Tenofovir disoproxil fumarate (TDF) monotherapy for 48 weeks provided a virological response comparable to that of TDF and entecavir (ETV) combination therapy in patients infected with ETV-resistant hepatitis B virus (HBV). Little long-term data in routine clinical practice are available regarding the optimal treatment of patients with ETV-resistant HBV.
We investigated the long-term antiviral efficacy of combination therapy of TDF+lamivudine (LAM) or TDF+ETV compared to that of TDF monotherapy in 73 patients with resistance to both LAM and ETV.
Patients were treated with TDF monotherapy (n=12), TDF+LAM (n=19), or TDF+ETV (n=42) for more than 6 months. The median duration of TDF-based rescue therapy was 37 months. Virologic response (VR) was found in 63 patients (86.3%). The rates of VR among the three groups (TDF monotherapy, TDF+LAM, and TDF+ETV) were not statistically different (log-rank
TDF monotherapy was as effective as combination therapy of TDF+LAM or TDF+ETV in maintaining long-term viral suppression in chronic hepatitis B patients with resistance to both LAM and ETV. HBV DNA level at the start of TDF rescue therapy was the only independent predictor of subsequent VR.
Hepatitis B virus (HBV) infection is a serious public health problem worldwide, with an estimated 2 billion infections, and a major cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC) [
Nucleos(t)ide analogues (NUCs) as an important class of antiviral drugs have changed the treatment paradigm and prognosis of CHB. Lamivudine (LAM), the first oral antiviral agent approved to treat HBV, is safe and well tolerated, even in patients with decompensated liver cirrhosis [
Tenofovir disoproxil fumarate (TDF) is a potent nucleotide analog recommended and used once-daily as a first line therapy for CHB patients [
Electronic medical records of CHB patients with ETV resistance in addition to prior LAM resistance were reviewed. Patients were treated with sequential ETV monotherapy due to genotypic LAM resistance. A total of 73 patients were treated with TDF alone or combination (with LAM or ETV) by clinician or patient choice from December 2012 to November 2015. All patients had hepatitis B surface antigen (HBsAg). Serum HBV DNA level was documented for at least 6 months before the start of LAM therapy. Patients with impaired renal function (serum creatinine > 1.5 mg/dL), autoimmune hepatitis, or antibodies against hepatitis C virus or human immunodeficiency virus (HIV) were excluded from this study. Additional criteria for exclusion were: pregnancy, lactation, and alcohol abuse (> 40 g/d ethanol). Diagnoses of chronic hepatitis and liver cirrhosis were based on liver biopsy features or on clinical, laboratory, and ultrasound data if liver biopsy data were unavailable. Written informed consents were obtained from all of patients participating in this study. This research was approved by the Institutional Review Board at the Ulsan University Hospital (UUH 2016-09-002, approved on Sep. 20, 2016).
Liver and kidney function tests were performed every three months during TDF based rescue treatment. HBV DNA levels were quantified using COBAS TaqMan HBV test (Roche, Branchburg, NJ, USA) with a lower detection limit of 12 IU/mL (60 copies/mL). Genotypic resistance to ETV was defined as the emergence of ETV resistance mutations in the presence of lamivudine resistance substitutions M204I/V ± L180M. When a viral breakthrough had developed before TDF-based rescue therapy, we tested a restriction fragment mass polymorphism (RFMP; Genematrix, Youngin, Korea) to identify LAM (rt180, rt204), ADV (rt181, rt236), and ETV (rt173, rt184, rt202, rt250). The specific HBV genotypes were identified using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the surface gene of HBV genome. The two fragments of the HBV genome between the nucleotide positions 2823 and 2845 and 61 and 80 were amplified by PCR. PCR products were treated with restriction enzymes. Patients underwent surveillance for HCC every 6 months with serial abdominal ultrasound and serum α-fetoprotein measurements.
A virologic response (VR) was defined as the absence of serum HBV DNA by PCR assay (< 12 IU/mL) on two consecutive measurements during TDF treatment. Hepatitis B envelop antigen (HBeAg) seroconversion was defined as the loss of HBeAg accompanied by the detection of anti-HBe. Partial virologic response (PVR) was defined as a decrease in HBV DNA of more than 1 log10 IU/mL but with detectable HBV DNA after 6 months of antiviral therapy. Virologic breakthrough (VBT) was defined as a > 1 log10 IU/mL increase in serum HBV DNA from the nadir on two consecutive measurements or in the last available measurement. Safety and tolerability were evaluated by the occurrence of adverse events (AEs), serious AEs (SAEs), laboratory abnormalities, discontinuation of the study drug due to AEs, or death. Specific markers of renal abnormalities included confirmed (defined as two consecutive visits) increase in serum creatinine of at least 0.5 mg/dL above the baseline value, serum phosphorus values < 2 mg/dL, and creatinine clearance < 50 mL/min.
Serum HBV DNA (IU/mL) levels were logarithmically transformed for statistical analysis. Continuous variables were compared using the one-way analysis of variance (ANOVA). Categorical variables were compared using the χ2 test. The cumulative probability rates of clinical outcomes were calculated using Kaplan-Meier method. To identify the factors predictive of outcome among the baseline variables, the variables for clinical outcomes were compared using the χ2 test or univariate logistic regression. Variables with a
The baseline characteristics of the 73 CHB patients are summarized in
To define whether there was any difference in the rate of VR in TDF alone, TDF+LAM, or TDF+ETV therapy, VR rates were compared according to the variables using a log-rank test. The baseline characteristics of the TDF monotherapy (n=12), TDF+LAM (n=19), and TDF+ETV (n=42) treatment groups are shown in
Of the 73 patients, 36 (the presence of ETV+ADV salvage treatment) received combination therapy of ETV+ADV as salvage therapy for LAM and ETV resistance prior to TDF based rescue therapy. The remaining 37 patients (the absence of ETV+ADV salvage treatment) only received ETV monotherapy prior to TDF based rescue therapy. The presence of ETV+ADV salvage treatment group had significantly lower baseline AST, ALT (
To define whether there were any differences in the rates of VR according to the clinical and virological factors (such as genotypic resistance profile, the presence of ETV+ADV salvage treatment or TDF monotherapy vs. combination therapy with LAM or ETV), VR rates according to these variables were compared using a logistic regression analysis (
To determine whether an optimal cut-off level of HBV DNA at baseline of TDF treatment could predict VR, we analyzed the HBV DNA cut-off values could provide maximal predictive efficacy. Our results revealed that the best cut-off value of HBV DNA level at baseline for the prediction of VR was 5.61 log10 IU/mL, with a sensitivity and specificity of 80.6% and 70.0%, respectively. Using cut-off value of HBV DNA at baseline, the cumulative VR rates in patients with HBV DNA levels ≥ 5.61 log10 IU/mL (n=19) and those with HBV DNA levels < 5.61 log10 IU/mL (n=54) were 22.7% and 77.9% at 12 months and 73.2% and 98.2% at 24 months, respectively (
No clinically significant AEs were observed during the TDF-based treatment. Mean creatinine level and estimated glomerular filtration rate did not change during the treatment period. Two patients (2.7%) had an increase in serum creatinine. However, no patient had an increase in serum creatinine of > 0.5 mg/dL above the baseline value. Mild hypophosphatemia (a serum phosphorus level of < 2.7 mg/dL) was detected in one patient without change in serum creatinine. HCC occurrence was not detected in any patient during the follow-up period.
In our study, the long-term TDF based rescue therapy from community clinic-based settings demonstrated strong viral suppression in patients who had failed in prior treatment with ETV and LAM. We also found that TDF monotherapy was as effective as the combination therapy of TDF+ETV or TDF+LAM for viral suppression in CHB patients who showed genotypic resistance to both LAM and ETV. Moreover, multivariate analysis revealed that the HBV DNA level at the start of TDF rescue therapy was the only independent predictor of subsequent VR.
Unfortunately, single ETV salvage therapy as one of the treatment options for CHB patients with LAM resistance was not satisfactory [
We evaluated the efficacy of TDF+ETV or TDF+LAM combination therapy compared to that of TDF monotherapy in CHB patients who developed resistance to LAM and ETV. In our study, 42 patients received TDF+ETV combination therapy, 19 patients received TDF+LAM combination therapy, and 12 received TDF monotherapy. The rates of VR among the three groups (TDF monotherapy, TDF+LAM, and TDF+ETV) were not statistically different (log-rank
Many pretreatment variables have been investigated to identify predictive factors for the selection of patients most likely to respond to antiviral therapy [
This study had several limitations. First, a retrospective study design was used, in spite of a long-term follow-up period. Second, TDF-resistant mutational analysis was not performed in patients with continued viremia or who experienced VBT during TDF rescue therapy due to lack of TDF mutation test in our institution at that study time. Third, patient compliance to these long term treatment regimens may be poorer and less controlled than compliance to short term strictly monitored treatments in clinical trials. Despite these shortcomings, our results may be valuable to demonstrate the antiviral efficacy and safety in patients with LAM and ETV resistant HBV treated with TDF based regimens. These results may be helpful for clinicians’ actual practical care of these difficult-to–treat HBV patients. To verify the efficacy and safety of TDF based rescue regimen, further large cohort studies with a long follow-up duration are warranted.
In conclusion, in CHB patients with resistance to LAM and ETV, TDF based rescue therapy was well tolerated without significant adverse events such as renal toxicity. TDF monotherapy was as effective as the combination therapy of TDF+LAM or TDF+ETV in maintaining viral suppression in CHB patients with LAM- and ETV-resistance. Therefore, add-on therapy with LAM or ETV appeared to be unnecessary, because it did not provide further benefit over TDF alone regarding VR. Moreover, multivariate analysis revealed that HBV DNA level at the start of TDF rescue therapy was the only predictor of subsequent VR. This observation suggests that switching to TDF should be done as early as genotypic resistance is detected so that we can maximize the efficacy of treatment in CHB patients with CHB with resistance to ETV.
Conception and design the work: Neung Hwa Park and Jung Woo Shin
Data collection: Hee-Jeong Jeon, Yujin Yang, Jin-Hee Noh, JaeSung Ahn, Hyung Rae Kim, and Jae Ho Lee
Data analysis and interpretation: Seok Won Jung and Jung Woo Shin
Drafting the article: Hee-Jeong Jeon and Neung Hwa Park
Critical revision of the article: Seok Won Jung and Neung Hwa Park
Final approval of the manuscript: All authors
This work was supported by Priority Research Center Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology (2009-0094050).
Mean reduction rates of HBV DNA level from baseline between TDF monotherapy, TDF+LAM, and TDF+ETV combination therapy groups. The mean reduction in serum HBV DNA concentration was not significantly different among the three treatment groups. HBV, hepatitis B virus; TDF, tenofovir disoproxil fumarate; ETV, entecavir; LAM, lamivudine.
Cumulative rates of VR according to TDF rescue therapy. The rates of VR among the three groups (TDF monotherapy, TDF+LAM, and TDF+ETV) were not statistically significant at 12 months (59.3%, 78.9%, and 51.8%, respectively) or at 24 months (88.4%, 94.7%, and 84.2%). VR, virologic response; TDF, tenofovir disoproxil fumarate; ETV, entecavir; LAM, lamivudine.
Cumulative rates of VR according to pretreatment HBV DNA level. The cumulative VR rates in patients with HBV DNA level ≥ 5.61 log10 IU/mL (n=19) and those with HBV DNA level < 5.61 log10 IU/mL (n=54) were 22.7% and 77.9% at 12 months and 73.2% and 98.2% at 24 months, respectively. VR, virologic response; HBV, hepatitis B virus.
The baseline characteristics of the studied patients (n=73)
Value | |
---|---|
Age (years) | 53.0 (27-79) |
Gender (male/female) | 54/19 |
Diagnosis (chronic hepatitis/cirrhosis) | 37/36 |
AST (IU/L) | 29 (13-425) |
ALT (IU/L) | 32.0 (8-589) |
HBV DNA (log10 IU/mL) | 4.11 (1.42-8.23) |
HBeAg positivity (n, %) | 63 (86.3) |
Duration of LAM therapy (months) | 32 (15-144) |
Duration of ETV therapy (months) | 26.5 (20-70) |
Duration of TDF-based rescue therapy (months) | 37 (6-45) |
ETV resistant mutations (+M204I/V ± L180M) | |
169SMT,184IALT, 202G, 250LV,184LV 202G | 7, 23, 22, 7, 5 |
Continuous variables are expressed as medians with range.
AST, aspartate transaminase; ALT, alanine transaminase; HBV, hepatitis B virus; HBeAg, hepatitis B e antigen; LAM, lamivudine; ETV, entecavir; TDF, tenofovir disoproxil fumarate.
The baseline characteristics of the TDF monotherapy, TDF + LAM, and TDF + ETV treatment groups
TDF (n=12) | TDF+LAM (n=19) | TDF+ETV (n=42) | ||
---|---|---|---|---|
Age (years) | 55.5 ± 13.4 | 54.8 ± 10.5 | 52.6 ± 9.4 | 0.592 |
Gender (male/female) | 8/4 | 13/6 | 33/9 | 0.577 |
Diagnosis (chronic hepatitis/cirrhosis) | 7/5 | 10/9 | 20/22 | 0.792 |
AST (IU/L) | 41.7 ± 36.0 | 26.7 ± 6.8 | 51.4 ± 68.2 | 0.263 |
ALT (IU/L) | 48.8 ± 50.1 | 33.1 ± 13.5 | 61.8 ± 95.3 | 0.393 |
HBV DNA (log10 IU/mL) | 4.10 ± 2.80 | 3.20 ± 1.03 | 4.69 ± 1.89 | 0.021 |
HBeAg positivity (n, %) | 8 (66.7) | 17 (89.5) | 38 (90.5) | 0.096 |
Duration of LAM therapy (months) | 32.9 ± 29.7 | 40.5 ± 21.3 | 31.5 ± 29.3 | 0.518 |
Duration of ETV therapy (months) | 23.4 ± 20.1 | 26.7 ± 12.0 | 28.1 ± 13.4 | 0.613 |
Duration of TDF therapy (months) | 25.8 ± 14.4 | 38.2 ± 1.3 | 33.6 ± 9.8 | 0.003 |
Continuous variables are expressed as means ± standard deviations.
TDF, tenofovir disoproxil fumarate; ETV, entecavir; LAM, lamivudine; AST, aspartate transaminase; ALT, alanine transaminase; HBV, hepatitis B virus; HBeAg, hepatitis B e antigen.
Overall clinical outcomes in the TDF alone, TDF+LAM, and TDF+ETV therapy groups
TDF (n=12) | TDF+LAM (n=19) | TDF+ETV (n=42) | ||
---|---|---|---|---|
HBeAg seroconversion (n=64, [n ,%]) | 0/8 (0) | 2/17 (11.8) | 4/39 (10.3) | 0.161 |
VR (n, %) | 9/12 (75.0) | 19/19 (100) | 35/42 (83.3) | 0.099 |
VBT (n, %) | 1 (8.3) | 0 (0) | 1 (2.4) | 0.222 |
PVR (n, %) | 5 (41.7%) | 5 (26.3) | 20 (47.6) | 0.293 |
ALT normalization (n=23, [n, %]) | 2/4 (50) | 2/3 (66.7) | 10/16 (62.5) | 0.879 |
Values are presented as n (%) unless otherwise indicated.
TDF, tenofovir disoproxil fumarate; ETV, entecavir; LAM, lamivudine; HBeAg, hepatitis B e antigen; VR, virologic response; VBT, virological breakthrough; PVR, partial virologic response; ALT, alanine transaminase.
Univariate and multivariate analyses of the predictive factors for virologic response during TDF-based rescue therapy
Variables | Univariate |
Multivariate |
||||
---|---|---|---|---|---|---|
HR | 95% CI | HR | 95% CI | |||
Age (years) | 0.961 | 0.911-1.013 | 0.141 | |||
Gender (male gender) | 0.923 | 0.303-2.814 | 0.888 | |||
Diagnosis (CH/LC) | 1.896 | 0.706-5.092 | 0.204 | |||
Duration of TDF therapy | 0.948 | 0.813-1.106 | 0.499 | |||
AST | 0.998 | 0.987-1.008 | 0.662 | |||
ALT | 0.997 | 0.987-1.007 | 0.507 | |||
HBeAg positivity | 1.229 | 0.282-5.363 | 0.784 | |||
Pretreatment HBV DNA level | 0.699 | 0.547-0.893 | 0.004 | 0.723 | 0.627-0.834 | < 0.001 |
ETV mutation profiles | 0.898 | 0.164-4.921 | 0.901 | |||
Presence of ETV/ADV before TDF therapy | 0.593 | 0.356-0.988 | 0.045 | 0.611 | 0.201-1.866 | 0.387 |
Rescue therapy regimen (TDF monotherapy vs. TDF combination therapy) | 1.052 | 0.395-2.805 | 0.919 |
TDF, tenofovir disoproxil fumarate; HR, hazard ratio; CI, confidence interval; CH, chronic hepatitis; LC, liver cirrhosis; AST, aspartate aminotransferase; ALT, alanine aminotransferase; HBeAg, hepatitis B e antigen; HBV, hepatitis B virus; ETV, entecavir; ADV, adefovir dipivoxil; LAM, lamivudine.