Genetic Evidence for Genotoxic Effect of Entecavir, an Anti-Hepatitis B Virus Nucleotide Analog

Trends in the cytogenetic and immunologic status of healthy persons; Kazakhstan, 2007-2022

Environmental pollution can affect immune health and genome stability. We have studied the immunological and cytogenetic status of healthy urban (Almaty City, which has high levels of air pollution) and rural residents of southern Kazakhstan, over the past 15 years. Differences between the groups in plasma immunoglobulin levels and chromosomal aberration frequencies were noted. Over the 15-year study period, decreases of immunoglobulin levels and increases of chromosomal aberration frequencies were observed and correlated with place of residence and ecological status of the region of residence; both ecological deterioration and the coronavirus pandemic are likely to have had negative effects.

Extrahepatic malignancies and antiviral drugs for chronic hepatitis B: A nationwide cohort study

BACKGROUND/AIMS

Chronic hepatitis B (CHB) is related to an increased risk of extrahepatic malignancy (EHM), and antiviral treatment is associated with an incidence of EHM comparable to controls. We compared the risks of EHM and intrahepatic malignancy (IHM) between entecavir (ETV) and tenofovir disoproxil fumarate (TDF) treatment.

METHODS

Using data from the National Health Insurance Service of Korea, this nationwide cohort study included treatment-naïve CHB patients who initiated ETV (n=24,287) or TDF (n=29,199) therapy between 2012 and 2014. The primary outcome was the development of any primary EHM. Secondary outcomes included overall IHM development. E-value was calculated to assess the robustness of results to unmeasured confounders.

RESULTS

The median follow-up duration was 5.9 years, and all baseline characteristics were well balanced after propensity score matching. EHM incidence rate differed significantly between within versus beyond 3 years in both groups (P<0.01, Davies test). During the first 3 years, EHM risk was comparable in the propensity score-matched cohort (5.88 versus 5.84/1,000 person-years; subdistribution hazard ratio [SHR]=1.01, 95% confidence interval [CI]=0.88-1.17, P=0.84). After year 3, however, TDF was associated with a significantly lower EHM incidence compared to ETV (4.92 versus 6.91/1,000 person-years; SHR=0.70, 95% CI=0.60-0.81, P<0.01; E-value for SHR=2.21). Regarding IHM, the superiority of TDF over ETV was maintained both within (17.58 versus 20.19/1,000 person-years; SHR=0.88, 95% CI=0.81-0.95, P<0.01) and after year 3 (11.45 versus 16.20/1,000 person-years; SHR=0.68, 95% CI=0.62-0.75, P<0.01; E-value for SHR=2.30).

CONCLUSION

TDF was associated with approximately 30% lower risks of both EHM and IHM than ETV in CHB patients after 3 years of antiviral therapy.

HeberNasvac: Development and Application in the Context of Chronic Hepatitis B

The immune system plays a central role in controlling acute hepatitis B infection and in patients resolving chronic hepatitis B (CHB). Given that 221 million (75%) of CHB patients reside in low- and middle-income countries, the development of a vaccine with therapeutic properties represents a rational and cost-effective approach more than a romantic endeavor. This review systematically analyzes the key variables related to the safety, efficacy, and effectiveness of CHB treatments. HeberNasvac experience is revisited for addressing the challenges and potentialities of therapeutic vaccines, as well as the current roadblocks in research and development, registration, and large-scale implementation.

How to cite this article

Aguilar JC, Akbar SMF, Al-Mahtab M, et al. HeberNasvac: Development and Application in the Context of Chronic Hepatitis B. Euroasian J Hepato-Gastroenterol 2024;14(2):221-237.

Tenofovir vs Entecavir Among Patients With HBV-Related HCC After Resection

Importance

Tenofovir disoproxil and entecavir are both commonly used first-line antiviral treatments, but their comparative recurrence and overall survival (OS) benefits remain unclear.

Objective

To explore differences of tenofovir disoproxil vs entecavir in recurrence-free survival (RFS) and OS after liver resection with curative intent in patients with hepatocellular cancer (HCC) related to hepatitis B virus (HBV).

Design, Setting, and Participants

This retrospective cohort study was conducted at Eastern Hepatobiliary Surgery Hospital, a tertiary referral hospital in Shanghai, China, between January 4, 2015, and April 1, 2023. Participants included patients with HBV-related HCC who underwent liver resection with curative intent from January 2015 to December 2018. Patients who received tenofovir disoproxil were matched with patients who received entecavir in a 1:1 ratio using propensity score matching. Data were analyzed from April 3 to May 31, 2023.

Exposures

Receiving tenofovir disoproxil or entecavir as antiviral treatment for HBV.

Main Outcomes and Measures

Primary end points were RFS and OS rates.

Results

Among 4451 patients (mean [SD] age, 58.1 [10.0] years; 3764 male [84.6%]; median [range] follow-up, of 51 [3 to 91] months), 989 patients in each of the groups were selected in propensity score matching. Baseline characteristics were comparable. In propensity score-matched groups, OS rates were 92.2% at 1 year, 70.9% at 3 years, and 54.2% at 5 years in the entecavir group, compared with 90.9% at 1 year, 75.2% at 3 years, and 64.0% at 5 years in the tenofovir disoproxil group. RFS rates were 83.9% at 1 year, 50.0% at 3 years, and 43.3% at 5 years in the entecavir group, compared with 85.3% at 1 year, 55.6% at 3 years, and 51.4% at 5 years in the tenofovir disoproxil group. Patients in the tenofovir disoproxil group had better OS (hazard ratio, 0.82; 95% CI, 0.72 to 0.94; P = .004) and RFS rates (hazard ratio, 0.81; 95% CI, 0.72 to 0.92; P = .001) compared with the entecavir group. Restricted mean survival time differences of entecavir vs tenofovir disoproxil groups were -0.05 (95% CI, -0.18 to 0.08) months at 1 year (P = .45), 0.20 (95% CI, -0.62 to 1.03) months at 3 years (P = .63), and 1.82 (95% CI, 0.14 to 3.51) months at 5 years (P = .03).

Conclusions and Relevance

These findings suggest that in patients undergoing curative liver resection for HBV-related HCC, tenofovir disoproxil was associated with better long-term OS and RFS rates compared with entecavir, providing insights for antiviral treatment.

Safety of entecavir antiviral therapyduring an accidental pregnancy in patients with chronic hepatitis B

The present study aimed to investigate the effects of accidental pregnancy CHB patients' reproductive age on their offspring during entecavir (ETV) antiviral therapy. A total of 112 couples were retrospectively enrolled, and they were divided into an observational and control group. A total of 53 couples who had accidental pregnancies while receiving long-term ETV antiviral medication were recruited for the observational group. The control group consisted of 59 couples who became pregnant accidentally while receiving long-term tenofovir disoproxil fumarate (TDF) antiviral treatment. All mothers persisted in their pregnancies in the observational group, and ETV was promptly replaced with TDF. Every mother remained pregnant and continued to use TDF in the control group. The maternal and baby safety profiles, including the prevalence of congenital disabilities, were comparable across the observational and control groups at delivery. In addition, no unusual indications or symptoms of the newborns were noted during the follow-up intervals of 28, 48, and 96 weeks postpartum. Initiating ETV or TDF in early and middle pregnancy seems safe for mothers and infants. Important data from the present study support using ETV in early-mid gestational accidental pregnancies and the prompt substitution of TDF antiviral medication for ETV.

Extrahepatic carcinogenicity of oral nucleos(t)ide analogues in chronic hepatitis B carriers: A 35,000-Korean outcome study

Evidence on the carcinogenicity of oral nucleos(t)ide analogues (NAs) is inconclusive and lacks data on the effects by chemical structure of the NAs in patients with chronic hepatitis B (CHB). We aimed to provide definitive results on this issue using a large set of CHB patients and data on all major NA drugs. The study population consisted of 10,331 patients with CHB receiving primary NA treatment for more than 6 months, and 24,836 untreated controls followed for at least as long as the treated patients. Using the inverse-probability-of-treatment-weighted (IPTW) method, the cumulative incidence of extrahepatic cancers was compared in the treated and untreated patients and across the cyclopentane, L-nucleoside and acyclic phosphonate categories of NAs. Analyses of individual cancers as sub-endpoints were also performed. The cumulative incidence of overall extrahepatic malignancies did not differ between the two groups in the IPTW cohort (hazard ratio [HR] 1.002; 95% confidence interval [CI] [0.859-1.169]). Similar statistical trends were observed in analyses across the three NA chemical subsets and controls. Per-cancer analyses indicated that NA treatment was significantly associated with increased risks of colorectal/anal cancers (HRs [95% CI], 1.538 [1.175-2.013]) and lymphoma (1.784 [1.196-2.662]). Conversely, breast cancer (HRs [95% CI], 0.669 [0.462-0.967]) and prostate cancer (0.521 [0.329-0.825]) were less prevalent in the NA-treated group. In conclusion, prolonged NA treatment presents carcinogenic risks for colorectal/anal and lymphoid tissues in CHB patients, although it does not affect most extrahepatic organs. The protective effect of NAs on breast and prostate cancers should be confirmed.

Hepatitis B Virus Treatment and Hepatocellular Carcinoma: Controversies and Approaches to Consensus

BACKGROUND

Long-term therapy with nucleos(t)ide analogs (NAs) such as entecavir (ETV) and tenofovir disoproxil fumarate (TDF) favorably affects the incidence of hepatocellular carcinoma (HCC) on the basis of data from randomized or matched control studies. Recent data suggest a lower HCC incidence after 5 years of ETV or TDF therapy in chronic hepatitis B (CHB) patients, especially those with baseline cirrhosis.

SUMMARY

Three controversial issues remain to be resolved regarding hepatitis B virus (HBV) treatment and HCC. (1) The efficacy of antiviral treatment for the prevention of HCC is not established. The guidelines of the American Association for the Study of Liver Diseases (AASLD), the Asian Pacific Association for the Study of the Liver (APASL), and the European Association for the Study of the Liver (EASL) for the management of HBV infection state that antiviral treatment of HBV with interferon and NAs prevents the development of HCC. Among experts in CHB treatment, however, there is disagreement on the HCC prevention effects of antiviral treatment. (2) The rationale for antiviral management in patients with high HBV DNA and normal levels of alanine aminotransferase is unclear. The AASLD, EASL, and APASL guidelines do not recommend antiviral treatment for immune-tolerant CHB patients, and the terms and methods of treating such patients remain to be clarified. (3) The efficacy of first-line treatment with NAs, including ETV, TDF, and tenofovir alafenamide fumarate (TAF), to prevent HCC in CHB patients remains unknown. Several studies have produced controversial results regarding the effects of NAs on the risk and prevention of HCC. In the present review, we discuss these 3 issues, citing recent studies and clinical management guidelines from major international associations.

KEY MESSAGES

Suggested approaches for reaching a consensus including applying the propensity score matching method, performing randomized controlled studies, and performing clinical studies with larger numbers of subjects and longer follow-up.

Differential Effectiveness of Tenofovir and Entecavir for Prophylaxis of Hepatocellular Carcinoma in Chronic Hepatitis B Patients Depending on Coexisting Cirrhosis and Prior Exposure to Antiviral Therapy: A Systematic Review and Meta-analysis

GOALS

This meta-analysis evaluated the comparative effectiveness of tenofovir disoproxil fumarate (TDF) versus entecavir (ETV) in reducing the risk of hepatocellular carcinoma (HCC).

BACKGROUND

It is unclear whether TDF or ETV is more effective in reducing the risk of HCC in chronic hepatitis B (CHB) patients with or without underlying cirrhosis.

METHODS

We searched the MEDLINE database through April 13, 2020, for studies involving CHB treated with TDF and/or ETV. Primary and secondary outcomes were the incidence of HCC and overall survival, respectively, calculated as risk ratios (RRs). Adjusted results were further evaluated by pooling propensity score matched cohorts.

RESULTS

Of the 229 records identified, 17 studies were included in the quantitative analysis. TDF treatment was associated with a significantly lower risk of HCC development [RR, 0.63; 95% confidence interval (CI), 0.43-0.93; P=0.024] and mortality (RR, 0.69; 95% CI, 0.57-0.84; P=0.003) than ETV treatment. Moreover, TDF significantly lowered HCC risk in patients with cirrhosis (RR, 0.69; 95% CI, 0.56-0.84) and antiviral treatment-naive patients (RR, 0.59; 95% CI, 0.35-0.98) compared with ETV. Among treatment-naive patients, TDF significantly prolonged survival compared with ETV (RR, 0.69; 95% CI, 0.52-0.91).

CONCLUSIONS

TDF likely confers a lower risk of HCC development and longer survival in patients with CHB, especially among treatment-naive patients and those with underlying cirrhosis, than ETV.

Hepatocellular carcinoma risk in patients with HBV-related liver disease receiving antiviral therapy

Hepatitis B virus (HBV) is a major health problem worldwide, with approximatively 240 million people living with a chronic HBV infection. HBV chronic infection remains the major cause of hepatocellular carcinoma worldwide, with more than half of HCC patients being chronic HBV carriers, even if underlying mechanisms of tumorigenesis are not totally understood. HBV-related HCC can be prevented by reducing the exposure to HBV by vaccination or by treatment of CHB infection. Current treatment of CHB are Peg-IFN alpha and oral NUCs. Treating HBV infection, either with IFN or NUCs, substantially reduces the risk of HCC development, even if antiviral therapy fails to completely eliminate HCC risk. Among treated patients, cirrhosis, HBeAg negative at baseline and failure to remain in virological remission were associated with an increased risk of HCC. The reduction of the risk of developing HCC during antiviral therapy is largely dependent upon the maintenance of virological remission, since viral load is found to be the most important factor leading to cirrhosis and its complications, including liver cancer development. The question whether Peg-IFN-alpha is superior to NUCs and whether there is a superior agent among NUCs is still controversial. Several studies demonstrated that antiviral therapy with NUCs could reduce the risk of HCC recurrence after curative treatment of HBV-related HCC.

Comparison of tenofovir versus entecavir on reducing incidence of hepatocellular carcinoma in chronic hepatitis B patients: A systematic review and meta-analysis

BACKGROUND AND AIM

Studies had shown that tenofovir (TDF) and entecavir (ETV) are widely used as the first-line therapy to inhibit hepatitis B virus replication, which can reduce the risk of hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB) patients, but it was unclear which nucleos(t)ide analogue was most effective. Therefore, we performed a meta-analysis and a systematic review to compare the incidence of HCC in CHB patients who are either on TDF or ETV.

METHODS

For this study, the following databases were searched for clinical trials published from its inception until November 2019: PubMed, Web of Science, MEDLINE, Embase, and Cochrane Library.

RESULTS

A total of 11 eligible studies were selected, including 70 864 patients. The meta-analysis showed that TDF was superior to ETV with regard to the incidence of HCC, the incidence of death or transplantation, and virologic response. There were no significant differences in terms of biochemical response and loss of seroconversion response among the entire cohort.

CONCLUSIONS

The conclusion was that CHB patients treated with TDF had a reduced incidence of HCC compared with patients treated with ETV.

Risk of Hepatocellular Carcinoma in Patients Treated With Entecavir vs Tenofovir for Chronic Hepatitis B: A Korean Nationwide Cohort Study

Importance

Entecavir and tenofovir disoproxil fumarate have comparable efficacy in achieving surrogate end points, including virologic response, and are equally recommended as first-line treatments for patients with chronic hepatitis B (CHB). However, it is unclear whether treatment with these drugs is associated with equivalent clinical outcomes, especially development of hepatocellular carcinoma (HCC).

Objective

To compare entecavir and tenofovir in terms of the risk of HCC and death or liver transplant in patients with CHB infection.

Design, Setting, and Participants

A nationwide historical population cohort study involving treatment-naive adult patients with CHB who started treatment with entecavir (n = 11 464) or tenofovir disoproxil fumarate (n = 12 692) between January 1, 2012, and December 31, 2014, using data from the Korean National Health Insurance Service database. As validation, a hospital cohort of patients with CHB treated with entecavir (n = 1560) or tenofovir (n = 1141) in a tertiary referral center between January 1, 2010, and December 31, 2016, were analyzed. Nationwide cohort data were retrieved from January 1, 2010, to December 31, 2016, and hospital cohort data from January 1, 2010, to October 31, 2017.

Main Outcomes and Measures

Cumulative incidence rates of HCC and death and transplant rates.

Results

Among the population cohort of 24 156, the mean (SD) age was 48.9 (9.8) years, and 15 120 patients (62.6%) were male. Among the hospital cohort of 2701, the mean (SD) age was 48.8 (10.5) years and 1657 patients (61.3%) were male. In the population cohort, the annual incidence rate of HCC was significantly lower in the tenofovir group (0.64 per 100 person-years [PY]) than in the entecavir group (1.06 per 100 PY). By multivariable-adjusted analysis, tenofovir therapy was associated with a significantly lower risk of HCC (hazard ratio [HR], 0.61; 95% CI, 0.54-0.70) and all-cause mortality or transplant (HR, 0.77; 95% CI, 0.65-0.92) compared with entecavir. The tenofovir group also showed a significantly lower risk of HCC in the 10 923-pair propensity score-matched population cohort (HR, 0.62; 95% CI, 0.54-0.70) and 869-pair propensity score-matched hospital cohort (HR, 0.68; 95% CI, 0.46-0.99) compared with the entecavir group.

Conclusions and Relevance

This study suggests that tenofovir treatment was associated with a significantly lower risk of HCC compared with entecavir treatment in a population-based cohort of adults with CHB; these findings were validated in a hospital cohort. Given the poor prognosis of patients with HCC, these findings may have considerable clinical implications in prevention of this cancer in patients with CHB infection.

Brca1 is involved in tolerance to adefovir dipivoxil‑induced DNA damage

Nucleos(t)ide analogues (NAs) are currently the most important anti‑viral treatment option for patients with chronic hepatitis B (CHB). Adefovir dipivoxil (ADV), a diester pro‑drug of adefovir, has been widely used for the clinical therapy of hepatitis B virus infection. It has been previously reported that adefovir induced chromosomal aberrations (CAs) in the in vitro human peripheral blood lymphocyte assay, while the genotoxic mechanism remains elusive. To evaluate the possible mechanisms, the genotoxic effects of ADV on the TK6 and DT40 cell lines, as well as DNA repair‑deficient variants of DT40 cells, were assessed in the present study. A karyotype assay revealed ADV‑induced CAs, particularly chromosomal breaks, in wild‑type DT40 and TK6 cells. A γ‑H2AX foci formation assay confirmed the presence of DNA damage following treatment with ADV. Furthermore, Brca1‑/‑ DT40 cells exhibited an increased sensitivity to ADV, while the knockdown of various other DNA damage‑associated genes did not markedly affect the sensitivity. These comprehensive genetic studies identified the genotoxic capacity of ADV and suggested that Brca1 may be involved in the tolerance of ADV‑induced DNA damage. These results may contribute to the development of novel drugs against CHB with higher therapeutic efficacy and less genotoxicity.

A mechanism for semaphorin-induced apoptosis: DNA damage of endothelial and myogenic cells in primary cultures from skeletal muscle

One hallmark of cancer is its ability to recruit a vascular supply to support rapid growth. Suppression of angiogenesis holds potential as a second-line or adjuvant therapy to stunt cancer growth, progression, metastasis, and post-resection regeneration. To begin to test the hypothesis that semaphorin 3A and 3F together, will induce endothelial cell apoptosis by inducing DNA damage, mixed primary cultures isolated from normal adult mouse skeletal muscle were treated for 48 hr with Sema3A ± Sema3F (100ng/mL). Changes in surviving-cell density, DNA synthesis, DNA repair (gamma-Histone 2AX, γH2AX, an indirect measure for DNA damage), and apoptotic DNA fragmentation (TUNEL staining) were assayed in cultures of CD31+ endothelial and desmin+ muscle cells. Sema3F increased DNA damage-associated DNA repair in both cell types. Co-treatment with Sema3A+3F increased γH2AX staining ~25-fold over control levels, and further increased apoptosis compared to control and Sema3A alone. Results were negated by treatment with neutralizing anti-semaphorin antibodies and are interpreted as suggesting that Sema3A may sensitize endothelial but not muscle cells to Sema3F-induced DNA damage. These preliminary findings on a complex system of interacting cells may contribute to developing applications that could target angiogenic regulatory mechanisms for their therapeutic potential against cancer progression and metastasis.

Multiple repair pathways mediate cellular tolerance to resveratrol-induced DNA damage

Resveratrol (RSV) has been reported to exert health benefits for the prevention and treatment of many diseases, including cancer. The anticancer mechanisms of RSV seem to be complex and may be associated with genotoxic potential. To better understand the genotoxic mechanisms, we used wild-type (WT) and a panel of isogenic DNA-repair deficient DT40 cell lines to identify the DNA damage effects and molecular mechanisms of cellular tolerance to RSV. Our results showed that RSV induced significant formation of γ-H2AX foci and chromosome aberrations (CAs) in WT cells, suggesting direct DNA damage effects. Comparing the survival of WT with isogenic DNA-repair deficient DT40 cell lines demonstrated that single strand break repair (SSBR) deficient cell lines of Parp1^-/-, base excision repair (BER) deficient cell lines of Polβ^-/-, homologous recombination (HR) mutants of Brca1^-/- and Brca2^-/- and translesion DNA synthesis (TLS) mutants of Rev3^-/- and Rad18^-/- were more sensitive to RSV. The sensitivities of cells were associated with enhanced DNA damage comparing the accumulation of γ-H2AX foci and number of CAs of isogenic DNA-repair deficient DT40 cell lines with WT cells. These results clearly demonstrated that RSV-induced DNA damage in DT40 cells, and multiple repair pathways including BER, SSBR, HR and TLS, play critical roles in response to RSV- induced genotoxicity.