Treatment strategies using adefovir dipivoxil for individuals with lamivudine-resistant chronic hepatitis B

Tenofovir disoproxil fumarate (TDF) vs. emtricitabine (FTC)/TDF in lamivudine resistant hepatitis B: A 5-year randomised study

BACKGROUND & AIMS

Long-term treatment with tenofovir disoproxil fumarate (TDF) alone, or in combination with emtricitabine (FTC) is associated with sustained viral suppression in patients with lamivudine resistant (LAM-R) chronic hepatitis B (CHB).

METHODS

LAM-R CHB patients were randomised 1:1 to receive TDF 300mg or FTC 200mg and TDF 300mg once daily in a prospective, double blind, study. The proportion of patients with plasma hepatitis B virus (HBV) DNA<69IU/ml (<400copies/ml) at week 96 (primary efficacy endpoint) was reported previously. Here we present week 240 follow-up data.

RESULTS

Overall, 280 patients were randomised to receive TDF (n=141) or FTC/TDF (n=139), and 85.4% completed 240weeks of treatment. At week 240, 83.0% of patients in the TDF arm, and 82.7% of patients in the FTC/TDF treatment arm had HBV DNA<69IU/ml (p=0.96). Rates of normal alanine aminotransferase (ALT) and normalised ALT were similar between groups (p=0.41 and p=0.97 respectively). Hepatitis B e antigen loss and seroconversion at week 240 were similar between groups, (p=0.41 and p=0.67 respectively). Overall, six patients achieved hepatitis B surface antigen (HBsAg) loss and one patient (FTC/TDF arm) had HBsAg seroconversion by week 240. No TDF resistance was observed up to week 240. Treatment was generally well tolerated, and renal events were mild and infrequent (∼8.6%). The mean change in bone mineral density at week 240 was -0.98% and -2.54% at the spine and hip, respectively.

CONCLUSIONS

TDF monotherapy was effective and well tolerated in LAM-R CHB patients for up to 240weeks.

LAY SUMMARY

The goal of oral antiviral treatment for chronic hepatitis B (CHB) is to achieve and maintain undetectable HBV DNA levels. Treatment options with enhanced potency, and low risk of resistance development for patients infected with lamivudine resistant (LAM-R) HBV are required. Tenofovir disoproxil fumarate (TDF) monotherapy was effective and well tolerated without TDF resistance development in CHB patients with LAM-R, for up to 240weeks. Clinical trial number: NCT00737568.

Molecular diagnosis and treatment of drug-resistant hepatitis B virus

Oral antiviral agents have been developed in the last two decades for the treatment of chronic hepatitis B (CHB). However, antiviral resistance remains an important challenge for long-term CHB therapy. All of the clinically available oral antiviral agents are nucleoside or nucleotide analogues that target the activity of viral reverse transcriptase (RT), and all are reported to have resistant mutations. Since the hepatitis B virus (HBV) RT, like other viral polymerases, lacks proofreading activity, the emergence of drug-resistance occurs readily under selective pressure from the administration of antiviral agents. The molecular diagnosis of drug-resistant HBV is based on sequence variations, and current diagnostic methods include sequencing, restriction fragment polymorphism analysis, and hybridization. Here, we will discuss the currently available molecular diagnosis tools, in vitro phenotypic assays for validation of drug-resistant HBV, and treatment options for drug-resistant HBV.

Antiviral therapy delays esophageal variceal bleeding in hepatitis B virus-related cirrhosis

AIM: To investigate the effect of antiviral therapy with nucleoside analogs in hepatitis B virus (HBV)-related cirrhosis and esophageal varices.

METHODS: Eligible patients with HBV-related cirrhosis and esophageal varices who consulted two tertiary hospitals in Beijing, China, the Chinese Second Artillery General Hospital and Chinese PLA General Hospital, were enrolled in the study from January 2005 to December 2009. Of 117 patients, 79 received treatment with different nucleoside analogs and 38 served as controls. Bleeding rate, change in variceal grade and non-bleeding duration were analyzed. Multivariate Cox proportional hazard regression was used to identify factors related to esophageal variceal bleeding.

RESULTS: The bleeding rate was decreased in the antiviral group compared to the control group (29.1% vs 65.8%, P < 0.001). Antiviral therapy was an independent factor related to esophageal bleeding in multivariate analysis (HR = 11.3, P < 0.001). The mean increase in variceal grade per year was lower in the antiviral group (1.0 ± 1.3 vs 1.7 ± 1.2, P = 0.003). Non-bleeding duration in the antiviral group was prolonged in the Kaplan-Meier model. Viral load rebound was observed in 3 cases in the lamivudine group and in 1 case in the adefovir group, all of whom experienced bleeding. Entecavir and adefovir resulted in lower bleeding rates (17.2% and 28.6%, respectively) than the control (P < 0.001 and P = 0.006, respectively), whereas lamivudine (53.3%) did not (P = 0.531).

CONCLUSION: Antiviral therapy delays the progression of esophageal varices and reduces bleeding risk in HBV-related cirrhosis, however, high-resistance agents tend to be ineffective for long-term treatment.