61 FACTORS INFLUENCING PROGRESSION OF LIVER FIBROSIS IN PATIENTS WITH CHRONIC HEPATITIS C: RESULTS OF THE 3-YEAR T2S-918-HCV STUDY WITH HCVE1 THERAPEUTIC VACCINATION

Function of the HCV E1 envelope glycoprotein in viral entry and assembly

HCV envelope glycoproteins, E1 and E2, are multifunctional proteins. Until recently, E2 glycoprotein was thought to be the fusion protein and was the focus of investigations. However, the recently obtained partial structures of E2 and E1 rather support a role for E1 alone or in association with E2 in HCV fusion. Moreover, they suggest that HCV harbors a new fusion mechanism, distinct from that of other members of the Flaviviridae family. In this context, E1 aroused a renewed interest. Recent functional characterizations of E1 revealed a more important role than previously thought in entry and assembly. Thus, E1 is involved in the viral genome encapsidation step and influences the association of the virus with lipoprotein components. Moreover, E1 modulates HCV–receptor interaction and participates in a late entry step potentially fusion. In this review, we outline our current knowledge on E1 functions in HCV assembly and entry.

Global elimination of hepatitis C virus infection: Progresses and the remaining challenges

Today, with the introduction of interferon-free direct-acting antivirals and outstanding progresses in the prevention, diagnosis and treatment of hepatitis C virus (HCV) infection, the elimination of HCV infection seems more achievable. A further challenge is continued transmission of HCV infection in high-risk population specially injecting drug users (IDUs) as the major reservoir of HCV infection. Considering the fact that most of these infections remain undiagnosed, unidentified HCV-infected IDUs are potential sources for the rapid spread of HCV in the community. The continuous increase in the number of IDUs along with the rising prevalence of HCV infection among young IDUs is harbinger of a forthcoming public health dilemma, presenting a serious challenge to control transmission of HCV infection. Even the changes in HCV genotype distribution attributed to injecting drug use confirm this issue. These circumstances create a strong demand for timely diagnosis and proper treatment of HCV-infected patients through risk-based screening to mitigate the risk of HCV transmission in the IDUs community and, consequently, in the society. Meanwhile, raising general awareness of HCV infection, diagnosis and treatment through public education should be the core activity of any harm reduction intervention, as the root cause of failure in control of HCV infection has been lack of awareness among young drug takers. In addition, effective prevention, comprehensive screening programs with a specific focus on high-risk population, accessibility to the new anti-HCV treatment regimens and public education should be considered as the top priorities of any health policy decision to eliminate HCV infection.

AS, Liz AL, Lisset GF, Sacha LDV, Elena FB. Clinical Evaluation of Terap C Vaccine in Combined Treatment with Interferon and Ribavirin in Patients with Hepatitis C

BACKGROUND

An estimated 170 million individuals worldwide are infected with the hepatitis C virus (HCV). Although treatment options using a combination of pegylated interferon and ribavirin (P-IFN/RBV) are available, sustained clearance of the virus is only achieved in approximately 40% of individuals infected with HCV genotype 1. Recent advances in the treatment of HCV using directly acting antiviral agents have been achieved; however, treatment can be very expensive and is associated with substantial side effects. The development of a new treatment modality is needed. One possible modality could be specific immunotherapy. Terap C is a therapeutic vaccine candidate composed of pIDKE2, a plasmid expressing HCV structural antigens, with a recombinant HCV core protein, Co.120.

OBJECTIVE

To assess the safety and efficacy of concomitant therapy with the candidate vaccine, Terap C, IFN α-2b and ribavirin in untreated individuals with HCV genotype 1 infection.

METHODS

This was a Phase II randomized, placebo-controlled, double-blind clinical trial evaluating the safety and efficacy of Terap C concomitant with IFN α-2b/RBV in 92 treatment-naïve patients with HCV genotype 1 infection. The study was conducted at the Gastroenterology Institute in Havana, Cuba. Patients were randomly assigned to 1 of 5 groups. The control group (Group 1) received IFN α-2b/RBV and placebo for 48 weeks. Groups 2 and 3 were administered Terap C 6 and 9 times, respectively, in addition to standard IFN α-2b/RBV treatment. In groups 4 and 5, Terap C was introduced 12 weeks after the initiation of IFN α-2b/RBV and administered 6 and 9 times, respectively, concomitant with IFN α-2b/RBV.

RESULTS

All patients showed some adverse events. Out of 3615 adverse events, only 18.8% were considered to be probably associated with administration of Terap C. Most events (47.4%) were considered to be improbably associated with of administration Terap C. Only 33.8% were considered possibly temporarily associated with Terap C, and can be explained by the use of conventional IFN α-2b + RBV or by HCV itself. The most common adverse events (≥65%) observed were pain at the injection site, headache, asthenia, psychiatric disturbances, fever, and gastrointestinal symptoms. Regarding sustained virological response, a 20% superiority was observed in the patients who received concomitant Terap C treatments from the beginning of the study compared with those who started after Week 12.

CONCLUSIONS

Vaccination with Terap C in patients with chronic HCV infection was safe and well tolerated. Clinical trial protocol code: IG/VHI/HC/0701; Public Register Code: RPCEC00000074.

Progress in the development of vaccines for hepatitis C virus infection

The hepatitis C virus (HCV), first described in 1989, is now a leading cause of liver cirrhosis and hepatocellular carcinoma. With more than 170 million people infected globally, this virus is a major public health issue. The current standard therapy is based on interferon in combination with ribavirin. This costly therapy often fails to completely clear the infection and is associated with adverse side effects. Recent anti-HCV therapies are interferon-free direct-acting antiviral (DAA) regimens for HCV, including simeprevir, sofosbuvir, and ledipasvir, which have effects on non-structural proteins. DAA regimens have several advantages, such as specifically targeting HCV viral replication, accompanied by very high sustained virological response rates and lower side effects like flu-like syndrome. These facts plus the fact that most HCV cases progress to chronic infection suggest the potential need for an efficient HCV vaccine. Different innovative methods, including methods based on peptide, recombinant protein, DNA, vector-based, and virus-like particles, have been introduced for the development of HCV vaccines. An extensive number of studies have been published on these vaccines, and some vaccines were even tested in clinical trials. In the current review, progress in the development of preventive and therapeutic vaccines against the HCV is reviewed in the context of peptide vaccines, recombinant protein vaccines, HCV-like particle, DNA vaccines and viral vectors expressing HCV genes.

[Molecular aspects of the antiviral response against hepatitis C virus implicated in vaccines development]

Hepatitis C is a contagious liver disease caused by hepacivirus of the Flaviviridae family. It has a RNA genome, a unique highly variable molecule. It encodes ten proteins which are necessary to infect cells and multiply. Replication occurs only in hepatocytes. Because of its wide genomic variability and the absence of symptoms, it is difficult to make an early diagnosis and successful treatment. In this review we analyze the molecular mechanism by which the virus infects the hepatocytes and causes the disease. We focused the analysis on different therapies, with the possibility of improving treatment with the use of new specific vaccines. We highlight the use of new therapies based on nucleic acids, mainly DNA vectors. In the near future, once this treatment is adequately evaluated in clinical trials, and the costs are calculated, it could be a very beneficial alternative to conventional methods.

Advances in hepatitis C virus vaccines, part two: advances in hepatitis C virus vaccine formulations and modalities

INTRODUCTION

Developing a vaccine against HCV is an important medical and global priority. Unavailability and potential dangers associated with using attenuated HCV viral particles for vaccine preparation have resulted in the use of HCV genes and proteins formulated in novel vaccine modalities.

AREAS COVERED

In part one of this review, advances in basic knowledge for HCV vaccine design were provided. Herein, a detailed and correlated patents (searched by Espacenet) and literatures (searched by Pubmed) review on HCV vaccine formulations and modalities is provided, including: subunit, DNA, epitopic-peptide/polytopic, live vector- and whole yeast-based vaccines. Less-touched areas in vaccine studies such as mucosal, plant-based, and chimeric HBV/HCV vaccines are also discussed. Furthermore, results of preclinical/clinical studies on selected HCV vaccines as well as pros and cons of different strategies are reviewed. Finally, potential strategies for creation and/or improvement of HCV vaccine formulations are discussed.

EXPERT OPINION

Promising outcomes of a few HCV vaccine modalities in phase I/II clinical trials predict the accessibility of at least partially effective vaccines to inhibit or treat the chronic state of HCV infection (specially in combination with standard antiviral therapy). ChronVac-C (plasmid DNA), TG4040 (MVA-based), and GI-5005 (whole yeast-based) might be the most obvious HCV vaccine candidates to be approved in the near future.

Vaccination for hepatitis C virus: closing in on an evasive target

Hepatitis C virus (HCV) infects more than 170 million people globally and is a leading cause of liver cirrhosis, transplantation and hepatocellular carcinoma. Current gold-standard therapy often fails, has significant side effects in many cases and is expensive. No vaccine is currently available. The fact that a significant proportion of infected people spontaneously control HCV infection in the setting of an appropriate immune response suggests that a vaccine for HCV is a realistic goal. A comparative analysis of infected people with distinct clinical outcomes has enabled the characterization of many important innate and adaptive immune processes associated with viral control. It is clear that a successful HCV vaccine will need to exploit and enhance these natural immune defense mechanisms. New HCV vaccine approaches, including peptide, recombinant protein, DNA and vector-based vaccines, have recently reached Phase I/II human clinical trials. Some of these technologies have generated robust antiviral immunity in healthy volunteers and infected patients. The challenge now is to move forward into larger at-risk or infected populations to truly test efficacy.

Progress in the development of preventive and therapeutic vaccines for hepatitis C virus

Hepatitis C virus (HCV) is a blood borne disease estimated to chronically infect 3% of the worlds' population causing significant morbidity and mortality. Current medical therapy is curative in approximately 50% of patients. While recent treatment advances of genotype 1 infection using directly acting antiviral agents (DAAs) are encouraging, there is still a need to develop vaccine strategies capable of preventing infection. Moreover, vaccines may also be used in future in combination with DAAs enabling interferon-free treatment regimens. Viral and host specific factors contribute to viral evasion and present important impediments to vaccine development. Both, innate and adaptive immune responses are of major importance for the control of HCV infection. However, HCV has evolved ways of evading the host's immune response in order to establish persistent infection. For example, HCV inhibits intracellular interferon signalling pathways, impairs the activation of dendritic cells, CD8(+) and CD4(+) T cell responses, induces a state of T-cell exhaustion and selects escape variants with mutations CD8(+) T cell epitopes. An effective vaccine will need to produce strong and broadly cross-reactive CD4(+), CD8(+) T cell and neutralising antibody (NAb) responses to be successful in preventing or clearing HCV. Vaccines in clinical trials now include recombinant proteins, synthetic peptides, virosome based vaccines, tarmogens, modified vaccinia Ankara based vaccines, and DNA based vaccines. Several preclinical vaccine strategies are also under development and include recombinant adenoviral vaccines, virus like particles, and synthetic peptide vaccines. This paper will review the vaccines strategies employed, their success to date and future directions of vaccine design.