Frequency and risk factors of renal impairment during long-term adefovir dipivoxil treatment in chronic hepatitis B patients

Fanconi syndrome induced by adefovir dipivoxil: a case report and clinical review

More than 150 cases of Fanconi syndrome (FS) or hypophosphatemia osteomalacia induced by low-dose adefovir dipivoxil (ADV) have been reported since 2002, when ADV was introduced for the long-term treatment of hepatitis B virus (HBV) infection. Because the life expectancy of HBV-infected individuals has increased, the adverse effects of long-term treatment with antiviral therapies are increasingly observed, and nephrotoxicity is one of the most severe adverse effects of ADV. Therefore, the number of cases may be far higher than reported. Moreover, ADV-induced FS is often misdiagnosed or diagnosed long after it first develops. ADV-induced FS may seriously decrease patient quality of life and lead to bone fractures and even disability. Although progress has been made in the identification of biomarkers and treatments, few systematic clinical guidelines or clinical reviews for FS induced by ADV have been reported. In this study, we highlighted the recent progress toward understanding of FS induced by ADV, described a clinical case, and summarized the primary characteristics and laboratory findings of this disease.

Follow-Up of Adefovir Dipivoxil Induced Osteomalacia: Clinical Characteristics and Genetic Predictors

Adefovir dipivoxil (ADV) is widely used for chronic hepatitis B therapy in China. To explore the clinical features and prognosis of ADV-induced osteomalacia and to analyze the association between osteomalacia and genetic variants in 51 drug transporters genes. Clinical and follow-up data of the ADV-treated patients were collected. Target capture sequencing was used to identify genetic variations of 51 drug transporter genes. A total of 193 hepatitis B patients treated with ADV were enrolled, of whom 140 had osteomalacia. The other 53 without osteomalacia were included in the control group. The median duration of ADV treatment before the onset of osteomalacia was 6.5 years (range:1.5–7 years). We found that most patients with osteomalacia had hypophosphatemia, high serum alkaline phosphatase levels, hypouricemia, nondiabetic glycosuria, proteinuria. Stopping ADV administration, supplementing calcitriol and calcium were effective treatments. During 3–6 months of follow-up, the clinical symptoms and biochemical indicators of patients with osteomalacia have been significantly improved. There was no significant difference in duration of adefovir treatment in patients with or without osteomalacia (p = 0.791). Through regression analysis, we found that age was a risk factor for osteomalacia [per 1 year, odds ratio (OR), 1.053; 95% confidence interval (95% CI), 1.020–1.087; p = 0.015]. 1992 single nucleotide variants were found using target capture sequencing. However, the associations of genetic variants of 51 drug transporter genes and the risk of osteomalacia were negligible. Osteomalacia is prone to occur in patients with chronic hepatitis B treated with long-term ADV at a therapeutic dose. After standard treatment, the prognosis is mostly good. We failed to find genetic variants that can predict the risk of ADV-induced osteomalacia.

Long-term Nucleotide Analogue Treatment Has Higher Levels of Renal Toxicities than Does Entecavir in Patients with Chronic Hepatitis B

Background/Aims

Renal toxicity is a concern in patients with chronic hepatitis B taking nucleotide analogues, such as adefovir (ADV) and tenofovir disoproxil fumarate (TDF). We sought to determine the long-term renal effects of nucleotide analogue treatment versus entecavir (ETV) treatment.

Methods

In this retrospective single-center study, we selected 87 patients who were treated with ADV and subsequently with TDF from June 2008 to December 2013. ETV-treated patients were matched by treatment duration. We analyzed the creatinine increase over 0.5 mg/dL, glomerular filtration rate (GFR) decrease over 25%, phosphorus decrease under 2.0 mg/dL, and dose reduction of antiviral agents.

Results

The median follow-up period was 60.0 months for both groups. The incidence of liver cirrhosis was higher in the ADV-TDF group than in the ETV group (32.2% vs 74.7%, p<0.01). Creatinine increased in both groups during follow-up, but the difference was not significant (5.7% and 2.3%, p=0.44). In addition, GFR decreased more often in the ADV-TDF group than in the ETV group (31.0% and 14.9%, p=0.01). After multivariate Cox regression analysis, ADV-TDF treatment was significantly associated with a GFR decrease over 25% (hazard ratio, 2.10; 95% confidence interval, 1.08 to 4.10; p=0.03) after adjusting for the baseline GFR decrease.

Conclusions

Patients taking nucleotide analogues had a significantly higher number of renal events than did those taking ETV. Clinicians should be aware of the development of renal toxicity in this patient population. Further long-term studies are warranted.

Cross-sectional retrospective analysis of clinical characteristics of chronic hepatitis B patients with oral antiviral treatment in eastern China

BACKGROUND

In China, more than 20 million patients with chronic hepatitis B need antiviral treatment. Side effects of antiviral treatment such as renal complications can be problematic, particularly in an aging population.

METHODS

The data were retrospectively extracted from the hospital medical charts of five centers in eastern China from January 1 to December 31, 2018.

RESULTS

A total of 8309 patients with CHB was enrolled in this study. The median age of the patients was 46 years. The prevalence of diabetes mellitus, hypertension, and hepatic cirrhosis was respectively 3.49%, 4.42%, and 23.72%. The prevalence of these comorbidities increased with age (P < 0.001). Of the patients with CHB, 5332 had complete renal function results. Among them, patients with an estimated glomerular filtration rate of < 60 mL/min/1.73m² accounted for 4.14%, and those with proteinuria for 8.33%. According to the definition of chronic kidney disease, the proportion of patients with chronic kidney disease was 11.37%. The prevalence of chronic kidney disease increased with age (P < 0.001). In a multivariate analysis, age group [odds ratio (OR) = 2.387], diabetes mellitus (OR = 1.486), hypertension (OR = 2.557), hepatic cirrhosis (OR = 1.295), and a history of exposure to adefovir dipivoxil (OR = 1.644) were significantly associated with CKD (P < 0.05). Among patients with CKD, 17.66% (107/606) had a history of lamivudine exposure, and 34.65% (210/606) had a history of nucleotide analogue exposure CONCLUSION: The management of Chinese patients with CHB should take into consideration age, previous medication history, and renal impairment.

Kinetics of hepatitis B surface antigen and estimated glomerular filtration rate in telbivudine-treated hepatitis B patients with different rescue strategies

This study investigated the kinetics of estimated glomerular filtration rate (eGFR) and quantitative hepatitis B surface antigen (qHBsAg) in telbivudine (LdT)-treated chronic hepatitis B (CHB) patients whose treatment was subsequently adjusted with the adding on adefovir or by switching to tenofovir disoproxil fumarate (TDF) as rescue. Of 295 CHB patients initially treated with LdT, 102 of them who subsequently receiving either adding-on adefovir (group A, n = 58) or switching to TDF (group B, n = 44) for more than 24 months were enrolled. Serial eGFR and qHBsAg levels (3 to 6 monthly) in both LdT monotherapy and rescue therapy periods were analyzed retrospectively. Subsequent decline of qHBsAg especially in rescue therapy period were noted (p<0.001 and p = 0.068 in group A and B). However, patients in group B achieved a significant increase of eGFR (p = 0.010) in LdT monotherapy period but had a significant decline of eGFR (p<0.001) in rescue therapy period. In contrast, patients in group A maintained eGFR levels in both periods. Meanwhile, switch to TDF (hazard ratio: 3.036; 95% confidence interval: 1.040-8.861; p = 0.042) was the sole factor related to the decrease of eGFR>20% from baseline. Both rescue therapies achieved subsequent declines of qHBsAg over time but caused different changes in eGFR. LdT-based rescue therapy maintained eGFR but TDF switching therapy descended eGFR. Therefore, it is essential to monitor patient's renal function intensively when switching from LdT to TDF as a rescue strategy.

Osteomalacia and renal failure due to Fanconi syndrome caused by long-term low-dose Adefovir Dipivoxil: a case report

Background

Progressive bone pain and fracture and abnormal positron emission tomography combined with a computed tomography are main reasons for the oncologists suspecting bone tumor. During the patient’s medical treatment, the oncologists’ unfamiliarity with adverse reactions to anti-HBV drugs were main reason for the long-term exposure to the drug and the adverse reaction (ADR) experienced by the patient.

Case presentation

A 63-year-old Chinese man had a 27-month history of progressive generalized bone pain combined with spontaneous fractures. Positron emission tomography combined with a computed tomography, revealed an abnormal increase in ribose metabolism and low positron serum inorganic phosphorus concentration (0.7; 0.78–1.65 mmol/L). Serum creatinine level was 252 μmol/L (53–97) μmol/L, and glomerular filtration rate was 22.79 mL/min/1.73 m². The patient was referred to a multidisciplinary clinic to clarify the diagnosis of myeloma or bone tumor for further treatment in 2017. His medical history revealed that he had a 30-year history of chronic hepatitis B infection. He had received lamivudine at a daily dose of 100 mg for 19 years (1990 to 2009), which had been changed to adefovir (10 mg/day) owing to lamivudine resistance in 2009. Based on the changes in the patient’s laboratory markers and the results of emission computed tomography and other radiographic findings, adefovir-induced hypophosphatemic osteomalacia due to acquired renal Fanconi syndrome was suspected by the clinical pharmacist. Considerable clinical improvement was observed after adefovir discontinuation and the administration of entecavir (1.0 mg, every other day).

Conclusion

Fanconi syndrome with osteomalacia can develop in patients with chronic hepatitis B infection being treated with adefovir at a conventional low dosage of 10 mg/day. This case highlights the importance of ADR as a differential diagnosis and the need of pharmacists with drug safety expertise expert in the patient management.

Retrospective analysis of the clinical characteristics of adefovir dipivoxil-induced Fanconi's syndrome in the Chinese population

WHAT IS KNOWN AND OBJECTIVE

To explore the clinical characteristics of adefovir dipivoxil-induced Fanconi's syndrome in the Chinese population and provide a reference for rational drug use in the clinic.

METHODS

By searching the CNKI, Wanfang, Chinese VIP, PubMed/MEDLINE, Web of Knowledge, Ovid, Elsevier and SpringerLink databases during 1 January 2008 to 31 December 2019, 78 studies of ADV-induced Fanconi's syndrome involving a total of 110 patients were collected and analysed retrospectively.

RESULTS AND DISCUSSION

Prolonged usage of adefovir dipivoxil at low doses to treat hepatitis B might cause Fanconi's syndrome as the first symptom, especially for use over 12 months.The main clinical manifestation was bone pain accompanied by hypophosphataemia, elevated alkaline phosphatase (ALP), urine glycosuria and urine protein. X-rays and bone mineral density (BMD) examinations were mainly used to characterized osteoporosis. The patients had pain relief within 1 week to 1 month, and the biochemical indicators returned to normal within from 2 to 4 months.

WHAT IS NEW AND CONCLUSION

Sufficient attention is required before and during exposure to long-term ADV therapy. The clinical picture, laboratory and radiograph alterations are important clues for ADV-induced Fanconi's syndrome.

Telbivudine and adefovir dipivoxil combination therapy improves renal function in patients with chronic hepatitis B: A STROBE-compliant article

Few studies have addressed the impact of adefovir dipivoxil (ADV)-based combination therapy on the renal function of patients with chronic hepatitis B (CHB). This study evaluated the effects of ADV combined with other antiviral nucleotide analogs (NAs) on renal function of patients with CHB, and analyzed the risk factors for more than 20% reduction of baseline estimated glomerular filtration rate (eGFR).The data of 164 patients with CHB were retrospectively analyzed in this study. Of the 164 patients, 42 received entecavir (ETV) combined with ADV (ETV + ADV group), 68 lamivudine (LAM) combined with ADV (LAM + ADV group), and 54 telbivudine (LDT) combined with ADV (LDT + ADV group). Serum creatinine (SCr) level, eGFR, and proportion of patients with eGFR ≥ 90 mL/min/1.73 m were observed. Also, the independent risk factors for more than 20% reduction of baseline eGFR were analyzed.After 104-week combination therapy, compared with the baseline level, SCr levels were significantly increased in the ETV + ADV group (67 μmol/L vs 73 μmol/L, P = .012) and LAM + ADV group (68 μmol/L vs 79 μmol/L, P = .008), but it was significantly decreased in the LDT + ADV group (69 μmol/L vs 64 μmol/L, P = .023). Compared with the baseline level, eGFR was significantly decreased in the ETV + ADV group (107.8 mL/min/1.73 m vs 96.1 mL/min 1.73/m, P = .004), and LAM + ADV group (105.4 mL/min/1.73 m vs 87.3 mL/min/1.73 m, P = .000), but it was significantly increased in the LDT + ADV group (104.1 mL/min 1.73/m vs 116.2 mL/min/1.73 m,P = .005). The proportion of patients with normal renal function (≥90 mL/min/1.73 m) was significantly higher in the LDT + ADV group than in the ETV + ADV group (P = .002) and LAM + ADV group (P = .001). Multivariate analysis showed that age (P = .035), male (P = .005), baseline eGFR (P < .001), LAM combined with ADV (P < .008), and ETV combined with ADV (P = .03) were independent risk factors for 20% reduction of baseline eGFR.As compared with ETV and ADV combination therapy as well as LAM and ADV combination therapy, LDT and ADV combination therapy can improve eGFR level, so LDT and ADV combination therapy is suitable for the patients with potential renal impairment.

Serum NGAL can act as an early renal safety biomarker during long-term nucleos(t)ide analogue antiviral therapy in chronic hepatitis B

Tubular renal toxicity is a side-effect of long-term therapy with nucleos(t)ide analogue(s) (NA) in chronic hepatitis B (CHB). There are no established surrogate markers in plasma of early NA-related toxicity. Neutrophil gelatinase-associated lipocalin (NGAL) is a protein produced by tubular cells following renal damage. We aimed therefore to retrospectively compare conventional renal markers (estimated glomerular filtration rates (eGFR) and urinary protein/creatinine ratio uPCR) with a sensitive biomarker (NGAL) in CHB patients on long-term NA therapy and assess the ability of new markers to predict NA-related renal toxicity (new onset of nonalbumin proteinuria). A total of 192 naïve CHB patients (median age 41 years, 78% males, 25% HBeAg+, 35% cirrhosis) were NA treated for at least 5 years (median 8.34 years, range 5.54-11.1 years). The eGFR and uPCR were compared at baseline and last clinical visit with serum NGAL concentrations measured by ELISA at same time-points and assessed according to the presence/absence of nonalbumin proteinuria at last visit. While baseline and last visit eGFR were similar (median:78 vs 84 mL/min), serum NGAL concentrations increased during therapy (median:9.4 vs 16.4 ng/mL, P < .05). The proportion of patients with proteinuria (uPCR > 15) increased between baseline and last visit (4.6% vs 21.4%, P < .05), with 30 (16%) patients having de novo nonalbumin proteinuria at last visit. High baseline NGAL concentrations were exclusive to patients with de novo nonalbumin proteinuria (median:31.7 vs 7.8 ng/mL, P < .01) and baseline NGAL levels >25 mg/mL were predictive of nonalbumin proteinuria at last visit (AUROC = 0.813). In conclusion, serum NGAL can act as a surrogate marker of early renal injury (de novo nonalbumin proteinuria) in CHB on long-term NA therapy.

Effect of adding on telbivudine or switching to telbivudine alone on therapeutic efficacy and renal function in chronic hepatitis B patients on adefovir dipivoxil monotherapy

AIM

To explore the serum conversion rate of hepatitis B e antigen (HBeAg) and renal function in patients with chronic hepatitis B (CHB) treated with aldefovir dipivoxil (ADV) plus telbivudine (L-DT).

METHODS

This retrospective cohort study included 42 patients with HBeAg-negative CHB who were on ADV (10 mg) monotherapy. Twenty patients were treated with L-DT add-on therapy (combination therapy group), and 22 patients were switched to ETV monotherapy (monotherapy group). At 24 and 48 wk, the conversion rate of HBeAg and renal function evaluated by estimated glomerular filtration rate (eGFR) were analyzed and compared between the two groups.

RESULTS

The eGFR at 24 and 48 wk did not differ significantly between the two groups (P = 0.773, 0.108). The eGFR in the combination therapy group was significantly higher at 48 wk than at baseline (t = -6.184, P < 0.05), but no significant difference was observed in the monotherapy group (t = -0.893, P > 0.05). The serum conversion rates of HBeAg at 24 wk and 48 wk were significantly higher in the combination therapy group than in the monotherapy group (P = 0.043, 0.034).

CONCLUSION

L-DT based treatment is effective in elevating the serum conversion rate of HBeAg, and long-term therapy is associated with sustained improvement of renal function, particularly among HBeAg-negative CHB patients treated with ADV.

Adefovir dipivoxil induced hypophosphatemic osteomalacia in chronic hepatitis B: a comparative study of Chinese and foreign case series

BACKGROUND

Adefovir dipivoxil (ADV)-induced renal tubular dysfunction and hypophosphatemic osteomalacia (HO) have been given great consideration in the past few years. However, no standard guidance is available due to a lack of powerful evidence from appropriate long-term prospective case-control studies and variations in the definition of renal adverse events. The aim of this study is to clarify clinical features of ADV-related HO in Chinese chronic hepatitis B patients with long-term ADV treatment in Chinese and non-Chinese comparative case series.

METHODS

Retrieval of case reports was based on Pubmed, CNKI, Wan Fang and VIP databases using the key words adefovir dipivoxil, hypophosphatemia, osteomalacia and Fanconi syndrome. We divided patients into Chinese (C group) and Foreign (F group) groups according to their nationality. Comparisons involving demographics, clinical manifestations, tests, treatment and prognosis were conducted between the two groups.

RESULTS

Of the patients screened, 120 Chinese patients were identified in the C group, and 32 non-Chinese patients were identified in the F group. The average age of the C group was younger than that of the F group (51.89 years ±10.96 years versus 56.47 years ±11.36 years, t = - 2.084, P = 0.039). No significant difference was found in gender (male to female, 3.29:1 versus 3:1, χ ²  = 0.039, P = 0.844). Although there was no significant difference in the duration of ADV therapy before ostalgia onset, the C group tended to develop adverse events earlier, by 2-3 years, while the F group developed adverse events at 4-5 years (Z = - 1.517, P = 0.129). Prognosis was good after adjustment of the ADV dose and supplemental administration of phosphate and calcitriol. Time to resolution of tubular dysfunction was commenced at the first month, and Chinese patients were more prone to recover in the first 3 months than non-Chinese patients (91.3% of patients in the C group versus 56.3% in the F group, Z = - 3.013, P = 0.003).

CONCLUSIONS

Sufficient attention is required for middle-aged males before and during exposure to long-term ADV therapy, regardless of nationality. The clinical picture, laboratory and radiograph alterations are important clues for those patients and are usually characterized by polyarthralgia, renal tubular dysfunction and mineralization defects. Implementation of an early renal tubular injury index is recommended for patients with higher risk, which would prevent further renal injury.

Clinical features of hypophosphatemic osteomalacia induced by long-term low-dose adefovir dipivoxil

Objective

To investigate the predictors of hypophosphatemic osteomalacia induced by adefovir dipivoxil (ADV) and to monitor for early detection.

Patients and methods

Hospitalized patients who were diagnosed with ADV-related hypo-phosphatemic osteomalacia were recruited and retrospectively analyzed in our hospital from January 2012 to December 2016. A telephone interview was conducted at 1, 3, 6, 9, 12, and 24 months after cessation of ADV.

Results

In the 8 patients enrolled in the study, the hypophosphatemic osteomalacia symptoms developed at an average of 5.14 (4–7) years since ADV treatment (10 mg/d). The average alkaline phosphatase (ALP) level was 279.50 (137–548) U/L, which was significantly higher than the normal level (45–125 U/L). The serum phosphorus level was an average of 0.59 (0.43–0.69) mmol/L, which was lower than the normal range (2.06–2.60 mmol/L). Serum calcium levels of the enrolled patients remained within normal limits. Reduced estimated glomerular filtration rate (eGFR <29 mL/min/1.73 m²) was seen in 4 cases. The clinical manifestations were mainly progressive systemic bone and joint pain, frequent fractures, trouble in walking, height reduction (4–6 cm), and so on. After cessation of ADV, symptoms like bone pain resolved gradually. Serum phosphorus level restored to normal in 4.5 months after the withdrawal of ADV. However, in 4 patients, renal function failed to return to normal in 24 months.

Conclusion

More attention should be paid to the duration of ADV treatment. The level of serum phosphorus and ALP, as well as renal function, should be monitored for early detection of potential adverse drug reactions.

Hypophosphatemia predicts a failure to recover from adefovir-related renal injury after dose reduction in lamivudine-resistant hepatitis B patients

AIM

In chronic hepatitis B patients receiving 10 mg adefovir, dose reduction is recommended when renal injury appears. However, recovery is not always achieved and markers that recommend switching to another antiviral agent are unknown. We investigated adefovir-related renal injury, recovery after dose reduction, and their predictors.

METHODS

The renal injury in 77 chronic hepatitis B patients receiving 10 mg adefovir and recovery after dose reduction to alternate day administration in those with adefovir-related renal injury were assessed. The predictors for >20% estimated glomerular filtration rate (eGFR) decline following treatment with 10 mg adefovir and for >20% eGFR recovery after dose reduction were investigated.

RESULTS

The adefovir dose was reduced in 26 patients (34%) at 59 ± 30 (mean ± standard deviation) months of 10 mg adefovir treatment because of decreases in eGFR (cumulative incidence 27%), serum phosphorus (9%), and uric acid (16%) levels, and increases in alkaline phosphatase (20%), bone type alkaline phosphatase (18%), urinary α1-microglobulin (18%), and urinary N-acetyl-β-D-glucosaminidase (18%) levels. The only significant predictor for >20% eGFR decline was age ≥50 years at the start of 10 mg adefovir treatment. The cumulative eGFR recovery rate was 42% at 42 ± 27 months after dose reduction, and ≥2.5 mg/dL serum phosphorus level at dose reduction was the only significant predictor for >20% eGFR recovery after dose reduction.

CONCLUSION

Patients aged ≥50 years are predisposed to adefovir-related renal injury and switching to another antiviral agent rather than adefovir dose reduction is recommended when hypophosphatemia is observed.

Factors Related to Significant Improvement of Estimated Glomerular Filtration Rates in Chronic Hepatitis B Patients Receiving Telbivudine Therapy

BACKGROUND AND AIM

The improvement of estimated glomerular filtration rates (eGFRs) in chronic hepatitis B (CHB) patients receiving telbivudine therapy is well known. The aim of this study was to clarify the kinetics of eGFRs and to identify the significant factors related to the improvement of eGFRs in telbivudine-treated CHB patients in a real-world setting.

METHODS

Serial eGFRs were calculated every 3 months using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. The patients were classified as CKD-1, -2, or -3 according to a baseline eGFR of ≥90, 60-89, or <60 mL/min/1.73 m², respectively. A significant improvement of eGFR was defined as a more than 10% increase from the baseline.

RESULTS

A total of 129 patients were enrolled, of whom 36% had significantly improved eGFRs. According to a multivariate analysis, diabetes mellitus (DM) (p = 0.028) and CKD-3 (p = 0.043) were both significantly related to such improvement. The rates of significant improvement of eGFR were about 73% and 77% in patients with DM and CKD-3, respectively.

CONCLUSIONS

Telbivudine is an alternative drug of choice for the treatment of hepatitis B patients for whom renal safety is a concern, especially patients with DM and CKD-3.

Effect of 48-week pegylated interferon α-2a or nucleos(t)ide analogue therapy on renal function in Chinese patients with chronic hepatitis B

Background

Controversy remains as to whether antiviral agents contribute to renal dysfunction in patients with chronic hepatitis B virus (HBV) infection. Thus, the aim of study was to analyze the changes in renal function of chronic hepatitis B (CHB) patients in response to anti-HBV therapy and the association with treatments.

Method

We performed a retrospective observational cohort study to investigate factors associated with renal function in 249 Chinese CHB patients who were treated with pegylated interferon α-2a (PEG-IFN-α-2a) or nucleos(t)ide analogues for 48 weeks. Changes of estimated glomerular filtration rate (eGFR), which was computed with both the Chronic Kidney Disease Epidemiology Collaboration and the Modification of Diet in Renal Disease formulas, were tested by repeated measures One-way analysis of variance within groups. A linear mixed effects model for repeated measures was also used to evaluate the association between baseline information and eGFR changes over time in all enrolled patients. The model considered the baseline age, sex, HBV DNA, aminotransferase, blood urea nitrogen, treatment group, time, and group-by-time interaction as fixed effects and incorporated random effects for individual subjects.

Results

The eGFR increased in patients given PEG-IFN-α-2a, decreased in patients given adefovir, but remained stable in patients given entecavir. Age and blood urea nitrogen were significant negative predictive factors for eGFR changes.

Conclusion

In real-life study, PEG-IFN-α-2a therapy in CHB patients increased eGFR, thus may associate with renoprotective effects when compared with adefovir or entecavir therapies.

Relationship between nephrotoxicity and long-term adefovir dipivoxil therapy for chronic hepatitis B: A meta-analysis

BACKGROUND

To assess the relationship between adefovir dipivoxil and renal function after anti-hepatitis B virus therapy and elucidate the risk factors involved.

METHODS

Based on the requirements of the Cochrane systematic review methodology, 21 observational articles on adefovir dipivoxil-associated renal dysfunction were obtained by searching various databases, between January 1, 1995 and July 1, 2016. The Newcastle Ottawa Scale was used to evaluate risk bias. Parameters for 4276 chronic hepatitis B patients were analyzed by Review Manager and R software, and glomerular filtration rate, creatinine clearance, and serum creatinine values were extracted to evaluate renal function.

RESULTS

Renal dysfunction was more likely to occur in patients receiving the adefovir dipivoxil therapy (odds ratio [OR] 1.98, 95% confidence interval [CI] 1.40-2.80) than the none-adefovir dipivoxil group. Subgroup analysis showed that renal function predictive value is higher for glomerular filtration rate (OR 2.42, 95% CI 1.34-3.14), compared with serum creatinine levels (OR 1.51, 95% CI 0.75-3.04). The rate of adefovir dipivoxil-associated renal dysfunction was 12% (95% CI 0.08-0.16). Older patients and patients with renal insufficiency, hypertension, and diabetes mellitus were more prone to developing adefovir dipivoxil-associated renal dysfunction; however, integrated raw data were insufficient for further detailed analysis.

CONCLUSION

Long-term adefovir dipivoxil therapy is connected to renal dysfunction in chronic hepatitis B, necessitating the monitoring of kidney function.

Comparison of the Efficacies and Safety of Combined Therapy between Telbivudine Plus Adefovir and Lamivudine Plus Adefovir in Patients with Hepatitis B Virus Infection in Real-World Practice

Background and Aim

Chronic hepatitis B infection remains a significant health issue worldwide. This study evaluated the efficacy and safety of combined therapy using lamivudine plus adefovir (LAM+ADV) versus telbivudine plus adefovir (LdT+ADV) and the corresponding renal function change and safety.

Methods

This study enrolled a total of 171 patients (110 patients received LAM+ADV and 60 patients received LdT+ADV). We analyzed the changes in renal function using the estimated glomerular filtration rate (eGFR). The DNA undetectable rate, hepatitis B e antigen (HBeAg) seroconversion rate, and alanine aminotransferase (ALT) normalization rate were analyzed. We checked the serum uric acid, phosphate and creatine kinase, and lactic acid levels to analyze safety. We observed these patients for 48 to 240 weeks and checked their serum profile every 6 months.

Results

There was no statistically significant difference between the two groups in anti-hepatitis B virus (HBV) efficacy in terms of DNA undetectable rate, ALT normalization rate, and HBeAg seroconversion rate. Both the LAM+ADV and LdT+ADV groups had stable or improved renal function. However, a higher eGFR was found in the LdT+ADV group with continuous serum fluctuation during 3 years of combined therapy as well as a higher serum creatine kinase level.

Conclusions

Long-term LdT+ADV combined therapy and LAM+ADV combined therapy were both associated with stable or improved renal function. The clinical efficacy was similar between the two groups, but the LdT group had a higher serum creatine kinase level. We need to monitor the data regularly in clinical practice.

Circulating kidney injury molecule-1 is a novel diagnostic biomarker for renal dysfunction during long-term adefovir therapy in chronic hepatitis B

The aim of this study was to evaluate serum kidney injury molecule-1 (KIM-1) as a new diagnostic marker of renal dysfunction in chronic hepatitis B (CHB) patients receiving long-term adefovir dipivoxil (ADV) treatment.We retrospectively enrolled 85 patients treated with ADV and 85 patients treated with entecavir (ETV) monotherapy, for at least 6 months. The 2 groups were matched for baseline age (± 5 years), sex, and estimated glomerular filtration rate (eGFR). Serum creatinine, cystatin C, and KIM-1 concentrations were measured, and eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine-cystatin C equation, at baseline and last follow-up.eGFR decreased by 10-20% from baseline in 11/85 (14.1%) patients, 20-30% in 5/85 (5.9%), and ≥ 30% in 2/85 (2.4%) patients treated with ADV. Serum KIM-1 was more significantly increased after ADV treatment 86.53 (10.20-355.40) pg/mL than ETV treatment 61.54 (10.53-200.56) pg/mL (P < 0.01). Furthermore, serum KIM-1 was positively correlated with serum cystatin C (r = 0.47; P < 0.001) and negatively correlated with eGFR (r = -0.46; P < 0.001). The area under the receiver operating characteristic curve (AUC-ROC) of serum KIM-1 for identifying renal dysfunction in all enrolled patients was 0.94 (95% confidence interval [95% CI], 0.87 to 1.02; P < 0.001), while the AUC-ROC of serum creatinine was only 0.82 (95% CI, 0.60 to 1.03; P < 0.01).Serum KIM-1 is a promising new diagnostic biomarker of renal dysfunction during long-term ADV therapy for CHB patients.

Renal Function in Nucleos(t)ide Analog-Treated Patients With Chronic Hepatitis B: A Systematic Literature Review and Network Meta-Analysis

INTRODUCTION

Renal safety is an important factor in selecting the most appropriate nucleos(t)ide analog (NA) treatment for patients with chronic hepatitis B (CHB). This systematic literature review and network meta-analysis aimed to assess renal function associated with telbivudine treatment compared to other NAs in patients with CHB.

METHODS

A systematic literature search via Medline, Medline In-Process, Embase, and the Cochrane library for publications of randomized controlled trials and observational studies was conducted. Network meta-analysis was performed to compare renal function with telbivudine treatment versus other NAs after 1 year of therapy.

RESULTS

Overall, 40 (six randomized controlled and 34 observational) studies were included for review. Telbivudine consistently showed an improvement in renal function as measured by an estimated glomerular filtration rate (eGFR) over various time points regardless of the method of measurement. Changes in eGFR (mL/min) from baseline and corresponding 95% credible intervals with various NAs were as follows: monotherapies (telbivudine: 7.78 [6.91, 8.65], entecavir: -1.07 [-4.80, 2.62], lamivudine: -6.08 [-13.35, 1.15], tenofovir: -9.53 [-14.31, -4.89]) and combination therapies (telbivudine + adefovir: 8.37 [-34.00, 50.34], telbivudine + tenofovir: 8.29 [-0.05, 16.64], entecavir + adefovir: 4.15 [-38.55, 46.37], telbivudine + lamivudine: 0.51 [-11.77, 12.96], and lamivudine + adefovir: -0.39 [-42.48, 41.21]). At 1 year, the change in eGFR from baseline was significantly higher with telbivudine compared to other NAs.

CONCLUSION

The systematic literature review and network meta-analysis provide evidence that telbivudine is associated with significant improvement in renal function in patients with CHB, either alone or in combination with other NAs.

FUNDING

Novartis Pharma AG.

Early kidney injury during long-term adefovir dipivoxil therapy for chronic hepatitis B

AIM: To evaluate urine β2-microglobulin (β2-M), retinol-binding protein (RBP) excretion, and renal impairment with adefovir dipivoxil (ADV) for chronic hepatitis B.

METHODS: We enrolled 165 patients with chronic hepatitis B infection who were treated with ADV monotherapy (n = 90) or ADV plus lamivudine combination therapy (n = 75). An additional 165 chronic hepatitis B patients treated with entecavir were recruited as controls. We detected serum creatinine, urine β2-M, and RBP levels, and estimated the glomerular filtration rate (eGFR) at the initiation of antiviral therapy and every 6 mo for a period of five years.

RESULTS: Urine β2-M abnormalities were observed in patients during the first (n = 3), second (n = 7), third (n = 11), fourth (n = 16), and fifth (n = 21) year of ADV treatment. Urinary RBP abnormalities were observed in patients during the first (n = 2), second (n = 8), third (n = 12), fourth (n = 15), and fifth (n = 22) year of ADV treatment. eGFR decreased 20%-30% from baseline in 20 patients, 30%-50% in 12 patients, and > 50% in 3 patients during the five years of treatment. Further analysis indicated that decreases in eGFR of ≥ 30% relative to the baseline level correlated significantly with urine RBP and β2-M abnormalities. In contrast, both serum creatinine and eGFR remained stable in patients treated with entecavir, and only one of these patients developed a urine β2-M abnormality, and two developed urine RBP abnormalities during the five years of treatment.

CONCLUSION: Urine RBP and β2-M are biomarkers of renal injury during long-term ADV treatment for chronic hepatitis B, and indicate when treatment should be switched to entecavir.

Antiviral treatment for chronic hepatitis B in renal transplant patients

Chronic hepatitis B infection is frequent in renal transplant patients. It negatively impacts long term outcomes reducing graft and patient survival. Current guidelines clearly define who needs treatment, when to start, what is the first line therapy, how to monitor treatment response, when to stop, and how patients must be controlled for its safety. There is some data showing a favorable safety and efficacy profile of nucleos(t)ide analogue (NUC) treatment in the renal transplant setting. Entecavir, a drug without major signs of nephrotoxicity, appears to be the first option for NUC naïve patients and tenofovir remains the preferred choice for patients with previous resistance to lamivudine or any other NUC. Renal transplant recipients under antiHBV therapy should be monitored for its efficacy against HBV but also for its safety with a close renal monitoring. Studies including a large number of patients with long term treatment and follow up are still needed to better demonstrate the safety and efficacy of newer NUCs in this population.

Differences in nephrotoxicity risk and renal effects among anti-viral therapies against hepatitis B

BACKGROUND

Results are conflicting with respect to the renal effects of anti-viral agents used for hepatitis B virus infection.

AIM

To compare short and long-term renal effects in real-life settings and to determine risk factors for renal impairment during treatment.

METHODS

2221 treatment-naïve patients were enrolled. Among these, 895 (302 lamivudine, 27 telbivudine, 282 entecavir, 273 tenofovir and 11 adefovir initiated patients) had 'repeated measures' of creatinine (baseline, 1st, 6th, 12th and 24th month of treatment). Telbivudine and adefovir groups were excluded from further analysis because of the low number of patients. We calculated the glomerular filtration rate (GFR) using the Modification of Diet in Renal Disease (MDRD) formula at each time point. Hypophosphataemia was also recorded. Risk factors for renal impairment were analysed.

RESULTS

Tenofovir caused a decline in GFR at each time point when compared to baseline levels. However, lamivudine and entecavir did not change GFR. GFR-shifting from ≥90 to 60-89 mL/min/1.73 m(2) was comparable among groups. The proportion of patients whose baseline creatinine increased more than 25% was comparable among all anti-virals. GFR showed a decline in patients who switched from entecavir to tenofovir. One patient with compensated cirrhosis needed to change from tenofovir because of renal safety. Seven and three patients developed transient hypophosphataemia in the tenofovir and lamivudine groups, respectively.

CONCLUSIONS

Although tenofovir caused a decline in GFR, differences between the anti-viral agents do not appear to be so impressive. In patients with and without renal risk factors at baseline, there is no impact of anti-virals, including tenofovir.

Association between adefovir dipivoxil treatment and the risk of renal insufficiency in patients with chronic hepatitis B: A meta-analysis

Adefovir dipivoxil (ADV) is an effective antiviral drug against hepatitis B virus. The renal tolerance of ADV at the currently approved dose of 10 mg daily for the treatment of chronic hepatitis B (CHB) remains controversial. The present meta-analysis was therefore performed to evaluate the renal safety of ADV treatment in patients with CHB. Two independent investigators searched MEDLINE, Embase and China National Knowledge Infrastructure databases for eligible studies published in English or Chinese until June 1, 2014. The Peto odds ratios (Peto ORs) or the rates of each study were analyzed. Seven randomized controlled trials (RCTs), four cohort studies and six single-arm studies were identified. ADV treatment was not associated with a higher incidence of nephrotoxicity in RCTs [Peto OR, 1.781; 95% confidence interval (CI), 0.637-4.979; P=0.271] but appeared to increase nephrotoxicity significantly in cohort studies (Peto OR, 2.682; 95% CI, 1.470-4.894; P=0.001); the significant increase was further observed in CHB patients receiving long-term ADV treatment in cohort studies (Peto OR, 2.275; 95% CI, 1.127-4.593; P=0.022). The analysis based on single-arm studies showed that the rate of renal dysfunction in the ADV-treated patients was 10.6% (95% CI, 0.059-0.185); the subgroup analysis with the standard of createnine levels showed a lower rate (6.9%, 95% CI, 0.013-0.298) than those in the overall studies. In conclusion, although current evidence indicated a positive link between treatment with ADV in CHB patients and an increased risk of renal dysfunction, optimally designed studies are required for definitive conclusions.

Safety and efficacy of entecavir in adefovir-experienced patients

BACKGROUND AND AIM

Suboptimal viral suppression with adefovir (ADV) poses a challenge in managing chronic hepatitis B. Few studies have evaluated the efficacy of entecavir (ETV) in ADV-experienced patients. Our aim is to assess treatment effectiveness of ETV in ADV-experienced patients.

METHODS

ADV-experienced patients switched to ETV were enrolled from six US clinics. Patients completed a median of 24 months of ETV after switch. Patients were categorized into partial responders (detectable HBV-DNA at switch) or complete responders (undetectable HBV-DNA at switch) to ADV. Primary and secondary outcome measurements were complete viral suppression (CVS, HBV-DNA < 60 IU/mL) and biochemical response (BR, alanine aminotransferase [ALT] < 40 U/L), respectively.

RESULTS

A total of 120 patients were included in the analysis (80 ADV partial responders; 40 ADV complete responders). In partial responders, CVS rate was 84% after 24 months of ETV. BR rate was 58% at switch to ETV and increased to 90% after 24 months. All complete responders continued to experience CVS after switch. On multivariate analysis inclusive of age, male gender, ALT level at switch, and history of lamivudine (LAM) exposure, we identified positive, hepatitis B e antigen status before ADV and higher HBV-DNA level at time of switch as significant independent negative predictors of CVS. In eight patients with ADV resistance, seven achieved CVS after 24 months of ETV, and all achieved BR.

CONCLUSION

In ADV-experienced patients, high rates of CVS and BR can be achieved/sustained after switching to ETV, including those with ADV resistance or with prior exposure to LAM.

Renal dysfunction and hypophosphatemia during long-term lamivudine plus adefovir dipivoxil therapy in patients with chronic hepatitis B

BACKGROUND

Renal dysfunction and Fanconi's syndrome associated with hypophosphatemia caused by long-term administration of low-dose adefovir dipivoxil (ADV) has been reported in recent years. The aim of this retrospective study was to determine the incidence and factors associated with renal dysfunction and hypophosphatemia in patients with hepatitis B infection on long-term treatment with ADV and lamivudine (LAM).

METHODS

The study subjects were 292 patients treated with 10 mg/day ADV and 100 mg/day LAM for more than 6 months. We evaluated estimated glomerular filtration rate (eGFR), serum creatinine and serum phosphate level at the start of ADV and every 6 months.

RESULT

During a median treatment duration of 64 months, 28 (9.6 %) patients developed renal impairment (defined as eGFR < 50 ml/min/1.73 m(2)), and 73 (27.1 %) developed hypophosphatemia, including 14 with persistent hypophosphatemia. The cumulative incidences of renal impairment at 1, 3, and 5 years were 1.4, 7.5, 10.5 %, respectively, and those of hypophosphatemia were 6.8, 20.6, 26.7 %, respectively. Multivariate analysis identified old age, liver cirrhosis and hypertension as determinants of renal impairment, and male sex, HCC, low baseline serum phosphate as determinants of hypophosphatemia. Three of the 14 patients with persistent hypophosphatemia developed Fanconi's syndrome; their serum creatinine level remained normal, but eGFR was lower than at baseline.

CONCLUSION

Long-term treatment of hepatitis B with low-dose (10 mg/day) ADV and LAM can potentially cause renal impairment and hypophosphatemia. We advocate regular monitoring of serum phosphate and evaluation of eGFR, in addition to serum creatinine, in such patients.

Then and now: The progress in hepatitis B treatment over the past 20 years

The ultimate goals of treating chronic hepatitis B (CHB) is prevention of hepatocellular carcinoma (HCC) and hepatic decompensation. Since the advent of effective antiviral drugs that appeared during the past two decades, considerable advances have been made not only in controlling hepatitis B virus (HBV) infection, but also in preventing and reducing the incidence of liver cirrhosis and HCC. Furthermore, several recent studies have suggested the possibility of reducing the incidence of recurrent or new HCC in patients even after they have developed HCC. Currently, six medications are available for HBV treatment including, interferon and five nucleoside/nucleotide analogues. In this review, we will examine the antiviral drugs and the progresses that have been made with antiviral treatments in the field of CHB.

Telbivudine improves renal function in patients with chronic hepatitis B

BACKGROUND & AIMS

There is a close relationship between chronic hepatitis B virus infection and chronic renal disease. We analyzed changes in renal function using different markers of glomerular filtration rate (GFR) in multiple studies of telbivudine treatment of patients with chronic hepatitis B virus infection.

METHODS

We used serum creatinine-based equations (ie, Cockcroft-Gault, Modification of Diet in Renal Disease, and Chronic Kidney Disease Epidemiology Collaboration) to estimate GFR (eGFR) in adults with chronic hepatitis B virus infection and compensated liver disease who participated in a phase III, randomized, double-blind study comparing the efficacy and safety of telbivudine (600 mg/d) and lamivudine (100 mg/d) for 2 years (the GLOBE study) and in long-term extension studies (4-6 years), as well as in patients with decompensated cirrhosis (2 years).

RESULTS

eGFRs calculated using the Cockcroft-Gault, Modification of Diet in Renal Disease, and Chronic Kidney Disease Epidemiology Collaboration equations were concordant, indicating improved renal function in telbivudine-treated patients during the 2-year GLOBE study (there was an 8.5% increase in mean eGFR, based on the Modification of Diet in Renal Disease equation). Improved renal function was maintained for 4-6 years. Increased eGFR with telbivudine treatment was also observed in patients at increased risk for renal impairment: patients with baseline eGFRs of 60-89 mL/min/1.73 m(2) (+17.2%), older than 50 years (+11.4%), and with liver fibrosis/cirrhosis (+7.2% for patients with Ishak fibrosis score at 5-6). In decompensated patients with high renal risk, eGFR was also improved on telbivudine (+2.0%).

CONCLUSIONS

In global trials of patients with compensated and decompensated cirrhosis, long-term telbivudine therapy was associated with a sustained improvement of renal function-particularly among patients with increased risk of renal impairment. The mechanisms of this renal protective effect remain to be determined.

Hypophosphatemic osteomalacia and renal Fanconi syndrome induced by low-dose adefovir dipivoxil: a case report and literature review suggesting ethnic predisposition

WHAT IS KNOWN AND OBJECTIVE

Adefovir dipivoxil (ADV) is one of the commonly used antiviral agents in the treatment of chronic hepatitis B (CHB) infection. Safety of a daily dose of 10 mg ADV is advocated by the registration trials. We report a case of severe hypophosphatemic osteomalacia and renal Fanconi syndrome induced by low-dose ADV in a CHB-related cirrhosis patient, and discuss the case through a thorough review of other cases reported in the literature.

CASE SUMMARY

A 48-yr-old Chinese man with CHB-related cirrhosis developed severe progressive generalized bone pain and muscle weakness after receiving ADV 10 mg daily for 54 months. The laboratory results showed severe hypophosphatemia and features of proximal renal tubule dysfunction. Imaging studies were consistent with osteomalacia. After discontinuation of ADV, his symptoms resolved, laboratory abnormalities normalized and imaging studies showed improvement. In addition to our case, 12 other patients have been reported to have developed hypophosphatemic osteomalacia induced by low-dose ADV. Most of the reported cases were of subjects of East-Asian ethnicity. After discontinuation or reduction of ADV, serum phosphate level increased and clinical symptoms significantly improved in all cases.

WHAT IS NEW AND CONCLUSION

Hypophosphatemic osteomalacia and renal Fanconi syndrome can be associated with low-dose ADV. Clinicians treating CHB patients with ADV 10 mg daily over long periods of time should be aware of this infrequent but serious complication.

Resolution of adefovir-related nephrotoxicity by adefovir dose-reduction in patients with chronic hepatitis B

BACKGROUND

Chronic hepatitis B patients (CHB) treated with adefovir were followed up to evaluate nephrotoxicity and its outcome.

AIM

To assess the incidence of renal dysfunction during adefovir therapy in Asian patients and factors associated with it, and evaluate strategies to improve adefovir-related renal dysfunction and their impact on viral suppression.

METHODS

Chronic hepatitis B clinic patients from a tertiary hospital on adefovir treatment, with their clinical and laboratory parameters were extracted from the hospital electronic clinical database in an observational study design. Patients were excluded if they had liver/renal transplant, baseline renal impairment or were on dialysis. Adefovir-related renal dysfunction was defined as adefovir-related abnormal serum creatinine (ARASC) > 125 μmol/L (males), >90 μmol/L (females); adefovir-related abnormal GFR <60 mL/min; and adefovir-related increased serum creatinine >0.5 mg/dL, without other known causes of nephrotoxicity.

RESULTS

A total of 271/383 adefovir-treated patients were suitable for analysis and 33(12%) patients developed abnormal serum creatinine. Cumulative increase in proportion of patients with ARASC was 33.8% and GFR ≤60 mL/min was 38.3% by 6 years, while serum creatinine increase ≥0.5 mg/dL was 21.48% by 5 years. Using multivariate analysis, the only independent baseline predictor of ARASC was GFR ≤76.1 mL/min. Patients who had ARASC had similar levels of viral suppression to those who did not have ARASC. Those who had ARASC either continued adefovir (24%), switched therapy (24%) or had adefovir dose reduction (52%). ARASC resolved and GFR normalised in almost all patients after either switching therapy or reducing adefovir dose, with no difference between the two strategies (P = 0.737). Those with adefovir dose reduction had no significant increase in HBV DNA (P = 0.170).

CONCLUSIONS

Adefovir-related renal dysfunction occurred in a significant number of adefovir-treated patients, but reduction of the dose led to renal improvement without compromising treatment efficacy.

A meta-analysis of nucleos(t)ide analogues in patients with decompensated cirrhosis due to hepatitis B

BACKGROUND

The effect of nucleos(t)ide analogues therapy in patients with decompensated cirrhosis remains unclear.

AIM

The purpose of this study was to evaluate the effect of nucleos(t)ide analogues on decompensated cirrhotic patients.

METHODS

An online search within PubMed, Web of Science, Embase, Cochrane Central of Register of Controlled Trials and China Biology Medicine disc from 1998-01-01 to 2011-09-05 was conducted. A meta-analysis was performed. Relative risks of mortality rate, Child-Pugh-Turcotte score and hepatitis B e-antigen (HBeAg) seroconversion of the decompensated patients were studied.

RESULTS

Eight studies involving 511 patients were included. Data showed that lamivudine and telbivudine significantly decreased the mortality rate (relative risk 0.36, 95 % confidence interval 0.25-0.54), improved the Child-Pugh-Turcotte scores (mean difference -3.23, 95 % confidence interval -3.98 to -2.48) and promoted HBeAg seroconversion (relative risk 7.48, 95 % confidence interval 2.31-24.20).

CONCLUSION

For patients with decompensated cirrhosis, lamivudine and telbivudine significantly decrease the mortality rate and disease severity. Also, they promote their HBeAg seroconversion.

Treatment of HBV related cirrhosis

Until very recently, hepatitis B virus (HBV)-associated cirrhosis was often regarded as an irreversible condition. It is associated with strongly increased mortality and a high risk of the development of hepatocellular carcinoma (HCC). Indeed, the incidence of HCC per 100 person years was shown to be 2-3.7 in patients with cirrhosis compared with only 0.3-0.6 in patients with active hepatitis B without cirrhosis and 0.02-0.2 in asymptomatic carriers. Liver transplantation was considered to be the only medical intervention, which could resolve this condition and which could improve the general condition of these patients. However, it is now becoming increasingly evident that long-term suppression of viral replication allows the regenerative potential of the liver to reverse even high grade liver fibrosis. For the management of HBV-related cirrhosis, it is therefore important to provide effective treatment and to identify and avoid risk factors for the development of cirrhosis and hepatic decompensation.

Hepatitis B e antigen-suppressing mutations enhance the replication efficiency of adefovir-resistant hepatitis B virus strains

Hepatitis B e antigen (HBeAg) negative hepatitis B virus (HBV) infections caused by precore (PC) or basal core promoter (BCP) mutations are associated with disease progression and complications. PC or BCP mutations may enhance the replication capacity of distinct drug-resistance-associated polymerase mutations, but their effect on adefovir-resistant HBV mutants is unclear. Importantly, BCP mutations were an independent risk factor for virological breakthrough in lamivudine-resistant patients treated with adefovir. We aimed at addressing the functional consequences of PC and BCP mutations on the replication and drug susceptibility of adefovir-resistant HBV mutants. Therefore, HBV constructs with wild type (WT) or adefovir-resistant rtN236T, rtA181V and rtA181T mutations, with or without concomitant PC or BCP mutations, were analysed in vitro using molecular assays. The adefovir-resistant polymerase mutations rtN236T, rtA181V and rtA181T showed a drastically reduced viral replication compared with WT. Interestingly, additional PC or BCP mutations enhanced the reduced replication efficacy of adefovir-resistant constructs and restored HBV replication to WT level. HBV rtA181T mutants displayed abolished hepatitis B surface antigen (HBsAg) secretion, owing to a sW172* stop codon in the overlapping envelope gene. All rtN236T- or rtA181V/T-containing constructs, regardless of concomitant PC or BCP mutations, were resistant to adefovir, but remained susceptible to telbivudine, entecavir and tenofovir. In conclusion, adefovir drug resistance mutations reduced viral replication, which can be significantly increased by additional HBeAg-suppressing PC or BCP mutations. Because increased HBV replication in HBeAg-negative patients has been associated with an unfavourable clinical course, close monitoring appears indispensable during adefovir treatment in HBeAg-negative patients.