[Combination therapy in chronic hepatitis B]

Hepatitis B virus infection: An insight into infection outcomes and recent treatment options

Hepatitis B virus (HBV) currently infects an estimated population of 2 billion individuals in the world, including 400 million people with chronic HBV infection. HBV virology, replication and the host's immune response to HBV infection contribute to different infection outcomes. Acute hepatitis HBV infection is self-limiting but it leaves a residual infection that can become active in an individual during immunosuppression. In chronic HBV infection, the virus persistently replicates in hepatocytes leading to immune mediated hepatocellular damage. Despite the inability to remove the virus in more than 70 % of patients, current treatments for chronic HBV infection, interferon alpha and antiviral nucleotide/nucleoside analogues, aim to reduce viral replication to prevent or at least delay the progression to cirrhosis and hepatocellular carcinoma. In both self resolved acute and persistent HBV infection, the long term existence of chromatinised covalently closed circular DNA (cccDNA) in the nuclei of infected hepatocytes cannot be targeted by current treatments to eliminate these templates to eradicate the viral persistence. Identifying the mechanisms involve in the removal of infected hepatocytes will be useful as treatment options. In this context, DNA based novel therapeutic and immunization strategies might help to remove stable cccDNA and thus viral persistence.

De novo combination of lamivudine and adefovir versus entecavir monotherapy for the treatment of naïve HBeAg-negative chronic hepatitis B patients

PURPOSE

Either combination treatment or monotherapy using agents with a high genetic barrier are recommended for hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (CHB). The aim of this study was to compare effect of naïve HBeAg-negative CHB patients with either de novo combination of lamivudine (LAM) and adefovir dipivoxil (ADV) or entecavir (ETV) monotherapy.

METHODS

HBeAg-negative CHB patients (n = 71) with ALT levels between 2 and 10 times the upper normal limit and HBV DNA levels >10(4) copies/mL were enrolled. Patients were treated with either LAM 100 mg plus ADV 10 mg per day (n = 31) or ETV 0.5 mg per day (n = 40) for 48 weeks.

RESULTS

The average reduction in HBV DNA level compared with baseline were 5.16 ± 1.69 log in the LAM + ADV group and 5.36 ± 1.70 log in the ETV group by week 48 (P = 0.624). The virological response (VR) rates were 80.65 and 77.5%, the biochemical response (BR) rates were 93.55 and 90.00% at week 48 in the LAM + ADV and ETV groups, respectively. There was no significant difference in the VR and BR between the two groups. During the 48-week treatment period, virological breakthrough and serious side effects were not noted in any patient.

CONCLUSIONS

Both LAM + ADV combination therapy and ETV monotherapy are effective in naïve HBeAg-negative CHB patients, but further studies are needed to obtain long-term results.

[Analogs combination therapy in chronic hepatitis B: when and how?]

Hepatitis B virus (HBV) genomic variability is responsible for the complexity of the viral quasi-species and its evolution during the course of infection. The persistence of infected cells promotes the selection of drug-resistant strains. The development of nucleoside analogs without cross-resistance has provided a rationale for combination therapy. De novo combination, with low genetic barrier drugs, prevents the emergence of resistance in the short-term for drugs with a low genetic barrier and improves the control of infection. Long-term studies are needed to determine whether de novo combination is beneficial for analogs with a high genetic barrier as well. The add-on strategy is a standard in case of emergence of resistant mutants. This strategy needs to be implemented as early as possible before the virological breakthrough, especially if the viral suppression is sub-optimal. Clinical trials are mandatory in order to assess whether a) de novo combination is better than an early add-on strategy; and b) whether in case of sub-optimal viral suppression, an early add-on strategy is better in the long-term than a switch to a more potent drug with a high genetic barrier.