Comparison of hepatitis B virus genotypes B and C among chronically hepatitis B virus-infected patients who received nucleos(t)ide analogs: A multicenter retrospective study

Long-read deep sequencing analysis of hepatitis B virus quasispecies in two elderly cases of interspousal transmission

Hepatitis B virus (HBV) can be transmitted within a family, but an interspousal transmission in elderly cases is rare and the change of viral quasispecies during the event is unclear. We experienced two acute hepatitis B males (AH1 and AH2, 67 and 71 years old, respectively) whose HBV was transmitted from their wives with chronic HBV infection (CH1 and CH2, 67 and 66 years old, respectively). To clarify the characteristics of HBV quasispecies in such cases, we performed long-read deep sequencing of HBV preS1/preS2/S domain using samples from the 2 couples. HBV full-genome sequences determined with direct sequencing showed that the HBV sequences belonged to subgenotype B1. AH1 was 98.0-99.2 % identical to CH1, and AH2 was 98.5-99.5 % identical to CH2, whereas the identity between AH1 and AH2 was 96.9 %. The long-read deep sequencing of amplicons including preS1/preS2/S domains with PacBio Sequel IIe showed the numbers of nucleotides with >5 % substitution frequencies in AH1, AH2, CH1 and CH2 were 0 (0 %), 4 (0.31 %), 39 (3.06 %) and 28 (2.20 %), respectively, indicating that CH1 and CH2 were more heterogeneous than AH1 and AH2. From a phylogenetic analysis based on the deep sequencing, minor CH1/CH2 clones that were close to AH1/AH2 clones were considered to be substantially distinct from the major populations in CH1/CH2. The major population formed during chronic infection under the immune pressure might not be suitable to establish new infection and this might be one of the reasons why the transmission had not occurred for a long time after marriage.

ELISA genotyping of hepatitis B virus in China with antibodies specific for genotypes B and C

Hepatitis B virus (HBV) causes hepatitis B (HB) and distinct HBV genotypes can lead to different prognoses. However, HBV genotyping is rarely done in clinics, because the traditional method by PCR-based DNA sequencing is impractical for clinical diagnosis with tedious process and low success rate. Herein, we have established an ELISA-based genotyping method to quickly determine the HBV genotypes of HB patients in China. First, two commercial antibodies, 16D12 and 6H3 specific for HBV genotypes B and C respectively, are chosen as capture antibodies, since these two genotypes dominate in China. Then two home-made genotype-specific antibodies, B19 and C04, are used as the detection antibodies for genotypes B and C in sandwiched ELISA. The ELISA kit shows high sensitivity (> 95%) and specificity (> 95%) in detecting genotypes B and C of Chinese HB patients. Moreover, the ELISA kit has demonstrated higher success rate (98.7%) than PCR-based DNA sequencing (93.5%) and a commercial PCR-based genotyping kit (92.2%) for sera with HBV DNA ≥ 1000 IU/mL and HBsAg ≥ 250 IU/mL. Such an advantage is more obvious for the sera with HBV DNA < 1000 IU/mL. The kappa analysis between the ELISA and PCR-based DNA sequencing results exhibits a kappa of 0.836, indicating a good correlation.

Usefulness of the Fibrosis-4 index and alanine aminotransferase at 1 year of nucleos(t)ide analog treatment for prediction of hepatocellular carcinoma in chronic hepatitis B patients

AIM

Nucleos(t)ide analogs do not completely prevent hepatocellular carcinoma (HCC) in chronic hepatitis B virus infection. This study aimed to evaluate the dynamics of a non-invasive liver fibrosis marker, the Fibrosis-4 (FIB-4) index, for predicting HCC development.

METHODS

Among a total of 882 chronically hepatitis B virus infection-infected patients who were treated with nucleos(t)ide analogs, 472 patients without HCC history whose FIB-4 at baseline and 1 year of treatment was obtained were evaluated for the incidence of HCC.

RESULTS

The median FIB-4 was 2.00 at baseline and was significantly reduced to 1.58 at 1 year (P < 0.001), but the reduction was small at 2 years or later. When a receiver operating characteristic analysis of FIB-4 was performed to predict HCC within 5 years, the area under the curve of FIB-4 at 1 year was higher than that at baseline (0.676 vs. 0.599). The HCC incidence was significantly higher in patients with FIB-4 ≥1.58 than in those with FIB-4 <1.58 (14.8% vs. 3.6% at 10 years, P < 0.001). Additionally, an abnormal alanine aminotransferase (≥31 U/L) at 1 year was an independent risk for HCC. When a fibrosis and alanine aminotransferase-1 (FAL-1) score was evaluated as an applicable number of FIB-4 ≥1.58, and alanine aminotransferase ≥31 as 0, 1, and 2, the HCC risk in patients with score 2 was significantly higher than in those with score 1 or score 0 (24.1% vs. 9.8% vs. 0.7% at 10 years, P < 0.001).

CONCLUSIONS

FIB-4 ≥1.58 and alanine aminotransferase ≥31 at 1 year of nucleos(t)ide analog was an independent risk factor for HCC development, and a score using these factors stratified the risk of HCC.

Relevance of HBx for Hepatitis B Virus-Associated Pathogenesis

The hepatitis B virus (HBV) counts as a major global health problem, as it presents a significant causative factor for liver-related morbidity and mortality. The development of hepatocellular carcinomas (HCC) as a characteristic of a persistent, chronic infection could be caused, among others, by the pleiotropic function of the viral regulatory protein HBx. The latter is known to modulate an onset of cellular and viral signaling processes with emerging influence in liver pathogenesis. However, the flexible and multifunctional nature of HBx impedes the fundamental understanding of related mechanisms and the development of associated diseases, and has even led to partial controversial results in the past. Based on the cellular distribution of HBx-nuclear-, cytoplasmic- or mitochondria-associated-this review encompasses the current knowledge and previous investigations of HBx in context of cellular signaling pathways and HBV-associated pathogenesis. In addition, particular focus is set on the clinical relevance and potential novel therapeutic applications in the context of HBx.

Alanine aminotransferase levels as therapeutic targets after nucleotide/nucleoside analog therapy in patient with chronic hepatitis B

AIM

Alanine aminotransferase (ALT) is a criterion for the introduction of nucleotide/nucleoside analog (NA), and ALT levels are decreased by NA treatment. However, the association between post-treatment ALT levels and hepatocellular carcinoma (HCC) risk remains unclear. To fill this gap, we aimed to establish a target value of ALT level during NA treatment.

METHODS

In total, 413 patients with chronic hepatitis B who received entecavir, tenofovir alafenamide, or tenofovir disoproxil fumarate were enrolled. The subsequent development of HCC was examined and a target value of ALT level during NA treatment as a risk marker for HCC was evaluated.

RESULTS

The median follow-up duration was 5.1 years, during which time 27 patients (8.6%) developed HCC. ALT level at the start of treatment was not associated with HCC development (p = 0.08). When stratified by ALT at 1 year after NA initiation, the cumulative 3- and 5-year rates of HCC for patients with ALT ≥21 IU/L were 11.5% and 18.1%, and those with ALT <21 IU/L was 2.3% and 6.5%, respectively. Patients with ALT <21 IU/L had a significantly lower risk of HCC development compared with patients with ALT ≥21 IU/L (p = 0.002). In multivariable analysis adjusting age, sex, and platelet counts, ALT ≥21 IU/L was an independent risk factor of HCC development with hazard ratio of 4.5 (95% confidence interval: 1.01-20.4).

CONCLUSIONS

ALT <21 IU/L at 1 year after NA initiation has a lower risk of HCC and could be used as a target value for NA treatment.

Switching to Tenofovir Alafenamide Fumarate in Chronic Hepatitis B Patients Who Had Detectable HBV DNA during Treatment with Entecavir

Nucleos(t)ide analogues (NAs) suppress hepatitis B virus (HBV) replication, but the risk of hepatocellular carcinoma still remains. The presence of detectable HBV DNA in the serum during NA therapies for chronic hepatitis B patients has been reported to be associated with the risk of hepatocellular carcinoma. In this study, we investigated the antiviral effect of switching from entecavir (ETV) to tenofovir alafenamide fumarate (TAF) in chronic hepatitis B patients who had detectable HBV DNA in the serum at least once within a year. Among a total of 77 cases in 7 hospitals that switched NAs from ETV to TAF, 23 patients with detectable HBV DNA in a year before switching were analyzed. When the detection frequencies of HBV DNA in the 1st and 2nd years after switching to TAF were analyzed, they were significantly lower than those in the year before switching (68.8% vs. 34.1% for the 1st year and 21.3% for the 2nd year, P < 0.001 for both). The HBsAg decline tended to be larger after switching than before (-2.5% vs. -3.0% for 1st year and -3.1% for 2nd year), but the difference was not significant. One patient died of a cardiovascular event 11 months after the treatment switch, but no adverse effects due to TAF including renal function were observed. In conclusion, it was suggested that switching from ETV to TAF might be effective to suppress the HBV DNA level further in patients whose HBV DNA is detectable, even if at a very low level.

Non-Achievement of Alanine Aminotransferase Normalization Associated with the Risk of Hepatocellular Carcinoma during Nucleos(t)ide Analogue Therapies: A Multicenter Retrospective Study

Patients with a chronic hepatitis B virus (HBV) infection who are treated with nucleos(t)ide analogues (NAs) are still at risk for hepatocellular carcinoma (HCC), and it has been clinically questioned whether patients with a high risk of HCC can be identified efficiently. We aimed to clarify the risk factors associated with the development of HCC during NA therapies. A total of 611 chronically HBV-infected patients without a history of HCC, who were treated with NAs for more than 6 months (median 72 months), from 2000 to 2021, were included from 16 hospitals in the Tohoku district in Japan. Incidences of HCC occurrence were analyzed with clinical factors, including on-treatment responses. Alanine aminotransferase (ALT) normalization, based on the criteria of three guidelines, was analyzed with other parameters, including the age−male−ALBI−platelets (aMAP) risk score. During the observation period, 48 patients developed HCC, and the cumulative HCC incidence was 10.6% at 10 years. Non-achievement of ALT normalization at 1 year of therapy was mostly associated with HCC development when ALT ≤ 30 U/L was used as the cut-off (cumulative incidence, 19.9% vs. 5.3% at 10 years, p < 0.001). The effectiveness of the aMAP risk score at the start of treatment was validated in this cohort. A combination of an aMAP risk score ≥ 50 and non-achievement of ALT normalization could stratify the risk of HCC significantly, and notably, there was no HCC development in 103 patients without these 2 factors. In conclusion, non-achievement of ALT normalization (≤30 U/L) at 1 year might be useful in predicting HCC during NA therapies and, in combination with the aMAP risk score, could stratify the risk more precisely.

Molecular Mechanisms during Hepatitis B Infection and the Effects of the Virus Variability

The immunopathogenesis and molecular mechanisms involved during a hepatitis B virus (HBV) infection have made the approaches for research complex, especially concerning the patients’ responses in the course of the early acute stage. The study of molecular bases involved in the viral clearance or persistence of the infection is complicated due to the difficulty to detect patients at the most adequate points of the disease, especially in the time lapse between the onset of the infection and the viral emergence. Despite this, there is valuable data obtained from animal and in vitro models, which have helped to clarify some aspects of the early immune response against HBV infection. The diversity of the HBV (genotypes and variants) has been proven to be associated not only with the development and outcome of the disease but also with the response to treatments. That is why factors involved in the virus evolution need to be considered while studying hepatitis B infection. This review brings together some of the published data to try to explain the immunological and molecular mechanisms involved in the different stages of the infection, clinical outcomes, viral persistence, and the impact of the variants of HBV in these processes.

Envelope Proteins of Hepatitis B Virus: Molecular Biology and Involvement in Carcinogenesis

The envelope of hepatitis B virus (HBV), which is required for the entry to hepatocytes, consists of a lipid bilayer derived from hepatocyte and HBV envelope proteins, large/middle/small hepatitis B surface antigen (L/M/SHBs). The mechanisms and host factors for the envelope formation in the hepatocytes are being revealed. HBV-infected hepatocytes release a large amount of subviral particles (SVPs) containing L/M/SHBs that facilitate escape from the immune system. Recently, novel drugs inhibiting the functions of the viral envelope and those inhibiting the release of SVPs have been reported. LHBs that accumulate in ER is considered to promote carcinogenesis and, especially, deletion mutants in the preS1/S2 domain have been reported to be associated with the development of hepatocellular carcinoma (HCC). In this review, we summarize recent reports on the findings regarding the biological characteristics of HBV envelope proteins, their involvement in HCC development and new agents targeting the envelope.

Dynamic evaluation of hepatocellular carcinoma prediction models in patients with chronic hepatitis B receiving nucleotide/nucleoside analogue treatment

Carcinogenesis risk scores for chronic hepatitis B have been proposed, but it remains unclear whether these scores during nucleoside/nucleotide analogue (NA) therapy are useful for risk assessment. In this study, we examined changes of these scores and the predictability during NA treatment. 432 patients with no history of hepatocellular carcinoma (HCC) treated with NA were enrolled. PAGE-B, modified PAGE-B (mPAGE-B), and REACH-B scores were calculated at NA administration, 1 and 2 years after administration. The median follow-up duration was 5.1 years, during which 37 patients (8.6%) developed HCC. Cumulative incidence HCC development in patients with high risk of PAGE at NA administration, and 1 and 2 years after NA administration was significantly higher than those with intermediate and low-risk groups (p < .05 for all time points), whereas HCC incidence in patients with high risk of mPAGE-B and REACH-B at 2 years after NA administration were equivalent to those with intermediate and low-risk groups (p = .2 for mPAGE-B, and p = .1 for REACH-B). The area under the receiver operating characteristic (AUROC) for HCC development of PAGE-B at NA administration, and 1 and 2 years after administration were 0.773, 0.803 and 0.737, respectively. The AUROCs of PAGE-B at each point were continuously higher than those of REACH-B (0.646, 0.725, and 0.653, respectively) and mPAGE-B (0.754, 0.734, and 0.678, respectively).PAGE-B score has a high diagnostic accuracy for HCC development at any time point during NA treatment, indicating its potential use as a real-time monitor of HCC development.

Hepatitis B Virus Reactivation with Discontinuation of Nucleoside Analogue in Patients Who Received Allogeneic Hematopoietic Stem Cell Transplantation

Reactivation of hepatitis B virus (HBV) is known to occur frequently after hematopoietic stem cell transplantation (HSCT). The reactivation can be prevented by nucleos(t)ide analogue (NA), but it is unclear how long NA should be continued. Here, we report 3 cases of HBV reactivation with discontinuation of NA following the discontinuation of immunosuppressive therapies after HSCT. Three male patients aged 34, 59, and 54 years received allogeneic HSCT (allo-HSCT) for chronic myeloid leukemia, mixed phenotype acute leukemia, and myelodysplastic syndrome, respectively. Before HSCT, 2 patients were positive for hepatitis B surface antigen (HBsAg) and 1 patient was negative for HBsAg and positive for antibodies to hepatitis B core antigen. NA (lamivudine or entecavir) was started at the same time as HSCT and stopped after the discontinuation of immunosuppressive therapies. In all patients, the serum HBV DNA levels were increased after the discontinuation of NAs. Two of the three patients developed severe hepatitis with high levels of HBV DNA (7.5 and 7.4 log IU/mL, respectively). A patient without hepatitis was re-administered NA soon after the HBV DNA started to increase (3.3 log IU/mL). Interestingly, the 2 patients who developed hepatitis cleared HBsAg promptly after the recovery from hepatitis and they could stop NAs without the reversion of HBsAg. It was speculated that transplanted immune cells, which were naïve for HBV, react strongly with HBV antigens that were increased after the NA discontinuation. The discontinuation of NA after allo-HSCT is not recommended generally because strong hepatitis might be induced even after several years.

Switching to tenofovir disoproxil fumarate in entecavir-treated chronic hepatitis B patients: A pilot randomized controlled study

Although hepatitis B surface antigen (HBsAg) removal is considered the goal of chronic hepatitis B treatment, it can rarely be achieved with nucleos(t)ide analogues (NAs). It has been reported that tenofovir disoproxil fumarate (TDF) is superior in reducing HBsAg compared with entecavir (ETV) in treatment-naïve patients; however, the effect of TDF in patients who have received NAs is still unclear. The aim of the present study was to evaluate the efficacy of switching from ETV to TDF in patients who were already receiving ETV. A pilot randomized controlled study for 2 years in patients who had been treated with ETV for >1 year and did not exhibit drug resistance was performed (Clinical trial registration: UMIN000021948, UMIN-CTR, May 1, 2016). A total of 20 patients were enrolled and 19 patients were randomized into 2 groups, a TDF-switching group (n=12) or an ETV-continuing group (n=7). The mean change in HBsAg levels after 2 years was greater in the TDF group compared with the ETV group, but the difference was not significant (-0.25 vs. -0.06 log IU/ml). In the TDF group, hepatitis B e antigen (HBeAg)-positive patients at baseline showed significantly greater changes in HBsAg (-0.63 vs. -0.03 log IU/ml; P=0.030). In contrast, no difference between HBeAg-positive and HBeAg-negative patients was observed in the ETV group. No significant differences of estimated glomerular filtration rate and inorganic phosphorus changes were observed among the TDF and ETV groups. In conclusion, a significant HBsAg decrease was not achieved after switching from ETV to TDF in the overall analysis, but HBeAg-positive patients showed a larger HBsAg decrease after switching treatment.

Loss of HBsAg in Patients with High Levels of HBV-DNA During Treatment with Nucleoside or Nucleotide Analogs

Background: HBsAg is synthesized in the endoplasmic reticulum and is necessary for the formation of complete HBV particles. A decreased synthesis of this antigen leads to an intracellular inhibition of virus production. Methods: The study aimed to assess the incidence of HBsAg elimination among 1,290 patients who suffered from chronic HBV infection undergoing an antiviral treatment with nucleoside or nucleotide analogs (NAs). Furthermore, possible predictive factors for this elimination were analyzed. Results: A permanent HBsAg loss was confirmed in 3% of the patients, which was more frequent in men than in women (4.4% vs. 1.9%; P = 0.009). The HBsAg elimination occurred in 5% of HBeAg (+) patients and 2.8% of HBeAg (-) patients. The age of patients whose HBsAg was eliminated was higher than the age of the remaining patients (60 vs. 51 y/o). The effect of initially used pegylated interferon alfa (PEG-IFN) therapy on the HBsAg elimination was not observed. It occurred with the use of entecavir (ETV) and tenofovir (TDF); however, among patients treated with ETV, HBsAg was significantly more often eliminated in HBeAg (+) patients. Conclusions: The HBsAg elimination in patients undergoing antiviral treatment occurs more often in men, patients with positive HBeAg before treatment, individuals above 60 years, and patients treated with ETV.

Hepatocellular carcinoma incidence with tenofovir versus entecavir in chronic hepatitis B: a systematic review and meta-analysis

BACKGROUND

It is unclear whether tenofovir disoproxil fumarate and entecavir differ in their association with risk of hepatocellular carcinoma in patients with chronic hepatitis B, and previous meta-analyses have shown conflicting conclusions with substantial heterogeneity. We aimed to analyse the updated data and elucidate the source of heterogeneity.

METHODS

We searched PubMed, Embase, Web of Science, and the Cochrane library for relevant studies with time-to-event data for incident hepatocellular carcinoma occurring in patients with chronic hepatitis B who received tenofovir disoproxil fumarate or entecavir monotherapy with follow-up of at least 1 year. Studies published between Jan 1, 2006, and April 17, 2020, and abstracts from international conferences in 2018 and 2019 were included. We pooled covariate adjusted hazard ratios (HRs) for hepatocellular carcinoma using a random-effects model, assessed heterogeneity among included studies using the I2 statistic and Cochran's Q test, and identified the source of heterogeneity using prespecified subgroup analyses. This study is registered with PROSPERO, ID CRD42020176513.

FINDINGS

31 studies involving 119 053 patients were analysed. The 5-year cumulative incidence of hepatocellular carcinoma was 5·97% (95% CI 5·81-6·13, 28 studies) for entecavir and 3·06% (2·86-3·26, 13 studies) for tenofovir disoproxil fumarate in studies with unmatched populations (p<0·0001). For all eight studies matched by propensity score, the 5-year cumulative incidence was 3·44% (95% CI 3·08-3·80) for entecavir and 3·39% (2·94-3·83) for tenofovir disoproxil fumarate (p=0·87). Analysis of 14 comparative studies with covariate adjustment found that tenofovir disoproxil fumarate and entecavir had similar risk of hepatocellular carcinoma (primary outcome); adjusted HR 0·88, 95% CI 0·73-1·07; p=0·20), although heterogeneity was significant (I2=56·4%, p=0·0038). In a subgroup analysis for hospital-based clinical cohorts, there was no difference in hepatocellular carcinoma incidence between the two regimens (adjusted HR 1·03, 95% CI 0·88-1·21; I2=0%). However, tenofovir disoproxil fumarate was associated with a lower risk of hepatocellular carcinoma compared with entecavir in administrative database research (adjusted HR 0·67, 0·59-0·76; I2=0%).

INTERPRETATION

Our study found no significant difference between tenofovir disoproxil fumarate and entecavir in their association with incident hepatocellular carcinoma. We suggest that treatment should be guided by patient tolerability and affordability rather than whether one drug is more effective than the other.

FUNDING

Supported in part by E-DA Hospital (EDAHP 106008; EDAHP 103046).

Cross-Protection of Hepatitis B Vaccination among Different Genotypes

Hepatitis B (HB) vaccination is the most effective method for preventing HB virus (HBV) infection. Universal HB vaccination containing recombinant HB surface antigens (HBsAg) is recommended. Our data revealed that human monoclonal HB surface antibody (anti-HBs) from individuals inoculated with genotype C-based HB vaccine induced cross-protection against HBV genotype A infection. An in vitro infection model demonstrated anti-HBs-positive sera from individuals inoculated with genotype A- or C-based HB vaccine harbored polyclonal anti-HBs that could bind to non-vaccinated genotype HBV. However, because there were low titers of anti-HBs specific for HBsAg of non-vaccinated genotype, high anti-HBs titers would be required to prevent non-vaccinated genotype HBV infection. Clinically, the 2015 Centers for Disease Control and Prevention guidelines state that periodic monitoring of anti-HBs levels after routine HB vaccination is not needed and that booster doses of HB vaccine are not recommended. However, the American Red Cross suggests that HB-vaccine-induced immune memory might be limited; although HB vaccination can prevent clinical liver injury (hepatitis), subclinical HBV infections of non-vaccinated genotypes resulting in detectable HB core antibody could not be completely prevented. Therefore, monitoring anti-HBs levels after routine vaccination might be necessary for certain subjects in high-risk groups.

Clinical features of chronic hepatitis B patients with low hepatitis B surface antigen levels and determinants of hepatitis B surface antigen seroclearance

BACKGROUND AND AIM

A low hepatitis B surface antigen (HBsAg) level is reported to be predictive of future HBsAg seroclearance. A hospital-based cohort study was conducted to clarify the clinical features of patients with low HBsAg levels and to demonstrate the usefulness of low HBsAg levels for predicting HBsAg seroclearance.

METHODS

A total of 1459 patients with chronic hepatitis B were included in the study. Of these, 587 had repeated measurements for HBsAg levels and two or more records of HBsAg-positive results. HBsAg levels were measured with a commercially available HBsAg assay. Based on a cut-off index (COI) of 2000, a high HBsAg level was defined as HBsAg ≥2000 COI, and a low HBsAg level was defined as HBsAg <2000 COI.

RESULTS

The proportion of patients with low HBsAg levels at baseline tended to increase with age. Patients with low HBsAg levels at baseline had significantly older age, lower transaminase levels, and lower hepatitis B virus (HBV) DNA levels than those with high HBsAg levels. The annual HBsAg seroclearance rate was 1.30%/year. The cumulative incidences of HBsAg seroclearance differed significantly by HBsAg level at baseline (<2000 vs ≥2000 COI), age (≥50 vs <50 years), and HBV DNA level (<4.0 vs ≥4.0 log copies/mL). Cox proportional hazards regression analyses showed that low HBsAg level (<2000 COI) and low HBV DNA level (<4.0 log copies/mL) were significantly associated with HBsAg seroclearance.

CONCLUSION

Aging was one of the factors affecting HBsAg level. HBsAg seroclearance was significantly associated with low HBsAg level and low HBV DNA level at baseline.

Hepatitis B surface antigen reduction as a result of switching from long-term entecavir administration to tenofovir

Background and Aim

Loss of hepatitis B surface antigen (HBsAg) is an important goal in the treatment of chronic hepatitis B. We investigated whether switching from long‐term entecavir (ETV) administration to tenofovir (TFV) (tenofovir alafenamide [TAF] or tenofovir disoproxil fumarate [TDF]) could contribute to the reduction of HBsAg levels.

Methods

The degree of HBsAg reduction by 48 weeks in 30 patients following switching from ETV to TFV was compared with results from 147 patients who continued ETV as a control.

Results

TFV group switched to TFV after mean 6.79 years of ETV administration. HBV‐DNA levels remained below 1.0 log IU/mL in all cases in both groups during 48 weeks. Median HBsAg reduction at 48 weeks was 0.075 (−0.05 to 0.38) log/IU/mL in the TFV switch group, and 0.070 (−0.28 to 0.50) in the ETV continuation group, which was not statistically significant (p = 0.5). In a subgroup of hepatitis B e antigen negative patients whose HBsAg had not been reduced (HBsAg reduction ≤0 log IU/mL) in the 48 weeks prior to entry into the study, HBsAg reduction was significantly higher in the TFV switch group than in the ETV continuation group (0.15 [0.07–0.135] in TFV, 0.09 [−0.14 to 0.25] log IU/mL in ETV, p = 0.04).

Conclusion

Although HBsAg reduction is equivalent with ETV continuation and switching to TFV in all patients at 48 weeks, switching from ETV to TFV could provide an alternative therapeutic strategy toward HBsAg elimination in a specific subpopulation of patients.