Future trends in managing hepatitis C

Advances in Antiviral Delivery Systems and Chitosan-Based Polymeric and Nanoparticulate Antivirals and Antiviral Carriers

Current antiviral therapy research is focused on developing dosage forms that enable highly effective drug delivery, providing a selective effect in the organism, lower risk of adverse effects, a lower dose of active pharmaceutical ingredients, and minimal toxicity. In this article, antiviral drugs and the mechanisms of their action are summarized at the beginning as a prerequisite background to develop relevant drug delivery/carrier systems for them, classified and briefly discussed subsequently. Many of the recent studies aim at different types of synthetic, semisynthetic, and natural polymers serving as a favorable matrix for the antiviral drug carrier. Besides a wider view of different antiviral delivery systems, this review focuses on advances in antiviral drug delivery systems based on chitosan (CS) and derivatized CS carriers. CS and its derivatives are evaluated concerning methods of their preparation, their basic characteristics and properties, approaches to the incorporation of an antiviral drug in the CS polymer as well as CS nanoparticulate systems, and their recent biomedical applications in the context of actual antiviral therapy. The degree of development (i.e., research study, in vitro/ex vivo/in vivo preclinical testing), as well as benefits and limitations of CS polymer and CS nanoparticulate drug delivery systems, are reported for particular viral diseases and corresponding antivirotics.

Basic answers to complicated questions for the course of chronic hepatitis C treatment

Hepatitis C virus infection is a long-lasting disease, which causes chronic hepatitis, liver cirrhosis and hepatocellular carcinoma, thus leading to liver-related death. Currently, the optimal treatment for chronic hepatitis C infection is the combination of pegylated interferon and ribavirin. The aim of this review is to assess the long-term clinical outcomes of interferons alone or in combination with ribavirin in the management of chronic hepatitis C.

Altered thymic function during interferon therapy in HCV-infected patients

Interferon alpha (IFNα) therapy, despite good efficacy in curing HCV infection, leads to major side effects, in particular inducement of a strong peripheral T-cell lymphocytopenia. We here analyze the early consequences of IFNα therapy on both thymic function and peripheral T-cell homeostasis in patients in the acute or chronic phase of HCV-infection as well as in HIV/HCV co-infected patients. The evolution of T-cell subsets and T-cell homeostasis were estimated by flow cytometry while thymic function was measured through quantification of T-cell receptor excision circles (TREC) and estimation of intrathymic precursor T-cell proliferation during the first four months following the initiation of IFNα therapy. Beginning with the first month of therapy, a profound lymphocytopenia was observed for all T-cell subsets, including naïve T-cells and recent thymic emigrants (RTE), associated with inhibition of intrathymic precursor T-cell proliferation. Interleukin (IL)-7 plasma concentration rapidly dropped while lymphocytopenia progressed. This was neither a consequence of higher consumption of the cytokine nor due to its neutralization by soluble CD127. Decrease in IL-7 plasma concentration under IFNα therapy correlated with the decline in HCV viral load, thymic activity and RTE concentration in blood. These data demonstrate that IFNα-based therapy rapidly impacts on thymopoiesis and, consequently, perturbs T-cell homeostasis. Such a side effect might be detrimental for the continuation of IFNα therapy and may lead to an increased level of infectious risk, in particular in HIV/HCV co-infected patients. Altogether, this study suggests the therapeutic potential of IL-7 in the maintenance of peripheral T-cell homeostasis in IFNα-treated patients.

Treatment options for hepatitis C and the rationale for low response rates in African Americans

Hepatitis C virus (HCV), the leading cause for liver transplantation, is emerging as1 of the infections that pose public health problems in the world since about 170 million people worldwide are infected with this virus. Inequality in addressing racial/ethnic disparities in treatment for hepatitis C is a pressing problem. HCV is more common among African Americans than among other racial groups in the United States. Although African Americans have been shown to have a lower rate of viral clearance and a higher rate of chronic hepatitis C, they may have at the same time a much lower rate of fibrosis progression compared to Caucasians. The purpose of this study is to summarize treatment options available for hepatitis C in African Americans and to describe the different mechanisms thought to be the reasons for the disparate response to treatment in African Americans.

Do statins reduce hepatitis C RNA titers during routine clinical use?

AIM: To compare hepatitis C virus (HCV) titers in patients with chronic hepatitis C with and without exposure to 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins).

METHODS: Medical records were reviewed for 6463 patients with documented HCV infection at a single center between March 2004 and September 2006. Patients with confirmed viremia and meeting inclusion criteria were assigned to one of three groups: Group A (n = 50), dyslipidemic patients with statin usage during HCV RNA polymerase chain reaction (PCR) determination; Group B (n = 49), dyslipidemic patients with prior or future statin usage but not at the time of HCV RNA PCR determination; and Group C (n = 102), patients without statin usage during the study period. The primary analysis explored the effect of statin therapy on HCV viremia. Secondary analyses assessed class effect, dose response, and effect of other lipid-lowering therapies on HCV viral titers.

RESULTS: Median HCV RNA titers did not significantly differ among the three groups (Group A: 4 550 000 IU/mL, Group B: 2 850 000 IU/mL, Group C: 3 055 000 IU/mL). For those subjects with longitudinal assessment of HCV viremia prior to and while on statins, there were no significant differences between pre- and post-HCV viral titers. Additionally, no differences in HCV titers were observed at any dose level of the most prescribed statin, simvastatin. However, hypertriglyceridemia independently correlated with HCV titers, and niacin exposure was associated with significantly lower viral titers (P < 0.05).

CONCLUSION: There was no apparent effect of statins on HCV viral replication in this analysis. Further investigation is warranted to explore the possible antiviral properties of triglyceride-lowering agents and their potential role as adjuncts to standard HCV therapy.

Clinical management of HIV/hepatitis C virus coinfection

PURPOSE

The purpose of this study was to review the current management of hepatitis C virus (HCV) in persons coinfected with HIV.

DATA SOURCES

Comprehensive review of current scientific literature derived from electronic databases, article bibliographies, and conference abstracts.

CONCLUSIONS

HCV treatment is feasible in the individual coinfected with HIV; however, therapy is complex and requires intensive monitoring and support to achieve the outcome of viral eradication. New strategies to improve HCV treatment rates, adherence to therapy, and virological response rates are needed in this patient population.

IMPLICATIONS FOR PRACTICE

Nurse practitioners are crucial to the management of the HIV/HCV-coinfected patient. This patient population requires detailed clinical monitoring, education, side effect management, and strategies to improve adherence to therapy.

Molecular virology of the hepatitis C virus: implication for novel therapies

With the advent of second-generation agents that for the first time specifically target individual HCV proteins, HCV-specific therapy has arrived. The study of HCV molecular virology has helped make this possible and is helping us to identify additional new antiviral targets that will be targeted by third-generation drugs. Key to these efforts is the development of high-efficiency HCV replicons. The future effective pharmacologic control of HCV will likely consist of a cocktail of simultaneously administered virus-specific agents with independent targets. This should minimize the emergence of resistance against any single agent. The way we treat HCV should change dramatically over the next few years.

Long-term treatment with the combination of amantadine and ribavirin in hepatitis C nonresponders. A case series

In this report, we describe five cases of chronic hepatitis C that have been treated with the combination of amantadine and ribavirin for an average of 44 months, emphasizing one case where the patient showed improvement in liver biopsy after treatment, worsening on removal, then a repeated improvement with re-initiation. The five patients in this report belong to a pool of sixty patients from a 6 month pilot study using amantadine and ribavirin where treatment was subsequently continued. The mean ALT was 82.8+/-32 U/L pre-treatment and 33.8+/-17.3 U/L post-treatment (p=0.02). The mean Knodell score was 7+/-1 pre-treatment and 3.6+/-1.5 post-treatment (p=0.13). The mean viral load was 584,155+/-248,027 lU/ml pre-treatment and 225,878+/-190,143 IU/ml post-treatment (p=0.05). In this case series we provide provocative data on the long-term use of ribavirin and amantadine in the HCV non-responder.

Therapeutic issues in HIV/HCV-coinfected patients

The importance of treating hepatitis C virus (HCV)-associated morbidities in a growing population of patients coinfected with human immunodeficiency virus (HIV) has increased since the introduction of highly active antiretroviral therapy. As a result, investigative attention is turning to HCV-related liver disease and treatment-associated issues in coinfection. HIV/HCV-coinfected patients have higher HCV RNA loads and show more rapid progression of fibrosis than do monoinfected patients. Combination therapy with pegylated interferon plus ribavirin (RBV) is the standard of care for HCV in coinfected patients. Therapy slows fibrosis progression, but toxicity prevents identification of the most effective RBV dose. Coinfected patients have about a threefold greater risk of antiretroviral therapy-associated hepatotoxicity than patients with HIV only. Other challenges include anaemia, mitochondrial toxicity, drug-drug interactions and leucopenia. Thus, chronic hepatitis C should be treated in HIV/HCV-coinfected patients, but steps must be taken to prevent and treat potential toxicities. The first European Consensus Conference on the Treatment of Chronic Hepatitis B and C in HIV Co-infected Patients was held March 2005 in Paris to address these issues. This article reviews the peer-reviewed literature and expert opinion published from 1990 to 2005, and compares results with presentations and recommendations from the Consensus Conference to best present current issues in coinfection.

Evaluating replication-defective vesicular stomatitis virus as a vaccine vehicle

We have generated replication-competent (VSV-C/E1/E2) and nonpropagating (VSVDeltaG-C/E1/E2) vesicular stomatitis virus (VSV) contiguously expressing the structural proteins of hepatitis C virus (HCV; core [C] and glycoproteins E1 and E2) and report on their immunogenicity in murine models. VSV-C/E1/E2 and VSVDeltaG-C/E1/E2 expressed high levels of HCV C, E1, and E2, which were authentically posttranslationally processed. Both VSV-expressed HCV E1-E2 glycoproteins were found to form noncovalently linked heterodimers and appeared to be correctly folded, as confirmed by coimmunoprecipitation analysis using conformationally sensitive anti-HCV-E2 monoclonal antibodies (MAbs). Intravenous or intraperitoneal immunization of BALB/c mice with VSV-C/E1/E2 or VSVDeltaG-C/E1/E2 resulted in significant and surprisingly comparable HCV core or E2 antibody responses compared to those of control mice. In addition, both virus types generated HCV C-, E1-, or E2-specific gamma interferon (IFN-gamma)-producing CD8(+) T cells, as determined by enzyme-linked immunospot (ELISPOT) analysis. Mice immunized with VSVDeltaG-C/E1/E2 were also protected against the formation of tumors expressing HCV E2 (CT26-hghE2t) and exhibited CT26-hghE2t-specific IFN-gamma-producing and E2-specific CD8(+) T-cell activity. Finally, recombinant vaccinia virus (vvHCV.S) expressing the HCV structural proteins replicated at significantly lower levels when inoculated into mice immunized with VSV-C/E1/E2 or VSVDeltaG-C/E1/E2, but not with control viruses. Our data therefore illustrate that potentially safer replication-defective VSV can be successfully engineered to express high levels of antigenically authentic HCV glycoproteins. In addition, this strategy may therefore serve in effective vaccine and immunotherapy-based approaches to the treatment of HCV-related disease.

Development of prophylactic and therapeutic vaccines against hepatitis C virus

The hepatitis C virus was discovered 15 years ago as the agent responsible for most cases of transfusion-associated hepatitis non-A, non-B. At present, 180 million people worldwide are estimated to be infected with the virus, producing severe and progressive liver disease in millions and representing the most common reason for liver transplantation in adults. Although the spread of the virus can be halted by the application of primary prevention strategies, such as routine testing of blood donations, inactivation of blood products and systematic use of disposable needles and syringes, the development of a prophylactic vaccine could facilitate the control of this infection and protect those at high risk of being infected with hepatitis C virus. As the present therapy of chronic hepatitis C virus infections, consisting of a combined administration of pegylated interferon-alpha and ribavirin, is only successful in 50% of patients infected with genotype 1, and is costly and associated with serious side effects, there is an urgent need for better tolerated and more effective treatment modalities, and a therapeutic vaccine may be the solution. This review first provides an overview of the present knowledge regarding the interaction between the virus and immune system of the infected host, with special attention given to the possible mechanisms responsible for chronic evolution of the infection. The numerous candidate vaccines that have been developed in the past 10 years are discussed, including the studies in which their immunogenicity has been examined in rodents and chimpanzees. Finally, the only studies of therapeutic vaccines performed in humans to date are considered.

Majority of patients with hepatitis C express physical, mental, and social difficulties with antiviral treatment

OBJECTIVE

The hepatitis C virus can be successfully treated in up to 60% of infected patients. However, treatment is long and is associated with significant side-effects. We investigated difficulties with this treatment as it is an important factor in patient adherence.

METHODS

Patients receiving hepatitis C treatment in a tertiary referral center were enrolled in a cross-sectional study. Demographic data, functional and emotional status, and co-morbidities were collected from patients or abstracted from the medical records. All participants underwent a semistructured interview, which was analysed by blinded coders.

RESULTS

A total of 65 patients (mean age 46.1 years; 38.5% women) were enrolled. Fifty-two (80%) described moderate to severe problems attributed to treatment, with a predominance of physical difficulties (fatigue 74% of cases; flu-like symptoms 32%). Approximately one third of patients (38%) experienced depression during treatment. In 31% of cases, physical or emotional problems forced patients to quit their jobs or reduce employment. One fifth attributed deteriorating relationships with friends and family to adverse treatment effects. Necessary lifestyle adjustments, such as alcohol abstinence, caused frictions with friends in 22% of the participants.

CONCLUSIONS

Our findings show a high prevalence of significant adverse effects in patients undergoing antiviral therapy. Whereas the nature and severity of these adverse reactions is consistent with earlier reports, we identified implications with worsening private and professional relationships. To encourage appropriate levels of adherence, healthcare providers should seek information about these indirect treatment effects as they monitor their patients on therapy.

Treating HCV with ribavirin analogues and ribavirin-like molecules

Nucleos(t)ide analogues have proven useful in the treatment of viral infections. Ribavirin is a nucleoside, guanosine analogue, whose mechanisms of action include inhibition of inosine monophosphate dehydrogenase (IMPDH), which is the key step in de novo guanine synthesis, a requirement for viral replication. In combination with pegylated interferon alfa, ribavirin is the standard of care for the treatment of chronic hepatitis C today. However, the medication is associated with significant haemolytic anaemia, which may require dose reduction, discontinuation or treatment with recombinant human erythropoietin. Dose reduction also appears to decrease sustained viral clearance rates. Newer IMPDH inhibitors are in various stages of development. Viramidine, a liver-targeting prodrug of ribavirin, has demonstrated significant antiviral activity and erythrocyte-sparing properties. It is currently in Phase 3 trials. Clinical trials of merimepodib, another investigational IMPDH inhibitor, have completed enrolment for a Phase 2b study as a third medication for administration with pegylated interferon plus ribavirin. Although other IMDPH inhibitors also have antiviral activity, these medications appear best suited as immunosuppressive medications at this time.

Molecular virology of the hepatitis C virus: implication for novel therapies

The study of hepatitis C virus (HCV) molecular virology is helping to shape the future of our anti-HCV strategies by identifying new antiviral targets. With the advent of agents that specifically target individual HCV proteins, HCV-specific therapy has arrived. Key to these efforts is the development of high-efficiency HCV replicons. The future effective pharmacologic control of HCV will likely consist of a cocktail of simultaneously administered virus-specific agents with independent targets. This should minimize the emergence of resistance against any single agent. The way we treat HCV should change dramatically over the next few years.

Nonresponders to Previous Chronic Hepatitis C Treatment

The main strategy governing treatment of chronic hepatitis C is the prevention of future liver complications. There is good evidence that curing hepatitis C infection prevents progression of liver disease and allows histologic regression to occur. Therefore, the primary goal of medical treatment is to cure the viral infection. Combination therapy with peginterferon alfa and ribavirin is the current standard of care; there are no other medical therapies currently available. Those who failed to respond to an earlier version of antiviral therapy should strongly consider treatment with peginterferon/ribavirin if possible. Nearly half of patients who start peginterferon/ribavirin are unable to achieve a sustained disappearance of infection. If there were problems related to dosing or adherence the first time around, it is reasonable to consider re-treating with more aggressive support. Nonresponders to the current therapy who have early-stage liver disease can afford to wait until new antiviral agents come along in the next 5 to 10 years. However, physicians should encourage nonresponding patients with advanced fibrosis to consider experimental alternatives in the meantime, provided there is a logical rationale for the treatment proposed. Some re-treatment strategies still aim to cure the hepatitis C virus infection whereas others focus on limiting liver damage. The best candidates for the first strategy are patients who had temporary clearance of the virus during previous treatment and those with hepatitis C virus genotype 2 or 3 infection. Logical candidates for the second strategy are those who already have advanced fibrosis. It is preferable to pursue further attempts at treatment within the framework of a controlled trial. Studies with strong rationales include those investigating high-dose peginterferon/ribavirin, long-term peginterferon suppression, potential immune modulators, and potential inhibitors of liver fibrosis. The rationales are weaker for re-treatment with a second brand of peginterferon/ribavirin, daily standard interferon plus ribavirin, and ribavirin monotherapy.