| Background and AimsHepatitis B Virus (HBV) infection is a serious global public health issue, and there are about 350 million people who were chronically infected with hepatitis B virus. Chronic Hepatitis B (CHB) might progress to late stage liver disease including cirrhosis, decompensation and hepatocellular carcinoma (HCC) which are related to persistent HBV replication. Therefore, the purpose of treatment is to delay the development of late stage liver diseases and prolong the life expectancy through long term suppression of virus replication. Currently, European Association for the Study of the Liver (EASL), American Association for the Study of Liver Diseases (AASLD), Asian Pacific Association for the Study of the Liver (APASL) clinical practice guideline recommend interferon alfa (IFNa), pegylated interferon alfa (PEG-IFNa), lamivudine (LAM), adefovir dipivoxil (ADV), telbivudine (L-dT), entecavir (ETV) and tenovofir (TDF) to treat CHB. The endpoints of antiviral therapy include alanine aminotransferase (ALT) normalization, undetectable HBV DNA, hepatitis B e antigen (HBeAg) loss and seroconversion, Hepatitis B surface antigen (HBsAg) loss and seroconversion. The ideal endpoint of antiviral therapy is to achieve HBsAg loss or seroconversion. However, most patients can hardly achieve this goal, even though treated with PEG-IFN, as the incidence of HBsAg clearance is rather low, about 2.95% for HBeAg positive patients and 3.3% for HBeAg negative after 48 weeks treatment and 24 weeks of posttreatment follow-up. Another study involved 322 patinets who received LAM monotherapy for at least 10 years showed that the rate of HBsAg clearance is only about 1% per year.Several studies have shown that serum HBsAg titer is associated with intrahepatic HBV DNA and covalently closed circular DNA (cccDNA). In recent years, with the widely use of HBsAg commercial quantification test, HBsAg quantification is applied to monitor the antiviral response in CHB patients who receive PEG-IFN therapy. Some studies indicate that on-treatment HBsAg decline is associated with off-treatment HBsAg clearance in patients with treatment of PEG-IFN. Furthermore, the kinetics of serum HBsAg during PEG-IFN therapy can predict off-treatment sustained virological response.However, study on HBsAg titer decline during long term nucleos(t)ide analogues (NAs) therapy is rare. Moreover, whether serum HBsAg will show different kinetics in CHB patients who receive different NAs is still not clarified. Previous studies mainly focused on the comparison of HBsAg kinetics between two different NAs in HBeAg positive or negative CHB patients, The comparison of HBsAg kinetics among multiple different NAs, however, is rarely reported.The aim of this study is to investigate HBsAg kinetics in CHB patients who receive NAs monotherapy for at least 3 years, and to evaluate the estimated time of HBsAg clearance among different NAs.Subjects and methods1. PatientsThis is a retrospective study analyzing HBsAg kinectics in 293 consecutive CHB patients who received NAs monotherapy for at least 3 years at the outpatient clinic of Nanfang Hospital between January 2005 and June 2011. All patients were HBsAg-positive for at least 6 months prior to treatment. Inclusion criteria included persistently undetectable HBV DNA during continuous NAs monotherapy (LAM, ADV, LdT or ETV). Exclusion criteria was as following:previous antiviral treatment with NAs or IFN-based strategies, virological breakthrough during the treatment duration, switched to or added with other antiviral agents due to poor virologic response, poor compliance, HCC, liver transplantation, co-infection with hepatitis C or D and other liver diseases not caused by HBV. Serum samples were stored at-30℃ until tested. Patients were treated with either LAM (100mg/d), ADV (10mg/d), LdT (600mg/d) or ETV (0.5mg/d). Serum HBsAg and HBV-DNA quantification were measured at baseline, year 1, year 2 and year 3. The study was conducted in compliance with the Declaration of Helsinki and in accordance with the Medical Ethics Committee of NanFang Hospital. All the patients enrolled gave written informed consent.2. Laboratory testSerum HBV DNA levels were measured using a real-time PCR quantification. HBV serological markers, including HBeAg, antibody to HBeAg (anti-HBe), antibody to HBsAg (anti-HBs), were determined with commercially available testes (Abbott Laboratories, Chicago, IL, USA). Serum HBsAg levels were quantified using Elecsys HBsAg Ⅱ quant assay (Roche Diagnostics, Branchburg,German), with a linear range of 0.05 to 52000 IU/mL.3. Statistical analysisStatistical analyses were conducted by SPSS version 19.0 (SPSS,Chicago,IL,USA). Continuous variables were expressed as median (interquartile range). Categorical variables were expressed as frequency and percentages. All data were assessed for normality using a Shapiro-Wilk test and categorical data were compared using a Kruskal-Wallis statistical test. Categorical variables were compared by Chi-square test. The duration of treatment required to achieve HBsAg loss was estimated by applying a linear equation calculated by interpolating the median logarithmic decline over time for each single drug. The difference with P value of<0.05 was considered statistically significant.ResultFrom January 2005 to June 2011, a total of 358 CHB patients were treated with NAs monotherapy (either LAM 100mg/d, ADV 10mg/d, LdT 600mg/d or ETV 0.5mg/d) for at least 3 years at the outpatient clinic of Nanfang Hospital. A total of 65 patients were excluded due to previous antiviral treatment history (n=10), co-infection with hepatitis C or D (n=8), diagnosis of HCC during treatment (n=2), poor compliance (n=3), decompensated liver cirrhosis (n=19) and unavailability of serum samples (n=23). Finally,293 patients were enrolled according to the criteria. Among them,143 were HBeAg positive with 18 being treated with LAM,11 with ADV,40 with LdT and 74 with ETV. Median age was 33 years (IQR 28-39). At baseline, the median serum HBV DNA level was 6.9 log10 IU/mL (IQR 5.8-7.9); median ALT level was 139 U/L (IQR 78-259) and median serum HBsAg level was 3.7 log10 IU/mL (IQR 3.2-4.4). The other 150 patients were HBeAg negative with 23 being treated with LAM,37 with ADV,27 with LdT and 63 with ETV. Median age was 40 years (IQR 34-48); at baseline median serum HBV DNA level was 5.4 log10 IU/mL (IQR 4.0-6.2); median ALT level was 78 U/L (IQR 49-181) and median serum HBsAg level was 3.2 log10 IU/mL (IQR 2.9-3.6). All the patients were HBV DNA undetectable during antiviral therapy.1. Baseline characteristicsBaseline variables, including the gender ratio, prevalence of cirrhosis, ALT level and HBsAg titers were comparable among different treatment groups in HBeAg-positive patients, except for serum HBV DNA level and age. For the HBeAg-negative patients, gender ratio, prevalence of cirrhosis and HBsAg titers were comparable among different treatment groups other than HBV DNA level, ALT level and age.2. Kinectics of serum HBsAg titers in different treatment groupsIn HBeAg positive patients, the baseline median serum HBsAg titers were 3.6 log10 IU/mL,3.7 log10 IU/mL,3.9 log10 IU/mL and 3.6 log10 IU/mL respectively for patients treated with LAM, ADV, LdT and ETV. The baseline HBsAg titers were not significantly different among the four treatment groups (p=0.926). The HBsAg titers significantly decline as compared to baseline in all treatment groups after 3 years treatment (P=0.010,0.033,0.002,0.000 for LAM, ADV, LdT, ETV respectively). We observed that the median HBsAg levels declined from baseline to the first year were 0.27 log10 IU/mL,0.30 log10 IU/mL,0.10 log10 IU/mL, and 0.24 log10 IU/mL respectively among patients treated with LAM, ADV, LdT and ETV (P=0.686). The median HBsAg levels declined from baseline to the second year were 0.34 log10 IU/mL,0.36 log10 IU/mL,0.30 log10 IU/mL,0.41 log10 IU/mL respectively in patients with LAM, ADV, LdT and ETV (P=0.602) and the decline from baseline to the third year were 0.47,0.42,0.37 and 0.62 respectively (P= 0.759). The median level of HBsAg decline during antiviral therapy was equal to 0.16 log10 IU/mL/year,0.14 log10 IU/mL/year,0.12 log10 IU/mL/year,0.21 log10 IU/mL/year respectively with LAM, ADV, LdT and ETV. No statistically significant difference was observed among all treatment groups (P=0.759).In HBeAg negative CHB patients, the baseline median serum HBsAg titers were 3.2 log10 IU/mL,3.3 log10 IU/mL,3.3 log10 IU/mL and 3.3 log10 IU/mL respectively for patients treated with LAM, ADV, LdT and ETV. The baseline HBsAg titers were not significantly different among the four treatment groups (p=0.183). The HBsAg titers significantly declined as compared to baseline in all treatment groups after 3 years treatment (P=0.031,0.000,0.010,0.001 for LAM, ADV, LdT, ETV respectively).We observed that the median HBsAg decline from baseline to the first year were 0.01 log10 IU/mL,0.02 log10 IU/mL,0.01 log10 IU/mL,0.05 log10 IU/mL respectively in patients with LAM, ADV, LdT and ETV treatment (P=0.595). The median HBsAg decline from baseline to the second year were 0.13 log10 IU/mL,0.14 log10 IU/mL,0.07 log10 IU/mL,0.11 log10 IU/mL respectively in patients with LAM, ADV, LdT and ETV treatment (P=0.949) and the decline from baseline to the third year were 0.21,0.30,0.16 and 0.24 respectively (P=0.373). The median level of HBsAg decline during antiviral therapy was 0.07 log10 IU/mL/year,0.10 log10 IU/mL/year,0.05 log10 IU/mL/year,0.08 log10 IU/mL/year respectively with LAM, ADV, LdT and ETV. Also, no statistically significant difference was observed among all treatment groups (P=0.373).3. Estimation of time of HBsAg loss during therapyHBsAg loss was achieved in 2 patients both treated with ETV,1 from 74 ETV-treated HBeAg positive patients and 1 from 63 HBeAg negative. In HBeAg positive patients, the linear regression formulations were Y=-0.138x+3.499 (R2=0.6799) for treatment with LAM, Y=-0.108x+3.625 (R2=0.9027) for ADV, Y=-0.134x+3.830 (R2=0.6722) for LdT, Y=-0.131x+3.553 (R2=0.7694) for ETV. The extrapolated expected time of HBsAg loss was approximately 35,36,38,37 years for LAM, ADV, LdT and ETV respectively (P= 0.873). In HBeAg negative CHB patients, the linear regression formulations were Y=-0.074x+3.216 (R2=0.9428) for treatment with LAM, Y=-0.080x+3.304(R2=0.9390) for ADV, Y=-0.081x+3.284 (R2=0.9352) for LdT, Y=-0.071x+3.289 (R2=0.9715) for ETV. The extrapolated expected time of HBsAg loss was approximately 61,58,57,64 years for LAM, ADV, LdT and ETV respectively (P= 0.432).Conclusions1. Serum HBsAg titers gradually declined during long term antiviral therapy in different treatment groups, but the achievement of HBsAg loss seems to require almost decades of therapy.2. No statistically significant difference was observed in the level of HBsAg titers decline and the estimated time of HBsAg loss among the different treatment groups in HBeAg positive or negative CHB patients. The kinectics of HBsAg with less potent NAs (LAM, ADV) is close to that with the potent NAs (LdT, ETV), as long as patients have achieved persistent viral suppression.3. HBeAg negative patients need longer time to achieve HBsAg loss than HBeAg positive patients, even if at lower baseline HBsAg titers. |
PDF Full Text Request