Association of lamivudine-resistant mutational patterns with the antiviral effect of adefovir in patients with chronic hepatitis B

Inflammation Pharmacological Reaction and YMDD Mutational Patterns in Lamivudine Therapeutics Hepatitis B Virus

Background/Aims: Emergence of tyrosine-methionine-aspartate-aspartate (YMDD) motif in reverse transcriptase is a serious problem in chronic hepatitis B(CHB) patients after Lamivudine (LAM) therapy. However, the relationship between inflammation pharmacological reaction and YMDD mutational patterns of CHB has not been well-characterized. The aim of this study was to investigate the inflammation pharmacological reaction and different YMDD mutants patterns of CHB patients. Methods: We investigated the inflammation pharmacological reaction and YMDD mutational patterns through biochemical, serological and virological detection among 83 CHB patients, including 25 YMDD mutants, 25 under detection, and 33 control patients without YMDD mutants. Results: Prevalence of YMDD mutation patterns is different. Among 25 YMDD mutants patients, YIDD was the dominant mutation (72%), followed YVDD (16%) and the hybrid YIDD + YVDD (12%). The time course during the YMDD mutations was also different. 52.4% patients developed the mutation less than 12 months after the LAM therapy. Serum hepatitis B virus (HBV) DNA level in patients with YMDD mutants were significantly higher than that in control and negative groups. Serum HbsAg and HbeAg in patients with YMDD mutants were also higher than those in control and negative groups, despite no significant difference was found forserum HbeAb. ALT and AST levels were also significantly higher in mutants group. Conclusions: Illuminating inflammation pharmacological reaction and YMDD mutational patterns of CHB during pathological process may have implications for future therapy in YMDD mutation patients. This may have impact on the choice of treatment strategies for lamivudine-resistant HBV.

Hepatitis B Virus X Protein Promotes Degradation of SMC5/6 to Enhance HBV Replication

The hepatitis B virus (HBV) regulatory protein X (HBx) activates gene expression from the HBV covalently closed circular DNA (cccDNA) genome. Interaction of HBx with the DDB1-CUL4-ROC1 (CRL4) E3 ligase is critical for this function. Using substrate-trapping proteomics, we identified the structural maintenance of chromosomes (SMC) complex proteins SMC5 and SMC6 as CRL4(HBx) substrates. HBx expression and HBV infection degraded the SMC5/6 complex in human hepatocytes in vitro and in humanized mice in vivo. HBx targets SMC5/6 for ubiquitylation by the CRL4(HBx) E3 ligase and subsequent degradation by the proteasome. Using a minicircle HBV (mcHBV) reporter system with HBx-dependent activity, we demonstrate that SMC5/6 knockdown, or inhibition with a dominant-negative SMC6, enhance HBx null mcHBV-Gluc gene expression. Furthermore, SMC5/6 knockdown rescued HBx-deficient HBV replication in human hepatocytes. These results indicate that a primary function of HBx is to degrade SMC5/6, which restricts HBV replication by inhibiting HBV gene expression.

Multiplex detection of KRAS mutations by a matrix-assisted laser desorption/ionization-time of flight mass spectrometry assay

OBJECTIVES

Mutations of the Kirsten rat sarcoma viral oncogene (KRAS) gene are known to be important in the pathogenesis of a variety of cancers. Patients with mutant KRAS tumors do not respond to epidermal growth factor receptor (EGFR) inhibitors and fail to benefit from adjuvant chemotherapy. Testing for KRAS mutations is now being recommended as a tailored therapeutic strategy prior to anti-EGFR treatment; however, the low sensitivity of direct sequencing frequently leads to failure of detection of KRAS mutations in clinical samples.

DESIGN AND METHODS

We developed restriction fragment mass polymorphism (RFMP) assays, to detect KRAS mutations in codons 12, 13, and 61. We performed RFMP analysis for KRAS on DNA isolated from eight different KRAS mutant cell lines and 34 formalin-fixed paraffin-embedded (FFPE) lung cancer tissues.

RESULTS

Overall, the RFMP assay was in good concordance with direct sequencing analysis in the detection of KRAS mutations. By using dilutions of KRAS mutant DNA in wild type DNA from mutation cell lines with a known KRAS status, we confirmed that the RFMP assay has a higher analytical sensitivity, requiring only 3% of cells in a sample to have mutant alleles, compared to direct sequencing, which had a detection threshold of ~25%. In the FFPE samples, RFMP successfully detected KRAS genotypes in codons 12, 13, and 61.

CONCLUSION

The RFMP might be efficiently applicable for the detection of KRAS mutations in a clinical setting, particularly for tumor samples containing abundant non-neoplastic cells.

Partial virological response to adefovir add-on lamivudine rescue therapy in patients with lamivudine-resistant chronic hepatitis B

BACKGROUND/AIMS

In patients with lamivudine (LAM)-resistant chronic hepatitis B (CHB) receiving adefovir (ADV) add-on LAM therapy, insufficient viral suppression or the appearance of additional ADV resistance has remained unresolved. This study determined the partial virological response (PVR) criteria to predict a virological response (VR) at week 96 in these patients.

METHODS

96 patients with LAM-resistant CHB (ADV add-on LAM therapy >2 years) were analyzed. For predicting VR at week 96, the area under the receiver operating characteristic curve values at different time points were compared to establish the optimal time point, and the maximal Youden index was calculated to determine the optimal cut-off hepatitis B virus (HBV) DNA level.

RESULTS

50 (52.1%) patients achieved VR at 2 years after ADV add-on LAM therapy. The optimal PVR criteria were determined to be HBV DNA 500 IU/ml at week 48. 44 (45.8%) patients who met optimal PVR criteria showed a significantly higher risk for detectable HBV DNA levels at week 96 than those with a favorable VR (HBV DNA <500 IU/ml) at week 48.

CONCLUSIONS

This study suggested optimal PVR criteria in patients with LAM-resistant CHB receiving ADV add-on LAM therapy. Modification of the antiviral agent regimen should be considered if the serum HBV DNA level exceeds 500 IU/ml at week 48.

Restriction fragment mass polymorphism (RFMP) analysis based on MALDI-TOF mass spectrometry for detecting antiretroviral resistance in HIV-1 infected patients

Viral genotype assessment is important for effective clinical management of HIV-1 infected patients, especially when access and/or adherence to antiretroviral treatment is reduced. In this study, we describe development of a matrix-assisted laser desorption/ionization-time of flight mass spectrometry-based viral genotyping assay, termed restriction fragment mass polymorphism (RFMP). This assay is suitable for sensitive, specific and high-throughput detection of multiple drug-resistant HIV-1 variants. One hundred serum samples from 60 HIV-1-infected patients previously exposed to nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs) were analysed for the presence of drug-resistant viruses using the RFMP and direct sequencing assays. Probit analysis predicted a detection limit of 223.02 copies/mL for the RFMP assay and 1268.11 copies/mL for the direct sequencing assays using HIV-1 RNA Positive Quality Control Series. The concordance rates between the RFMP and direct sequencing assays for the examined codons were 97% (K65R), 97% (T69Ins/D), 97% (L74VI), 97% (K103N), 96% (V106AM), 97% (Q151M), 97% (Y181C), 97% (M184VI) and 94% (T215YF) in the reverse transcriptase coding region, and 100% (D30N), 100% (M46I), 100% (G48V), 100% (I50V), 100% (I54LS), 99% (V82A), 99% (I84V) and 100% (L90M) in the protease coding region. Defined mixtures were consistently and accurately identified by RFMP at 5% relative concentration of mutant to wild-type virus while at 20% or greater by direct sequencing. The RFMP assay based on mass spectrometry proved to be sensitive, accurate and reliable for monitoring the emergence and early detection of HIV-1 genotypic variants that lead to drug resistance.

The influence of YMDD mutation patterns on clinical outcomes in patients with adefovir add-on lamivudine combination treatment

BACKGROUND/AIM

The aim of this study was to assess the patterns of lamivudine (LAM)-resistant mutations and the influence on biochemical and virological responses to adefovir (ADV) add-on LAM combination therapy in patients with LAM-resistant chronic hepatitis B (CHB).

METHODS

Seventy-eight CHB patients with confirmed genotypic resistance to LAM, who initiated ADV add-on LAM combination treatment, were enrolled at our institution between April 2007 and April 2009.

RESULTS

The baseline tyrosine-methionine-aspartate-aspartate (YMDD) mutation patterns were as follows: rtM204I 45 (57.7%); and rtM204V + rtM204I/V 33 (42.3%). The decrease in the mean ± standard deviation (SD) serum log(10) HBV-DNA level did not differ between the patients carrying the rtM204I vs. rtM204IV +rtM204I/V mutations at 3, 6 and 12 months after the initiation of ADV add-on LAM combination treatment. The proportion of patients who achieved ALT normalization (<40 IU/L) 12 months after the initiation of ADV add-on LAM combination treatment were significantly higher in patients with a rtM204I mutation than rtM204V+ rtM204I/V mutations (39 [86.7%] vs. 22 [66.7%], P = 0.05). The proportion of patients in whom the log(10) HBV-DNA decreased <2 log(10) copies/ml, 6 months after the initiation of ADV add-on LAM combination treatment (non-responders), was significantly higher in patients with a rtM204V + rtM204I/V mutations than rtM204I mutation (7 [21.2%] vs. 2 [4.4%], P = 0.032).

CONCLUSION

Biochemical response at 12 months from baseline was better in patients with a rtM204I mutation than rtM204V+ rtM204I/V mutations. In addition, early treatment failure was more common in patients with rtM204V+ rtM204I/V mutations than a rtM204I mutation.

Analysis of hepatitis B virus X gene (HBx) mutants in tissues of patients suffered from hepatocellular carcinoma in China

Hepatitis B virus (HBV) X (HBx) gene multi-site mutations are a frequent event in the clinical hepatocellular carcinoma (HCC) tissues. It has been reported that the mutation of the HBx plays a crucial role in the development of HBV-related HCC. To identify the novel mutations of HBx in the HCC tissues, we examined and analyzed the sequences of HBx gene in 60 cases of HCC tumor tissues and paratumor tissues from China by polymerase chain reaction (PCR). The mutation patterns of HBx were analyzed by comparing the tumor tissues with non-tumor tissues. The data showed that 44 cases of tissues out of 60 patients were HBV-positive. Our results showed that the mutations at amino acid 30, 88, 144 from tumor samples and at amino acid 31, 43, 87, 94 from non-tumor samples were highly frequent events. Interestingly, we found that a novel type of HBx linked-mutations, such as at aa L30F/S144A, was 29.5% (13/44) positive in the tumor tissues. However, the role of HBx gene mutations at aa L30F/S144A relative to wild type HBx gene is unclear in hepatocarcinogenesis. The novel HBx linked-mutations may be significant in the development of HCC.

Current Nucleos(t)ide Analogue Therapy for Chronic Hepatitis B

Although the prevalence of chronic hepatitis B has decreased considerably in recent years due to widespread use of the hepatitis B virus (HBV) vaccine, its prevalence still remains high in adults, and this can place a significant burden on health care in areas with endemic HBV. Since the introduction of nucleos(t)ide analogues (NUCs), there has been marked improvement in the care of patients with chronic hepatitis B, resulting in increased survival. However, the emergence of drug resistance in patients treated with NUCs is a major concern. The number of multi-drug resistant patients is increasing, and many patients may not respond to the currently available drugs. In this review, we describe the current status of NUC therapy for antiviral-naïve and -resistant patients.

Initial virological response and viral mutation with adefovir dipivoxil added to ongoing Lamivudine therapy in Lamivudine-resistant chronic hepatitis B

BACKGROUND

Although adefovir dipivoxil (ADV) has been used for antiviral treatment of lamivudine (LAM)-resistant chronic hepatitis B (CHB) patients, the long-term efficacy of this treatment is not well understood. Initial virological response (IVR) has been reported to be an important factor in relation to the development of ADV-resistance.

AIMS

We therefore examined the factors associated with IVR and ADV mutation in these patients.

METHODS

Forty-nine LAM-resistant CHB patients with ADV add-on LAM therapy, 47% of whom were hepatitis B e-antigen (HBeAg)-positive with median treatment duration of 23 months, were enrolled in this study. Patients were classified into IVR and non-IVR groups on the basis of viral suppression status. Mutational analysis of the HBV polymerase/reverse transcriptase (rt) domain was performed by PCR-direct sequencing.

RESULTS

Serum HBV DNA was undetectable (<2.6 log10 copies/mL) in 67, 82, and 84% of patients at 24, 48, and 96 weeks, respectively, after ADV add-on LAM therapy. IVR was achieved in 82% of patients, and ALT normalized at week 24 in 90% of IVR and 78% of non-IVR patients. The lower pretreatment HBV DNA level and virus-containing mutations other than double mutation of rtL180M + rtM204V were significantly associated with IVR (P=0.002 and P=0.014, respectively). ADV-resistant mutations in the RT motif, reported previously, were not detected.

CONCLUSION

IVR is useful for predicting the antiviral efficacy of ADV and LAM combination therapy in LAM-resistant CHB.

Genotypic resistance profile of hepatitis B virus (HBV) in a large cohort of nucleos(t)ide analogue-experienced Chinese patients with chronic HBV infection

The study investigated the hepatitis B virus (HBV) genotypic resistance profile in 1803 nucleos(t)ide analogue (NA)-experienced Chinese patients with chronic HBV infection. Serum HBV DNA was extracted, and the reverse transcriptase region was analysed by a high-sensitive direct PCR sequencing and verified by clonal sequencing if necessary. Drug-resistant mutations were detected in 560 of the 1803 patients, including 214 of 490 patients who received lamivudine (LAM), 35 of 428 patients who received adefovir (ADV), five of 18 patients who received telbivudine and 306 of 794 patients who received various sequential/combined NA therapies. ADV-resistant mutations were detected in 36 of 381 patients who received LAM and then switched-to ADV in contrast to one of 82 patients who received ADV add-on LAM. Entecavir (ETV)-resistant mutations were detected not only in LAM- and ETV-treated patients but also in LAM-treated ETV-naïve patients. Double mutations rtM204I and rtL180M were detected more frequently in genotype C than in genotype B virus, and patients infected with this mutant had higher alanine transaminase levels than those infected with mutant containing the rtM204I substitution alone. Multidrug-resistant HBV strains were identified in eight patients, including two novel strains with mutational patterns rtL180M + A181V + S202G + M204V + N236T and rtL180M + S202G + M204V + N236T. The results provide new information on HBV genotypic resistance profiles in a large cohort of Chinese patients with chronic HBV infection and may have important clinical implication for HBV drug resistance management in China.

Hepatitis B virus (HBV) subgenotypes C2 and B2 differ in lamivudine- and adefovir-resistance-associated mutational patterns in HBV-infected Chinese patients

We aimed to study the prevalence and clinical implications of hepatitis B virus (HBV) subgenotypes in Chinese patients. A total of 4,300 patients, mainly from northern China, were enrolled, including 182 patients with acute hepatitis B and 4,118 patients with chronic HBV infection who had been exposed to nucleoside or nucleotide analogs. HBV genotypes/subgenotypes were determined by direct sequencing of the HBV S/Pol region. The prevalence rates were 0.40% for HBV/B1, 14.30% for HBV/B2, 0.25% for HBV/B3, 0.35% for HBV/B4, 1.05% for HBV/C1, 81.72% for HBV/C2, 0.93% for HBV/C3, 0.16% for HBV/C4, and 0.84% for HBV/D. In chronic HBV infection, patients with HBV/B2 were younger and had lower ΗBeAg positive rates than patients with HBV/C2. The incidence of lamivudine-resistant mutations was significantly higher in HBV/C2 compared to HBV/B2 (27.9% versus 19.8%; P<0.01), and the significant difference was observed only for rtM204I and not rtM204V. In addition, compensatory mutations were more frequently detected in HBV/C2. The incidence of adefovir-resistant mutations was similar between the two subsets, but HBV/C2 inclined to show rtA181V (3.6% for C2 versus 0.9% for B2; P<0.01), while HBV/B2 inclined to show rtN236T (4.5% for versus 2.5% for C2; P<0.01). The ratios of HBV/B2 to HBV/C2 infection were 1.7 (110/65), 5.7 (2,653/463), 7.5 (520/69), 8.0 (48/6), and 15.3 (183/12) for acute hepatitis B, chronic hepatitis B, liver cirrhosis, acute-on-chronic liver failure, and hepatocellular carcinoma, respectively. In conclusion, HBV/C2 and HBV/B2, two prevalent subgenotypes, differ in lamivudine- and adefovir-resistance-associated mutational patterns. HBV/C2-infected patients are more likely to have disease progression than HBV/B2-infected ones.

Current status of liver diseases in Korea: hepatitis B

Hepatitis B virus (HBV) infection is the one of the most common causes of the liver diseases in Korea. Since the discovery of Australia antigen (hepatitis associated antigen, or HBsAg later), hepatitis associated antigen was tested widely. HBsAg was detected in 6.6-8.6% in 1980's. Later, it decreased to 5.7% in 1990's. Remarkably, seropositivity of the children deceased to 0.2% after the nationwide vaccination program. Although hepatitis B vaccines are highly effective, the failure rate of perinatal prophylaxis in babies born to HBsAg positive mother was reported to be 4.25%. Treatment of chronic hepatitis B was initiated after the introduction of interferon alpha. Lamivudine opened a new era of oral antiviral agent, and it has been widely used in Korea since 1999. Adefovir was proven to have a good efficacy for lamivudine-resistant chronic hepatitis B. Newer potent antiviral agents such as entecavir, clevudine, and telbivudine are available currently. Further studies are warranted for understanding factors influencing natural history, improving treatment outcomes, and overcoming vaccine non-response.