Nami Mori

Emergence of a Novel Lamivudine-Resistant Hepatitis B Virus Variant with a Substitution Outside the YMDD Motif

ABSTRACT Lamivudine is a major drug approved for treatment of chronic hepatitis B virus (HBV) infection. Emergence of drug-resistant mutants with amino acid substitutions in the YMDD motif is a well-documented problem during long-term lamivudine therapy. Here we report a novel lamivudine-resistant strain of HBV with an intact YMDD motif, which included an amino acid substitution, rtA181T, in the reverse transcriptase (RT) domain of HBV polymerase. The substitution also induced a unique amino acid substitution (W172L) in the overlapping hepatitis B surface (HBs) protein. The YMDD mutant strains were not detected even by using the sensitive peptide nucleic acid-mediated PCR clamping method. The detected nucleotide substitution was accompanied by the emergence of an additional nucleotide substitution that induced amino acid change (S331C) in the spacer domain. The rtA181T mutant strain displayed a threefold decrease in susceptibility to lamivudine in in vitro experiments in comparison with the wild type. In vivo analysis using human hepatocyte-chimeric mice confirmed the resistance of this mutant strain to lamivudine. We developed a method to detect this novel rtA181T mutation and a previously reported rtA181T mutation with the HBs stop codon using restriction fragment length polymorphism PCR and identified one patient with the latter pattern among 40 patients with lamivudine resistance. In conclusion, although the incidence is not high, we have to be careful regarding the emergence of lamivudine-resistant mutant strains with intact YMDD motif.

HBx protein is indispensable for development of viraemia in human hepatocyte chimeric mice.

The non-structural X protein, HBx, of hepatitis B virus (HBV) is assumed to play an important role in HBV replication. Woodchuck hepatitis virus X protein is indispensable for virus replication, but the duck hepatitis B virus X protein is not. In this study, we investigated whether the HBx protein is indispensable for HBV replication in vivo using human hepatocyte chimeric mice. HBx-deficient (HBx-def) HBV was generated in HepG2 cells by transfection with an overlength HBV genome. Human hepatocyte chimeric mice were infected with HBx-def HBV with or without hepatic HBx expression by hydrodynamic injection of HBx expression plasmids. Serum virus levels and HBV sequences were determined with mice sera. The generated HBx-def HBV peaked in the sucrose density gradient at points equivalent to the generated HBV wild type and the virus in a patients serum. HBx-def HBV-injected mice developed measurable viraemia only in continuously HBx-expressed liver. HBV DNA in the mouse serum increased up to 9 log(10) copies ml(-1) and the viraemia persisted for more than 2 months. Strikingly, all revertant viruses had nucleotide substitutions that enabled the virus to produce the HBx protein. It was concluded that the HBx protein is indispensable for HBV replication and could be a target for antiviral therapy.

Serum HBV RNA is a predictor of early emergence of the YMDD mutant in patients treated with lamivudine

Lamivudine (LAM) is a nucleoside analogue widely used for the treatment of chronic hepatitis B virus (HBV) infection. Emergence of resistant strains with amino acid substitutions in the tyrosine‐methionine‐aspartate‐aspartate (YMDD) motif of reverse transcriptase is a serious problem in patients on LAM therapy. The amount of covalently closed circular DNA in the serum is reported to be higher in patients who develop YMDD mutants than in those without mutants. However, there is no useful serum marker that can predict early emergence of mutants during LAM therapy. Analysis of patients who were treated with entecavir (n = 7) and LAM (n = 36) showed some patients had high serum levels of HBV RNA. Median serum levels of HBV RNA were significantly higher in patients in whom the YMDD mutant had emerged within 1 year (n = 6, 1.688 log copies/ml) than in those in whom the YMDD mutant emerged more than 1 year after treatment (n = 12, 0.456 log copies/ml, P = 0.0125) or in whom the YMDD mutant never emerged (n = 18, 0.688 log copies/ml, P = 0.039). Our results suggest that HBV RNA is a valuable predictor of early occurrence of viral mutation during LAM therapy. (HEPATOLOGY 2007;45:1179–1186.)

Pharmacokinetics, efficacy and safety of daclatasvir plus asunaprevir in dialysis patients with chronic hepatitis C: pilot study

The aim of this study was to evaluate the pharmacokinetic profile of daclatasvir (DCV) and asunaprevir (ASV) dual therapy in haemodialysis patients infected with hepatitis C virus (HCV). Eighteen haemodialysis patients and 54 patients with normal renal function were treated with DCV and ASV dual therapy for 24 weeks. We evaluated the pharmacokinetic profiles of DCV and ASV and examined the rate of sustained virological response 12 weeks after the end of treatment (SVR12) and incidence of adverse events during treatment of haemodialysis patients infected with chronic HCV genotype 1 infection. To adjust for potential differences in baseline characteristics between haemodialysis patients and patients with normal renal function, we used propensity scores case–control matching methods. Area under the plasma concentration time curve from 0 to 6 h (AUC0–6 h) of DCV was slightly lower in haemodialysis patients than in patients with normal renal function (P > 0.6). AUC0–6 h of ASV was significantly lower in haemodialysis patients (P = 0.012). SVR12 rates were 100% (18/18) for haemodialysis and 96.2% (52/54) for patients with normal renal function. Changes in mean log10 HCV RNA levels and viral response were higher in haemodialysis patients compared to patients with normal renal function. No discontinuations due to adverse events occurred. In conclusion, DCV and ASV dual therapy for HCV infection is effective and safe with similar results in haemodialysis patients compared to patients with normal renal function.

Establishment of an infectious genotype 1b hepatitis C virus clone in human hepatocyte chimeric mice.

The establishment of clonal infection of hepatitis C virus (HCV) in a small-animal model is important for the analysis of HCV virology. A previous study developed models of molecularly cloned genotype 1a and 2a HCV infection using human hepatocyte-transplanted chimeric mice. This study developed a new model of molecularly cloned genotype 1b HCV infection. A full-length genotype 1b HCV genome, HCV-KT9, was cloned from a serum sample from a patient with severe acute hepatitis. The chimeric mice were inoculated intrahepatically with in vitro-transcribed HCV-KT9 RNA. Inoculated mice developed viraemia at 2 weeks post-infection, and this persisted for more than 6 weeks. Passage experiments indicated that the sera of these mice contained infectious HCV. Interestingly, a similar clone, HCV-KT1, in which the poly(U/UC) tract was 29 nt shorter than in HCV-KT9, showed poorer in vivo infectivity and replication ability. An in vitro study showed that no virus was produced in the culture medium from HCV-KT9-transfected cells. In conclusion, this study developed a genetically engineered genotype 1b HCV-infected mouse. This mouse model will be useful for the study of HCV virology, particularly the mechanism underlying the variable resistance of HCV genotypes to interferon therapy.

Randomized trial of high-dose interferon-α-2b combined with ribavirin in patients with chronic hepatitis C : correlation between amino acid substitutions in the core/NS5A region and virological response to interferon therapy

The aim of this study was to compare the efficacy of high‐dose interferon (IFN)‐α‐2b with standard dose of IFN‐α‐2b in combination with ribavirin (RBV) for patients with chronic hepatitis C virus (HCV) infection, and to investigate the predictive factors associated with virological response. Two hundred Japanese patients with high HCV viral load (>100 KIU/ml) were randomized to 6 or 10 mega units (MU) of 24‐week IFN‐α‐2b with RBV. Predictive factors were investigated; including pretreatment amino acid (aa) sequences of the core region and the IFN‐sensitive determining region (ISDR). The sustained virological response rate was not different in the two groups (24% vs. 30%) but the incidence of depression was significantly higher in the 10 MU group than 6 MU group (7% vs. 0%, P = 0.02). Younger age (<60) and HCV genotype (2a/b) were significant predictors of sustained virological response. In patients infected with genotype 1b, substitutions of core aa 70 and/or 91 were predictive for non‐virological response (P < 0.001), and substitutions in the ISDR was observed frequently in virological responders. Early viral kinetics study showed that serum HCV core antigen decreased more slowly in both patients with aa 70 and/or 91 substitutions in the core and with absence of substitutions in the ISDR. In conclusion, the use of a higher dose of IFN‐α‐2b in combination with RBV did not improve virological response but resulted in higher incidence of depression. Amino acid substitutions in the core and ISDR are predictive of virological response to the therapy in patients with genotype 1b and high viral load. J. Med. Virol. 81:640–649, 2009

G-to-A Hypermutation in Hepatitis B Virus (HBV) and Clinical Course of Patients with Chronic HBV Infection

BACKGROUND The apolipoprotein B messenger RNA editing enzyme, catalytic polypeptide-like family of cytidine deaminases induce G-to-A hypermutation in hepatitis B virus (HBV) genomes and play a role in innate antiviral immunity. The clinical relevance of this protein family is unknown. METHODS We analyzed 33 instances in which 17 patients with chronic HBV infection experienced >2 increases of >100 IU/L in alanine aminotransferase (ALT) level; we used a quantitative differential DNA denaturation polymerase chain reaction assay to quantify the hypermutated HBV genomes observed during 21 of these 33 increases in ALT level. RESULTS Of the 9 increases in ALT level that involved a >5-fold increase (relative to basal levels) in the number of hypermutated genomes observed, 8 were associated with a >2-log reduction in plasma HBV DNA level. In contrast, a corresponding decrease in plasma HBV DNA level was observed for only 1 of the 12 increases in ALT level that did not involve an increase in the number of hypermutated genomes ( P<.001). Hepatitis B e antigen clearance was often observed in patients who experienced an increase in the number of hypermutated genomes. Interferon treatment induced hypermutation in HBV genomes in an animal model. However, there was no apparent increase in the number of hypermutated genomes among the majority of patients who received interferon therapy, probably because the number of hypermutated genomes had already increased prior to the initiation of therapy. CONCLUSION Our results suggest that a marked increase in the number of hypermutated genomes represents a strong immunological host response against the virus and is predictive of hepatitis B e antigen clearance and plasma HBV DNA level reduction.

Efficacy of Percutaneous Cementoplasty for Bone Metastasis from Hepatocellular Carcinoma

Objective: To assess the efficacy of percutaneous cementoplasty for painful bone metastasis from hepatocellular carcinoma (HCC). Methods: Cementoplasty was performed for 22 metastatic bone tumors in 13 patients. All patients had intractable pain and were diagnosed as metastatic bone tumor from HCC. The ostyneedle was inserted in the center of the site of bone metastasis under CT guidance. VAS score, Tokuhashi score and Frankel score were used for assessment of the efficacy of cementoplasty. We also assessed the response to treatment, adverse events and prognosis. Results: Only the VAS score, but not Tokuhashi and Frankel scores, improved after cementoplasty. Cementoplasty for painful bone metastasis provided relief of severe pain but did not improve prognosis, neurological function or survival. Eleven of 13 (85%) patients showed CR or PR and the mean pain-free period was 5 months, including a 10-month pain-free period in one case. No major complications were encountered. Conclusions: Percutaneous cementoplasty can provide pain relief and improvement of quality of life, though without survival benefits, for HCC patients with painful bone metastasis.

Combination therapy of oral fluoropyrimidine anticancer drug S-1 and interferon alpha for HCC patients with extrahepatic metastases.

Purpose: There is no standard treatment for hepatocellular carcinoma (HCC) patients with extrahepatic metastases. We assessed the efficiency and safety of the oral fluoropyrimidine anticancer drug S-1 combined with interferon alpha (IFN-α) for HCC patients with extrahepatic metastases. Methods: Twenty-nine HCC patients with extrahepatic metastases received S-1/IFN. One cycle of combination therapy represented 2 weeks followed by 2–4 weeks of rest. In each cycle, S-1 was administrated orally at 80–120 mg (depending on body surface area) every day and IFN-α intramuscularly at 5 million units thrice weekly. Results: The overall response of 29 patients was complete response (CR) in 4 (14%), partial response (PR) in 1, stable disease in 4, progressive disease in 12, and dropout in 8 patients. Objective response (CR + PR) was 17%. The time to progression and survival rate were significantly higher in patients with lung metastases (n = 19) than in those with painful bone metastases (n = 7; p = 0.0058 and 0.0015). With regard to NCI-CTC grade 3 adverse reactions, 3 (10%), 3 (10%) and 2 (7%) patients developed anorexia, leukopenia, and neutropenia, respectively. No grade 4 adverse reaction or toxicity-related death occurred. Conclusion: S-1/IFN is a potentially safe and suitable combination therapy for HCC patients with extrahepatic metastases, especially those with lung metastases.

Amino acid substitutions in core and NS5A regions of the HCV genome can predict virological decrease with pegylated interferon plus ribavirin therapy.

BACKGROUND The current standard therapy for chronic hepatitis C is pegylated interferon (PEG-IFN) plus ribavirin (RBV) combination therapy. Recently, it has been reported that amino acid (aa) substitutions in the core region, as well as the IFN-sensitivity-determining region (ISDR), were predictive of non-virological response (NVR), sustained virological response (SVR) and early virological response. Despite the importance of these two predictive factors for combination therapy, their interaction is poorly understood. METHODS A total of 117 patients who were treated with PEG-IFN-α2b plus RBV combination therapy were selected for participation in this study. We determined the aa sequences in the core region and ISDR by direct sequencing and analysed them along with clinical data to identify predictive factors for therapeutic response. RESULTS The aa sequences in the core region and γ-glutamyl transpeptidase (GTP) levels were associated with SVR and NVR, but aa sequences in the ISDR were not. However, substitutions at both aa 70 and aa 91 in the core region without substitutions in the ISDR and higher levels of γ-GTP were independent predictive factors for NVR. Wild-type aa 70 and aa 91 in the core region, higher platelet counts and lower levels of γ-GTP were independent predictive factors for SVR. CONCLUSIONS These results indicate that analyses of aa substitutions in both the core region and the ISDR are useful for predicting the effectiveness of combination therapy, and could help to avoid therapy exposure for patients who have a low probability of SVR.