Long-term effects of lamivudine treatment in Japanese chronic hepatitis B patients

Predictors of kidney tubular dysfunction induced by adefovir treatment for chronic hepatitis B

AIM: To investigate the predictors of proximal kidney tubular dysfunction (PKTD) induced by adefovir dipivoxil (ADV) treatment for chronic hepatitis B.

METHODS: Seventy-nine patients (age at the evaluation of PKTD: 56.9 ± 10.7 years) with chronic hepatitis B undergoing long-term oral antiviral nucleos(t)ide analogue treatment were consecutively recruited. PKTD was defined by the presence of at least two of the following five abnormalities: phosphate diabetes, nondiabetic glucosuria, metabolic acidosis, β₂-microglobulinuria, or renal hypouricemia. The single-nucleotide polymorphisms (SNPs) in the SLC22A6 gene encoding human organic anion transporter 1 (hOAT1) and ABCC2 encoding multidrug resistance protein 2 (MRP2) were analyzed using the TaqMan Allelic Discrimination Demonstration Kit.

RESULTS: Nine (30.0%) of the 30 ADV-treated patients were diagnosed with PKTD, while no patients without ADV developed PKTD (P < 0.001). Three patients with ADV were diagnosed with symptomatic osteomalacia. Among the patients who took ADV, those with PKTD were of higher age at initiation, had significantly longer treatment duration, and had a significantly lower body mass index than those without PKTD. The incidence of PKTD dramatically increased after 96 mo from the start of ADV administration. In contrast, the SNPs were not correlated with PKTD. Logistic regression analysis extracted older age at initiation (OR = 5.0, 95%CI: 1.1-23.4; P = 0.040) and longer treatment duration (OR = 3.2, 95%CI: 1.2-8.6; P = 0.020) as significant factors associated with PKTD.

CONCLUSION: Our results suggest that the tubular function of the kidney of older patients undergoing long-term ADV treatment should be carefully evaluated.

Decreased antigenicity profiles of immune-escaped and drug-resistant hepatitis B surface antigen (HBsAg) double mutants

BACKGROUND

Selective pressure from either the immune response or the use of nucleoside analogs in antiviral therapy could be driving the emergence of HBV mutants. Because of the overlap of the open reading frame (ORF) S for the HBsAg and ORF P for viral polymerase, rtM204I and rtM204V mutations in the polymerase would produce sI195M and sW196S in the HBsAg. The combined effects of immune-escaped mutations (sT118M, sG145K, sG145R) and drug-resistant mutations (rtM204I, rtM204V) on the antigenicity profiles of HBsAg has not been widely explored.

METHODS

To determine the combined effects of immune-escaped and drug-resistant mutants on the antigenicity profiles of HBsAg, recombinant plasmids encoding HBsAg double mutants were constructed using site-directed mutagenesis. The supernatant from each plasmid transfection was analyzed for HBsAg in the western-blotting and five of the most commonly used commercial ELISA kits in China.

RESULTS

Western-blotting assay showed the successful expression of each HBsAg mutant. All five ELISA kits manifested similar avidity, which were demonstrated by the slope of the curves, for the sT118M mutant, and sT118M-rtM204I (sT118M-sI195M) and sT118M-rtM204V (sT118M-sW196S) double mutants, suggesting that drug-resistant YMDD mutants caused negligible losses in the antigenicity of immune-escaped sT118M HBsAg. In contrast, the presence of the rtM204I (sI195M) mutation, but not rtM204V (sW196S) in combination with the sG145K mutation significantly reduced the avidity of sG145K HBsAg. The rtM204I (sI195M) mutation also decreased the antigenicity profiles for sG145R HBsAg.

CONCLUSIONS

Drug-resistant mutations rtM204I (sI195M) and rtM204V (sW196S) caused significant reduction in antigenicity for the immune-escaped HBsAg mutants sG145K and sG145R, which may hamper HBV diagnosis and disease control from HBV blood-transfusion transmissions in China. The development of ELISA kits with a greater sensitivity for drug-resistant and immune-escaped HBsAg warrants further consideration.

Correlation of the occurrence of YMDD mutations with HBV genotypes, HBV-DNA levels, and HBeAg status in Chinese patients with chronic hepatitis B during lamivudine treatment

BACKGROUND

Continuous lamivudine therapy is associated with high rates of YMDD mutations, which are the main causes of drug resistance. The current study explores the association of the emergence of YMDD mutations with pretherapy HBV genotype, HBV-DNA levels, HBeAg status, and serum alanine aminotransferase (ALT) levels in Chinese patients receiving lamivudine therapy for chronic hepatitis B.

METHODS

A total of 319 chronic hepatitis B patients who received lamivudine therapy for more than a year were enrolled in this study. YMDD mutations, HBV genotype, HBV-DNA levels, HBeAg status, and ALT levels were determined prior to their lamivudine treatment and every three months for a year of this therapy.

RESULTS

Among the 319 patients, 137 (42.95%) were infected with genotype B and 182 (57.05%) with genotype C. Up to 94 patients (29.47%) developed YMDD mutations within one year of lamivudine therapy. Furthermore, 50 patients with HBV genotype B and 44 patients with genotype C developed YMDD mutations (36.50% vs 24.18%, P<0.05). Logistic regression analysis showed that pretherapy HBV genotype, HBV-DNA levels, and HBeAg status are independent factors for the emergence of YMDD mutations (HBV genotype: OR=2.159, 95% CI 1.291-3.609, P=0.003; HBV-DNA: OR=1.653, 95% CI 1.231-2.218, P=0.001; HBeAg: OR=2.021, 95% CI 1.201-3.399, P=0.008).

CONCLUSIONS

HBV genotype, HBV-DNA levels, and HBeAg status at baseline are the independent factors associated with the emergence of YMDD mutations among Chinese patients receiving lamivudine therapy for chronic hepatitis B. These findings are helpful to the development of therapeutic strategies for these patients.

Longitudinal assessment of liver stiffness by transient elastography for chronic hepatitis B patients treated with nucleoside analog

AIM

  To evaluate the association between liver stiffness measured by transient elastography (FibroScan) and the efficacy of long-term nucleoside analog (NA) treatment for patients with chronic hepatitis B.

METHODS

  Study 1: Forty-four chronic HBV patients had liver stiffness measured by FibroScan and underwent liver biopsy. Study 2: Group A: 22 patients started NA treatment at entry and FibroScan was done annually for 3 years. Group B: 23 patients started NA treatment prior to pretreatment FibroScan measurement, and FibroScan was done for from 3 to 5 years after the start of NA treatment.

RESULTS

  Study 1: The FibroScan values were significantly correlated with fibrosis stage (r = 0.672, P < 0.0001). Optimal cutoff of FibroScan values were 6.1 kPa for ≥ F1, 6.3 kPa for ≥ F2, 8.9 kPa for ≥ F3 and 12.0 kPa for F4. Study 2: For Group A, the baseline median FibroScan value was 8.2 kPa. FibroScan values significantly decreased annually for 3 years after the start of NA treatment (6.4 kPa, 5.8 kPa and 5.3 kPa at years 1, 2 and 3, respectively). For Group B, the FibroScan values did not significantly improve over the 3 years after the start of NA treatment.

CONCLUSIONS

  Liver stiffness, measured by transient elastography, of chronic hepatitis B patients treated with NA showed a rapid decline in the first 3 years followed by a more steady transition for from 3 to 5 years irrespective of long term virological effect.