Characteristics of adefovir resistance in patients with or without lamivudine-resistant hepatitis B virus treated with adefovir: a 4-year experience

Efficacy Comparison of Tenofovir and Entecavir in HBeAg-Positive Chronic Hepatitis B Patients with High HBV DNA

Objectives. To compare entecavir (ETV) and tenofovir disoproxil fumarate (TDF) effects in chronic hepatitis B (CHB) patients with high HBV DNA. Method. 96 patients treated initially with tenofovir (TDF group) or entecavir (ETV group) were included in this retrospective study. The following parameters were assessed: HBeAg and hepatitis B e antibody (anti-HBe) status, serum alanine aminotransferase (ALT), and HBV-DNA levels at weeks 4, 12, 24, 36, 48, 60, 72, and 96; time to ALT normalization, undetectable HBV-DNA levels, and HBeAg seroconversion; total duration of follow-up and adverse reactions. Results. The patients included 66 (69%) and 30 (31%) individuals administered ETV and TDF, respectively, comprising 75% males. They were 35.1 ± 4.5 and 33.7 ± 4.6 years old in ETV and TDF groups, respectively. At 36 weeks, the response rate was significantly higher in the TDF group than in ETV treated patients (90% versus 69.7%, p = 0.03). At 48 weeks, less patients administered ETV showed undetectable HBV-DNA levels compared with the TDF group (86.4% versus 96.7%), a non-statistically significant difference (p = 0.13). Only 1 ETV treated patient developed virological breakthrough at 48–96 w. No adverse reactions were found. Conclusion. ETV and TDF are comparable in efficacy and safety to suppress HBV-DNA replication in HBeAg-positive CHB patients with high HBV DNA.

Effects of topical oxygen therapy on ischemic wound healing

[Purpose] This study evaluated the effects of topical oxygen therapy on the hind limb wounds of rats under ischemic conditions. [Subjects and Methods] Twelve injured rats were treated with topical oxygen on skin wounds located on the hind limb and compared with twelve injured control rats. Indexes including gross morphology of the wound, wound healing time, wound healing rate, and histological and immunohistochemical staining of sections of wound tissue were examined at different time points after intervention. [Results] The wound healing time was shorter in the topical oxygen therapy group than the control group. The wound healing rate and granulation tissue formation in the topical oxygen therapy group showed significant improvement on days 3, 7, and 14. Through van Gieson staining, the accumulation of collagen fiber in the topical oxygen therapy group was found to have improved when compared with the control group on day 7. Through semiquantitative immunohistochemical staining, many more new vessels were found in the topical oxygen therapy group compared with the model control group on day 7. [Conclusion] The results of the experiment showed that topical oxygen therapy improved ischemic wound healing.

The feasibility of discontinuing lamivudine in lamivudine-resistant chronic hepatitis B patients on lamivudine and adefovir combination therapy

OBJECTIVES

This study investigated the antiviral efficacy of adefovir (ADV) rescue therapy and the feasibility of lamivudine (LAM) discontinuation in LAM-resistant chronic hepatitis B (CH-B) patients who had attained a virological response (VR) with LAM + ADV combination therapy.

METHODS

The VR and virological breakthrough (VBT) were analyzed in 106 consecutively enrolled LAM-resistant CH-B patients who received ADV rescue therapy during a mean follow-up period of 55.2 months. Seventy-four patients achieved VR, and were divided into the LAM-discontinuation group (n = 39) and the LAM-continuation group (n = 35). The VR and VBT between the 2 groups were compared.

RESULTS

For all 106 LAM-resistant CH-B patients, the overall cumulative probabilities of VR at 1, 2, 3 and 5 years of ADV rescue therapy were 40.6, 55.7, 64.6 and 81.3%, respectively. The cumulative probabilities of VBT at 1, 2, 3 and 5 years were 0, 2.9, 8.8 and 13.9%, respectively. Whether they discontinued or continued LAM after achieving VR on LAM + ADV therapy, VR and VBT were not significantly different during a mean follow-up period of 40.4 months.

CONCLUSIONS

There was a good long-term VR with ADV rescue therapy for LAM-resistant CH-B patients. Moreover, discontinuing LAM was found to be feasible for patients who attained VR during ADV + LAM therapy.

Antiviral effect of entecavir in nucleos(t)ide analogue-naïve and nucleos(t)ide analogue-experienced chronic hepatitis B patients without virological response at week 24 or 48 of therapy

We investigated the antiviral effect of entecavir in nucleos(t)ide analogue (NA)-naïve and NA-experienced chronic hepatitis B patients without virological response (VR, HBV DNA < 300 copies/mL) at week 24 or 48. A total of 369 NA-naïve and 181 NA-experienced patients treated with entecavir monotherapy were analysed. Of the 369 NA-naïve patients, 34 did not achieve VR at week 48. Of them, patients with HBV DNA ≤ 2000 copies/mL at week 48 achieved a higher VR rate than those with HBV DNA >2000 copies/mL (18/23 vs 3/11, P = 0.004). Two naïve patients with HBV DNA >2000 copies/mL developed entecavir- or lamivudine-resistant mutants. In 98 lamivudine-experienced patients without ever having lamivudine resistance, most patients with VR (72/72) and partial VR (300-10(4) copies/mL; 20/23) at week 24 or VR at week 48 (89/91) could maintain or achieve VR after prolonged therapy. In 75 patients with prior resistance to lamivudine, prolonged entecavir therapy led to low VR rate in those without VR at week 24 (13/45) or 48 (4/34) and high entecavir-resistance rate in those with or without VR at week 24 (6/30 with and 23/45 without) and 48 (8/41 with and 21/34 without). VR at week 48 was an independent predictor (HR 0.14, 95% CI 0.06-0.33) for entecavir-resistant mutant development among the 75 patients with prior lamivudine-resistant mutants. In conclusion, prolonged entecavir treatment resulted in a poor response in naïve patients with HBV DNA >2000 copies/mL at week 48 and patients with prior lamivudine-resistant mutants without VR at week 24 or 48.

Hepatitis B e antigen-suppressing mutations enhance the replication efficiency of adefovir-resistant hepatitis B virus strains

Hepatitis B e antigen (HBeAg) negative hepatitis B virus (HBV) infections caused by precore (PC) or basal core promoter (BCP) mutations are associated with disease progression and complications. PC or BCP mutations may enhance the replication capacity of distinct drug-resistance-associated polymerase mutations, but their effect on adefovir-resistant HBV mutants is unclear. Importantly, BCP mutations were an independent risk factor for virological breakthrough in lamivudine-resistant patients treated with adefovir. We aimed at addressing the functional consequences of PC and BCP mutations on the replication and drug susceptibility of adefovir-resistant HBV mutants. Therefore, HBV constructs with wild type (WT) or adefovir-resistant rtN236T, rtA181V and rtA181T mutations, with or without concomitant PC or BCP mutations, were analysed in vitro using molecular assays. The adefovir-resistant polymerase mutations rtN236T, rtA181V and rtA181T showed a drastically reduced viral replication compared with WT. Interestingly, additional PC or BCP mutations enhanced the reduced replication efficacy of adefovir-resistant constructs and restored HBV replication to WT level. HBV rtA181T mutants displayed abolished hepatitis B surface antigen (HBsAg) secretion, owing to a sW172* stop codon in the overlapping envelope gene. All rtN236T- or rtA181V/T-containing constructs, regardless of concomitant PC or BCP mutations, were resistant to adefovir, but remained susceptible to telbivudine, entecavir and tenofovir. In conclusion, adefovir drug resistance mutations reduced viral replication, which can be significantly increased by additional HBeAg-suppressing PC or BCP mutations. Because increased HBV replication in HBeAg-negative patients has been associated with an unfavourable clinical course, close monitoring appears indispensable during adefovir treatment in HBeAg-negative patients.

Efficacy of 3 years of adefovir monotherapy in chronic hepatitis B patients with lamivudine resistance

AIM

To study the effect of rescue monotherapy with adefovir (ADV) in patients with chronic hepatitis B (CHB) who developed drug resistance to lamivudine (LAM).

METHODS

A total of 76 treated CHB patients with resistance to LAM were enrolled in the present study. The patients' baseline characteristics, such as age, gender, blood tests and hepatitis B virus (HBV) DNA were collected; therapy duration and the response of each patient were also recorded. ADV monotherapy was set as the observation group A. Twenty-four patients with LAM resistance, who were set as group B, accepted combined therapy with LAM + ADV. Patients were followed up at 0, 12, 24, 52, 104 and 156 wk. Hepatitis B surface antigen status, hepatitis B e antigen (HBeAg)/anti-HBe status, HBV DNA level and biochemical indexes were monitored. Sequencer of HBV polymerase gene was performed on the ABI 3730 automated sequencer. If no desired effects had been achieved during the course of treatment, patients' choices were also taken into account. The control group was tested at the same time.

RESULTS

In the two groups, 27 cases developed viral breakthrough after LAM treatment response. The remaining 49 cases underwent biochemical rebound accompanied by rtM204I/V or rtL180M mutation. In group A, 52 cases finished 156 wk of ADV monotherapy; of whom, 36 cases were HBeAg positive and 16 HBeAg negative. In patients whose baseline HBV DNAs were 10(3)-10(5) copies/mL, 88.8% of patients' HBV DNAs were lower than the lower test limit (10(3) copies/mL) after 12 to 156 wk of ADV treatment. In patients whose baseline HBV DNAs were ≥ 10(6) copies/mL, 41.1%-47.0% of patients' HBV DNAs were lower than the lower test limit after the same course of ADV therapy (χ(2) were 4.35-5.4, 41.1%-47.0% vs 88.8% group 10(3)-10(5) copies/mL, P < 0.01). In group A, seroconversion of HBeAg developed in 8 of 36 cases (22.2%). In group B, 24 cases finished 156 wk of LAM + ADV; of whom, 17 cases were HBeAg positive and 7 HBeAg negative. In patients whose baseline HBV DNAs were 10(3)-10(5) copies /mL, 81.8% of patients' HBV DNAs were lower than the lower test limit (10(3) copies/mL) after 12 to 156 wk of treatment. In the patients whose baseline HBV DNAs were ≥ 10(6) copies/mL, 46.1%-53.8% of patients' HBV DNAs were lower than the lower test limit after the same course of LAM + ADV therapy (χ(2) were 4.1-5.0, 46.1%-53.8% vs 81.8% group 10(3)-10(5) copies/mL, P < 0.05-0.01). In group B, 4 of 17 cases (23.5%) developed seroconversion of HBeAg. Treatment outcomes in groups A and B were comparable.

CONCLUSION

In both group A and B, the ratios of virological response have similar efficacy in patients with lower baseline HBV DNAs.

Adefovir dipivoxil in chronic hepatitis B: history and current uses

INTRODUCTION

The nucleotide analogue adefovir dipivoxil (ADV) was approved in 2002 for the treatment of chronic infection with hepatitis B virus (HBV), in both hepatitis B e antigen (HBeAg)-positive and -negative patients. ADV 10 mg daily has been associated with improved liver histology, decreased levels of HBV DNA and alanine aminotransferase (ALT), and seroconversion of HBeAg.

AREAS COVERED

This paper reviews the use of ADV as a first-line treatment for chronic hepatitis B and as an add-on therapy in chronic HBV-infected patients with lamivudine resistance. In the years since its launch, clinical resistance to ADV has emerged, and tenofovir and entecavir have shown greater efficacy in reducing viral load.

EXPERT OPINION

Many patients who started antiviral therapy with ADV (either as monotherapy or in combination with lamivudine) remain on this agent because they have undetectable viremia, but its future use will probably diminish because of the availability of more potent drugs. ADV is generally well tolerated, though the 10 mg dose is associated with low risk of nephrotoxicity.

Treatment response and evolution of HBV resistance during lamivudine plus adefovir or entecavir therapy in patients with adefovir-resistant mutants

BACKGROUND

Here, we investigated the treatment response and evolution of HBV resistance during lamivudine (LAM) plus adefovir (ADV) and entecavir (ETV) monotherapy in patients with ADV-resistant mutants.

METHODS

Of the 53 patients with ADV-resistant mutants, 25 received combined LAM plus ADV therapy (LAM+ADV group) and 28 received ETV monotherapy (ETV group) for at least 12 months (median 24 months and range 12-67 months).

RESULTS

During 24 months therapy, no significant difference was noted in HBV DNA reduction from baseline, HBV DNA<200 copies/ml, hepatitis B e antigen loss and ALT normalization between the two groups. In the LAM+ADV group, patients with single rtN236T resistant mutation had higher rates of undetectable HBV DNA than those with the double mutant rtA181T/V+rtN236T at months 3-18 of therapy. No virological breakthrough occurred except for one patient with rtN236T resistant mutation who experienced virological and biochemical breakthrough after the emergence of an additional rtA181T mutant under LAM+ADV therapy. Of the 28 patients receiving ETV monotherapy, ETV-resistant mutants developed in 8. The cumulative rates of ETV-resistant mutations and virological breakthrough at months 12, 24 and 36 were 3.6%, 25.7% and 46.8%, respectively. ADV-resistant mutations were rapidly replaced by LAM-resistant mutations (median 12 months) followed by ETV-resistant mutations.

CONCLUSIONS

There was no significant difference in virological response between the LAM+ADV and ETV groups in patients with ADV-resistant mutants. LAM+ADV were less effective in patients with the double mutant rtA181T/V+rtN236T than the single rtN236T mutation. The incidence of ETV-resistant mutation was high in patients with LAM/ADV-resistant mutants treated with ETV monotherapy.