness of our modeling approach was assessed by comparing the magnitude of simulated drug-drug interactions using probe drugs to that observed in clinical studies.

RESULTS

Simulated pharmacokinetics and drug-drug interactions were in concordance with available clinical data. Although the simulated drug-drug interactions with antidepressants were overall weak to moderate according to the classification of the US FDA, fluoxetine and venlafaxine represent better candidates from a pharmacokinetic standpoint for patients on efavirenz and venlafaxine or citalopram for patients on boosted protease inhibitors.

CONCLUSION

The modest magnitude of interaction could be explained by the fact that antidepressants are substrates of multiple isoforms and thus metabolism can still occur through CYPs that are weakly impacted by efavirenz or boosted protease inhibitors. These findings indicate that IVIVE is a useful tool for predicting drug-drug interactions and designing prospective clinical trials, giving insight into the variability of exposure, sample size and time-dependent induction or inhibition.

Hepatitis C virus protease inhibitor-resistance mutations: our experience and review

Direct-acting antiviral agents (DAAs) for hepatitis C virus (HCV) infection are one of the major advances in its medical treatment. The HCV protease inhibitors boceprevir and telaprevir were the first approved DAAs in the United States, Europe, and Japan. When combined with peginterferon plus ribavirin, these agents increase sustained virologic response rates to 70%-80% in treatment-naïve patients and previous-treatment relapsers with chronic HCV genotype 1 infection. Without peginterferon plus ribavirin, DAA mono-therapies increased DAA-resistance mutations. Several new DAAs for HCV are now in clinical development and are likely to be approved in the near future. However, it has been reported that the use of these drugs also led to the emergence of DAA-resistance mutations in certain cases. Furthermore, these mutations exhibit cross-resistance to multiple drugs. The prevalence of DAA-resistance mutations in HCV-infected patients who were not treated with DAAs is unknown, and it is as yet uncertain whether such variants are sensitive to DAAs. We performed a population sequence analysis to assess the frequency of such variants in the sera of HCV genotype 1-infected patients not treated with HCV protease inhibitors. Here, we reviewed the literature on resistance variants of HCV protease inhibitors in treatment naïve patients with chronic HCV genotype 1, as well as our experience.

Treatment as prevention and cure towards global eradication of hepatitis C virus

The availability of curative, direct-acting antiviral drugs against hepatitis C virus (HCV) sparks an ethical call for HCV eradication and provides essential tools to spearhead the effort. Challenges include increasing awareness of the chronic hepatitis C epidemic, garnering sufficient public, private, and governmental financial will to invest in the necessary resources, developing pangenotypic drug regimens for global application, and mitigating ethical concerns. To achieve these goals, stakeholders including clinicians, public health professionals, legislators, advocates, and industry can employ a variety of strategies such as increasing HCV screening, implementing treatment as prevention, and improving linkage to care, as well as developing innovative pricing and payment solutions, stimulating innovation through local drug development in high-prevalence regions, continuing vaccine development, and creating efficiencies in the marketing and distribution of educational materials and drug treatments.

Prevalence of hepatitis C virus subgenotypes 1a and 1b in Japanese patients: ultra-deep sequencing analysis of HCV NS5B genotype-specific region

Background

Hepatitis C virus (HCV) subgenotypes 1a and 1b have different impacts on the treatment response to peginterferon plus ribavirin with direct-acting antivirals (DAAs) against patients infected with HCV genotype 1, as the emergence rates of resistance mutations are different between these two subgenotypes. In Japan, almost all of HCV genotype 1 belongs to subgenotype 1b.

Methods and Findings

To determine HCV subgenotype 1a or 1b in Japanese patients infected with HCV genotype 1, real-time PCR-based method and Sanger method were used for the HCV NS5B region. HCV subgenotypes were determined in 90% by real-time PCR-based method. We also analyzed the specific probe regions for HCV subgenotypes 1a and 1b using ultra-deep sequencing, and uncovered mutations that could not be revealed using direct-sequencing by Sanger method. We estimated the prevalence of HCV subgenotype 1a as 1.2-2.5% of HCV genotype 1 patients in Japan.

Conclusions

Although real-time PCR-based HCV subgenotyping method seems fair for differentiating HCV subgenotypes 1a and 1b, it may not be sufficient for clinical practice. Ultra-deep sequencing is useful for revealing the resistant strain(s) of HCV before DAA treatment as well as mixed infection with different genotypes or subgenotypes of HCV.