Hepatitis C Virus-Genotype 3: Update on Current and Emergent Therapeutic Interventions

Differential Expression of the Host Lipid Regulators ANGPTL-3 and ANGPTL-4 in HCV Infection and Treatment

Host lipid metabolism reprogramming is essential for hepatitis C virus (HCV) infection and progression to severe liver disease. Direct-acting antivirals (DAAs) achieve a sustained virological response (SVR) in most patients, but virus eradication does not always protect against hepatocellular carcinoma (HCC). Angiopoietin-like protein-3 (ANGPTL-3) and angiopoietin-like protein-4 (ANGPTL-4) regulate the clearance of plasma lipids by inhibiting cellular lipase activity and possess emerging roles in tumourigenesis. We used ELISA and RT-qPCR to investigate ANGPTL-3 and ANGPTL-4 expression in HCV patients with characterised fibrosis throughout the natural history of hepatitis C and in long-term HCV infection in vitro, before and after DAA treatment. ANGPTL-3 was decreased in patients with advanced fibrosis compared to other disease stages, while ANGPTL-4 was progressively increased from acute infection to cirrhosis and HCC, peaking at the advanced fibrosis stage. Only ANGPTL-3 mRNA was down-regulated during early infection in vitro, although both ANGPTLs were increased later. DAA treatment did not alter ANGPTL-3 levels in advanced fibrosis/cirrhosis and in HCV infection in vitro, in contrast to ANGPTL-4. The association between ANGPTLs and fibrosis in HCV infection was underlined by an inverse correlation between the levels of ANGPTLs and serum transforming growth factor- β (TGF-β). Collectively, we demonstrate the pivotal role of advanced fibrosis in defining the expression fate of ANGPTLs in HCV infection and after treatment and propose a role for ANGPTL-3 as a contributor to post-treatment deregulation of lipid metabolism that could predispose certain individuals to HCC development.

Association of the Sialylation of Antibodies Specific to the HCV E2 Envelope Glycoprotein with Hepatic Fibrosis Progression and Antiviral Therapy Efficacy

The E2 envelope glycoprotein of the hepatitis C virus (HCV) is a major target of broadly neutralizing antibodies that are closely related to a spontaneous cure of HCV infection. There is still no data about the diversity of E2-specific antibodies (Abs) glycosylation. The aim of this study was to analyze the level and sialylation of E2 IgG Abs, the relation of the respective changes to hepatic fibrosis (F) progression and their possible association with the efficacy of interferon-α-2a plus ribavirin (IFN-RBV) antiviral therapy. One hundred three HCV infected treatment-naive patients were examined using ELISA with E2 recombinant protein as antigen and sialic acid-specific Sambucus nigra agglutinin. The efficacy of the IFN-RBV treatment of patients with HCV dominant 1b and 3a genotypes (GT) was evaluated. A significant decrease of E2 Abs sialylation in the late stages of fibrosis was found irrespective of HCV genotype. On this basis, the F4 stage of fibrosis can be discriminated from its F0 or F1-3 stage by an about 75-79% accuracy. HCV infection of 1b genotype is associated with the production of lower sialylated E2 Abs, a higher frequency of F4 stage fibrosis, and a worse response to antiviral therapy. The increased SNA reactivity of E2 Abs was observed in patients with a sustained virological response (SVR). The proportion of SVR responders was significantly higher among patients with 3a genotype. However, for both dominant HCV genotypes (3a and 1b), an increased sialylation of E2 IgG was associated with a higher rate of patients with sustained virological response to antiviral therapy. Thus, the association of alterations of anti-E2 IgG Abs sialylation with hepatic fibrosis stage, HCV genotype, and the efficacy of antiviral therapy enables using these changes as novel noninvasive predictive biomarkers. The clinical potential of these findings is discussed.

Interplay of Amino Acid Residues at Positions 28 and 31 in NS5A Defines Resistance Pathways in HCV GT2

Hepatitis C virus (HCV) genotype (GT) 2 represents approximately 9% of all viral infections globally. While treatment outcomes for GT2-infected patients have improved substantially with direct-acting antiviral agents (DAAs) compared to interferon-α, the presence of polymorphisms in NS5A can impact efficacy of NS5A inhibitor-containing regimens. Thus, pathways of NS5A resistance were explored in GT2 subtypes using elbasvir, an NS5A inhibitor with broad genotype activity. Resistance selection studies, resistance analysis in NS5A-inhibitor treated virologic failures, antiviral activities in replicons bearing a panel of GT2 subtype sequences and amino acid substitutions introduced by site-directed mutagenesis were performed to define determinants of inhibitor susceptibility. Elbasvir showed differential antiviral activity in replicons bearing GT2 sequences. The EC₅₀ values for replicons bearing reference NS5A sequences for GT2a and GT2b were 0.003 and 3.4 nanomolar (nM) respectively. Studies with recombinant replicons demonstrated crosstalk between amino acid positions 28 and 31. The combination of phenylalanine and methionine at positions 28 and 31 respectively, conferred the highest potency reduction for elbasvir in GT2a and GT2b. This combination was observed in failures from the C-SCAPE trial. Addition of grazoprevir, an NS3/4A protease inhibitor, to elbasvir more effectively suppressed the emergence of resistance in GT2 at modest inhibitor concentrations (3X EC₉₀). Ruzasvir, a potent, pan-genotype NS5A inhibitor successfully inhibited replicons bearing GT2 resistance-associated substitutions (RASs) at positions 28 and 31. The studies demonstrate crosstalk between amino acids at positions 28 and 31 in NS5A modulate inhibitor potency and may impact treatment outcomes in some HCV GT2-infected patients.

Efficacy and safety of alisporivir for the treatment of hepatitis C infection

Alisporivir (ALV) (previously known as Debio 025) is a potent, pangenotypic host-targeting antiviral oral agent acting on cyclophilin A, which is necessary for HCV replication. Areas covered: This article reviews the therapeutic efficacy and safety of ALV for the treatment of HCV infection. Expert opinion: Direct-acting antivirals (DAAs) have revolutionized the HCV antiviral treatment paradigm with success rates well above 95% for all HCV genotypes. However, challenges still remain in certain patient populations such as those who have developed resistance and have experienced multi-DAA failure. To cure HCV infection, a treatment regimen must combine antiviral potency and a high barrier to resistance. ALV fulfills this need as shown by the studies evaluating its clinical efficacy. Nevertheless, ALV missed the chance to be included in the HCV treatment armamentarium after the FDA halted clinical studies following reports of serious side effects (three cases of pancreatitis, one lethal). However, it is possible that ALV could still be considered for HCV-infected non-cirrhotic patients that are infected with a multiresistant virus or with HCV genotype 3, although it must be said that the drug industry would be reluctant to invest in new antivirals if the current clinical need is effectively met.

Satisfactory virological response and fibrosis improvement of sofosbuvir-based regimens for Chinese patients with hepatitis C virus genotype 3 infection: results of a real-world cohort study

Background

Chronic hepatitis C virus (HCV) genotype (GT) 3 infection with advanced liver disease has emerged as a challenging to treat by direct-acting antivirals (DAAs), but the efficacy of DAAs in Chinese HCV-GT3 patients is rarely reported. This study aimed to analyze the efficacy of sofosbuvir (SOF)-based regimens in Chinese patients with HCV-GT3 and compensated liver disease.

Methods

This was a registered retrospective study. All patients had completed at least 12 weeks SOF-based regimens therapy (with or without RBV), and were followed up for at least 24 weeks after therapy discontinuation. The primary endpoint was sustained virological response 24 weeks after end of therapy (SVR24).

Results

A total of 102 patients who completed at least 12 weeks therapy were finally included, with 57 in SOF + Daclatasvir (SOF + DCV), 24 in SOF + DCV + ribavirin (RBV) and 21 in SOF/Velpatasvir (SOF/VEL). The total SVR24 rate was achieved in 90.20% (92/102), with 85.96% (49/57) in SOF + DCV, 91.67% (22/24) in SOF + DCV + RBV and 100.00% (21/21) in SOF/VEL. Among 10 relapsed patients (8 in SOF + DCV and 2 in SOF + DCV + RBV), the short course (12 weeks) of therapy and no RBV addition may be the leading cause. In this cohort, the SVR24 rate was not statistically different between patients with and without cirrhosis (81.82% [27/33] vs. 94.20% [65/69], P = 0.073). Additionally, both FIB-4 (4.03 vs. 2.08, P < 0.001) and APRI (2.15 vs. 0.68, P < 0.001) scores were significant improved from baseline to week 24 after completion of therapy, regardless of the presence of cirrhosis.

Conclusion

SOF-based regimens are highly effective in viral clearance and fibrosis remission for Chinese patients with HCV-GT3 infection. If available, SOF/VEL should be first considered.

Hepatitis C virus genotype 3: clinical features, current and emerging viral inhibitors, future challenges

Hepatitis C virus (HCV) represents a global burden on healthcare that affects over 150 million people worldwide. In the past, HCV genotype 3 was considered difficult to treat relative to other genotypes. Genotype 3 has been associated with a higher rate of complications, including fatty liver disease, fibrosis, hepatocellular carcinoma and mortality. However, with the advent of first- and second-generation direct-acting antivirals, genotype 3 can be treated effectively. Additionally, these new drugs are well tolerated by patients and have significantly fewer side effects compared to ribavirin and interferon-based regimens. However, while great strides have been made in overcoming biological barriers, our next challenge lies in overcoming economic and financial obstacles if we are to eradicate HCV genotype 3. Herein, we review the clinical features associated with HCV genotype 3, current and emerging treatment regimens, and challenges associated with treatment.

Current status and future development of infectious cell-culture models for the major genotypes of hepatitis C virus: Essential tools in testing of antivirals and emerging vaccine strategies

In this review, we summarize the relevant scientific advances that led to the development of infectious cell culture systems for hepatitis C virus (HCV) with the corresponding challenges and successes. We also provide an overview of how these systems have contributed to the study of antiviral compounds and their relevance for the development of a much-needed vaccine against this major human pathogen. An efficient infectious system to study HCV in vitro, using human hepatoma derived cells, has only been available since 2005, and was limited to a single isolate, named JFH1, until 2012. Successive developments have been slow and cumbersome, as each available system has been the result of a systematic effort for discovering adaptive mutations conferring culture replication and propagation to patient consensus clones that are inherently non-viable in vitro. High genetic heterogeneity is a paramount characteristic of this virus, and as such, it should preferably be reflected in basic, translational, and clinical studies. The limited number of efficient viral culture systems, in the context of the vast genetic diversity of HCV, continues to represent a major hindrance for the study of this virus, posing a significant barrier towards studies of antivirals (particularly of resistance) and for advancing vaccine development. Intensive research efforts, driven by isolate-specific culture adaptation, have only led to efficient full-length infectious culture systems for a few strains of HCV genotypes 1, 2, 3, and 6. Hence research aimed at identifying novel strategies that will permit universal culture of HCV will be needed to further our understanding of this unique virus causing 400 thousand deaths annually.

SVR 24 Achievement Two Weeks After a Tripled Dose of Daclatasvir in an HCV Genotype 3 Patient

Directly-acting antivirals (DAA) have changed the chronic hepatitis C virus (HCV) infection therapeutic scenario allowing virus eradication in more than 95% of patients, independently from the genotype, with 12 to 24-week treatment regimens. We describe a 51-year-old Pakistani man with a chronic HCV-genotype 3 (GT3a) infection with moderate liver fibrosis, who achieved sustained virological response (SVR) 24 after a tripled dose of Daclatasvir (DCV) taken erroneously associated to Sofosbuvir (SOF). The patient had a concomitant intestinal TB infection whose treatment had been delayed in order to firstly eradicate HCV to reduce the liver toxicity of anti-mycobacterial drugs. Thanks to the cultural mediator support, we explained to the patient the correct posology of each drug to take during the day consisting of 12 week SOF (400 mg daily) plus DCV (60 mg daily) regimen. He returned 13 days after for a programmed visit and we were surprised to learn that he had taken 3 pills of DCV (180 mg/daily) instead of one, thus ending DCV assumption after only 9 days while SOF was taken correctly. He complained no symptoms. We immediately performed blood test that showed alteration of lactate dehydrogenase, creatine phosphokinase, and creatin kinase MB activity. At day 15 we stopped SOF closely monitoring the patient. Blood test alterations returned normal after one week of treatment suspension, HCV viremia remained suppressed after 4, 12 and 24 weeks proving HCV eradication. If confirmed, these data could suggest that higher doses of DCV, if tolerated, might be employed in short-time HCV-GT3 treatment.

Pharmacokinetic and pharmacodynamic evaluation of daclatasvir, asunaprevir plus beclabuvir as a fixed-dose co-formulation for the treatment of hepatitis C

INTRODUCTION

Many reports have evaluated the clinical efficacy and safety of the fixed-dose all-oral combination of daclatasvir, asunaprevir, and beclabuvir (DCV-TRIO), which was approved in Japan in December 2016 for the treatment of hepatitis C genotype (GT)-1 infection. Areas covered: This article reviews the pharmacodynamic and pharmacokinetic properties of the DCV-TRIO combination. The topics covered include data regarding the drug's absorption, distribution, metabolism, excretion, and antiviral activity strategies. Its therapeutic efficacy and safety in GT-1 infection from phase 2/3 clinical trials are also discussed. Expert opinion: The ideal regimen for the treatment of Hepatitis C virus infection should be potent, pangenotypic, Ribavirin-free, safe, co-formulated, and affordable. Considering these characteristics, DCV-TRIO is neither pangenotypic nor potent enough against GT-1a, regardless of the presence or absence of cirrhosis. Other potential limitations of this regimen are its dosification (twice-daily), and the fact that since it includes a protease inhibitor, it is contraindicated in decompensated cirrhosis. For these reasons, it has only been approved in Japan, where more than 70% of the patients are infected with GT-1b. However, this co-formulation might still have a place in the treatment of non-cirrhotic patients infected with GT-1b provided that massive access to treatment is facilitated.

Natural NS5A inhibitor resistance associated substitutions in hepatitis C virus genotype 1 infected patients from Italy

OBJECTIVES

Genetic variability in NS5A is associated with different levels of resistance to the currently licensed NS5A inhibitors. The aim of this study was to detect NS5A inhibitor resistance associated substitutions (RASs) in hepatitis C virus (HCV) genotype 1 (GT1) patients who are naive to direct-acting HCV antivirals.

METHODS

Amplification, Sanger sequencing and phylogenetic analysis of the HCV NS5A region were performed on plasma obtained from 122 consecutive patients with HCV chronic infection attending four different clinics in Italy.

RESULTS

NS5A inhibitor RASs were detected in 14/61 (23.0%) HCV GT1b and 3/61 (4.9%) HCV GT1a infected patients (p 0.007). The pan-genotypic RAS Y93H was detected in 1 (1.6%) GT1a and 4 (6.6%) GT1b patients. GT1a sequences clustered into two different clades with RASs detected in 1/34 (2.9%) clade I and 2/27 (7.4%) clade II sequences.

CONCLUSIONS

Although the impact of naturally occurring NS5A RASs might be limited with upcoming pan-genotypic treatment regimens, this information is still useful to map naturally occurring HCV variants in different geographic areas in the context of current HCV therapy.

Treatment of hepatitis C with new fixed dose combinations

INTRODUCTION

The advent of oral direct-acting antivirals (DAA) has revolutionized the hepatitis C virus (HCV) therapeutic landscape providing cure rates over 90%. However, a subset of patients remains at higher risk for treatment failure, including those infected with: i) genotype 3 and cirrhosis; ii) resistance-associated substitutions (RAS) occurring either as natural polymorphisms or selected after prior DAA failure; and iii) poor drug adherence associated with social disabilities (homeless, psychiatric illnesses, injection drug use, alcoholism, etc.). Whereas discovery of new DAA with increased antiviral activity across all genotypes and over RAS may enhance efficacy, development of fixed dose combinations (FDC) may be the best way to improve drug adherence in difficult-to-treat HCV populations. Areas covered: Three FDC regimens are in the last steps of clinical development for treating hepatitis C. Two distinct nucleotide analogues that inhibit the HCV polymerase, sofosbuvir and uprifosbuvir, are part of the FDC from Gilead and Merck, respectively. The AbbVie dual FDC does not include a polymerase inhibitor. All three new FDC include second-generation NS3 protease inhibitors and NS5A inhibitors active across all HCV genotypes and over common RAS. Expert opinion: Hepatitis C cure rates over 95% are expected with all three next-coming DAA, even in the most difficult-to-treat and/or cure patient populations. These regimens would be particularly needed for the growing number of prior DAA failures. Co-formulations and 8-week shorter treatment lengths will help to overcome drug adherence challenges in certain populations.

Evaluation of sofosbuvir, velpatasvir plus voxilaprevir as fixed-dose co-formulation for treating hepatitis C

INTRODUCTION

The fixed-dose combination of three direct-acting antivirals (DAA), namely sofosbuvir, velpatasvir and voxilaprevir is the first pangenotypic, single tablet regimen developed for the treatment of HCV infection. Areas covered: The pharmacokinetics, pharmacodynamics, efficacy and safety of the co-formulation are reviewed. Information on drug absorption, distribution, metabolism and excretion of each of the three antivirals is evaluated. Finally, antiviral activity, safety and potential for drug interactions in phase II/III clinical trials in distinct patient populations are discussed. Expert opinion: The triple co-formulation of sofosbuvir-velpatasvir-voxilaprevir represents a major step towards HCV eradication. It depicts high efficacy even in patients infected with viruses harboring resistance-associated substitutions (RAS), including those selected after DAA failures. Likewise, very high success rates and good tolerance are seen in special patient populations, including decompensated cirrhotics, HIV coinfection, organ transplantation or renal insufficiency. A pill once daily for 8 weeks gives SVR rates above 95%. In prior DAA failures, extending treatment to 12 weeks maximizes SVR rates.