The bioavailability time of commonly used thymidine analogues after intraperitoneal delivery in mice: labeling kinetics in vivo and clearance from blood serum.

Detection of synthetic thymidine analogues after their incorporation into replicating DNA during the S-phase of the cell cycle is a widely exploited methodology for evaluating proliferative activity, tracing dividing and post-mitotic cells, and determining cell-cycle parameters both in vitro and in vivo. To produce valid quantitative readouts for in vivo experiments with single intraperitoneal delivery of a particular nucleotide, it is necessary to determine the time interval during which a synthetic thymidine analogue can be incorporated into newly synthesized DNA, and the time by which the nucleotide is cleared from the blood serum. To date, using a variety of methods, only the bioavailability time of tritiated thymidine and 5-bromo-2'-deoxyuridine (BrdU) have been evaluated. Recent advances in double- and triple-S-phase labeling using 5-iodo-2'-deoxyuridine (IdU), 5-chloro-2'-deoxyuridine (CldU), and 5-ethynyl-2'-deoxyuridine (EdU) have raised the question of the bioavailability time of these modified nucleotides. Here, we examined their labeling kinetics in vivo and evaluated label clearance from blood serum after single intraperitoneal delivery to mice at doses equimolar to the saturation dose of BrdU (150 mg/kg). We found that under these conditions, all the examined thymidine analogues exhibit similar labeling kinetics and clearance rates from the blood serum. Our results indicate that all thymidine analogues delivered at the indicated doses have similar bioavailability times (approximately 1 h). Our findings are significant for the practical use of multiple S-phase labeling with any combinations of BrdU, IdU, CldU, and EdU and for obtaining valid labeling readouts.

Deoxycytidine and Deoxythymidine Treatment for Thymidine Kinase 2 Deficiency.

OBJECTIVE: Thymidine kinase 2 (TK2), a critical enzyme in the mitochondrial pyrimidine salvage pathway, is essential for mitochondrial DNA (mtDNA) maintenance. Mutations in the nuclear gene, TK2, cause TK2 deficiency, which manifests predominantly in children as myopathy with mtDNA depletion. Molecular bypass therapy with the TK2 products, deoxycytidine monophosphate (dCMP) and deoxythymidine monophosphate (dTMP), prolongs the life span of Tk2-deficient (Tk2-/- ) mice by 2- to 3-fold. Because we observed rapid catabolism of the deoxynucleoside monophosphates to deoxythymidine (dT) and deoxycytidine (dC), we hypothesized that: (1) deoxynucleosides might be the major active agents and (2) inhibition of deoxycytidine deamination might enhance dTMP+dCMP therapy. METHODS: To test these hypotheses, we assessed two therapies in Tk2-/- mice: (1) dT+dC and (2) coadministration of the deaminase inhibitor, tetrahydrouridine (THU), with dTMP+dCMP. RESULTS: We observed that dC+dT delayed disease onset, prolonged life span of Tk2-deficient mice and restored mtDNA copy number as well as respiratory chain enzyme activities and levels. In contrast, dCMP+dTMP+THU therapy decreased life span of Tk2-/- animals compared to dCMP+dTMP. INTERPRETATION: Our studies demonstrate that deoxynucleoside substrate enhancement is a novel therapy, which may ameliorate TK2 deficiency in patients. Ann Neurol 2017;81:641-652.

Determination of telbivudine in the plasma of chronic hepatitis B patients in long-term treatment by high-performance liquid chromatographic-tandem mass spectrometry.

Creatine kinase elevation is commonly reported in telbivudine-treated patients. However, little is known about the relationship between this adverse drug reaction and plasma concentration. In this study, a sensitive, rapid and safe quantitative bioanalytical method has been established by using LC-MS/MS for the determination of telbivudine in a clinical study of chronic hepatitis B patients. The assay was linear in a dynamic 10-10,000 ng/mL range (r2 > 0.999) and total analysis time was 6 min in this method. The validated method was applied to quantitatively determine plasma concentration in chronic hepatitis B patients during long-term telbivudine treatment. The results revealed that telbivudine concentration in the creatine kinase-elevated group (707.92-2788.78 ng/mL) was significantly higher than those with normal creatine kinase (412.63-1108.32 ng/mL). This method was adapted for therapeutic drug monitoring.

Reduction of covalently closed circular DNA with long-term nucleos(t)ide analogue treatment in chronic hepatitis B.

BACKGROUND AND AIMS: Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA), a mini-chromosome essential for HBV replication, is supposed to be resistant to nucleos(t)ide analogue treatment. We investigated the effect of long-term nucleos(t)ide analogue treatment on cccDNA. METHODS: Among 129 patients who had been enrolled in previous international nucleos(t)ide analogue clinical trials and had liver biopsies at baseline and one year after treatment, we recruited 43 patients on long-term continuous treatment for 72 to 145months for a third liver biopsy. Serum HBV DNA, hepatitis B surface antigen (HBsAg) levels, total intrahepatic HBV DNA (ihHBV DNA), cccDNA, HBV pregenomic RNA (pgRNA) as well as histologic changes were examined. RESULTS: At the time of the third biopsy, serum HBV DNA levels were undetectable in all but one patient. The median levels of HBsAg, ihHBV DNA, and cccDNA were 2.88logIU/ml, 0.03copies/cell, and 0.01copies/cell, respectively. Compared to baseline levels, there was reduction of HBsAg levels by 0.54log (71.46%), ihHBV DNA levels by 2.81log (99.84%), and cccDNA levels by 2.94log (99.89%), with 49% having cccDNA levels below the detection limit. One patient had undetectable HBsAg. The median pgRNA level, measured only in the third biopsy, was 0.021copies/cell, with 40% of patients having undetectable pgRNA. CONCLUSIONS: Long-term nucleos(t)ide analogue treatment induced marked depletion of cccDNA in the majority of patients while serum HBsAg levels, though reduced, were detectable in all but one patient. Whether cccDNA depletion is sustained and associated with better patient outcome requires further study. LAY SUMMARY: It is generally presumed that a form of hepatitis B virus DNA, called covalently closed circular DNA (cccDNA), which hides inside the nuclei of liver cells of patients with chronic hepatitis B, cannot be reduced by antiviral treatment. The present study showed that with prolonged treatment (median period 126months), cccDNA can be markedly reduced, with 49% of liver biopsies having undetectable cccDNA. This suggests that viral replication capacity would be very low after prolonged antiviral treatment.

Safety and efficacy of telbivudine for chronic hepatitis B during the entire pregnancy: Long-term follow-up.

The management of hepatitis B virus (HBV) infection in pregnancy is a unique issue. Telbivudine (LdT) is recommended to block HBV mother-to-child transmission (MTCT) in the third trimester. However, the safety of LdT treatment during the entire pregnancy for the long-term growth of infants is unclear. The aim of this study was to evaluate the efficacy and long-term safety of LdT for the entire pregnancy period. This retrospective cohort study included 40 pregnant women and 43 children from 2011 to 2017. The antiviral effects and maternal abnormalities were evaluated. In addition, adverse events regarding infants at delivery and HBV vaccination outcomes were recorded. The status of physical development in the children during follow-up was also evaluated. Among pregnant women, the rates of HBV DNA flare were 5.00% during pregnancy and 7.50% postpartum, and the HBeAg seroconversion rates were 7.50% during pregnancy and 7.50% postpartum. No severe maternal abnormalities were observed. Regarding the infants, no one was positive for HBsAg, and only one infant was negative for anti-HBs in children over 7 months of age. Furthermore, no birth defects or severe adverse events were observed at delivery, and 97.67% normal height and 93.02% normal weight in children were observed on follow-up until 5 years of age. In conclusion, LdT use for the entire pregnancy is both effective for treating pregnant women and blocking HBV MTCT. Moreover, LdT is safe for women and infants. Most importantly, the long-term follow-up indicated that LdT is safe and does not affect the growth of children.

Prospective cohort study on the efficacy and safety of telbivudine used throughout pregnancy in blocking mother-to-child transmission of hepatitis B virus.

Women with chronic hepatitis B should maintain nucleotide analogue treatment to prevent disease progression during pregnancy. The aim of this study was to prospectively evaluate the efficacy and safety of telbivudine used throughout pregnancy for preventing hepatitis B virus (HBV) mother-to-child transmission (MTCT). From January 2012 to June 2014, women who were receiving telbivudine therapy and became pregnant were enrolled in group A at 28 weeks of gestation. Pregnant women with an HBV DNA level >106  IU/mL were enrolled in either group B (telbivudine started at 28 weeks of gestation) or group C (control group without treatment). MTCT was defined as infants who were positive for serum hepatitis B surface antigen at 7 months after birth. There were 41, 179 and 177 pregnant women (397 infants) enrolled in groups A, B and C, respectively. The HBV DNA load at 28 weeks of gestation and delivery was 1.50 ± 0.62 vs 1.45 ± 0.61, 8.05 ± 0.37 vs 4.24 ± 0.89 and 7.94 ± 0.62 vs 7.86 ± 0.73 log10 IU/mL in groups A, B and C, respectively. The rate of MTCT in group C was 4.60%, which was significantly higher than the rates in groups A and B (0% and 0.6%, respectively) (P = .043). The difference between group A and group B was not significant. The rates of neonatal congenital abnormalities were 2.4%, 0.6% and 2.3% in groups A, B and C, respectively, and there were no significant differences (P = .140). Telbivudine used throughout pregnancy may be safe and effective for mothers and infants, but it may not enhance the efficacy of an HBV MTCT block compared with treatment starting at 28 weeks of gestation (NCT02253485).

Long-term outcome of telbivudine versus entecavir in treating higher viral load chronic hepatitis B patients without cirrhosis.

Chronic hepatitis B (CHB) patients with higher hepatitis B virus (HBV) load (higher viral load [HVL], HBV DNA ≥1 × 107 copies/mL) require antiviral therapy, but data for evaluating the long-term outcome of this therapy with antiviral agents remain limited. We comparatively evaluated the efficacy and the safety of nucleoside analogues in 179 noncirrhotic CHB patients with HVL over 5 years. The HBeAg-positive (n = 104) or HBeAg-negative (n = 75) patients were treated consecutively with telbivudine (LdT, n = 88) or entecavir (ETV, n = 91) and evaluated for viral response, drug resistance and safety. HBV DNA, viral serology, biochemistries, HBV mutation and off-therapy relapse were determined. The cumulative rates of HBV DNA negativity were 86.4% and 94.5% for LdT and ETV at year 5, respectively. The rates of early viral response (EVR, HBV DNA <103 copies/mL at month 6) under LdT and ETV treatments were 58.0% and 34.1%, respectively (P < .05). Hepatitis B e antigen (HBeAg) and Hepatitis B surface antigen (HBsAg) loss-seroconversions were 47.7% and 18.2% on LdT and 16.5% and 2.2% on ETV (P < .01). Eighteen patients (age 28.2 ± 3.1) experienced HBsAg loss-seroconversion, followed by 33 ± 4.6 month off-therapy without a relapse. Viral mutations and serum creatine kinase elevation were 9.1% and 8.0% on LdT, but only 1.1% and 0% on ETV. Both LdT and ETV suppressed HBV replication in HVL CHB patients within 5 years. LdT therapy achieved a higher EVR, HBeAg and HBsAg seroconversion, especially in the younger patients, whereas ETV caused lower drug resistance and fewer adverse events. This finding might help to identify the optimal treatment for CHB patients with HVL.

Telbivudine therapy for gravidas with chronic hepatitis B infection and patients at risk of renal impairment.

Hepatitis B virus infection is currently the most important cause of chronic viral hepatitis worldwide and is one of the most frequent causes of end-stage liver disease. With the international implementation of the hepatitis B vaccine and combined prophylaxis for infants born to HBsAg(+) mothers, the prevalence of hepatitis B has decreased remarkably. However, intra-uterine transmission has become a critical bottleneck for eliminating hepatitis B infection. The efficacy of nucleos(t)ide analogs on inhibiting hepatitis B replication has been widely confirmed, and the quality of life and the survival of individuals with chronic hepatitis B (CHB) have improved to a great degree. However, with the availability of long-term antiviral treatment and the ever increasing ageing population, renal disorders should be considered when choosing antiviral medicines. The antiviral efficacy and safety of telbivudine (LdT) have been shown in patients with CHB infection, and LdT is approved as a class B drug for pregnancy. Furthermore, the renal protective function of LdT has been demonstrated recently. In this review, we will focus on the efficacy and safety of LdT in gravidas with CHB infection, as well as the renal protective function of LdT in CHB patients. LdT might provide physicians with a solid option for effectively treating patients with CHB, especially gravidas or those either with or at risk of renal impairment.

Comparison of 208-week sequential therapy with telbivudine and entecavir in HBeAg-positive chronic hepatitis B patients with suboptimal responses to 24 weeks of Peg-IFNα-2a therapy: An open-labelled, randomized, controlled, "real-life" trial.

The purpose of the study was to compare the efficacy and safety of 208-week sequential therapy with telbivudine and entecavir in HBeAg-positive chronic hepatitis B (CHB) patients with suboptimal responses to 24 weeks of Peg-IFNα-2a therapy. This was an open-label, randomized, controlled, "real-life" trial. HBeAg-positive CHB patients with serum HBV DNA ≥5.0 lg IU/mL and a < 1 lg IU/mL decline of HBsAg level from baseline who underwent at least 24 weeks of Peg-IFNα-2a therapy were included. Enrolled patients were randomized to receive either telbivudine (600 mg/d, n = 95) or entecavir (0.5 mg/d, n = 95) for 208 consecutive weeks. Six patients were lost to follow-up (4 patients in the telbivudine group and 2 in the entecavir group). Treatment was combined with adefovir when week 24 HBV DNA levels declined to <2 lg IU/mL versus baseline, when viral breakthrough occurred during treatment,or when HBV DNA remained detectable at 52 weeks (HBV DNA ≥500 IU/mL). Responses and safety were assessed after 208 weeks of treatment. There were no significant differences among the baseline characteristics, including age, gender, and ALT, HBV DNA, HBsAg or HBeAg levels. After 208 weeks of treatment, there was no significant difference in the rates of undetectable HBV DNA (HBV DNA<500 IU/mL) between the telbivudine group and the entecavir group (84/91,92.31% vs 88/93,94.62%, respectively, P = .525). More patients in the telbivudine group than the entecavir group achieved HBeAg clearance (74.73% vs 46.24%, respectively, P < .001) and HBeAg seroconversion (64.84% vs 38.71%, respectively, P < .001). Univariate analysis (Enter, a = 0.05) of both groups showed that telbivudine, male gender and baseline HBeAg levels were significantly correlated with HBeAg seroconversion after 208 weeks of sequential therapy. Cox regression analysis (Enter, a = 0.05) of the telbivudine group showed that the HBeAg seroconversion rate at 208 weeks was significantly correlated with gender (male) (P = .006, HR=4.406), baseline HBeAg level (P = .005, HR=0.433) and 24 w-HBeAg level reduction of more than 0.5 lg IU/ml from baseline (P = .027, HR=0.487). All patients tolerated sequential telbivudine treatment; only slightly elevated creatine kinase levels were observed. Stratification analysis found that patients with baseline HBeAg levels less than 3 lg COI who switched to telbivudine may have had significantly improved HBeAg seroconversion rates. In conclusion, telbivudine promotes HBeAg seroconversion that merits investigation in HBeAg-positive CHB patients with suboptimal responses to 24 weeks of Peg-IFNα-2a therapy. We would suggest that patients with baseline HBeAg levels under 3 lg COI switch to telbivudine to achieve higher HBeAg seroconversion rates and use the early reductions in HBeAg levels (24 weeks) to guide treatment.

Telbivudine therapy for chronic hepatitis B: A journey to identify super-responders and to optimize treatment using the roadmap model.

Hepatitis B virus (HBV) infection is one of the most serious health problems worldwide with a high risk for cirrhosis and liver cancer. Several antiviral agents have been approved for the treatment of chronic hepatitis B, leading to a rapid reduction in HBV DNA and normalization of serum alanine aminotransferase levels. Telbivudine, a potent inhibitor of HBV replication, has been shown to be well tolerated. Because of the emergence of drug resistance, optimization strategies for telbivudine therapy have been shown to improve patient responses. Optimal baseline characteristics in so-called super-responders have been used to predict the virological response. Baseline HBV DNA levels < 9 log10 copies/mL (2 × 108 IU/mL) or alanine aminotransferase levels of more than or equal to twofold the upper limit of normal in HBeAg-positive patients and HBV DNA < 7 log10 copies/mL (2 × 106 IU/mL) in HBeAg-negative patients were strong predictors for virological response. In addition, the roadmap model, based on early virological response at week 24 of therapy, is considered as a powerful tool to identify patients at risk of treatment failure (HBV DNA ≥ 300 copies/mL, i.e. 60 IU/mL) and to reduce the risk of antiviral resistance. When considering pre-treatment characteristics and on-treatment responses, telbivudine may provide physicians with a wide choice of options to effectively treat patients with chronic hepatitis B, especially those with or at risk of renal impairment, or women of childbearing age.

Hepatic flare after telbivudine withdrawal and efficacy of postpartum antiviral therapy for pregnancies with chronic hepatitis B virus.

BACKGROUND AND AIM: The efficacy of telbivudine for breaking vertical transmission of hepatitis B virus has been well established. Data on the risk of postpartum flare after telbivudine withdrawal and efficacy of extended antiviral therapy after delivery are limited. METHODS: Chronic hepatitis B virus-infected women who received telbivudine beginning at week 24 or 28 of gestation were enrolled and then followed up to 52 weeks postpartum. Virological and biochemical parameters were assessed. RESULTS: Of the 241 women who finished 52 weeks of follow-up, 33.6% had elevated serum alanine aminotransferase (ALT) during pregnancy. Telbivudine administration resulted in ALT normalization in 85.2% before delivery. Compared with women having a normal ALT level throughout pregnancy, those with elevated ALT had a significantly higher rate of ALT flare after telbivudine withdrawal (25.0% vs 11.9%; χ2 = 4.273, P = 0.039). Multivariate analysis indicated that only ALT elevation during pregnancy correlated with postpartum flare after telbivudine withdrawal. Those women with elevated ALT during pregnancy continued antiviral treatment to 52 weeks postpartum and had a significantly higher HBeAg seroconversion rate (P = 0.001) and a notable decrease in HBsAg titers (P = 0.001). CONCLUSION: It is safe for the majority of women to withdraw telbivudine after delivery, whereas exciting serological response encourages extended antiviral therapy for mother with ALT elevation during pregnancy.

[Efficacy of 104-week sequential therapy with telbivudine or entecavir in HBeAg-positive chronic hepatitis B patients with suboptimal responses to 24-week therapy with pegylated interferon-α-2a].

OBJECTIVE: To investigate the efficacy and safety of 104-week sequential therapy with telbivudine or entecavir in HBeAg-positive chronic hepatitis B (CHB) patients with suboptimal responses to 24-week pegylated interferon-α-2a (PEG-IFN-α-2a) therapy. METHODS: A total of 130 HBeAg-positive CHB patients with HBV DNA≥5.0 lg IU/ml and a reduction in HBsAg quantitation < 1 lg IU/ml compared with baseline who received PEG-IFN-α-2a therapy for 24 weeks were enrolled and randomly divided into telbivudine group and entecavir group, and 5 of them were lost. HBeAg clearance rate and seroconversion rate, HBV DNA clearance rate, safety, and drug resistance rate at week 104 were observed. The t-test, chi-square test, or multivariate Cox regression analysis were used for statistical analysis of different types of data. RESULTS: At week 104 of treatment, HBV DNA clearance rate showed no significant difference between the telbivudine group and entecavir group (P = 0.363), and the telbivudine group had significantly higher HBeAg clearance rate and HBeAg seroconversion rate than the entecavir group (HBeAg clearance rate: 61.29% vs 23.81%, P < 0.01; HBeAg seroconversion rate: 51.61% vs 19.05%, P < 0.01). Male sex and telbivudine therapy were baseline predictors of HBeAg seroconversion. The multivariate Cox regression analysis (Forward LR, a = 0.05) showed that the presence or absence of HBeAg seroconversion at week 104 was significantly associated with male sex (HR = 4.917), a reduction in HBsAg > 0.5 lg IU/ml at week 12 of treatment compared baseline (HR = 3.514), and a reduction in HBeAg > 1 lg COI at week 12 of treatment compared baseline (HR = 8.651). CONCLUSION: In HBeAg-positive CHB patients with suboptimal responses to 24-week PEG-IFNα-2a therapy, the sequential therapy with telbivudine helps achieve better HBeAg clearance rate and seroconversion rate compared with the sequential therapy with entecavir and can be used as a therapeutic regimen for such patients. A reduction in HBeAg > 1 lg COI at week 12 of treatment compared baseline can be used as a predictive factor for HBeAg seroconversion at week 104.

Telbivudine or lamivudine use in late pregnancy safely reduces perinatal transmission of hepatitis B virus in real-life practice.

UNLABELLED: Little observational data exist describing telbivudine (LdT) or lamivudine (LAM) use in late pregnancy for preventing hepatitis B mother-to-child transmission (MTCT) in real-world settings. During the period of January 2009 to March 2011, we enrolled hepatitis B e antigen-positive mothers with HBV DNA >6 log10 copies/mL in China. At gestation week 28, the mothers received LdT or LAM until postpartum week 4 or no treatment (NTx). The study endpoints were the safety of LdT/LAM use and MTCT rates. Of the 700 mothers enrolled, 648 (LdT/LAM/NTx=252/51/345) completed the 52-week study with 661 infants (LdT/LAM/NTx=257/52/352). On treatment, viral rebound occurred in 1.6% of mothers, all resulting from medication noncompliance. There was no genotypic mutation detected. At delivery, significantly lower HBV DNA levels were noted in mothers who received LdT or LAM versus NTx. Alanine aminotransferase flares were observed in 17.1% of treated mothers versus 6.3% of untreated mothers (P < 0.001). At birth, hepatitis B surface antigen (HBsAg) was detected in 20% and 24% of newborns in the treated and NTx groups, respectively. At week 52, an intention-to-treat analysis indicated 2.2% (95% confidence [CI]: 0.6-3.8) of HBsAg+ infants from the treated group versus 7.6% (95% CI: 4.9-10.3) in the NTx group (P50.001) and no difference of HBsAg+ rate between infants in the LdT and LAM groups(1.9% vs. 3.7%; P=0.758). On-treatment analysis indicated 0% of HBsAg+ infants in the treated group versus 2.84% in the NTx group (P=0.002). There were no differences for gestational age or infants' height, weight, Apgar scores, or birth defect rates between infants from the treated and untreated groups. CONCLUSIONS: LdT and LAM use in late pregnancy for highly viremic mothers was equally effective in reducing MTCT. The treatment was well tolerated with no safety concerns identified.

Is there an association of hepatitis B virus infection with minimal change disease of nephrotic syndrome? A clinical observational report.

The rate of hepatitis B virus (HBV) infection is high in the Chinese population, and the implications of HBV infection are widely recognized, and membranous nephropathy is the most common renal lesion to be associated with HBV infection. Minimal change disease (MCD) is one of the most important histopathological characteristics in patients with nephrotic syndrome. There is no any study to report that HBV infection is associated with the etiology of MCD. Herein, we report four MCD patients with HBV infection and speculate that there is an association of HBV infection with the pathological type of MCD. In this study, we also reported the treatment schedule for these four MCD patients, and found that the anti-virus alone and combination of anti-virus with immunosuppressive agent could obtain a benefit for MCD patients with HBV infection. However, a well-designed study should be performed to confirm this association.

Telbivudine and adefovir combination therapy for patients with chronic lamivudine-resistant hepatitis B virus infections.

We evaluated second-line salvage therapy with adefovir + telbivudine (group 1), adefovir followed by adefovir + telbivudine (group 2), or lamivudine + adefovir followed by adefovir + telbivudine (group 3) in hepatitis B patients with an inadequate virologic response to lamivudine treatment. Simple linear regression analysis showed that for each additional month of treatment, the most significant reduction in viral load occurred in group 1 (HBV DNA [Log10 IU/mL]: group 1, -0.149; group 2, -0.081; group 3, -0.123). Generalized estimating equation analysis revealed that compared to group 1, hepatitis B virus (HBV) DNA levels were 1.203 and 0.443 Log10 IU/mL higher in groups 2 and 3, respectively. Overall, a significant reduction in viral load (-0.060 Log10 IU/mL) was observed for each additional month of treatment. Adefovir + telbivudine treatment resulted in a significant reduction in HBV DNA levels. Moreover, telbivudine treatment resulted in a significant reduction in viral load (-0.050 Log10 IU/mL) compared to lamivudine treatment after the emergence of lamivudine resistance.

Comparing the efficacy and clinical outcome of telbivudine and entecavir naïve patients with hepatitis B virus-related compensated cirrhosis.

BACKGROUND AND AIM: There is limited data on the efficacy and outcome of telbivudine (LdT) therapy in patients with chronic hepatitis B and compensated cirrhosis. We evaluated LdT as first-line therapy in these patients and compared with those treated with entecavir (ETV). METHODS: We consecutively enrolled 88 chronic hepatitis B patients with compensated cirrhosis primarily treated with LdT at least for 2 years or less than 2 years but developed resistance, and evaluated the efficacy and clinical outcomes. Meanwhile, we matched a control group who treated with ETV for comparison. RESULTS: In LdT group, alanine aminotransferase normalization (65.8%), hepatitis B e antigen seroconversion (39.8%), hepatitis B virus (HBV) DNA undetectablility (71.6%), and virologic resistance (23.9%) were noted after 2 years treatment. Compared with ETV group, there were significant difference in HBV DNA undetectablility (P < 0.001) and virologic resistance (P < 0.001). In addition, the decline of serum hepatitis B surface antigen levels, hepatocellular carcinoma development, mortality, disease progression, and the change of renal function were similar. Cox regression analysis showed that pretreatment low albumin level and high model for end-stage liver disease scores were risk factors for disease progression. CONCLUSIONS: These results indicated that although LdT and ETV are similar in clinical outcomes for patients with HBV-related compensated cirrhosis, LdT still had lower HBV undetectablility and higher resistant rate after 2 years treatment, which was a challenge for being as first-line therapy in these patients who need lifelong therapy.

Extrahepatic effects of nucleoside and nucleotide analogues in chronic hepatitis B treatment.

Oral nucleoside/nucleotide analogues (NAs) are the mainstay of therapy for patients with chronic hepatitis B and are generally well tolerated. Despite this, the safety profile of NAs is of paramount importance since the majority of patients will require long-term treatment. All NAs can potentially affect human DNA polymerase with decrease in mitochondrial DNA, leading to manifestations of mitochondrial toxicity. As a class effect, therefore, NAs can potentially cause extrahepatic conditions, such as myopathy, nephropathy, neuropathy, and lactic acidosis. Indeed, effects on muscles, including myopathy and creatine kinase elevations, have been described with clevudine and telbivudine use. Both adefovir and tenofovir are associated with dose-dependent nephropathy, predominantly affecting the proximal renal tubules. Neuropathy appears to be rare, and most commonly reported in patients receiving combination therapy with telbivudine and interferon. Increased risk of lactic acidosis has also been described for those with impaired liver and renal function taking entecavir. Loss of bone mineral density and hypophosphatemia have been described with the use of NAs, although the overwhelming studies have been with human immunodeficiency virus-infected patients. However, not all extrahepatic effects are detrimental. Recent evidence has suggested a potential renal beneficial effect with the use of telbivudine. The effect of NAs on pregnancy appears to be minimal for all NAs, with telbivudine and tenofovir having a more favorable category B rating. Ongoing pharmacovigilance is essential to identify new and monitor existing extrahepatic effects associated with NA use.

Nonclinical Safety Profile of BMS-986001, a Nucleoside Transcriptase Inhibitor for Combination Retroviral Therapy.

Nucleoside reverse transcriptase inhibitors (NRTIs)/nucleotide reverse transcriptase inhibitors are key components of combination antiretroviral therapy for HIV infection. First-generation NRTIs are associated with mitochondrial toxicity in patients, mainly due to inhibition of human DNA polymerase γ (hDNA polγ) that manifests as adverse events such as lipodystrophy, lactic acidosis, myopathy, cardiomyopathy, or nephropathy in patients. In chronic nonclinical studies in rodents and nonrodents, eukaryotic (host) mitochondrial toxicity manifests as some drug-specific toxicities similar to human toxicity. BMS-986001, a novel thymidine analog with minimal hDNA polγ inhibition, has demonstrated antiretroviral activity in early clinical studies. The primary toxicity of BMS-986001 in rats and monkeys is bone marrow dyserythropoiesis with associated decreases in red blood cell mass. Additionally, at high doses, severe platelet reductions accompanied by cutaneous petechiae began during weeks 8 and 11 in 3 of 60 monkeys in chronic toxicity studies. In a 6-month study, platelet reductions required euthanasia of the 2 affected monkeys (300 mg/kg/d) at week 14, but with dose reduction (200 mg/kg/d) remaining monkeys had no platelet changes. One affected monkey (200 mg/kg/d) in a 9-month study completed dosing and its platelet counts recovered during a 1-month recovery. Formation of platelet-bound immunoglobulin in the presence of BMS-986001, together with rapid and complete platelet recovery in the absence of BMS-986001, suggested that platelet decreases in monkeys may be immune mediated. No findings indicative of mitochondrial toxicity were observed in rats or monkeys given BMS-986001, suggesting an improved safety profile compared to marketed NRTI or tenofovir disoproxil fumarate.

[Long-term efficacy and safety of telbivudine as monotherapy and as combination therapy with adefovir dipivoxil in HBeAg-positive chronic hepatitis B patients].

OBJECTIVE: To prospectively observe the long-term antiviral efficacy and safety of telbivudine (LDT) administered as a monotherapy and as a combination therapy with adefovir dipivoxil (ADV) in patients diagnosed with chronic hepatitis B (CHB) and positivity for hepatitis B e antigen (HBeAg). METHODS: A total of 140 patients with HBeAg-positive CHB were randomly divided into treatment groups for LDT monotherapy (n = 75; 600 mg orally, once daily) and LDT+ADV combination therapy (n = 65; LDT 600 mg plus ADV 10 mg orally, once daily). The shortest treatment course was 96 weeks and the longest was 240 weeks. At treatment weeks 12, 24, 48?, 96, 144, 192, and 240 patients were tested for hepatitis B virus (HBV) DNA, HBeAg seroconversion and ALT normalization time; in addition, the incidence and type of adverse drug reactions were recorded. Data were statistically analyzed to determine the significance of differences observed between groups. RESULTS: The rate of patients experiencing more than or equal to 2 log HBV DNA reduction was higher in the LDT + ADV group (92.3%(60/65) vs. LDT: 86.7%(65/75), X2 = 1.58). The HBV DNA negative rates of the LDT and LDT + ADV groups were 62.7% and 61.5% (X2 = 0.01) at week 24, 76.0% and 81.5% (X2 = 0.63) at week 48, 80.0% and 89.2% (X2 = 2.2) at week 96, 78.3% and 93.3% (X2 = 3.24) at week 144, 83.7% and 91.7% (X2 = 0.47) at week 192, and 93.3% and 88.9% at week 240 (comparison between two groups for each point P more than 0.05); both groups showed higher early and rapid sustained HBV DNA negative rates. For the HBeAg seroconversion, the rates of the LDT and LDT + ADV groups were 17.3% and 23.1% (X2 = 0.71) at week 24, 29.3% and 30.8% (X2 = 0.03) at week 48, 42.7% and 40.0% (X2 = 0.10) at week 96, 55.0% and 43.3% (X2 = 1.08) at week 144, 55.8% and 66.7% (X2 = 0.45) at week 192, and 63.3% and 66.7% at week 240; however, pairwise comparison showed no statistically significant differences between the groups (P more than 0.05). Similarly, there was no significant difference between the two groups in incidence of resistance at week 48 (4.0% and 1.5%), week 96 (5.3% and 3.1%), week 144 (10.0% and 3.3%, X2 = 1.23), week 192 (11.6% and 8.3%), and week 240 (13.3% and 11.1%) (all P more than 0.05). Three patients experienced muscle soreness (LDT, n = 2; LDT + ADV, n = 1) and two patients experienced increased creatine phosphokinase (LDT, n = 1; LDT + ADV, n = 1); all side effects resolved spontaneously or with symptom-appropriate treatment. CONCLUSION: The long-term efficacy of LDT as a monotherapy or as a combination therapy with ADV was similar and the two different treatment approaches were associated with similar rates of resistance. The long-term safety was good for both treatment approaches.

Mouse beta cell proliferation is inhibited by thymidine analogue labelling.

AIMS/HYPOTHESIS: Long-term labelling of mice with halogenated thymidine analogues is an established method for quantifying the contribution of beta cell proliferation to in vivo beta cell mass expansion in (re)generation models. The method is believed to give accurate information on the accrued number of cycling beta cells over a period of time. Multiple thymidine analogue labelling is applied for evaluating the duration of postmitotic quiescence in beta cells. We hypothesise, however, that long-term labelling by thymidine analogues hampers beta cell proliferation. METHODS: Thymidine analogues were administered for 7-14 days via the i.p. route to neonatal mice, or via drinking water to young mice with normal pancreases or adult mice with injured pancreases. The proliferation of insulin-positive cells was assessed by their expression of the proliferation markers Ki67 or phosphorylated histone H3 and by their incorporation of nucleotide analogues. RESULTS: In the mouse models of beta cell proliferation investigated herein, long-term administration of thymidine analogues decreased the percentage of Ki67(+) and phosphorylated histone H3(+) beta cells as compared with administration of normal drinking water. Proliferation was restored by washout of the analogue. Labelling with one analogue decreased the subsequent incorporation of another analogue by beta cells. CONCLUSIONS/INTERPRETATION: Long-term labelling with halogenated thymidine analogues is a biased method that underestimates the proliferation and re-division potential of mouse beta cells.