Long-term clearance of hepatitis C virus following interferon α-2b or peginterferon α-2b, alone or in combination with ribavirin

The basics and advances of immunomodulators and antigen presentation: a key to development of potent memory response against pathogens

INTRODUCTION

Immunomodulators are agents, which can modulate the immune response to specific antigens, while causing least toxicity to the host system. Being part of the modern vaccine formulations, these compounds have contributed remarkably to the field of therapeutics. Despite the successful record maintained by these agents, the requirement of novel immunomodulators keeps increasing due to the increasing severity of diseases. Hence, research regarding the same holds great importance.

AREAS COVERED

In this review, we discuss the role of immunomodulators in improving performance of various vaccines used for counteracting most threatening infectious diseases, mechanisms behind their action and criteria for development of novel immunomodulators.

EXPERT OPINION

Understanding the molecular mechanisms underlying immune response is a prerequisite for development of effective therapeutics as these are often exploited by pathogens for their own propagation. Keeping this in mind, the present research in the field of immunotherapy focuses on developing immunomodulators that would not only enhance the protection against pathogen, but also generate a long-term memory response. With the introduction of advanced formulations including combination of different kinds of immunomodulators, one can expect tremendous success in near future.

Reversal, maintenance or progression: what happens to the liver after a virologic cure of hepatitis C?

A sustained virological response (SVR) from HCV (synonymous with virological cure) leads to decreased mortality, morbidity and improved quality of life, as well as a reduced incidence of liver disease progression, including liver failure, cirrhosis and hepatocellular carcinoma. Large clinical trials comparing pre- and post-treatment liver biopsies demonstrate improvements in inflammation as well as fibrosis score following SVR. However, a small subset of patients display persistent hepatic inflammation and/or progress to cirrhosis despite SVR. In addition to conferring a risk of fibrosis progression, advanced fibrosis pre-treatment is a major risk factor for post-SVR hepatocellular carcinoma. In this review, we discuss the mechanisms of fibrosis regression uncovered using experimental fibrosis models and highlight potential mechanisms in those few patients with fibrosis progression despite SVR. We also introduce current concepts of fibrosis-dependent tumorigenesis post-SVR in patients with advanced disease. This article forms part of a symposium in Antiviral Research on "Hepatitis C: next steps toward global eradication."

Towards hepatitis C eradication from the HIV-infected population

Around 10-15% of the 35 million people living with HIV worldwide have chronic hepatitis C virus (HCV) infection and are prone to develop liver-related complications. Exposure to HCV is almost universal among injecting drug users and is on the rise among homosexual men. Response to peginterferon-ribavirin therapy is generally lower in coinfection compared to HCV monoinfection. For this reason, the advent of direct-acting antivirals (DAA) is eagerly awaited for this population. The results of trials using DAA in coinfection show that treatment response rates are similar to those obtained in HCV monoinfection. Thus, HIV should no longer be considered as a "special" population, as long as antiretroviral therapy is given and drug interactions are taken into account. Envisioning HCV eradication from the HIV population faces major challenges ahead, including identification of the large number of undiagnosed individuals, and ensuring wide access to the best but often expensive HCV medications. This article forms part of a symposium in Antiviral Research on "Hepatitis C: next steps toward global eradication".

[Which treatment options are validated for chronic viral hepatitis?]

BACKGROUND

In the last 10 years, a dramatic change has occurred in the treatment of chronic viral hepatitis, particularly in the area of hepatitis B and hepatitis C.

OBJECTIVES

Which treatment options of viral hepatitis are scientifically validated and can be recommended for practical use in consideration of current studies on the treatment of viral hepatitis and the German and European guidelines, respectively.

CURRENT DATA

The treatment of chronic hepatitis B continues to be based either on a long-term therapy with nucleos(t)ide analogues or a finite therapy with pegylated interferon alpha (PEG-IFN). Treatment of hepatitis D is also based on PEG-IFN; however, the relapse rate is high. The treatment of hepatitis C is currently based on the combination of PEG-IFN and ribavirin (RBV). To estimate the optimal duration of therapy and dosage, knowledge of previous treatments, genotype, and presence of cirrhosis is crucial. For genotype 1, the first direct acting antiviral drugs were approved in 2011. These drugs led to a significant increase in treatment success. In the upcoming years another dramatic change in the treatment of hepatitis C is anticipated, including an improved side effect profile, increased efficacy, and a greater degree of customization in difficult-to-treat patients. Acute hepatitis E is usually self-limiting, but can become chronic in immunocompromised patients, i.e., after organ transplantation. Reduction of immunosuppression may clear HEV and RBV shows antiviral efficacy.

CONCLUSION

Currently available therapies have a high disease control or chance for cure in hepatitis B and C. In Hepatitis C treatment, a massive change in future therapies is foreseeable. The hepatitis D co-infection remains difficult to treat. For hepatitis E, RBV is a promising off-label treatment option.

Persistence of hepatitis C virus during and after otherwise clinically successful treatment of chronic hepatitis C with standard pegylated interferon α-2b and ribavirin therapy

Resolution of chronic hepatitis C is considered when serum HCV RNA becomes repeatedly undetectable and liver enzymes normalize. However, long-term persistence of HCV following therapy with pegylated interferon-α/ribavirin (PegIFN/R) was reported when more sensitive assays and testing of serial plasma, lymphoid cells (PBMC) and/or liver biopsies was applied. Our aim was to reassess plasma and PBMCs collected during and after standard PegIFN/R therapy from individuals who became HCV RNA nonreactive by clinical testing. Of particular interest was to determine if HCV genome and its replication remain detectable during ongoing treatment with PegIFN/R when evaluated by more sensitive detection approaches. Plasma acquired before (n = 11), during (n = 25) and up to 12–88 weeks post-treatment (n = 20) from 9 patients and PBMC (n = 23) from 3 of them were reanalyzed for HCV RNA with sensitivity <2 IU/mL. Clone sequencing of the HCV 5′-untranslated region from plasma and PBMCs was done in 2 patients. HCV RNA was detected in 17/25 (68%) plasma and 8/10 (80%) PBMC samples collected from 8 of 9 patients during therapy, although only 5.4% plasma samples were positive by clinical assays. Among post-treatment HCV RNA-negative plasma samples, 9 of 20 (45.3%) were HCV reactive for up to 59 weeks post-treatment. Molecularly evident replication was found in 6/12 (50%) among PBMC reactive for virus RNA positive strand collected during or after treatment. Pre-treatment point mutations persisted in plasma and/or PBMC throughout therapy and follow-up. Therefore, HCV is not completely cleared during ongoing administration of PegIFN/R otherwise capable of ceasing progression of CHC and virus commonly persists at levels not detectable by the current clinical testing. The findings suggest the need for continued evaluation even after patients achieve undetectable HCV RNA post-treatment.