Efficacy of tenofovir-based rescue therapy in patients with lamivudine-resistant hepatitis B virus: A systematic review and meta-analysis

Resistant mutations within the hepatitis B virus reverse transcriptase sequence in treatment failure patients with chronic HBV infection in Vietnam

OBJECTIVES

We conducted this study to describe whether mutations in the gene coding for the enzyme reverse transcriptase (RT) were related to drugs used in the treatment of hepatitis B in Vietnam.

METHODS

Patients receiving antiretroviral therapy with evidence of treatment failure were included in the study. The RT fragment was cloned using the polymerase chain reaction technique after being extracted from patients' blood samples. The nucleotide sequences were analysed using Sanger method. The HBV drug resistance database contains mutations associated to resistance to existing HBV therapies. Medical records were accessed to collect information on patient parameters, such as treatment, viral load, biochemistry, and blood count.

RESULTS

Resistance mutations to lamivudine, telbivudine, and entecavir were found in the highest proportion (75-91.7%) of HBV samples from patients who had failed antiretroviral therapy. Only 20.8% of HBV strains had mutations exhibiting adefovir resistance, while none had mutations conferring tenofovir resistance. M204I/V, L180M, and L80I are frequent variants linked with resistance to lamivudine, telbivudine, and entecavir. In contrast, the A181L/T/V mutation was detected predominantly in tenofovir-resistant HBV strains. Following the drug resistance mutation test, patients achieved the greatest virological response after 24 weeks of therapy with tenofovir and entecavir at a daily dose of one tablet.

CONCLUSION

Lamivudine, telbivudine, and entecavir were all highly resistant to the RT enzyme modifications in 24 treatment failure patients, with M204I/V, L180M, and L80I being the most prevalent mutations. Tenofovir resistance mutations have not been found in Vietnam.

Effectiveness and Safety of Low Dose of Tenofovir Disoproxil Fumarate in Malagasy Patients with Chronic Hepatitis B

Background

Accessibility of full dose daily of tenofovir disoproxil fumarate (TDF) is limited in Madagascar with an estimated cost well above the purchasing power of Malagasy population.

Objective

The study is aimed at evaluating the efficacy and safety of low-dose tenofovir for the treatment of chronic hepatitis B (CHB).

Methods

This prospective cohort study from January 2018 to December 2020 was conducted in the Department of Hepato-Gastroenterology, University Hospital Joseph Raseta Befelatanana, Antananarivo, Madagascar. The patients enrolled in the study received low dose of TDF 900 mg/week (300 mg daily, three days per week).

Results

A total of 45 patients (male/female: 31/14) were included. The mean age was 45.1 ± 11.5 years. Fifteen patients were nucleos(t)ide (NA)-naïve, and 30 patients had prior NA therapy (NA-experienced). Thirty patients were HBeAg positive. A complete virological response (CVR) was achieved in 36/45 patients (80%) at 3 months, 41/45 (91.1%) at 6 months, and 43/45 (95.6%) at 12 months. High viral load at baseline was negative predictive factor of CVR at 3 months (HR: 0.14; 95% CI: 0.022-0.92; p: 0.041). There was no significant difference in response between HBeAg-positive and HBeAg-negative patients, NA-naïve and NA-experienced patients, and cirrhotic and noncirrhotic patients. Low dose of tenofovir was well tolerated. Ten patients (22.22%) had mild side effects. Mild renal failure was observed in 3 patients (6.7%) during follow-up.

Conclusion

Low dose of tenofovir is effective, safe, and well tolerated in a Malagasy population sample. These results still require verification in a large population.

Efficacy of tenofovir disoproxil fumarate switch therapy in chronic hepatitis B patients with suboptimal response to adefovir-based combination therapy

In the present study, the efficacy and safety of tenofovir disoproxil fumarate (TDF) switch therapy were assessed in patients with chronic hepatitis B exhibiting a suboptimal response to adefovir (ADV)-based combination therapy. First, the efficacy of the TDF switch therapy was retrospectively evaluated in 50 patients with chronic hepatitis B who failed to respond to ADV-based combination treatment. Among those, 48 patients with a median age of 35 years were hepatitis B e antigen (HBeAg)-positive and 17, 14 and 19 patients were previously treated with lamivudine (LAM) plus ADV, telbivudine plus ADV and entecavir (ETV) plus ADV, respectively. A total of 41 patients were treated with TDF alone and 9 with TDF plus ETV. The median time of follow-up was 102 weeks. The primary end-point was the cumulative probability of achieving a complete virologic response (CVR). The secondary end-points were the rate of alanine aminotransferase (ALT) normalization, HBeAg seroconversion in HBeAg-positive patients, and the plasma levels of creatinine and creatine kinase. The mean serum hepatitis B virus DNA levels prior to initiation of the TDF switch therapy were 4.8±1.6 log₁₀IU/ml. The cumulative probability of achieving a VR at 24, 48, 96 and 108 weeks was 52.0, 76.0, 89.8 and 94.9%, respectively. The cumulative probability of normalization of ALT at 12, 24, 36, 48, 60,72, 84, 96, 108, 120 and 132 weeks was 34, 44, 50, 58, 66, 70, 74, 80, 90, 92 and 94%, respectively. HBeAg seroconversion was achieved in 5 patients. During the follow-up, 6 patients suffered from a virologic breakthrough, 3 patients failed to respond to the TDF treatment and the remaining patients were able to obtain VR following the continuation of TDF treatment. Slightly elevated serum levels of creatinine were observed in one patient, whereas creatine kinase activity did not increase in any of the subjects. In conclusion, TDF switch therapy is efficient and safe for patients with chronic hepatitis B with a suboptimal response to ADV-based combination therapy.

Virological Response to Tenofovir Disoproxil Fumarate in HIV-Positive Patients with Lamivudine-Resistant Hepatitis B Virus Coinfection in an Area Hyperendemic for Hepatitis B Virus Infection

Background

Sequential addition of tenofovir disoproxil fumarate (TDF) is often needed for patients coinfected with HIV and hepatitis B virus (HBV) who develop HBV resistance to lamivudine after combination antiretroviral therapy (cART) containing only lamivudine for HBV. We aimed to assess the virological response of HBV to add-on TDF in patients coinfected with lamivudine-resistant HBV.

Methods

Between November 2010 and December 2014, 33 HIV/HBV-coinfected patients with lamivudine-resistant HBV and 56 with lamivudine-susceptible HBV were prospectively included. TDF plus lamivudine was used to substitute zidovudine or abacavir plus lamivudine contained in cART in patients with lamivudine-resistant HBV infection, while patients with lamivudine-susceptible HBV infection received TDF plus lamivudine as backbone of cART. Serial determinations of plasma HBV DNA load, HBV serologic markers, and liver and renal functions were performed after initiation of TDF-containing cART.

Results

Of 89 patients included, 38.6% tested positive for HBV envelope antigen (HBeAg) at baseline. The plasma HBV DNA level at enrollment of lamivudine-resistant and lamivudine-susceptible group were 6.1 ± 2.2 log₁₀ and 6.0 ± 2.2 log₁₀ copies/mL, respectively (p = 0.895). The cumulative percentage of HBV viral suppression in lamivudine-resistant and lamivudine-susceptible group was 81.8% and 91.1% at 48 weeks, respectively (p = 0.317), which increased to 86.7% and 96.2% at 96 weeks, respectively (p = 0.185). At 48 weeks, 11 patients testing HBeAg-positive at baseline failed to achieve viral suppression. In multivariate analysis, the only factor associated with failure to achieve viral suppression at 48 weeks was higher HBV DNA load at baseline (odds ratio, per 1-log₁₀ copies/mL increase, 1.861; 95% CI, 1.204–2.878). At 48 weeks, HBeAg seroconversion was observed in 5 patients (1 in the lamivudine-resistant group and 4 in the lamivudine-susceptible group; p = 0.166). During the study period, HBsAg levels decreased over time, regardless of lamivudine resistance. Loss of HBsAg was observed in 3 (3.4%) patients in the lamivudine-susceptible group.

Conclusions

Add-on TDF-containing cART in patients coinfected with lamivudine-resistant HBV achieved a similar rate of HBV viral suppression compared to TDF-containing cART as initial regimen in patients coinfected with lamivudine-susceptible HBV. A higher baseline HBV DNA load and HBeAg positivity were associated with failure to achieve HBV viral suppression.

Treatment of chronic hepatitis B with tenofovir

Tenofovir (TDF) is a potent hepatitis B virus (HBV) inhibitor with a high barrier to drug resistance, and it has been recommended as one of the first-line drugs to treat chronic hepatitis B (CHB). This paper reviews the recent advances in the treatment of CHB with TDF, especially in terms of its efficacy as first-line and second-line antiviral therapies as well as its role in the prevention of mother-to-child HBV transmission.

Treatment for hepatitis B in patients with drug resistance

Persistent hepatitis B virus (HBV) infections affect about 240 million patients worldwide that are at risk of developing liver cirrhosis or hepatocellular carcinoma. HBV is a small, partially double stranded DNA virus with four overlapping genes and a unique life cycle, which involves the generation of an RNA template for replication via reverse transcription. Mutations occur frequently during chronic infection, and particular selection pressures select distinct mutants. Nucleoside and nucleotide analogues like lamivudine (LMV), entecavir (ETV), telbivudine (LdT), adefovir dipivoxil (ADV) and tenofovir (TDF) are used to achieve long-term suppression of viral replication. Importantly, these drugs have different barriers to resistance, explaining the higher incidence of treatment failure in the past due to drug resistant viral strains for the older compounds LMV, LdT and ADV. On a molecular level, drug resistant mutations usually affect the reverse transcriptase domain of the HBV polymerase protein. Secondary compensatory mutations restore the replication fitness of the mutant virus. From a clinical point of view, patients undergoing antiviral therapy require regular testing for HBV DNA (every 3-6 months). In case of insufficient viral suppression or viral breakthrough (>1 log increase in HBV DNA above nadir), strict adherence to therapy needs to be ensured. If drug resistance is suspected or even molecularly confirmed, rescue therapy strategies exist, usually switching to a noncross-resistant antiviral drug. LMV, LdT and ETV resistant HBV can be treated with TDF monotherapy, ADV resistance with ETV or TDF, and insufficient responses to TDF may require ETV either as mono- or combination therapy. Complex treatment histories with many antivirals may sometimes necessitate the combination of highly effective antivirals like ETV and TDF. Novel treatment targets such as core (capsid) inhibitors, siRNA targeting protein translation, entry inhibitors or immune modulators aim at improving the efficacy of antivirals in order to (functionally) cure hepatitis B.