Review of direct-acting antiviral agents for the treatment of chronic hepatitis C

Targeted Degradation of HCV Polymerase by GalNAc-Conjugated ApTACs for Pan-Genotypic Antiviral Therapy with High Resistance Barriers

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease. Although interferon-free direct-acting antivirals have led to significant advancements in the treatment of HCV infection, the high genetic variability of the virus and the emergence of acquired drug resistance pose potential threats to their effectiveness. In this study, we develop a broad-spectrum aptamer-based proteolysis targeting chimera, designated dNS5B, which effectively degrades both pan-genotypic NS5B polymerase and drug-resistant mutants through ubiquitin proteasome system. To achieve hepatocyte-specific uptake, we further develop Gal-dNS5B by coupling the dNS5B with a trivalent N-acetylgalactosamine (tri-GalNAc), a ligand for the liver-specific asialoglycoprotein receptor. Gal-dNS5B exclusively accumulates in hepatocytes and suppresses HCV replication by degrading NS5B. Collectively, our research lays the groundwork for a scalable strategy in the development of antiviral medications aimed at addressing current and future challenges posed by hepatitis viruses and other re-emerging viral pandemics.

A Review on cLF36, a Novel Recombinant Antimicrobial Peptide-Derived Camel Lactoferrin

Lactoferrin is an antimicrobial peptide (AMP) playing a pivotal role in numerous biological processes. The primary antimicrobial efficacy of lactoferrin is associated with its N-terminal end, which contains various peptides, such as lactoferricin and lactoferrampin. In this context, our research team has developed a refined chimeric 42-mer peptide known as cLF36 over the past few years. This peptide encompasses the complete amino acid sequence of camel lactoferrampin and partial amino acid sequence of lactoferricin. The peptide's activity against human, avian, and plant bacterial pathogens has been assessed using different biological platforms, including prokaryotic (P170 and pET) and eukaryotic (HEK293) expression systems. The peptide positively influenced the growth performance and intestinal morphology of chickens challenged with pathogen bacteria. Computational methods and in vitro studies showed the peptide's antiviral effects against hepatitis C virus, influenza virus, and rotavirus. The chimeric peptide exhibited higher activity against certain tumor cell lines compared to normal cells, which may be attributed to the peptide's interaction with negatively charged glycosaminoglycans on the surface of tumor cells. Importantly, this peptide exhibited no toxicity against host cells and demonstrated remarkable thermal and protease stability in serum. In conclusion, while our investigations suggest that the chimeric peptide, cLF36, may offer potential as a candidate or complementary option to some available antibiotics, antiviral agents, and chemical pesticides, significant uncertainties remain regarding its cost-effectiveness, as well as its pharmacodynamic and pharmacokinetic characteristics, which require further elucidation.

Network Meta-analysis on Disconnected Evidence Networks When Only Aggregate Data Are Available: Modified Methods to Include Disconnected Trials and Single-Arm Studies while Minimizing Bias

BACKGROUND

Network meta-analysis (NMA) requires a connected network of randomized controlled trials (RCTs) and cannot include single-arm studies. Regulators or academics often have only aggregate data. Two aggregate data methods for analyzing disconnected networks are random effects on baseline and aggregate-level matching (ALM). ALM has been used only for single-arm studies, and both methods may bias effect estimates.

METHODS

We modified random effects on baseline to separate RCTs connected to and disconnected from the reference and any single-arm studies, minimizing the introduction of bias. We term our modified method reference prediction. We similarly modified ALM and extended it to include RCTs disconnected from the reference. We tested these methods using constructed data and a simulation study.

RESULTS

In simulations, bias for connected treatments for ALM ranged from -0.0158 to 0.051 and for reference prediction from -0.0107 to 0.083. These were low compared with the true mean effect of 0.5. Coverage ranged from 0.92 to 1.00. In disconnected treatments, bias of ALM ranged from -0.16 to 0.392 and of reference prediction from -0.102 to 0.40, whereas coverage of ALM ranged from 0.30 to 0.82 and of reference prediction from 0.64 to 0.94. Under fixed study effects for disconnected evidence, bias was similar, but coverage was 0.81 to 1.00 for reference prediction and 0.18 to 0.76 for ALM. Trends of similar bias but greater coverage for reference prediction with random study effects were repeated in constructed data.

CONCLUSIONS

Both methods with random study effects seem to minimize bias in treatment connected to the reference. They can estimate treatment effects for disconnected treatments but may be biased. Reference prediction has greater coverage and may be recommended overall.

HIGHLIGHTS

Two methods were modified for network meta-analysis on disconnected networks and for including single-arm observational or interventional studies in network meta-analysis using only aggregate data and for minimizing the bias of effect estimates for treatments only in trials connected to the reference.Reference prediction was developed as a modification of random effects on baseline that keeps analyses of trials connected to the reference separately from those disconnected from the reference and from single-arm studies. The method was further modified to account for correlation in trials with more than 2 arms and, under random study effects, to estimate variance in heterogeneity separately in connected and disconnected evidence.Aggregate-level matching was extended to include trials disconnected from the reference, rather than only single-arm studies. The method was further modified to separately estimate treatment effects and heterogeneity variance in the connected and disconnected evidence and to account for the correlation between arms in trials with more than 2 arms.Performance was assessed using a constructed data example and simulation study.The methods were found to have similar, and sometimes low, bias when estimating the relative effects for disconnected treatments, but reference prediction with random study effects had the greatest coverage.The use of reference prediction with random study effects for disconnected networks is recommended if no individual patient data or alternative real-world evidence is available.

Binding of GS-461203 and Its Halogen Derivatives to HCV Genotype 2a RNA Polymerase Drug Resistance Mutants

Hepatitis C Virus (HCV) is reported to develop GS-461203 resistance because of multiple mutations within the RNA-dependent RNA Polymerase (RdRp) of HCV. The lack of a high-resolution structure of these RdRp mutants in complex with GS-461203 hinders efforts to understand the drug resistance. Here we decipher the binding differences of GS-461203 in the wild type and mutated systems T179A or M289L of HCV RdRp Genotype 2a using homology modeling, molecular docking, and molecular dynamics simulation. Key residues responsible for GS-461203 binding were identified to be Arg48, Arg158, Asp318, Asp319, and Asp220, and that mutations T179A or M289L have caused conformational changes of GS-461203 in the RdRp active site. The affinities of GS-461203 were reduced in T179A system, but it became slightly stronger in the M289L system. Furthermore, we designed two new analogues of GS-461203 which encouragingly induced more stable interactions than GS-461203, and thus resulted in much better binding energies. This present study reveals how a single mutation, T179A or M289L, will modulate GS-461203 binding in HCV RdRp Genotype 2a, while introducing two novel analogues to overcome the drug resistance which may be good candidate for further experimental verification.

Liver Disease: Induction, Progression, Immunological Mechanisms, and Therapeutic Interventions

The liver is an organ with impressive regenerative potential and has been shown to heal sizable portions after their removal. However, certain diseases can overstimulate its potential to self-heal and cause excessive cellular matrix and collagen buildup. Decompensation of liver fibrosis leads to cirrhosis, a buildup of fibrotic ECM that impedes the liver’s ability to efficiently exchange fluid. This review summarizes the complex immunological activities in different liver diseases, and how failure to maintain liver homeostasis leads to progressive fibrotic tissue development. We also discuss a variety of pathologies that lead to liver cirrhosis, such as alcoholic liver disease and chronic hepatitis B virus (HBV). Mesenchymal stem cells are widely studied for their potential in tissue replacement and engineering. Herein, we discuss the potential of MSCs to regulate immune response and alter the disease state. Substantial efforts have been performed in preclinical animal testing, showing promising results following inhibition of host immunity. Finally, we outline the current state of clinical trials with mesenchymal stem cells and other cellular and non-cellular therapies as they relate to the detection and treatment of liver cirrhosis.

Kinase Inhibitors as Underexplored Antiviral Agents

Viral infections are a major health problem; therefore, there is an urgent need for novel therapeutic strategies. Antivirals used to target proteins encoded by the viral genome usually enhance drug resistance generated by the virus. A potential solution may be drugs acting at host-based targets since viruses are dependent on numerous cellular proteins and phosphorylation events that are crucial during their life cycle. Repurposing existing kinase inhibitors as antiviral agents would help in the cost and effectiveness of the process, but this strategy usually does not provide much improvement, and specific medicinal chemistry programs are needed in the field. Anyway, extensive use of FDA-approved kinase inhibitors has been quite useful in deciphering the role of host kinases in viral infection. The present perspective aims to review the state of the art of kinase inhibitors that target viral infections in different development stages.

Adolescent Hepatitis C: Prevalence, Impact, and Management Challenges

The prevalence of Hepatitis C virus infection (HCV), a leading cause of chronic liver disease worldwide, is rising in the United States (US) and other high-income countries, especially among youth and young adults. This surge in cases is closely associated with the opioid crisis and intravenous drug use (IVDU). However, its prevalence and impact on the adolescent population have not been thoroughly studied and therefore is poorly understood. The pediatric population tends to have milder liver disease and progression when compared to adults; however, there is a risk of developing liver cirrhosis, in addition to facing decreased quality of life and stigmatization from the disease. The recent approval of direct-acting antiviral (DAA) regimens for all HCV genotypes and age greater than 3 years has revolutionized its management. Therapy has shifted from the prolonged interferon-based regimens, to shorter duration, once daily oral pills that are highly effective, curative and with fewer side effects. Therapy is now indicated for all adolescents with hepatitis C virus infection, regardless of stage of liver disease, recent IVDU, or coinfection with HIV, therefore eliminating a lifetime risk of chronic liver disease, cirrhosis and hepatocarcinoma. Nonetheless, adolescents are rarely tested or treated for hepatitis C infection, and very few adolescents complete therapy. Implementation of point of care (POC) testing of high-risk youth at drug treatment centers or other juvenile facilities may be a good strategy to increase testing, diagnosis and therapy. This review article aims to educate pediatricians and other primary care providers to help decrease the existing knowledge gap on the subject.

Evolution of Hepatitis C Virus Treatment During the Era of Sofosbuvir-Based Therapies: A Real-World Experience in France

BACKGROUND

Treatment of hepatitis C virus (HCV) has been dramatically improved with the introduction of direct-acting antiviral agents (DAAs). Universal access to pangenotypic DAAs was provided in France from 2017, expanding the type of patients treated. Real-world studies are important to confirm effectiveness and safety in clinical practice, particularly in vulnerable populations.

AIMS

To assess real-world effectiveness and safety of sofosbuvir-based therapy in adults with chronic HCV infection before and after universal access to DAAs in France.

METHODS

This multicenter, non-interventional, prospective study assessed the effectiveness, safety, patient-reported outcomes and adherence with sofosbuvir-based regimens from October 2015 to July 2016 (Period 1: sofosbuvir-based therapy excluding sofosbuvir/velpatasvir) and from October 2017 to July 2018 (Period 2: pangenotypic sofosbuvir/velpatasvir-based therapy).

RESULTS

Baseline data were documented for 1029 patients. Overall, 797 (77%) had sustained virologic response data available ≥ 9 weeks after treatment completion. Per protocol response was high (97%) irrespective of age, alcohol consumption, recreational drug use, or HIV/HCV coinfection. Adverse events occurred in approximately 25% of patients with the majority experiencing Grade 1 or 2 events. Sofosbuvir-based regimens improved health-related quality of life from baseline to end of treatment in patients with data at all timepoints. Overall, 99% of patients reported total or almost total adherence to therapy.

CONCLUSIONS

Sofosbuvir-based therapy, including pangenotypic sofosbuvir/velpatasvir, is effective for the treatment of HCV in real-world clinical practice. This is an important step towards HCV elimination.

Impact of Blood Transfusion on the Prevalence of HHpgV-1, HPgV-1, and B19V Among Iranian HCV-infected Patients With Hemophilia

OBJECTIVE

Blood-derived products from patient with hemophilia treated by factor VIII concentrates are potential sources of transfusion-transmitted infections, including human immunodeficiency virus, hepatitis, human pegivirus-1 (HPgV-1), B19 virus, and also human hepegivirus-1 (HHpgV-1). In the current study, we investigated the impact of blood transfusion on the prevalence of HHpgV-1, HPgV-1, and B19 virus in plasma of Iranian patient with hemophilia after direct-acting antiviral treatment of hepatitis C virus (HCV) infections for the first time.

MATERIALS AND METHODS

A total of 170 patients with hemophilia who received direct-acting antivirals were enrolled in this study. Among them, 92 patients had a history of blood transfusion. The presence of HHpgV-1, HPgV-1, and B19 virus was detected by nested polymerase chain reaction analysis using the conserved primers. The plasmids harboring 5'-UTR and NS3 were used as positive controls for HPgV-1 and HHpgV-1, respectively.

RESULTS

Our data identified 3 individuals with HHpgV-1 viremia (1.76%), 11 individuals with HPgV-1 viremia (6.47%), and 33 individuals with B19 viremia (19.4%). All patients were negative for hepatitis B virus, human immunodeficiency virus, and HCV infections. These findings indicated lower transmissibility or higher rates of virus clearance for HHpgV-1, HPgV-1, and B19 virus as compared with other bloodborne human flaviviruses such as HCV. However, the prevalence of B19 virus was significantly higher than the other 2 viruses.

CONCLUSION

In general, these findings showed that the history of blood transfusion could increase the risk of viral transmission of bloodborne viruses among patient with hemophilia.

Social values for health technology assessment in Canada: a scoping review of hepatitis C screening, diagnosis and treatment

BACKGROUND

Health care system decision makers face challenges in allocating resources for screening, diagnosis and treatment of hepatitis C. Approximately 240,000 individuals are infected with the hepatitis C virus (HCV) in Canada. Populations most affected by HCV include Indigenous people, people who inject drugs, immigrants and homeless or incarcerated populations as well as those born between 1946 and 1965. Curative but expensive drug regimens of novel direct acting antivirals (DAAs) are available. We aim to identify social values from academic literature for inclusion in health technology assessments.

METHODS

We conducted a scoping review of academic literature to identify and analyze the social values and evidence-based recommendations for screening, diagnosis and treatment of HCV in Canada. After applying inclusion/exclusion criteria, we abstracted: type of intervention(s), population(s) affected, study location, screening methods, diagnostics and treatments. We then abstracted and applied qualitative codes for social values. We extracted social value statements and clustered them into one of 4 categories: (1) equity and justice, (2) duty to provide care, (3) maximization of population benefit, and (4) individual versus community interests.

RESULTS

One hundred and eighteen articles met our inclusion criteria on screening, diagnosis and treatment of HCV in Canada. Of these, 54 (45.8%) discussed screening, 4 (3.4%) discussed diagnosis and 60 (50.8%) discussed treatment options. Most articles discussed the general population and other non-vulnerable populations. Articles that discussed vulnerable populations focused on people who inject drugs. We coded 1243 statements, most of which fell into the social value categories of equity and justice, duty to provide care and maximization of population benefit.

CONCLUSION

The academic literature identified an expanded set of social values to be taken into account by resource allocation decision makers in financially constrained environments. In the context of hepatitis C, authors called for greater consideration of equity and justice and the duty to provide care in making evidence-based recommendations for screening, diagnosis and treatment for different populations and in different settings that also account for individual and community interests.

Real-life glecaprevir/pibrentasvir in a large cohort of patients with hepatitis C virus infection: The MISTRAL study

BACKGROUND AND AIMS

It is paramount to identify predictors of treatment failure with direct antiviral agents in 'field-practice' patients, including people who inject drugs (PWID). Data on the efficacy of glecaprevir/pibrentasvir (GLE/PIB) in a field-practice scenario are scant. The multicentre MISTRAL study enrolled 1177 patients, including PWID, to assess real-life efficacy and safety of GLE/PIB and to identify the predictive factors for this treatment.

METHODS

This was a prospective, longitudinal study. The outcome variable was the rate of sustained virological response (SVR) at week 12.

RESULTS

A total of 123 patients (10%) were infected from hepatitis C virus (HCV) 3. METAVIR fibrosis score was F4 in 104 subjects (9%); 118 patients (10%) were PWID. Overall, 1163/1177 (99%) patients achieved SVR. The baseline clinical factors discriminating between treatment success and treatment failure were age at treatment (P = 0.031) and creatinine level (P = 0.034). SVR rates were not influenced by gender, substance abuse, previous treatment, treatment duration, fibrosis or chronic kidney disease stage. Compared with non-substance users, the 118 PWID exhibited a significantly different genotype pattern distribution (χ²  < 0.001). A total of 40/118 (33.9%) of substance users were HCV3 compared to 83/1056 (7.9%) non-substance users. Only 6 patients (0.5%) reported a serious adverse event.

CONCLUSIONS

The MISTRAL study provides evidence of GLE/PIB efficacy in a field-practice scenario in a highly epidemic HCV area in southern Italy; it unveiled significant differences in genotype distribution among the most underserved and difficult-to-treat patient subgroups including PWID.

Direct-acting antivirals and visceral leishmaniasis: a case report

Background

Visceral leishmaniasis is a vector-borne parasitic disease caused by protozoa belonging to the genus Leishmania. The clinical presentation of visceral leishmaniasis strictly depends on the host immunocompetency, whereas depressive conditions of the immune system impair the capability to resolve the infection and allow reactivation from sites of latency of the parasite.

Case presentation

We describe a case of visceral leishmaniasis (VL) that occurred in a patient with chronic hepatitis C treated with direct-acting antiviral drugs (DAA). The hypothesized mechanism is the alteration of protective inflammation mechanisms secondary to DAA therapy. Downregulation of type II and III IFNs, their receptors, which accompany HCV clearance achieved during treatment with sofosbuvir and ribavirin might have a negative impact on a risk for reactivation of a previous Leishmania infection. We know indeed that IFN-γ is important to enhance killing mechanisms in macrophages, which are the primary target cells of Leishmania.

Conclusion

Since VL is endemic in Sicily as well as in other countries of the Mediterranean basin, physicians should be aware of the possible unmasking of cryptic Leishmania infection by DAAs.

[Chronic HCV infection: An internist's opinion (Part 2)]

Hepatitis C virus (HCV) infection results in not only chronic hepatitis and subsequent complications as liver cirrhosis and hepatocellular carcinoma, but also in a significant number of other diseases, the so-called extrahepatic manifestations of chronic HCV infection. In addition to lymphoproliferative and autoimmune disorders discussed in Part 1 of this review, many other diseases turned to be associated with chronic HCV infection. Part 2 of this review is dedicated to the analysis of the relationship of chronic HCV-infection to the development of some endocrine diseases, such as thyroiditis and diabetes mellitus, and cardiovascular disorders. It also provides the characteristics of the currently available antiviral agents and considers whether they may be used in patents with extrahepatic manifestations of chronic HCV infection.

Regulation of interferon signaling and HCV‑RNA replication by extracellular matrix

Although interferon (IFN)‑based treatment of patients with chronic hepatitis C virus (HCV) infection is widely applied, treatment resistance is often observed in patients with advanced liver fibrosis. Given that the molecular mechanisms of IFN resistance in liver fibrosis remain elusive, the present study investigated the effects of extracellular matrix (ECM) on IFN signaling in hepatic cells. The native HuH‑7 human hepatoma cell line and HuH‑7 cells were stably transfected with full‑length HCV‑RNA fused with Renilla luciferase (OR6 cells) were cultured on ECM‑coated dishes or non‑coated plastic dishes (NDs), and treated with human IFN‑α. In Huh‑7 cells cultured on coated dishes, the IFN‑stimulated response element (ISRE) luciferase activity was measured following ISRE plasmid transfection and the expression of IFN‑stimulated genes (ISG) were significantly lower than those in cells cultured on NDs. In addition, after IFN‑α treatment, the amount of HCV‑RNA and viral protein produced by OR6 cells cultured on coated dishes was higher than that produced by cells cultured on NDs. When cells were treated with β1‑integrin‑blocking antibody to disrupt the cell‑matrix interaction, the ISRE luciferase activity was restored, and the protein expression of ISG was increased, while that of HCV proteins was suppressed. Treatment of cells with integrin‑linked kinase (ILK) inhibitor or focal adhesion kinase (FAK) inhibitor restored the ISRE luciferase activity and expression of ISG proteins. These results suggested that β1‑integrin‑mediated signals affected the IFN signaling and promoted HCV replication. Therefore, the accumulation of ECM in liver fibrosis may impair IFN signaling through β1‑integrin‑mediated signaling involving ILK and FAK.

Chronic Hepatitis C: Do Generics Work as Well as Branded Drugs?

India has a large share of the hepatitis C virus (HCV) burden of the world. Unsafe medical practices and blood transfusions are the leading modes of transmission of HCV in India. The commonest HCV genotype in India is genotype 3 followed by genotype 1. While directly acting antivirals (DAAs) agents have become available at reasonable rates in India, cost of therapy remains a major barrier for control of HCV in India. Generic DAAs have been proven to be cost-saving in prior studies. We examined data from various studies in India and elsewhere using generic DAAs, and evaluated whether they are equally efficacious as the branded drugs. Since the availability of generic DAAs in the Indian market, there is a lot of real life data as well as prospective studies in special patient populations such as hematological disorders (thalassemia and hemophilia), chronic kidney disease, hemodialysis patients, post liver and renal transplant patients on immunosuppression, intravenous drug users, confections and other high risk groups. Control of HCV infection in India requires multi pronged approach. There is a need to formulate a health educational curriculum targeting not only the high-risk population but also the general population regarding the transmission of HCV. Adopting the dual approach of treating the old cases (decreasing the reservoir pool of HCV) and decreasing the incidence of new ones would help curtail the disease and decrease liver related mortality. In this scenario, the role of efficacious low cost generic medications is essential.

Cost-effectiveness of hepatitis C treatment using generic direct-acting antivirals available in India

BACKGROUND & AIMS

Availability of directly-acting antivirals (DAAs) has changed the treatment landscape of hepatitis C virus (HCV) infection. The high price of DAAs has restricted their use in several countries. However, in some countries such as India, generic DAAs are available at much cheaper price. This study examined whether generic DAAs could be cost-saving and how long it would take for the treatment to become cost-saving/effective.

METHODS

A previously-validated, mathematical model was adapted to the HCV-infected population in India to compare the outcomes of no treatment versus treatment with DAAs. Model parameters were estimated from published studies. Cost-effectiveness of HCV treatment using available DAAs was calculated, using a payer's perspective. We estimated quality-adjusted life years (QALYs), disability-adjusted life years (DALYs), total costs, and incremental cost-effectiveness ratio of DAAs versus no treatment. One-way and probabilistic sensitivity analyses were conducted.

RESULTS

Compared with no treatment, the use of generic DAAs in Indian HCV patients would increase the life expectancy by 8.02 years, increase QALYs by 3.89, avert 19.07 DALYs, and reduce the lifetime healthcare costs by $1,309 per-person treated. Treatment became cost-effective within 2 years, and cost-saving within 10 years of its initiation overall and within 5 years in persons with cirrhosis. Treating 10,000 HCV-infected persons could prevent 3400-3850 decompensated cirrhosis, 1800-2500 HCC, and 4000-4550 liver-related deaths. The results were sensitive to the costs of DAAs, pre- and post-treatment diagnostic tests and management of cirrhosis, and quality of life after sustained virologic response.

CONCLUSIONS

Treatment with generic DAAs available in India will improve patient outcomes, provide a good value for money within 2 years, and be ultimately cost-saving. Therefore, in this and similar settings, HCV treatment should be a priority from a public health as well an economic perspective.

In vitro selection of resistance to sofosbuvir in HCV replicons of genotype-1 to -6

BACKGROUND

Sofosbuvir is a nucleoside analogue inhibitor of the HCV NS5B polymerase approved for treatment of HCV-infected patients in combination with ribavirin or with other antivirals. It has activity against all genotypes of HCV. Resistance to sofosbuvir in genotype-1 and -2 HCV is conferred by the S282T substitution in NS5B.

METHODS

To begin to define the correlates of resistance to sofosbuvir in other genotypes, we performed selection experiments in cell culture using cell lines containing subgenomic replicons derived from genotypes-1b, -2a, -3a and -4a, or chimeric replicons in a genotype-1b background but encoding genotype-2b, -5a and -6a NS5B polymerase.

RESULTS

In every case, S282T was selected following passage in the presence of increasing concentrations of sofosbuvir for 10 to 15 weeks. When introduced as a site-directed mutant, S282T conferred reductions in sofosbuvir susceptibility of between 2.4 and 19.4-fold. Other substitutions observed during the selections had relatively less impact on susceptibility, such as N237S in genotype-6a (2.5-fold). Replication capacity was affected by the introduction of S282T in all genotypes to variable extents (3.2% to 22% of wild type).

CONCLUSIONS

These results confirm that S282T is the primary sofosbuvir resistance-associated substitution and that replication capacity is reduced when it is present in all genotypes of HCV.

Clinical efficacy of Rong-Yang-Jyh-Gan-Tang on patients with chronic hepatitis C: A double-blinded randomized placebo-controlled crossover study

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has been widely used by the Chinese population for treatment of chronic hepatitis. However, the efficacy of TCM for patients with chronic hepatitis has not been confirmed, mostly due to the lack of available scientific parameters such as serum viral load to evaluate treatment response.

AIM OF THE STUDY

We evaluated the efficacy of Rong-Yang-Jyh-Gan-Tang (RYJGT, composed of Long-Dan-Xie-Gan-Tang, Jia-Wei-Xia-Yao-San, Dan-Shen, and Hou-Po) on patients with chronic hepatitis C.

MATERIALS AND METHODS

Thirty-six patients with chronic hepatitis C who had no response to or had contraindications to interferon-ribavirin therapy were randomly allocated to receive RYJGT 15g/day or placebo for 12 weeks. After a 2-week washout period, patients were crossed over to receive placebo or RYJGT for another 12 weeks. Evaluation parameters included liver biochemistries, serum HCVRNA, side effects of RYJGT/placebo, and TCM symptoms.

RESULTS

Of the patients who had 12-week RYJGT treatment, 51.7% had decreased serum HCVRNA levels, whereas only 25.8% patients had decreased levels in the placebo group (p=0.036). TCM patterns of "Damp-Heat" and "Liver Qi Depression" had significantly improved after RYJGT treatment in comparison with the placebo. Logistic analyses showed that RYJGT treatment, and pre-treatment values of TCM symptoms of "Damp-Heat" and "Liver Qi Depression", were statistically significant factors in predicting the decrease in serum HCVRNA.

CONCLUSION

Chronic hepatitis C patients who received a 12-week RYJGT treatment had significantly higher HCVRNA decrease ratio, and improved TCM symptoms of "Damp-Heat" and "Liver Qi Depression", than those who received the placebo. Our results require further larger scale clinical trials.

Prevalence of sofosbuvir resistance-associated variants in Brazilian and worldwide NS5B sequences of genotype-1 HCV

BACKGROUND

The prevalence of natural polymorphisms associated with resistance to NS5B nucleoside/nucleotide (NI) sofosbuvir is distinct in different geographical regions. In Brazil, direct-acting anti-HCV therapy has recently changed with the introduction of interferon (IFN)-free regimens with sofosbuvir; however, the presence of resistant variants on clinical outcomes remains unknown. The aim of this study was to assess the natural polymorphisms associated with resistance to the NS5B NI sofosbuvir in Brazilian HCV-1 isolates and to compare it with that from other geographical regions.

METHODS

Nucleotide sequencing of the HCV NS5B gene was performed in serum samples of 95 therapy-naive Brazilian patients infected with subtype 1a (n=43) and 1b (n=52). The sequences were analysed along with 1,525 NS5B sequences from North America, Europe and Asia retrieved from public HCV databases.

RESULTS

In Brazilian HCV-1b patients who have never been exposed to a direct-acting anti-HCV drug, the C316N was detected in 15/52 (28.85%) patients, of these, 2 (3.85%) had single C316N variant, while 13 (25%) presented the double L159F-C316N mutant. A lower rate of L159F-C316N variants was detected in North American (n=9/238; 3.78%, P<0.001), European (n=17/281; 6.05%, P<0.001) and Asian (n=2/173; 1.16%, P<0.001) isolates. No sofosbuvir resistance-associated variants (RAVs) were identified in HCV-1a sequences.

CONCLUSIONS

Resistant variants to sofosbuvir were found at different frequencies in worldwide HCV-1b sequences but not in HCV-1a sequences. The high frequency of double mutation L159F-C316N observed in Brazilian HCV-1b patients contrast with the lower rate observed in the three continents studied. The association of these findings and the clinical implications awaits further analysis.

New direct-acting antivirals for patients with chronic HCV infection: can we monitor treatment using an HCV core antigen assay?

We evaluated the diagnostic usefulness of an HCV core antigen (HCV-Ag) assay in HCV-infected patients undergoing treatment with direct-acting antivirals. We analyzed 103 samples from 28 patients. Compared with RT-PCR, sensitivity was 96.2% and specificity was 100%. The correlation between techniques was excellent (Pearson coefficient: 0.871). HCV-Ag proved to be useful in patients with sustained viral response and in patients who experienced treatment failures.

ISG12a inhibits HCV replication and potentiates the anti-HCV activity of IFN-α through activation of the Jak/STAT signaling pathway independent of autophagy and apoptosis

Interferon stimulated (sensitive) genes (ISGs) are the effector molecules downstream of type I/III interferon (IFN) signaling pathways in host innate immunity. ISG12a can be induced by IFN-α. Although ISG12a has been reported to inhibit the replication of HCV, the exact mechanism remains to be determined. In this study, we investigated the possible mechanisms of ISG12a anti- HCV property by exploring the production of type I IFN and the activation of Janus kinase/signal transducer and activator of transcription (Jak/STAT) signaling pathway, apoptosis and autophagy in Huh7.5.1 cells transiently transfected with ISG12a over-expression plasmid. Interestingly, we found that ISG12a inhibited HCV replication in both Con1b replicon and the HCV JFH1-based cell culture system and potentiated the anti-HCV activity of IFN-α. ISG12a promoted the production of IFN α/β and activated the type I IFN signaling pathway as shown by increased p-STAT1 level, higher Interferon sensitive response element (ISRE) activity and up-regulated ISG levels. However, ISG12a over-expression did not affect cell autophagy and apoptosis. Data from our current study collectively indicated that ISG12a inhibited HCV replication and potentiated the anti-HCV activity of IFN-α possibly through induced production of type I IFNs and activation of Jak/STAT signaling pathway independent of autophagy and cell apoptosis.

Characterization of NS5A polymorphisms and their impact on response rates in patients with HCV genotype 2 treated with daclatasvir-based regimens

OBJECTIVE

Daclatasvir (DCV) is a pan-genotypic non-structural protein 5A (NS5A) inhibitor that is approved for treatment of hepatitis C virus (HCV) genotype (GT)1 and GT3 in the USA and GT1, GT3 and GT4 in Europe. We set out to examine the impact of daclatasvir-based regimens on the sustained virologic response (SVR) in patients with GT2 infection with respect to GT2 subtype and NS5A polymorphisms at amino acid positions associated with daclatasvir resistance.

METHODS

Analyses were performed on 283 GT2 NS5A sequences from five daclatasvir regimen-based clinical trials (ClinicalTrials.gov: NCT-01257204, NCT-01359644, NCT-02032875, NCT-02032888 and NCT-01616524) and 143 NS5A sequences from the Los Alamos HCV database. Susceptibility analyses of substitutions at amino acid positions associated with daclatasvir resistance and patient-derived NS5A sequences were performed using an in vitro HCV replication assay.

RESULTS

Of 13 GT2 subtypes identified from 426 NS5A sequences, the most prevalent were GT2a (32%), GT2b (48%) and GT2c (10%). The most prevalent NS5A polymorphism was L31M (GT2a = 88%; GT2b = 59%; GT2c = 10%). Substitutions identified in 96% of GT2 NS5A sequences exhibited daclatasvir EC₅₀ values ranging from 0.005 to 20 nM when tested in vitro. A similar range in daclatasvir EC₅₀ values was observed for 16 diverse GT2 patient-derived NS5A sequences (EC₅₀ = 0.005-60 nM). Depending on the daclatasvir-based regimen studied (daclatasvir/interferon-based or daclatasvir/sofosbuvir-based), SVR rates ranged from 90% to 100% in GT2 patients with the most prevalent baseline NS5A-L31M polymorphism, compared with from 96% to 100% without this polymorphism.

CONCLUSIONS

High SVR rates were achieved in patients infected with GT2 treated with daclatasvir-based regimens irrespective of GT2 subtype or baseline NS5A polymorphisms.

Metabolism and Disposition of Pan-Genotypic Inhibitor of Hepatitis C Virus NS5A Ombitasvir in Humans

Ombitasvir (also known as ABT-267) is a potent inhibitor of hepatitis C virus (HCV) nonstructural protein 5A (NS5A), which has been developed in combination with paritaprevir/ritonavir and dasabuvir in a three direct-acting antiviral oral regimens for the treatment of patients infected with HCV genotype 1. This article describes the mass balance, metabolism, and disposition of ombitasvir in humans without coadministration of paritaprevir/ritonavir and dasabuvir. Following the administration of a single 25-mg oral dose of [(14)C]ombitasvir to four healthy male volunteers, the mean total percentage of the administered radioactive dose recovered was 92.1% over the 192-hour sample collection in the study. The recovery from the individual subjects ranged from 91.4 to 93.1%. Ombitasvir and corresponding metabolites were primarily eliminated in feces (90.2% of dose), mainly as unchanged parent drug (87.8% of dose), but minimally through renal excretion (1.9% of dose). Biotransformation of ombitasvir in human involves enzymatic amide hydrolysis to form M23 (dianiline), which is further metabolized through cytochrome P450-mediated oxidative metabolism (primarily by CYP2C8) at the tert-butyl group to generate oxidative and/or C-desmethyl metabolites. [(14)C]Ombitasvir, M23, M29, M36, and M37 are the main components in plasma, representing about 93% of total plasma radioactivity. The steady-state concentration measurement of ombitasvir metabolites by liquid chromatography-mass spectrometry analysis in human plasma following multiple doses of ombitasvir, in combination with paritaprevir/ritonavir and dasabuvir, confirmed that ombitasvir is the main component (51.9% of all measured drug-related components), whereas M29 (19.9%) and M36 (13.1%) are the major circulating metabolites. In summary, the study characterized ombitasvir metabolites in circulation, the metabolic pathways, and the elimination routes of the drug.

The safety of daclatasvir for the treatment of hepatitis C

INTRODUCTION

The direct acting antiviral daclatasvir is an NS5A replication inhibitor active against the entire range of hepatitis C virus genotypes. It is a key step in establishing the goal of an all-oral, ribavirin-free, pan-genotypic regimen against hepatitis C.

AREAS COVERED

We review current literature including published abstracts and manuscripts. Evidence was obtained through PubMed/Medline search using listed keywords and through review of published abstracts.

EXPERT OPINION

Daclatasvir introduces a degree of pangenotypic potency currently lacking in other NS5A agents. Emerging literature suggests that daclatasvir in combination with other DAAs will represent a promising option in this difficult to treat populations including posttransplant, genotype 3 and HIV patients.

Disconnected by design: analytic approach in treatment networks having no common comparator

In a network meta-analysis, comparators of interest are ideally connected either directly or via one or more common comparators. However, in some therapeutic areas, the evidence base can produce networks that are disconnected, in which there is neither direct evidence nor an indirect route for comparing certain treatments within the network. Disconnected networks may occur when there is no accepted standard of care, when there has been a major paradigm shift in treatment, when use of a standard of care or placebo is debated, when a product receives orphan drug designation, or when there is a large number of available treatments and many accepted standards of care. These networks pose a challenge to decision makers and clinicians who want to estimate the relative efficacy and safety of newly available agents against alternatives. A currently recommended approach is to insert a distribution for the unknown treatment effect(s) into a network meta-analysis model of treatment effect. In this paper, we describe this approach along with two alternative Bayesian models that can accommodate disconnected networks. Additionally, we present a theoretical framework to guide the choice between modeling approaches. This paper presents researchers with the tools and framework for selecting appropriate models for indirect comparison of treatment efficacies when challenged with a disconnected framework. Copyright © 2016 John Wiley & Sons, Ltd.

The role of HCV proteins on treatment outcomes

For many years, the standard of treatment for hepatitis C virus (HCV) infection was a combination of pegylated interferon alpha (Peg-IFN-α) and ribavirin for 24–48 weeks. This treatment regimen results in a sustained virologic response (SVR) rate in about 50 % of cases. The failure of IFN-α-based therapy to eliminate HCV is a result of multiple factors including a suboptimal treatment regimen, severity of HCV-related diseases, host factors and viral factors. In recent years, advances in HCV cell culture have contributed to a better understanding of the viral life cycle, which has led to the development of a number of direct-acting antiviral agents (DAAs) that target specific key components of viral replication, such as HCV NS3/4A, HCV NS5A, and HCV NS5B proteins. To date, several new drugs have been approved for the treatment of HCV infection. Application of DAAs with IFN-based or IFN-free regimens has increased the SVR rate up to >90 % and has allowed treatment duration to be shortened to 12–24 weeks. The impact of HCV proteins in response to IFN-based and IFN-free therapies has been described in many reports. This review summarizes and updates knowledge on molecular mechanisms of HCV proteins involved in anti-IFN activity as well as examining amino acid variations and mutations in several regions of HCV proteins associated with the response to IFN-based therapy and pattern of resistance associated amino acid variants (RAV) to antiviral agents.

Identification, synthesis and pharmacological evaluation of novel anti-EV71 agents via cyclophilin A inhibition

In this work, the relationship between cyclophilin A (CypA) and EV71 prompted us to screen a series of small molecular CypA inhibitors which were previously reported by our group. Among them, compounds 1 and 2 were discovered as non-immunosuppressive anti-EV71 agents with an EC50 values of 1.07±0.17μM and 3.36±0.45μM in virus assay, respectively, which were desirably for the further study. The subsequent chemical modifications derived a novel class of molecules, among which compound 11 demonstrated the most potent anti-EV71 activity in virus assay (EC50=0.37±0.17μM), and low cytotoxicity (CC50>25μM). The following CypA enzyme inhibition studies indicated that there was not only the enzyme inhibition activity, undoubtedly important, functioning in the antiviral process, but also some unknown mechanisms worked in combination, and the further study is underway in our laboratory. Nevertheless, to the best of our knowledge, compound 11 was probably the most potent small molecular anti-EV71 agent via CypA inhibitory mechanism to date. Consequently, our study provided a new potential small molecule for curing EV71 infection.

ve-SEQ: Robust, unbiased enrichment for streamlined detection and whole-genome sequencing of HCV and other highly diverse pathogens

The routine availability of high-depth virus sequence data would allow the sensitive detection of resistance-associated variants that can jeopardize HIV or hepatitis C virus (HCV) treatment. We introduce ve-SEQ, a high-throughput method for sequence-specific enrichment and characterization of whole-virus genomes at up to 20% divergence from a reference sequence and 1,000-fold greater sensitivity than direct sequencing. The extreme genetic diversity of HCV led us to implement an algorithm for the efficient design of panels of oligonucleotide probes to capture any sequence among a defined set of targets without detectable bias. ve-SEQ enables efficient detection and sequencing of any HCV genome, including mixtures and intra-host variants, in a single experiment, with greater tolerance of sequence diversity than standard amplification methods and greater sensitivity than metagenomic sequencing, features that are directly applicable to other pathogens or arbitrary groups of target organisms, allowing the combination of sensitive detection with sequencing in many settings.

Asunaprevir (BMS-650032) for the treatment of hepatitis C virus

Asunaprevir, a second-generation NS3 protease inhibitor of hepatitis C virus (HCV), exhibits strong antiviral activity against HCV genotypes 1 and 4, but relatively weak activity against genotypes 2 and 3. For chronic HCV infection, asunaprevir with daclatasvir as an interferon-free dual treatment achieves a sustained virologic response of nearly 90% in genotype 1b, and a triple regimen with beclabuvir achieves an sustained virologic response >90%. Asunaprevir and daclatasvir dual treatment can be safely and effectively administered to liver transplant recipients with recurrent HCV. The major drawback of asunaprevir is its low threshold to resistance, which can be overcome by combining it with other direct-acting antivirals. Further studies of asunaprevir in combination with other direct-acting antivirals for the treatment of patients with HCV genotypes 1 or 4 and renal impairment or end-stage renal disease under hemodialysis, HIV-coinfection and liver and/or kidney transplant recipients are warranted.

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.

Boceprevir-Based Triple Antiviral Therapy for Chronic Hepatitis C Virus Infection in Kidney-Transplant Candidates

Background. There are few data on the combination of (pegylated-) interferon- (Peg-IFN-) α, ribavirin, and first-generation direct-acting antiviral agents (DAAs). Our aim was to describe the efficacy and safety of Peg-IFN-α, ribavirin, and boceprevir in hemodialysis patients. Patients. Six hemodialysis patients, chronically infected by genotype-1 HCV, were given Peg-IFN-α (135 µg/week), ribavirin (200 mg/d), and boceprevir (2400 mg/d) for 48 weeks. Results. At initiation of antiviral therapy, median viral concentration was 5.68 (3.78–6.55) log IU/mL. HCV RNA was undetectable in four of the six patients at week 4 and in all patients at week 24. A breakthrough was observed in two patients between weeks 24 and 48, and a third patient stopped antiviral therapy between weeks 24 and 48 because of severe peripheral neuropathy. At week 48, HCV RNA was undetectable in three patients. Of these, two patients relapsed within a month after antiviral therapy was stopped. Hence, only one patient had a sustained virological response; he was a previous partial responder. Overall, anemia was the main side effect. Conclusion. A triple antiviral therapy based on Peg-IFN-α, ribavirin, and boceprevir is not optimal at treating hemodialysis patients with chronic HCV infection. Studies using new-generation drugs are required in this setting.

Differential inhibition features of direct-acting anti-hepatitis C virus agents against human organic anion transporting polypeptide 2B1

Simeprevir (SMV), asunaprevir (ASV), daclatasvir (DCV) and sofosbuvir (SOF), which are direct-acting antiviral (DAA) agents, are expected to become essential pharmaceutical tools in the fight against the hepatitis C virus (HCV). However, because DAAs are taken orally, there is a potential risk of drug-drug interactions (DDIs) at the absorption step with co-administered drugs in the small intestine. Since it is known that organic anion transporting polypeptide 2B1 (OATP2B1) is one of the key transporters contributing to intestinal drug absorption, it is important to thoroughly understand the inhibition profiles of various DAAs in relation to OATP2B1 function in order to avoid unexpected DDIs. Therefore, using a cell-based transport assay, this study aimed at clarifying such DAA inhibition characteristics towards OATP2B1 function. The results of co-incubation inhibition assays showed that SMV and ASV strongly inhibited estrone sulfate (5 nM) uptake by OATP2B1, with half maximal inhibitory concentrations of 0.49 ± 0.12 μM and 0.16 ± 0.06 μM, respectively. Furthermore, it was found that SMV and ASV imposed long-lasting pre-incubation inhibitory effects on OATP2B1 function that enhanced their co-incubation inhibition potencies. On the other hand, no (or much less significant) inhibitory effects were observed for SOF or DCV. To summarise, these results show that SMV and ASV are co-incubation, as well as long-lasting pre-incubation, inhibitors of OATP2B1 function and therefore these inhibitions may lead to clinically relevant DDIs when used with OATP2B1 substrates.

Liver-related death among HIV/hepatitis C virus-co-infected individuals: implications for the era of directly acting antivirals

BACKGROUND

Potent, less toxic, directly acting antivirals (DAAs) for treatment of hepatitis C virus (HCV) infection promise to improve HCV cure rates among HIV/HCV-co-infected individuals. However, the costs of treatment will necessitate prioritization of those at greatest risk of liver-related death (LRD) for therapy. This study aims to provide guidance on who should be prioritized for DAA treatment.

METHODS

Three thousand, nine hundred and forty-one HCV antibody-positive PSHREG and FIB-4 are names not acronyms (EuroSIDA) patients with follow-up after 1 January 2000 were included, with causes of death classified using Coding causes of Death in HIV (CoDe) methodology. Crude death rates, competing-risks Cox proportional-hazards models and cumulative incidence functions were used to describe factors associated with LRD.

RESULTS

LRD accounted for 145 of 670 (21.6%) deaths in the study population. LRD rates peaked in those aged 35-45 years, and occurred almost exclusively in those with at least F2 fibrosis at baseline. In adjusted Cox models, risk factors for LRD included F4 or F2/F3 fibrosis [sub-distribution hazard ratio (sHR) 6.3, 95% confidence interval (CI) 4.1-9.6; and sHR 2.5, 95% CI 1.5-4.2 vs. F0/F1, respectively), CD4 cell count (sHR 0.83, 95% CI 0.73-0.95 per doubling) and hepatitis B surface antigen-positive (sHR 2.2, 95% CI 1.3-3.5 vs. hepatitis B surface antigen-negative). The 5-year probability of LRD was low in those with F0/F1 fibrosis (sHR 2.2%, 95% CI 1.7-2.9), but substantial in those with F2/F3 and F4 fibrosis (sHR 10.3%, 95% CI 7.6-13.5; and sHR 14.0%, 95% CI 10.3-18.3, respectively).

CONCLUSION

Treatment with DAAs should be prioritized for those with at least F2 fibrosis. Early initiation of cART with the aim of avoiding low CD4 cell counts should be considered essential to decrease the risk of LRD and the need for HCV treatment.

[Sexually transmitted coinfections. HIV coinfections]

Coinfections of sexually transmitted infections are frequent due to the same transmission routes which may facilitate the transmission of other sexually transmitted infections. Sexually transmitted coinfections are associated with atypical and generally more severe clinical features, more complications, resistency to treatment, unfavourable outcome, and worse prognosis. Sexually transmitted infections may increase the likelihood of acquiring and transmission of HIV infection. The authors summarize the most important characteristics of sexually transmitted infections (such as HIV and hepatitis B virus, HIV and hepatitis C virus, HIV and syphilis, HIV and gonorrhoeae, HIV and chlamydia coinfections). These infections are more frequent in HIV infected patients than in the normal population. The shared transmission routes, impairment of the immune response, elevated cytokine levels and the associated inflammatory milieu produce local tissue damage, breaches in mucosal epithelium, which increases the risk of human immunodeficiency virus infection. Regular screening for sexually transmitted infections, use of more sensitive diagnostic methods, improved reporting and avoidance of unsafe sexual behaviour among certain subpopulations as well as education are essential in the prevention of sexually transmitted coinfections.

β-D-2'-C-Methyl-2,6-diaminopurine Ribonucleoside Phosphoramidates are Potent and Selective Inhibitors of Hepatitis C Virus (HCV) and Are Bioconverted Intracellularly to Bioactive 2,6-Diaminopurine and Guanosine 5'-Triphosphate Forms

The conversion of selected β-D-2,6-diaminopurine nucleosides (DAPNs) to their phosphoramidate prodrug (PD) substantially blocks the conversion to the G-analog allowing for the generation of two bioactive nucleoside triphosphates (NTPs) in human hepatocytes. A variety of 2'-C-methyl DAPN-PDs were prepared and evaluated for inhibition of HCV viral replication in Huh-7 cells, cytotoxicity in various cell lines, and cellular pharmacology in both Huh-7 and primary human liver cells. The DAPN-PDs were pan-genotypic, effective against various HCV resistant mutants, and resistant variants could not be selected. 2'-C-Me-DAPN-TP and 2'-C-Me-GTP were chain terminators for genotype 1b HCV-pol, and single nucleotide incorporation assays revealed that 2'-C-Me-DAPN-TP was incorporated opposite U. No cytotoxicity was observed with our DAPN-PD when tested up to 50 μM. A novel, DAPN-PD, 15c, has been selected for further evaluation because of its good virologic and toxicologic profile and its ability to deliver two active metabolites, potentially simplifying HCV treatment.

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.

Alcohol and HCV: implications for liver cancer

Liver cancers are one of the deadliest known malignancies which are increasingly becoming a major public health problem in both developed and developing countries. Overwhelming evidence suggests a strong role of infection with hepatitis B and C virus (HBV and HCV), alcohol abuse, as well as metabolic diseases such as obesity and diabetes either individually or synergistically to cause or exacerbate the development of liver cancers. Although numerous etiologic mechanisms for liver cancer development have been advanced and well characterized, the lack of definite curative treatments means that gaps in knowledge still exist in identifying key molecular mechanisms and pathways in the pathophysiology of liver cancers. Given the limited success with current therapies and preventive strategies against liver cancer, there is an urgent need to identify new therapeutic options for patients. Targeting HCV and or alcohol-induced signal transduction, or virus-host protein interactions may offer novel therapies for liver cancer. This review summarizes current knowledge on the mechanistic development of liver cancer associated with HCV infection and alcohol abuse as well as highlights potential novel therapeutic strategies.

Cost-effectiveness of sofosbuvir plus ribavirin with or without pegylated interferon for the treatment of chronic hepatitis C in Italy

OBJECTIVE

Across Italy up to 7.3% of the population is infected with hepatitis C virus (HCV), with long-term complications resulting in high medical costs and significant morbidity and mortality. Current treatment options have limitations due to side effects, interferon intolerability and ineligibility, long treatment durations and low sustained virological response (SVR) rates, especially for the most severe patients). Sofosbuvir is the first nucleotide polymerase inhibitor with pan-genotypic activity. Sofosbuvir, administered with ribavirin (RBV) and with or without pegylated interferon (PEG-INF), resulted in >90% SVR across treatment-naïve (TN) genotype (GT) 1-6 patients. It is also the first treatment option for patients that are unsuitable for interferon (UI). This analysis evaluates the cost - effectiveness of sofosbuvir for GTs 1-6 in Italy.

RESEARCH DESIGN AND METHODS

A Markov model followed a cohort of 10,000 patients until they reached 80 years old. Approximately 20% of naïve and 30% of experienced patients initiated treatment at the cirrhosis stage. Comparators included PEG-INF + RBV for all GTs and plus telaprevir or boceprevir for GT1, or no treatment. Costs and outcomes were discounted at 3% and the cost perspective was that of the National Health Service in Italy.

RESULTS

Sofosbuvir was cost-effective with incremental cost-effectiveness ratios (ICERs) below €40,000/QALY in all patient populations, particularly in cirrhotic patients. The exception was for a mixed cohort of GT2 TN patients where the ICER was €68,500/QALY and for a cirrhotic cohort of GT4/5/6 where the ICER was €68,434/QALY. Nevertheless, the prevalence of HCV in this patient population is expected to be low. Results were robust to sensitivity analysis.

CONCLUSIONS

Sofosbuvir-based regimens are cost-effective in Italy, particular for the most severe patients. The interferon-free regimens are a real treatment option for UI patients. The high cure rates of this breakthrough treatment are expected to substantially reduce the burden of HCV in Italy.

Hepatitis C virus molecular evolution: Transmission, disease progression and antiviral therapy

Hepatitis C virus (HCV) infection represents an important public health problem worldwide. Reduction of HCV morbidity and mortality is a current challenge owned to several viral and host factors. Virus molecular evolution plays an important role in HCV transmission, disease progression and therapy outcome. The high degree of genetic heterogeneity characteristic of HCV is a key element for the rapid adaptation of the intrahost viral population to different selection pressures (e.g., host immune responses and antiviral therapy). HCV molecular evolution is shaped by different mechanisms including a high mutation rate, genetic bottlenecks, genetic drift, recombination, temporal variations and compartmentalization. These evolutionary processes constantly rearrange the composition of the HCV intrahost population in a staging manner. Remarkable advances in the understanding of the molecular mechanism controlling HCV replication have facilitated the development of a plethora of direct-acting antiviral agents against HCV. As a result, superior sustained viral responses have been attained. The rapidly evolving field of anti-HCV therapy is expected to broad its landscape even further with newer, more potent antivirals, bringing us one step closer to the interferon-free era.

NS5A inhibitor resistance-associated polymorphisms in Brazilian treatment-naive patients infected with genotype 1 hepatitis C virus

OBJECTIVES

Several promising NS5A protein inhibitors for hepatitis C virus (HCV) treatment, showing good antiviral activity, are currently being evaluated in clinical trials. However, viral breakthroughs associated with resistant variants have been observed, especially in patients infected with HCV-1a. We aimed to evaluate the occurrence of potential resistance mutations in the NS5A gene of HCV among Brazilian treatment-naive patients.

METHODS

Direct sequencing of the HCV NS5A gene was performed in serum samples of 106 treatment-naive patients infected with subtypes 1a (n = 52) and 1b (n = 54). The sequence variability, signature patterns in amino acid sequences and variants associated with NS5A inhibitors were evaluated.

RESULTS

The M28T and Y93H mutations were found in the subtype 1a sequences of two (3.85%) patients, and seven (13.46%) other patients presented the secondary mutation(s) H58P, E62D or H58P-E62D. For subtype 1b, the Y93H mutation was found in two (3.70%) patients and the substitutions R30Q, L31M, P58S and I280V were found in eight (14.81%) patients. Two distinct HCV-1a clades were distinguished by a phylogenetic analysis performed along with representative HCV-1a sequences and sequences containing HCV NS5A inhibitor resistance mutations retrieved from the Los Alamos database. All Brazilian sequences formed a large group of related sequences inside clade 1. It is noteworthy that 65.85% of sequences with substitution at sites 28, 30, 31 and 93 were found in clade 1.

CONCLUSION

Brazilian HCV-1a sequences presented a peculiar pattern of amino acid composition, mutations and frequencies, which is distinct from other previously characterized sequences from other locations. The association of these findings with the outcome of treatment with NS5A inhibitors awaits further analysis.

Infrequent development of resistance in genotype 1-6 hepatitis C virus-infected subjects treated with sofosbuvir in phase 2 and 3 clinical trials

BACKGROUND

Sofosbuvir is a chain-terminating nucleotide analogue inhibitor of the hepatitis C virus (HCV) NS5B RNA polymerase that is efficacious in subjects with HCV genotype 1-6 infection. Sofosbuvir resistance is primarily conferred by the S282T substitution in NS5B.

METHODS

NS5B sequencing and susceptibility testing of HCV from subjects infected with genotypes 1-6 who participated in phase 2 and 3 sofosbuvir clinical trials was performed.

RESULTS

No NS5B variants present at baseline among 1645 sofosbuvir-treated subjects were associated with treatment failure; sofosbuvir susceptibility was within 2-fold of reference. Among 282 subjects who did not achieve sustained virologic response, no novel sofosbuvir resistance-associated variants were identified, and the NS5B changes observed did not confer significant reductions in sofosbuvir susceptibility. In 1 subject with S282T observed at relapse 4 weeks after sofosbuvir monotherapy, the resistant variant (13.5-fold reduced sofosbuvir susceptibility, replication capacity <2% of control) became undetectable by deep sequencing 12 weeks after treatment. L159F and V321A were identified as treatment-emergent variants but did not confer resistance to sofosbuvir in the replicon system.

CONCLUSIONS

These data demonstrate a uniform susceptibility of subject-derived HCV to sofosbuvir, and also show that selection of sofosbuvir-resistant HCV is exceedingly rare and is associated with a significant reduction in viral fitness.