Antiviral therapy for chronic hepatitis B: Combination of nucleoside analogs and interferon

Global dynamics of multiple delays within-host model for a hepatitis B virus infection of hepatocytes with immune response and drug therapy

In this paper, a mathematical model describing the hepatitis B virus (HBV) infection of hepatocytes with the intracellular HBV-DNA containing capsids, cytotoxic T-lymphocyte (CTL), antibodies including drug therapy (blocking new infection and inhibiting viral production) with two-time delays is studied. It incorporates the delay in the productively infected hepatocytes and the delay in an antigenic stimulation generating CTL. We verify the positivity and boundedness of solutions and determine the basic reproduction number. The local and global stability of three equilibrium points (infection-free, immune-free, and immune-activated) are investigated. Finally, the numerical simulations are established to show the role of these therapies in reducing viral replication and HBV infection. Our results show that the treatment by blocking new infection gives more significant results than the treatment by inhibiting viral production for infected hepatocytes. Further, both delays affect the number of infections and duration i.e. the longer the delay, the more severe the HBV infection.

Correlation between entecavir penetration in peripheral blood mononuclear cells and HBV DNA decay during treatment of HBeAg-negative chronic hepatitis B

BACKGROUND

Recently, due to its high effectiveness and tolerability, the treatment of chronic hepatitis B with entecavir became a standard practice. However, limited knowledge is currently available about its pharmacokinetic behaviour and intracellular disposition. Recently, our group reported an inverse correlation between entecavir plasma concentrations and the HBV DNA decay at the first and third month of treatment, respectively. In this paper we investigated the penetration of entecavir in peripheral blood mononuclear cells (PBMC) and in plasma, in order to evaluate the relationship between intracellular penetration and response, in a cohort of naive patients with hepatitis B e antigen (HBeAg)-negative CHB.

METHODS

Thirty-three patients were prospectively enrolled and gave written informed consent: the monitoring of clinical parameters (for example, HBV DNA, hepatitis B surface antigen [HBsAg], alanine aminotransferase) was carried out at the baseline and then monthly. Entecavir intra-PBMC and plasma trough concentrations were measured at 1 month of treatment, through a validated method based on liquid chromatography coupled with tandem mass spectrometry.

RESULTS

While plasma entecavir analysis confirmed previous evidence of inverse correlation between drug concentrations and HBV DNA decrease after 3 months of treatment (r=-0.723; P<0.001), this correlation was not significant for intra-PBMC concentrations. When the intracellular disposition ratio (intra-PBMC/plasma concentration ratio) was considered, it showed a direct and significant correlation with HBV DNA decay at the third month (r=0.485; P=0.004).

CONCLUSIONS

These results suggest that the antiviral activity of entecavir is dependent on its intracellular uptake, thus resulting in lower plasma concentrations in patients who have a marked HBV DNA decrease during treatment.

Gene Therapy for Chronic HBV-Can We Eliminate cccDNA?

Chronic infection with the hepatitis B virus (HBV) is a global health concern and accounts for approximately 1 million deaths annually. Amongst other limitations of current anti-HBV treatment, failure to eliminate the viral covalently closed circular DNA (cccDNA) and emergence of resistance remain the most worrisome. Viral rebound from latent episomal cccDNA reservoirs occurs following cessation of therapy, patient non-compliance, or the development of escape mutants. Simultaneous viral co-infections, such as by HIV-1, further complicate therapeutic interventions. These challenges have prompted development of novel targeted hepatitis B therapies. Given the ease with which highly specific and potent nucleic acid therapeutics can be rationally designed, gene therapy has generated interest for antiviral application. Gene therapy strategies developed for HBV include gene silencing by harnessing RNA interference, transcriptional inhibition through epigenetic modification of target DNA, genome editing by designer nucleases, and immune modulation with cytokines. DNA-binding domains and effectors based on the zinc finger (ZF), transcription activator-like effector (TALE), and clustered regularly interspaced short palindromic repeat (CRISPR) systems are remarkably well suited to targeting episomal cccDNA. This review discusses recent developments and challenges facing the field of anti-HBV gene therapy, its potential curative significance and the progress towards clinical application.

Chronic hepatitis B: Immunological profile and current therapeutic vaccines in clinical trials

More than 250million people worldwide are chronically infected with hepatitis B virus (CHB), and over half a million die each year due to CHB-associated liver complications such as cirrhosis and hepatocellular carcinoma. The translation of immunological knowledge about CHB into therapeutic strategies aiming to a sustainable hepatitis B virus (HBV) clearance has been challenging. In recent years, however, the understanding on the immune effectors required to overcome chronicity has notably increased thanks to preclinical and clinical research. Therapeutic vaccination may prove to be useful for treating CHB patients when coupled with current antiviral agents and other immunomodulatory strategies. This review summarizes current data and future perspectives on therapeutic vaccination. Other treatment alternatives that could be combined with vaccines for a complete cure from hepatitis B virus infection are also discussed.

Anti-HBV drugs suppress the growth of HBV-related hepatoma cells via down-regulation of hepatitis B virus X protein

Chronic infection of hepatitis B virus (HBV) is closely associated with the development of hepatocellular carcinoma (HCC). Meta-analyses show that adjuvant anti-HBV therapy is effective for HBV-related HCC patients in clinical. However, the significance that anti-HBV drugs depress HCC is poorly understood. Here, we investigated the effects of telbivudine (LdT), entecavir (ETV) and interferon-α2b (IFN-α2b) on HBV-related HCC. Our data showed that the treatment with the drugs significantly suppressed the growth of HBV-expressing hepatoma cells in vitro and in vivo, but failed to work in HBV-free liver cells. We present the hypothesis that HBx may be involved in the event. As expected, we observed that the expression of HBx was down-regulated by the agents. Meanwhile, the expression of HBx downstream factors was significantly down-regulated. Interestingly, LdT, ETV and IFN-α2b lost the anti-proliferation effects on HBV-related hepatoma cells when the cells were treated with HBx siRNA. Moreover, combination of those drugs enhanced the anti-proliferation effects. In conclusion, LdT, ETV and IFN-α2b suppress the growth of HBV-related HCC through down-regulation of HBx. Our finding provides new insights into the mechanisms of anti-HBV drugs in HCC therapy.

A Meta-Analysis of the Efficacy of Interferon Monotherapy or Combined with Different Nucleos(t)ide Analogues for Chronic Hepatitis B

Background: The aim of the present study was to compare the efficacy of interferon (IFN) with or without different nucleos(t)ide analogues (NAs). Methods: The PubMed, Wan Fang and CNKI databases were searched to identify relevant trials up to May 2015. Meta-analysis was performed with Review Manager 5.0. The stability and reliability were evaluated by publication bias tests. Results: Fifty-six studies fulfilled the criteria for the meta-analysis. Compared with IFN monotherapy, combination therapy were superior in HBV DNA undetectable rate (Risk Ratio (RR) = 1.55, 95% confidence interval (CI): 1.44–1.66, p < 0.00001), HBeAg and HBsAg loss rate (RR = 1.38, 95% CI: 1.22–1.56, p < 0.00001; RR = 1.69, 95% CI: 1.03–2.78, p = 0.04, respectively) at the end of week 48 treatment. Sub-analysis showed the RRs of virological response for entecavir (ETV), adefovir (ADV), and lamivudine (LAM) were 1.64, 1.61 and 1.52, respectively; RRs of HBeAg loss rate were 1.34, 1.71 and 1.34, respectively. However, at the end of follow-up, IFN plus NAs therapy was better than IFN monotherapy only in terms of HBV DNA undetectable rate (p = 0.0007). Conclusions: Combination therapy was better than IFN monotherapy in virological and serological responses at the end of treatment. After follow-up, only HBV DNA undetectable rate was superior for combination therapy.

Combination or sequential therapy with entecavir and interferon in chronic hepatitis B patients: Current status, problems and prospects

Sixteen years have passed since the initial antiviral treatment of chronic hepatitis B (CHB). Goal of the antiviral treatment is not only to suppress viral replication, but to achieve sustained response after a limited period of treatment and then discontinuation of drugs. Nucleos(t)ide analogues (NAs) and interferons are two types of therapeutic agents with different antiviral mechanisms for treatment of CHB. Monotherapy with NAs or interferons can only achieve ideal goal in a part of CHB patients, and combination and/or sequential therapy with both is an important attempt for CHB treatment in recent years. For patients previously treated with NAs, interferons can be used to replace NAs or in combination with them for a limited period. If interferons do not show good efficacy, then NAs, alone or in combination with interferons, can be used. For patients with high viral load, initial combination therapy may show better efficacy. According to the baseline and response guidelines, the treatment plan should be optimized frequently, and the treatment compliance emphasized with maintenance, medication and examination, along with the administration of chronic diseases, in order to ensure that HBV DNA level is lower than baseline level. For those who have had a continuous drop of HBsAg and HBeAg levels, prolonged treatment or combination of the treatment with dendritic cell (DC) therapy and immunotherapy may achieve more persistent immune control.

Long-Term Efficacy of Tenofovir Disoproxil Fumarate Therapy in Nucleos(t)ide-Experienced Chronic Hepatitis B Patients

BACKGROUND AND OBJECTIVES

Tenofovir disoproxil fumarate (TDF) therapy is a therapeutic option for nucleos(t)ide analogue (NA)-experienced chronic hepatitis B (CHB) patients infected with hepatitis B virus (HBV). In this study, we evaluated the efficacy of TDF alone compared with the efficacy of TDF plus additional NA combinations in NA-experienced CHB patients.

METHODS

This retrospective cohort study included 108 patients with a serum HBV DNA level above 5.0 log10 IU/ml who were treated with TDF alone (monotherapy group) or TDF combined with additional NAs (combination therapy group) for 30 months.

RESULTS

At month 30, both therapies resulted in the suppression of HBV DNA levels: 66 of 66 patients (100 %) in the monotherapy group and 40 of 42 patients (95.23 %) in the combination therapy group achieved virologic suppression. Kaplan-Meier curves revealed median times for virologic suppression of 3.12 months in the monotherapy group and 5.23 months in the combination therapy group (p = 0.699). The probability of virologic suppression was comparable between treatment groups. At month 6, more patients achieved normal alanine aminotransferase (ALT) levels in the monotherapy group (p = 0.029). During the treatment period, no patients experienced severe renal dysfunction.

CONCLUSION

TDF monotherapy and TDF plus additional NAs have comparable antiviral efficacy in CHB patients after NA treatment failure.