Multidrug-resistant Hepatitis Research Articles

A case of liver cirrhosis with multidrug-resistant hepatitis B virus that responded to interferon therapy

A case of liver cirrhosis with multidrug-resistant hepatitis B virus that responded to interferon therapy

Clonal evolution of multidrug resistant hepatitis B virus during entecavir rescue therapy.

Analysing the mutation pattern of multidrug resistance (MDR) is important in the treatment of chronic hepatitis B (CHB). In this study, the evolutionary pattern of MDR mutations was investigated in patients receiving entecavir (ETV) rescue therapy. Eight CHB patients with lamivudine (LAM)- and adefovir (ADV)-resistant mutations showing suboptimal response to ETV and to subsequent ETV-plus-ADV therapy were enrolled. The clonal evolution of the mutation pattern was investigated through direct sequencing, multiplex restriction fragment mass polymorphism (RFMP), and clonal analysis and the utility of these methods was compared. Among 160 clones at baseline, wild-type hepatitis B virus (HBV) was present in 62 (38.8%), LAM-resistant mutations in 92 (57.6%) and ADV-resistant mutations in 55 (34.4%). LAM-resistant mutations increased to 70.6% at the end of ETV therapy and increased to 74.4% at the 12th month of ETV-plus-ADV therapy. During the same time periods, ETV-resistant mutations were present in 46.3% and 38.8%, and ADV-resistant mutations were present in 3.1% and 9.4% respectively. When 256 nucleotides from 32 samples were examined for mutations, clonal analysis detected 93 mutations (36.3%), direct sequencing detected 36 mutations (14.1%) and RFMP detected 73 mutations (28.5%). The sensitivity (73.1%, 95% CI; 64.1-82.1%) and specificity (96.9%, 95% CI; 94.4-99.4%) of RFMP were high, showing a concordance rate of 88.3% with the results from clonal analysis. All mutations exceeding 40% of the total clones detected by clonal analysis were also detected by RFMP. The clonal evolution of the mutation pattern in MDR HBV showed the selection of LAM-resistant (±ETV-resistant) HBV during ETV rescue therapy, which may be the primary reason for patients' suboptimal response. Multiplex RFMP is a useful method for detecting MDR mutations in clinical practice.

P0666 : Analyzing the mutation pattern of multi-drug resistant hepatitis B virus during entecavir rescue therapy

P0666 : Analyzing the mutation pattern of multi-drug resistant hepatitis B virus during entecavir rescue therapy

Multidrug‐resistant hepatitis B virus resulting from sequential monotherapy with lamivudine, adefovir, and entecavir: Clonal evolution during lamivudine plus adefovir therapy

Whether multidrug-resistant (MDR) hepatitis B virus (HBV) harbors mutations co-located in the same HBV clones that confer reduced sensitivity to antiviral therapy remains uncertain. This study investigated the evolution of MDR HBV strains developed from sequential monotherapy with lamivudine (LAM), adefovir (ADV), and entecavir (ETV) during LAM plus ADV salvage therapy. Sera were obtained from six patients who had developed sequential resistance to LAM, ADV, and ETV before and during LAM plus ADV therapy. The HBV genomes from each patient were amplified, cloned, and sequenced. Among 6 sets of 20 clones obtained before salvage therapy, all clones harbored the rtM204V mutation, and ETV-resistant mutations were detected with the rtM204V in 108 clones. The rtA181 mutation was not detected at baseline, but emerged in five patients during therapy. Among 9 sets of 20 clones obtained during salvage therapy, 39 clones harbored rtA181T/V ± rtN236T mutations, which were detected in the absence of rtM204 and ETV-resistant mutations in 37 clones (94.9%). Only two clones (5.1%) harbored both rtA181T/V and ETV-resistant mutations. The rtA181T/V mutation emerged after reversion from ETV-resistant mutants to wild-type HBV. Five patients achieved a partial virologic response to LAM plus ADV therapy. In conclusion, the majority of MDR mutations existed in different genomes. Suboptimal response to LAM plus ADV therapy may not result from the co-localization of MDR HBV mutations in the same genome, but instead the low antiviral potency of these drugs. Thus, more potent antiviral drug combinations may be an effective salvage therapy for patients infected with MDR HBV.

Characterization of hepatitis virus B isolated from a multi-drug refractory patient

Prolonged treatment of chronic hepatitis B (CHB) with nucleoside analogues (NAs) almost invariably engenders viral resistance, and sequential NAs monotherapy can promote multi-drug resistance. This study aimed to investigate the molecular characteristics and the mutation profile of multi-drug resistant hepatitis B virus (HBV). The complete genome of HBV isolated from a multi-drug refractory patient was amplified and cloned, and 22 clones were selected for sequencing. The homology of the full-length genome between clones ranged from 98.7% to 99.9%. A precore stop codon mutation of G1896A and basic core promoter (BCP) mutations A1762T/G1764A were detected in a majority of clones. A phylogenetic analysis showed that all clones were classified as subgenotype B2. Three mutations in the surface (S) antigen region, sC76Y, sP120T and sI195M, were detected in 100%, 100% and 77.3% of the clones, respectively. In the core (C) antigen region, a mutation at codon 135 (cP135Q) was detected in 100% of clones. Lamivudine (LAM)-resistant mutations, rtL180M and rtM204V/I were detected in 86.4% of clones. Adefovir (ADV) or entecavir (ETV)-resistant mutations were not detected. Several novel mutations, such as rtT128N, rtA222T, rtS256G, rtL271M, rtS332R, and rtN/T337D, were present in a majority of clones. Furthermore, six pairs of mutations in the overlapping reverse transcriptase (RT) gene and S gene were detected. In conclusion, the complex HBV mutation profile detected in the multi-drug refractory patient highlights the problems associated with the ongoing selection of mutations, including further compensatory mutations as well as potential cross-resistance mutations.

Current treatment of chronic HBV infection: A European perspective

Chronic hepatitis B infection remains a relatively common disease in European hepatology and gastroenterology practice. Current treatment guidelines in Europe discuss pegylated interferon-α or nucleoside analogues in treating chronic hepatitis B. The indications and the necessity for treatment are based mainly on the combination of three criteria: serum hepatitis B virus DNA concentrations, serum aminotransferase levels, and histologic grade and stage. The advent of potent nucleoside analogues with low rates of resistance has potentially simplified treatment. The pipeline of new agents to treat hepatitis B remains restricted, and cross-resistance is shared by several nucleosides. Thus, the guidelines emphasize the advantage and necessity of using potent agents with low rates of resistance as optimal therapy to avoid difficult-to-treat, multidrug-resistant hepatitis B.

Benefits and risks of combination therapy for hepatitis B #

In successful antiviral therapy of hepatitis B, drug combinations, particularly combinations without cross-resistance, can delay or prevent the emergence of drug-resistant mutants. Because drug-resistant mutants are archived and may limit future therapeutic options, prevention is important for long-term therapeutic efficacy. Additionally, combining drugs may achieve synergistic or additive antiviral effects compared with single drug therapy. Undesirable aspects of combination therapy include higher treatment costs and possibly lower adherence rates (due to pill number or complexity of regimen). Potentially harmful effects of combination therapy include higher rates of side effects, reduced efficacy due to drug competition, and the risk of multidrug-resistant hepatitis B virus (HBV) if combination therapy is insufficient to prevent resistance. Combination therapy has been shown to reduce the rate of drug resistance in chronic hepatitis B, but only when drugs with a low barrier to resistance are used (lamivudine, adefovir). Combination therapies may achieve greater degrees of HBV DNA suppression, but this has not been associated with higher rates of seroconversion (hepatitis B e antigen or hepatitis B surface antigen) compared to single drug therapy. The benefit of combination therapy has yet to be demonstrated with agents that are associated with a high barrier to resistance (tenofovir, entecavir). The use of combination therapy is recommended in specific patient groups: those with decompensated cirrhosis, those coinfected with human immunodeficiency virus and HBV who are on antiretroviral therapy, those who have undergone liver transplantation, and those with drug-resistant HBV infection. There is insufficient evidence to recommend combination therapy as first-line therapy for all patients with chronic hepatitis B.

Navigating the Maze of Hepatitis B Treatments

Navigating the Maze of Hepatitis B Treatments

Evolution of multi-drug resistant hepatitis B virus during sequential therapy

Multi-drug resistant hepatitis B virus (HBV) has been reported in hepatitis B patients who received sequential antiviral therapy. In vitro studies showed that HBV constructs with mutations resistant to lamivudine and adefovir have marked reduction in sensitivity to combination of lamivudine and adefovir, whereas constructs with mutations resistant to either drug remain sensitive to the other drug. We conducted this study to determine whether mutations conferring resistance to multiple antiviral agents co-locate on the same HBV genome in vivo and to describe the evolution of these mutations. Sera from six patients who had been found to have multi-drug resistant HBV mutations to lamivudine+adefovir, lamivudine+hepatitis B immunoglobulin (HBIG), or lamivudine+entecavir on direct sequencing were cloned after nested polymerase chain reaction (PCR). Analysis of 215 clones from 11 samples with multi-drug resistant mutations on direct sequencing showed that 183 (85%) clones had mutations to both therapies on the same genome; 31 clones had lamivudine-resistant mutants only. Clonal analysis of serial samples from three patients showed progressive evolution from all clones with lamivudine-resistant HBV mutations only to mixtures of clones that have multi-drug resistant mutations and clones that have lamivudine-resistant HBV mutations only, and ultimately all clones having multi-drug resistant HBV mutations. In conclusion, mutations conferring resistance to multiple antiviral agents co-locate on the same viral genome, suggesting that combination therapy directed against mutants resistant to each treatment may not be adequate in suppressing multi-drug resistant HBV. De novo combination therapy may prevent the emergence of multi-drug resistant mutants.