Understanding adefovir pharmacokinetics as a component of a transporter phenotyping cocktail.

PURPOSE: Adefovir (as dipivoxil) was selected as a probe drug in a previous transporter cocktail phenotyping study to assess renal organic anion transporter 1 (OAT1), with renal clearance (CLR) as the primary parameter describing renal elimination. An approximately 20% higher systemic exposure of adefovir was observed when combined with other cocktail components (metformin, sitagliptin, pitavastatin, and digoxin) compared to sole administration. The present evaluation applied a population pharmacokinetic (popPK) modeling approach to describe adefovir pharmacokinetics as a cocktail component in more detail. METHODS: Data from 24 healthy subjects were reanalyzed. After establishing a base model, covariate effects, including the impact of co-administered drugs, were assessed using forward inclusion then backward elimination. RESULTS: A one-compartment model with first-order absorption (including lag time) and a combination of nonlinear renal and linear nonrenal elimination best described the data. A significantly higher apparent bioavailability (73.6% vs. 59.0%) and a lower apparent absorption rate constant (2.29 h-1 vs. 5.18 h-1) were identified in the combined period compared to the sole administration period, while no difference was seen in renal elimination. The population estimate for the Michaelis-Menten constant (Km) of the nonlinear renal elimination was 170 nmol/L, exceeding the observed range of adefovir plasma maximum concentration, while the maximum rate (Vmax) of nonlinear renal elimination was 2.40 µmol/h at the median absolute estimated glomerular filtration rate of 105 mL/min. CONCLUSION: The popPK modeling approach indicated that the co-administration primarily affected the apparent absorption and/or prodrug conversion of adefovir dipivoxil, resulting in the minor drug-drug interaction observed for adefovir as a victim. However, renal elimination remained unaffected. The high Km value suggests that assessing renal OAT1 activity by CLR has no relevant misspecification error with the cocktail doses used.

Discovery of a potent and selective human AC2 inhibitor based on 7-deazapurine analogues of adefovir.

Adefovir based acyclic nucleoside phosphonates were previously shown to modulate bacterial and, to a certain extent, human adenylate cyclases (mACs). In this work, a series of 24 novel 7-substituted 7-deazaadefovir analogues were synthesized in the form of prodrugs. Twelve analogues were single-digit micromolar inhibitors of Bordetella pertussis adenylate cyclase toxin with no cytotoxicity to J774A.1 macrophages. In HEK293 cell-based assays, compound 14 was identified as a potent (IC50 = 4.45 µM), non-toxic, and selective mAC2 inhibitor (vs. mAC1 and mAC5). Such a compound represents a valuable addition to a limited number of small-molecule probes to study the biological functions of individual endogenous mAC isoforms.

Uricosuric Agents Affect Plasma and Kidney Concentration of Adefovir via Inhibition of Oat1 and Mrp2 in Rats.

Uricosuric agents lower serum uric acid levels by increasing urinary excretion via inhibition of urate transporter 1 (URAT1), urate reabsorption transporter in the renal proximal tubules. Probenecid and benzbromarone have been used as uricosurics, but these drugs inhibit organic anion transporters (OATs) in addition to URAT1. In this study, we investigated whether uricosuric agents interacted with adefovir, known as a substrate for OAT1, using Sprague-Dawley (SD) rats. Furthermore, involvement of other transporters, multi-drug resistance protein 2 (MRP2) in this interaction was examined using Mrp2-deficient rats. Probenecid and lesinurad increased plasma adefovir concentrations and decreased kidney-to-plasma partition coefficient (Kp) in these rats, presumably by inhibiting Oat1. Although benzbromarone had no effect on plasma adefovir concentration, it increased the Kp to 141% in SD rats. Since this effect was abolished in Mrp2-deficient rats, together with the MRP2 inhibition study, it is suggested that benzbromarone inhibits Mrp2-mediated adefovir excretion from the kidney. In contrast, dotinurad, a novel uricosuric agent that selectively inhibits URAT1, had no effect on the plasma and kidney concentrations of adefovir. Therefore, due to the lack of interaction with adefovir, dotinurad is expected to have low drug-drug interaction risk mediated by OAT1, and also by MRP2.

Effects of nucleos(t)ide analogs on hepatitis B surface antigen reduction with interferon-lambda 3 induction in chronic hepatitis B patients.

BACKGROUND & AIMS: Benefits of nucleos(t)ide analogs (NAs) on hepatitis B surface antigen (HBsAg) reduction and interferon-lambda3 (IFN-λ3) induction are still not known. This study aimed to investigate the effects of NAs on HBsAg reduction and association with serum IFN-λ3 levels in chronic hepatitis B (CHB) patients. METHODS: A total of 91 patients [51 treated with nucleoside analog entecavir hydrate (ETV) and 40 treated with nucleotide analog adefovir dipivoxil (ADV) or tenofovir disoproxil fumarate (TDF)] with clinically evident CHB (chronic hepatitis, 57; liver cirrhosis, 34) were enrolled in this study. Serum IFN-λ3 levels among patients receiving ETV and ADV/TDF were measured before the initiation of therapy and 1, 3, and 5 years post-therapy. RESULTS: The change (mean ± standard deviation) in serum HBsAg levels from baseline to year five was -0.38 ± 0.46 and -0.84 ± 0.64 log10 IU/ml in ETV and ADV/TDF groups, respectively (p = 0.0004). Higher serum IFN-λ3 levels were observed in ADV/TDF group compared with ETV group during treatment (p < 0.001). Serum IFN-λ3 levels showed negative correlation with HBsAg reduction in ADV/TDF group (r = -0.386, p = 0.038) at week 48. Nucleotide analogs (ADV/TDF) treatment has associated factors with -0.3 log HBsAg decline at 1 year, -0.5 log HBsAg decline at 3 years, and -0.8 log HBsAg decline at 5 years after NAs treatment on multivariate analysis. CONCLUSIONS: Nucleotide analog (ADV/TDF) treatment reduced HBsAg levels greater compared with nucleoside analog (ETV) in parallel with IFN-λ3 induction.

Renal safety and biochemical changes for 2 years after switching to tenofovir alafenamide from long-term other nucleotide analog treatment in patients with chronic hepatitis B.

BACKGROUND: Long-term use of nucleotide analogs such as adefovir (ADV) or tenofovir disoproxil fumarate (TDF) may cause renal impairment. Tenofovir alafenamide (TAF) has less systemic exposure than TDF did. The aims were to examine longitudinal changes in renal function and biochemical parameters for 2 years after switching from long-term ADV and TDF to TAF, and to explore factors associated with improved renal function after TAF in patients with chronic hepatitis B. METHODS: The prospective observational cohort study included 306 patients with chronic hepatitis B who underwent switching from long-term TDF or ADV to TAF. The primary outcome was the changes in estimated glomerular filtration rate (eGFR) after TAF. RESULTS: Among 306 patients, 190 (65.3%) and 106 (34.7%) had chronic kidney disease (CKD) stages 1-2 and 3a-4 at baseline. In patients with CKD stages 3a-4, the mean eGFR significantly increased until week 12 and plateaued from week 12 to year 2 (adjusted slope using linear mixed effect models: +9.01 ml/min/1.73 m2 /year until week 12; p < 0.001). In contrast, the mean eGFR plateaued from baseline to year 2 in the CKD stages 1-2 subgroup. Multivariate logistic regression showed that baseline CKD stage ≥3a, steeper decline in eGFR 1 year before TAF, and shorter duration of any nucleotide analog use was significantly associated with ≥10% improvement in eGFR in year 1. CONCLUSIONS: Switching from TDF or ADV to TAF resulted in favorable renal safety for 2 years. In CKD stage 3a-4 subgroup, eGFR after TAF was recovered in the first 12 weeks and subsequently stabilized.

A switch from tenofovir to entecavir prior to hepatitis B treatment cessation is associated with a reduced risk of off-therapy relapse: An observational study.

BACKGROUND AND AIM: In HBeAg negative chronic hepatitis B (CHB) patients, clinical relapse (CR) occurs more frequently, much earlier and often more severely after stopping tenofovir (TDF) and other nucleos(t)ide analogues (Nucs) than after stopping entecavir (ETV). It is unknown whether off-Nuc hepatitis flare can be alleviated by switching from one Nuc to another. METHODS: HBeAg-negative CHB patients who had stopped Nuc according to the APASL stopping rule and had been followed-up for > 48 weeks after Nuc cessation were recruited. Patients were classified as four groups: ETV monotherapy (mono-ETV), TDF monotherapy (mono-TDF), switched to ETV (switch-ETV), and switched to TDF (switch-TDF). Both switch groups had switched to the replacement Nuc > 12 weeks prior to end of therapy. Propensity score matching (PSM) was performed to minimize confounders among groups. Cox regression analysis was used to identify risks factors for off-Nuc CR and flares. RESULTS: A total of 1309 patients (1022 mono-ETV, 219 mono-TDF, 40 switch-ETV and 28 switch-TDF) were enrolled. The median time to CR was 39, 13, 38 and 14 weeks in mono-ETV, mono-TDF, switch-ETV and switch-TDF respectively (P < 0.001). After PSM, the mono-ETV (adjusted HR: 0.39, P < 0.001) and switch-ETV patients (adjusted HR: 0.41, P = 0.003) had both significantly later occurrence and lower rates of CR and flare. CONCLUSION: In summary, the incidence and timing of CR was determined by ETV or TDF in the last 3 months prior to end of treatment. Patients treated with non-ETV-Nuc switched to ETV > 12 weeks before end of the original Nuc therapy may reduce/defer CR.

Zirconium Molybdate Nanocomposites' Sensing Platform for the Sensitive and Selective Electrochemical Detection of Adefovir.

Adefovir (ADV) is an anti-retroviral drug, which can be used to treat acquired immune deficiency syndrome (AIDS) and chronic hepatitis B (CHB), so its quantitative analysis is of great significance. In this work, zirconium molybdate (ZrMo2O8) was synthesized by a wet chemical method, and a composite with multi-walled carbon nanotubes (MWCNTs) was made. ZrMo2O8-MWCNTs composite was dropped onto the surface of a glassy carbon electrode (GCE) to prepare ZrMo2O8-MWCNTs/GCE, and ZrMo2O8-MWCNTs/GCE was used in the electrochemical detection of ADV for the first time. The preparation method is fast and simple. The materials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and cyclic voltammetry (CV). It was electrochemically analysed by differential pulse voltammetry (DPV). Compared with single-material modified electrodes, ZrMo2O8-MWCNTs/GCE showed a vastly improved electrochemical response to ADV. Moreover, the sensor complements the study of the electrochemical detection of ADV. Under optimal conditions, the proposed electrochemical method showed a wide linear range (from 1 to 100 µM) and a low detection limit (0.253 µM). It was successfully tested in serum and urine. In addition, the sensor has the advantages of a simple preparation, fast response, good reproducibility and repeatability. It may be helpful in the potential applications of other substances with similar structures.

Immunoglobulin, nucleos(t)ide analogues and hepatitis B virus recurrence after liver transplant: A meta-analysis.

BACKGROUND: Prophylaxis with hepatitis B immunoglobulin (HBIG) represents an efficient strategy for reducing the risk of hepatitis B virus (HBV) recurrence after liver transplantation (LT). Unfortunately, the long-term use of HBIG presents high costs. Therefore, the use of prophylaxis based only on nucleos(t)ide analogues (NUC) has been recently postulated. The present meta-analysis aimed to evaluate the impact of HBIG ± NUC vs HBIG alone or NUC alone in post-LT HBV recurrence prophylaxis. MATERIALS AND METHODS: A systematic literature search was performed using PubMed and Cochrane databases. The primary outcome investigated was the HBV recurrence after LT. Three analyses were done comparing the effect of (a) HBIG + NUC vs HBIG alone; (b) HBIG+NUC vs NUC alone; and (c) HBIG alone vs NUC alone. Sub-analyses were also performed investigating the effect of low and high genetic barrierto-recurrence NUC. RESULTS: Fifty-one studies were included. The summary OR (95%CI) showed a decreased risk with the combination of HBIG + NUC vs HBIG alone for HBV recurrence, being 0.36 (95% CI = 0.22-0.61; P < .001). HBIG + NUC combined treatment reduced HBV reappearance respect to NUC alone (OR = 0.22; 95% CI = 0.16-0.30; P < .0001). Similarly, HBIG alone was significantly better than NUC alone in preventing HBV recurrence (OR = 0.20; 95% CI = 0.09-0.44; P < .0001). CONCLUSIONS: Prophylaxis with HBIG is relevant in preventing post-LT HBV recurrence. Its combination with NUC gives the best results in terms of protection. The present results should be considered in light of the fact that also old studies based on lamivudine use were included. Studies exploring in detail high genetic barrier-to-recurrence NUC and protocols with definite use of HBIG are needed.

Effect of Coformer Selection on In Vitro and In Vivo Performance of Adefovir Dipivoxil Cocrystals.

PURPOSE: This study aimed to improve the in vitro dissolution, permeability and oral bioavailability of adefovir dipivoxil (ADD) by cocrystal technology and clarify the important role of coformer selection on the cocrystal's properties. METHODS: ADD was cocrystallized with three small molecules (i.e., paracetamol (PA), saccharin (SAC) and nicotinamide (NIC)), respectively. The obtained ADD-PA cocrystal was characterized by DSC, TGA, PXRD and FTIR. Comparative study on dissolution rates among the three ADD cocrystals were conducted in water and pH 6.8 phosphate buffer. Besides, effects of coformers on intestinal permeability of ADD were evaluated via in vitro Caco-2 cell model and in situ single-pass intestinal perfusion model in rats. Furthermore, in vivo pharmacokinetic study of ADD cocrystals was also compared. RESULTS: Dissolution rates of ADD cocrystals were improved with the order of ADD-SAC cocrystal > ADD-PA cocrystal > ADD-NIC cocrystal. The permeability studies on Caco-2 cell model and single-pass intestinal perfusion model indicated that PA could enhance intestinal absorption of ADD by P-gp inhibition, while SAC and NIC did not. Further in vivo pharmacokinetic study showed that ADD-SAC cocrystal exhibited higher Cmax (1.4-fold) and AUC0-t (1.3-fold) of ADD than administration of ADD alone, and Cmax and AUC0-t of ADD-PA cocrystal were significantly enhanced by 2.1-fold and 2.2-fold, respectively, which was attributed to its higher dissolution and improved intestinal permeability. CONCLUSION: Coformer selection had an important role on cocrystal's properties, and cocrystallization of ADD with a suitable coformer was an effective approach to enhance both dissolution and bioavailability of ADD.

Efficacy of different nucleoside analog rescue therapies for entecavir-resistant chronic hepatitis B patients.

BACKGROUND: Entecavir (ETV) is recommended as a first-line anti-HBV treatment. However, many chronic hepatitis B patients initiate anti-HBV treatment such as lamivudine and telbivudine with low genetic barriers in China, which leads to compensatory mutations and increases the rate of ETV resistance. The management of ETV resistance in China is an essential clinical issue. METHODS: Patients from 2011 to 2017 with nucleos(t)ide analog resistance were screened and 72 patients with ETV resistance were included. These patients received different rescue therapies including an ETV and adefovir (ADV) combination therapy group (n = 25), a tenofovir (TDF) monotherapy group (n = 27), and an ETV and TDF combination therapy group (n = 20). Virologic, biochemical, and serologic responses were compared among the three groups. RESULTS: The rate of ETV resistance among all HBV-resistant variants increased from 6.04% in 2011 to 15.02% in 2017. TDF monotherapy and TDF combination groups showed similar rates of negative HBV DNA at 48 weeks (74.07% vs 70.00%, P > 0.05), while the ETV and ADV group showed the worst virologic response (28.00%). Also, TDF monotherapy and TDF combination therapy showed similar decline of HBV DNA at weeks 12, 24, and 48. There was no significant difference in the rates of HBeAg clearance, ALT normalization, and abnormal renal function among the three groups. CONCLUSIONS: TDF monotherapy showed a comparable virologic response to TDF and ETV combination therapy and a better virologic response than ETV and ADV combination therapy. Thus, TDF monotherapy is the preferred rescue therapy for ETV resistance.

Hepatitis B core related antigen in relation to intrahepatic and circulating viral markers, before and after combination therapy.

INTRODUCTION AND OBJECTIVES: Covalently closed circular (ccc)DNA acts as a viral reservoir in the liver of patients with a chronic hepatitis B (CHB) infection and can only be quantified in liver biopsies. Hepatitis B core-related antigen (HBcrAg) levels in plasma/serum have been proposed to reflect intrahepatic cccDNA-levels and may therefore monitor treatment efficacy. This study aimed to validate the relationship between HBcrAg and other intrahepatic and circulating viral markers in CHB patients with high viral load, before and after combination treatment. MATERIALS AND METHODS: Plasma/serum levels of HBcrAg, HBsAg, HBV-DNA, and HBV pregenomic RNA (HBV-pgRNA), and intrahepatic cccDNA and HBV-DNA levels and fibrosis scores were measured in 89 CHB patients with HBV-DNA levels of >100,000 copies/mL (17,182 IU/mL). Measurements were done before and after a 48-week treatment with pegylated interferon alfa-2a and adefovir in a prospective study (ISRCTN77073364). RESULTS: Baseline HBcrAg-values correlated strongly with intrahepatic cccDNA (ρ 0.77, p < 0.001), intrahepatic HBV-DNA (ρ 0.73, p < 0.001) and plasma/serum HBV-DNA (ρ 0.80, p < 0.001), HBV-pgRNA (ρ 0.80, p < 0.001), and to lesser extend HBsAg (ρ 0.56, p < 0.001). Baseline HBcrAg-levels could not predict functional cure (FC) but HBcrAg-levels declined more strongly in patients who developed FC or HBeAg-loss. Furthermore, most correlations persisted at the end of treatment and follow-up. CONCLUSIONS: HBcrAg reflects cccDNA transcription activity more accurately than HBsAg and may replace HBV-DNA as a marker during future treatment regimens, especially when cccDNA transcription is targeted or nucleot(s)ide analogues are included in the treatment regime.

Transforming growth factor ß (TGFß) cross-talk with the unfolded protein response is critical for hepatic stellate cell activation.

Transforming growth factor ß (TGFß) potently activates hepatic stellate cells (HSCs), which promotes production and secretion of extracellular matrix (ECM) proteins and hepatic fibrogenesis. Increased ECM synthesis and secretion in response to TGFß is associated with endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). TGFß and UPR signaling pathways are tightly intertwined during HSC activation, but the regulatory mechanism that connects these two pathways is poorly understood. Here, we found that TGFß treatment of immortalized HSCs (i.e. LX-2 cells) induces phosphorylation of the UPR sensor inositol-requiring enzyme 1α (IRE1α) in a SMAD2/3-procollagen I-dependent manner. We further show that IRE1α mediates HSC activation downstream of TGFß and that its role depends on activation of a signaling cascade involving apoptosis signaling kinase 1 (ASK1) and c-Jun N-terminal kinase (JNK). ASK1-JNK signaling promoted phosphorylation of the UPR-associated transcription factor CCAAT/enhancer binding protein ß (C/EBPß), which is crucial for TGFß- or IRE1α-mediated LX-2 activation. Pharmacological inhibition of C/EBPß expression with the antiviral drug adefovir dipivoxil attenuated TGFß-mediated activation of LX-2 or primary rat HSCs in vitro and hepatic fibrogenesis in vivo Finally, we identified a critical relationship between C/EBPß and the transcriptional regulator p300 during HSC activation. p300 knockdown disrupted TGFß- or UPR-induced HSC activation, and pharmacological inhibition of the C/EBPß-p300 complex decreased TGFß-induced HSC activation. These results indicate that TGFß-induced IRE1α signaling is critical for HSC activation through a C/EBPß-p300-dependent mechanism and suggest C/EBPß as a druggable target for managing fibrosis.

Adefovir dipivoxil induces DNA replication stress and augments ATR inhibitor-related cytotoxicity.

Replication stress is a common feature of cancer cells. Ataxia telangiectasia-mutated (ATM) and Rad3-related (ATR) signalling, a DNA damage repair (DDR) pathway, is activated by regions of single-stranded DNA (ssDNA) that can arise during replication stress. ATR delays cell cycle progression and prevents DNA replication fork collapse, which prohibits cell death and promotes proliferation. Several ATR inhibitors have been developed in order to restrain this protective mechanism in tumours. It is known, however, that despite other effective anticancer chemotherapy treatments targeting DDR pathways, resistance occurs. This begets the need to identify combination treatments to overcome resistance and prevent tumour cell growth. We conducted a drug screen to identify potential synergistic combination treatments by screening an ATR inhibitor (VE822) together with compounds from a bioactive small molecule library. The screen identified adefovir dipivoxil, a reverse transcriptase inhibitor and nucleoside analogue, as a compound that has increased cytotoxicity in the presence of ATR, but not ATM or DNA-dependant protein kinase (DNA-PK) inhibition. Here we demonstrate that adefovir dipivoxil induces DNA replication stress, activates ATR signalling and stalls cells in S phase. This simultaneous induction of replication stress and inhibition of ATR signalling lead to a marked increase in pan-nuclear γH2AX-positive cells, ssDNA accumulation and cell death, indicative of replication catastrophe.

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.

Monotherapy with tenofovir disoproxil fumarate for adefovir-resistant vs. entecavir-resistant chronic hepatitis B: A 5-year clinical trial.

BACKGROUND & AIMS: Tenofovir disoproxil fumarate (TDF) monotherapy has displayed non-inferior efficacy to TDF plus entecavir (ETV) combination therapy in patients with hepatitis B virus (HBV) resistant to ETV and/or adefovir (ADV). Nonetheless, the virologic response rate was suboptimal in patients receiving up to 144 weeks of TDF monotherapy. We aimed to assess the efficacy and safety of TDF monotherapy given for up to 240 weeks. METHODS: One trial enrolled patients with ETV resistance without ADV resistance (n = 90), and another trial included patients with ADV resistance (n = 102). Most patients (91.2%) also had lamivudine resistance. Patients were randomized 1:1 to receive TDF monotherapy or TDF + ETV combination therapy for 48 weeks, and then TDF monotherapy until week 240. We compared efficacy between the studies and safety in the pooled population at 240 weeks. RESULTS: At week 240, the proportion of patients with serum HBV DNA <15 IU/ml was not significantly different between the ETV and ADV resistance groups in the full analysis set (84.4% vs. 73.5%; p = 0.07), which was significantly different by on-treatment analysis (92.7% vs. 79.8%; p = 0.02). Virologic blips associated with poor medication adherence occurred in 7 patients throughout the 240 weeks. None developed additional HBV resistance mutations. Among the 170 HBV e antigen (HBeAg)-positive patients at baseline, 12 (7.1%) achieved HBeAg seroconversion at week 240. None achieved HBV surface antigen seroclearance. Significant decreases from baseline were observed at week 240 in the estimated glomerular filtration rate (-3.21 ml/min/1.73 m2 by the CKD-EPI equation, p <0.001) and bone mineral density (g/cm2) at the femur (-2.48%, p <0.001). CONCLUSIONS: Up to 240 weeks of TDF monotherapy provided an increasing virologic response rate in heavily pretreated patients with HBV resistant to ETV and/or ADV. However, it was associated with poor serological responses and decreasing renal function and bone mineral density. (ClinicalTrials.gov No, NCT01639066 and NCT01639092). LAY SUMMARY: In patients chronically infected with hepatitis B virus resistant to multiple drugs including lamivudine, entecavir, and/or adefovir, tenofovir disoproxil fumarate (TDF) monotherapy showed non-inferior efficacy compared with the combination therapy of TDF plus entecavir. Nonetheless, short-term TDF monotherapy was associated with suboptimal virologic response, and its long-term safety was uncertain. This study displayed that 240 weeks of TDF monotherapy provided a virologic response in most of those patients, but it was associated with poor serological responses and decreasing renal function and bone mineral density.

Synthesis, pharmacological evaluation, and mechanistic study of adefovir mixed phosphonate derivatives bearing cholic acid and l-amino acid moieties for the treatment of HBV.

The deficiency of nucleos(t)ide analogues (NAs) as anti-hepatitis B virus (HBV) drugs in clinical use is attributable to their insufficient enrichment in liver and non-target organ toxicity. We aimed to develop potent anti-HBV adefovir derivatives with hepatotrophic properties and reduced nephrotoxicity. A series of adefovir mono l-amino acids, mono cholic acid-drug conjugates were designed and synthesized, and their antiviral activity and uptake in rat primary hepatocytes and Na+-dependent taurocholate co-transporting polypeptide (NTCP)-HEK293 cells were evaluated. We isolated compound 6c as the optimal molecular candidate, with the highest antiviral activity (EC50 0.42 µmol/L, SI 1063.07) and highest cellular uptake in primary hepatocytes and NTCP-HEK293 cells. In-depth mechanistic studies demonstrated that 6c exhibited a lower toxicity in HK-2 cells when compared to adefovir dipivoxil (ADV). This is because 6c cannot be transported by the human renal organic anion transporter 1 (hOAT1). Furthermore, pharmacokinetic characterization and tissue distribution of 6c indicates it has favorable druggability and pharmacokinetic properties. Further docking studies suggested compounds with ursodeoxycholic acid and l-amino acid groups are better at binding to NTCP due to their hydrophilic properties, indicating that 6c is a potential candidate as an anti-HBV therapy and therefore merits further investigation.

Clinical and virological outcomes of entecavir therapy in patients with chronic hepatitis B: A real life experience.

BACKGROUND: Entecavir (ETV) is a nucleoside analogue (NA) that is effective for treatment of chronic hepatitis B (CHB) due to its low resistance rates and potent antiviral effects. We aimed to evaluate the clinical, biochemical and virological response to ETV in patients without a prior use of nucleos(t)ide (NA-naïve) vs. those who failed prior NA use (NA-experienced) in the treatment of CHB. METHODS: Patients treated between April 2012 and December 2017 were retrospectively studied. A comparison was made between patients treated with ETV in NA-naïve Vs. NA-experienced. Complete virological response (CVR) was defined as achieving undetectable HBV-DNA level, up to 15 IU/ml, partial virological response (PVR) as 15-200 IU/ml and >200 IU/ml for no virological response (NVR) after one year of therapy. RESULTS: Overall, 148 patients were included (69 NA-naïve and 79 NA-experienced). In NA-naïve group, 51%, 17% and 32% achieved CVR, PVR and NVR vs. 17%, 9% and 75% in NA-experienced group, respectively (p < 0.001). HBsAg seroconversion was achieved in 5.8% in NA-naïve group vs. 6.3% in NA-experienced group (p = 1.00). HBeAg seroconversion was 17% in NA-naïve group and 25% in NA-experienced group (p = 0.24). There was no significant difference in alanine transaminase normalization or in mortality rate between both groups; p = 0.87 and p = 1.00 respectively. CONCLUSION: ETV therapy in CHB results in a better virological response in NA-naïve patients compared to NA-experienced. There were no differences between both groups in regards to the rate of HBsAg or HBeAg seroconversions, biochemical improvements or mortality.

An improved synthesis of adefovir and related analogues.

An improved synthesis of the antiviral drug adefovir is presented. Problems associated with current routes to adefovir include capricious yields and a reliance on problematic reagents and solvents, such as magnesium tert-butoxide and DMF, to achieve high conversions to the target. A systematic study within our laboratory led to the identification of an iodide reagent which affords higher yields than previous approaches and allows for reactions to be conducted up to 10 g in scale under milder conditions. The use of a novel tetrabutylammonium salt of adenine facilitates alkylations in solvents other than DMF. Additionally, we have investigated how regioselectivity is affected by the substitution pattern of the nucleobase. Finally, this chemistry was successfully applied to the synthesis of several new adefovir analogues, highlighting the versatility of our approach.

Neutrophil gelatinase-associated lipocalin accurately predicts renal tubular injury in patients with chronic hepatitis B treated with nucleos(t)ide analogs.

AIM: Little is known about the impact of long-term use of nucleos(t)ide analogs on tubular function in patients with chronic hepatitis B. Previous studies showed that neutrophil gelatinase-associated lipocalin (NGAL) elevation was associated with renal tubular injury. We evaluated renal function markers and bone mineral density in patients treated long-term with adefovir dipivoxil (ADV) or entecavir (ETV). METHODS: In this cross-sectional study, we enrolled 78 patients (ADV, 36; ETV: 42), and 21 patients matched for age, observation time, and baseline estimated glomerular filtration rate from each group. RESULTS: Patients treated with ADV showed a significant increase in serum creatinine and urine ß2 -microglobulin, and decreased estimated glomerular filtration rate and bone mineral density. Furthermore, the median levels of NGAL in patients treated with ADV were significantly higher than those of ETV (12.5 ng/mL vs. 2.5 ng/mL, P = 0.020). The proportions of patients with proteinuria and phosphate <1 mmol/L in the ADV group were higher than those in the ETV group. Additionally, age, ß2 -microglobulin, phosphate, and ADV use were associated with altered NGAL levels on multivariate analysis. Among the commonly used biomarkers, NGAL was the most useful (odds ratio = 5.72; P = 0.005) and specific (92% specificity at 18.1 ng/mL cut-off) in predicting low bone mass. CONCLUSIONS: Patients with chronic hepatitis B treated long-term with ADV showed elevated urinary NGAL levels. Neutrophil gelatinase-associated lipocalin was more specific in predicting low bone mass during therapy compared with ß2 -microglobulin, phosphate, and creatinine. In general, this analysis examined the value of NGAL as a renal tubular injury indicator, resulting from ADV use.

Octadecyloxyethyl Adefovir Exhibits Potent in vitro and in vivo Cytotoxic Activity and Has Synergistic Effects with Ara-C in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) continues to be a deadly disease, with only 50-70% of patients achieving complete remission and less than 30% of adults having sustained long-term remissions. In order to address these unmet medical needs, we carried out a high-throughput screen of an in-house library of on- and off-patent drugs with the OCI/AML-2 cell line. Through this screen, we discovered adefovir dipi-voxil (adefovir-DP) as being active against human AML. In addition to adefovir-DP, there are second-generation formulations of adefovir, including octadecyloxyethyl adefovir (ODE-adefovir) and hexadecyloxypropyl adefovir (HDP-adefovir), which were designed to overcome the pharmacokinetic problems of the parent compound adefovir. Given the known clinical benefit of nucleoside analogs for the treatment of AML, we undertook studies to evaluate the potential benefit of adefovir-based molecules. In AML cell lines and patient samples, adefovir-DP and ODE-adefovir were highly potent, whereas HDP-adefovir was significantly less active. Interestingly, ODE-adefovir was remarkably less toxic than adefovir-DP towards normal hematopoietic cells. In addition, ODE-adefovir at a dose of 15 mg/kg/day showed potent activity against human AML in a NOD/SCID mouse model, with a reduction of human leukemia in mouse bone marrow of > 40% in all mice tested within 20 days of treatment. Based on its chemical structure, we hypothesized that the cytotoxicity of ODE-adefovir toward AML was through cell cycle arrest and DNA damage. Indeed, ODE-adefovir treatment induced cell cycle arrest in the S phase and increased levels of pH2Ax, indicating the induction of DNA damage. Furthermore, there was an increase in phospho-p53, transactivation of proapoptotic genes and activation of the intrinsic apoptotic pathway. Subsequent investigation unveiled strong synergism between ODE-adefovir and ara-C, making their coadministration of potential clinical benefit. Expression of MRP4, a nucleoside transporter, appeared to influence the response of AML cells to ODE-adefovir, as its inhibition potentiated ODE-adefovir killing. Taken together, our findings indicate that clinical development of ODE-adefovir or related compounds for the treatment of AML is warranted.