Antiviral efficacy of adefovir dipivoxil in the treatment of chronic hepatitis B subjects from Indian subcontinent

Current Scenario of Hepatitis B and Its Treatment in India

Hepatitis B is a significant public health problem in India, yet disease awareness is very low among the general population. The disease is mostly acquired horizontally, but the role of vertical transmission should not be underestimated. In spite of the fact that the majority of cases are e negative disease, most patients present in the advanced stage and even with hepatocellular carcinoma, the leading cause of which is hepatitis B. High-risk groups (especially tribals) also harbour significant disease burden and have a high prevalence of occult infection, supporting the potential of unknowingly spreading the disease. Findings on the relation of genotypes with disease severity or drug action have been conflicting. Though recently, oral antivirals with high genetic barrier to resistance have shown good viral suppression in the long term, e and s seroconversion is poor and relapse is universal upon therapy discontinuation. As no cure is possible with the currently available therapy, the target is long-term viral suppression by prolonged administration of oral antivirals; unfortunately, this leads to poor treatment adherence, which along with the high cost of therapy results in disease progression and spread of infection. At present, therefore, emphasis should be put on health education of the general and high-risk populations, along with health care workers to increase knowledge on such preventive measures as avoiding unsafe injection practices, high-risk sex, performing unnecessary injection and blood transfusion and providing proper screening of blood products; these efforts should be combined with intensive screening and aggressive vaccination programs, especially in high-risk groups and areas of high endemicity. Vaccination strategies are still below par and logistics should be developed for wider coverage; in addition, further research should be carried out on the efficacy and mode of usage for different types of vaccine.

Comparative evaluation of long-term monotherapies & combination therapies in patients with chronic hepatitis B: A pilot study

Background & objectives:

Reduction of viraemia in patients with chronic hepatitis B virus (HBV) infection using nucleoside/nucleotide analogues reduces fatal liver disease-related events, but development of resistance in virus presents serious clinical challenge. Therefore, comparative evaluation of prolonged antiviral monotherapy and combination therapies was prospectively studied to assess their influence on viral suppression, rapidity of response, development of drug resistance and surfacing mutants in chronic liver disease (CLD) patients.

Methods:

A total of 158 (62eAg-ve) chronic hepatitis B patients were prospectively studied for 24 months. Final analysis was performed on patients treated with lamivudine (LAM, n = 28), adefovirdipivoxil (ADV, n = 24), tenofovir disoproxil fumarate (TDF, n = 26), entecavir (ETV, n = 25), LAM + ADV (n = 28) and LAM + TDF (n = 27). Quantitative hepatitis B virus DNA was detected using real-time polymerase chain reaction. Multiple comparisons among drugs and genotypic mutations were analyzed.

Results:

Progressive biochemical and virological response were noted with all the regimens at 24 months except LAM and ADV which were associated with viral breakthrough (VBT) in 46.4 and 25 per cent, respectively. Mutations: rtM204V (39.3%), M204V+L180M (10.7%) while rtA181V (8.1%) and rtN236T (8.3%) were observed with LAM and ADV regimen, respectively. LAM + ADV combination therapy revealed VBT in seven per cent of the cases without mutations whereas TDF, ETV and LAM + TDF therapies neither showed VBT nor mutations.

Interpretation & conclusions:

LAM was the least potent drug among all therapeutic options followed by ADV. TDF and ETV were genetically stable antivirals with a strong efficacy. Among newer combination therapies, LAM + TDF revealed more efficacy in virological remission and acted as a profound genetic barrier on long term. Hence, newer generation molecules (TDF, ETV) and effective combination therapy should be a certain choice.