Safety of current antiviral drugs for chronic hepatitis B

INTRODUCTION

Oral nucleos(t)ide analogues (NUCs) are recommended as first-line therapy for chronic hepatitis B due to higher HBV-DNA suppression rates and safety profile. Long-term treatment with NUCs is often necessary to achieve durable viral suppression.

AREAS COVERED

This review provides an overview of the long-term safety data that have become available since entecavir (ETV) and tenofovir disoproxil fumarate (TDF) were first approved, and recent data on tenofovir alafenamide (TAF) in patients with CHB.

EXPERT OPINION

NUCs generally show remarkable safety in patients taking them for long periods. Nevertheless, renal and bone toxicity may occur in a minority of patients on TDF therapy. These effects have been overcome by the recent release of TAF. Moreover, the currently available data do not allow firm conclusions on superiority of TDF on ETV about HCC risk reduction. Observational studies involving more homogeneous cohorts are therefore needed; furthermore long-term studies assessing impact of TAF on this important topic are warranted.

Calcipotriol attenuates liver fibrosis through the inhibition of vitamin D receptor-mediated NF-κB signaling pathway

Liver fibrosis is an inevitable stage in the development of chronic liver disease to cirrhosis. Nonetheless, the interventional treatment and achieving control over the disease at this stage can substantially reduce the incidence of liver cirrhosis. To demonstrate these aspects, liver pathological sections of 18 patients with chronic liver disease are collected for research according to the degree of fibrosis. Further, the expressions of related proteins in each group are studied by the Western blot method. The cell proliferation and apoptosis are detected by CKK-8 and flow cytometry analyses. Further, a rat model with carbon tetrachloride (CCl₄)-induced liver fibrosis is employed to verify the effect and mechanism of VDR on the process of liver fibrosis in vivo. The expression of VDR in liver tissues of patients with liver fibrosis is negatively correlated with α-smooth muscle actin (α-SMA), Col-1, and liver fibrosis stages. Moreover, the tumor necrosis factor (TNF)-α stimulation could increase the proliferation of LX-2, up-regulate the expression of α-SMA, Col-1, NF-κB, p-IκBα, p-IKKβ, p-p65m, and some fibrosis factors, as well as down-regulate the expressions of VDR and matrix metalloproteinase-1 (MMP-1). Considering the protective actions of VDR, calcipotriol, a VDR agonist, effectively reduced the degree of liver fibrosis in a rat model of liver fibrosis by inhibiting the deposition of extracellular (ECM) and activation of hepatic stellate cells (HSCs), which is negatively correlated with the degree of liver fibrosis. Together, these shreds of evidence demonstrated that the calcipotriol showed great potential in effectively attenuating liver fibrosis.

Review article: long-term safety of nucleoside and nucleotide analogues in HBV-monoinfected patients

BACKGROUND

Nucleos(t)ide analogues (NUCs) for chronic hepatitis B treatment achieve high rates of viral suppression and are generally well tolerated. Entecavir (ETV) and tenofovir disoproxil fumarate (TDF) are the currently preferred first-line agents. The safety of these agents in clinical practice is particularly relevant since long-term treatment is usually required.

AIM

To summarise and critically discuss recent real-world evidence on the safety of treatment with ETV or TDF in hepatitis B virus (HBV)-monoinfected patients.

METHODS

PubMed and conference proceedings up to 15th June 2015 were searched using the terms ((((Hepatitis_B) OR HBV) AND ((tenofovir) OR entecavir)) AND (((lactic_acidosis) OR bone) OR renal)).

RESULTS

In selected populations included in registration studies, both ETV and TDF were well tolerated with no clinically significant renal toxicity or lactic acidosis. Growing 'real-world' clinical experience with these agents includes some reports of ETV-associated lactic acidosis and TDF-associated renal impairment; however, evidence from cohort studies appears to be conflicting. In the case of ETV-related lactic acidosis, a small number of cases have been reported, all in patients with decompensated cirrhosis. The degree of association between TDF treatment and changes in markers of renal function varies between studies: discrepancies may result from the use of different definitions and cut-offs for reporting renal toxicities, and differences in patient populations.

CONCLUSIONS

Pre-treatment and on-treatment monitoring of eGFR and phosphorus, with prompt appropriate dose adjustment or treatment switch can minimise the impact of NUC renal toxicity. Standardisation of measures of renal impairment and identification of early molecular markers remain an unmet need.

Decline in serum 25 hydroxyvitamin D levels in HIV-HBV-coinfected patients after long-term antiretroviral therapy

BACKGROUND

Vitamin D insufficiency plays an important role in the development of fibrosis in chronic liver disease.

METHODS

This was a cross-sectional study from Thailand. Liver fibrosis was assessed by transient elastography. Serum 25 hydroxyvitamin D (25[OH]D)<30 ng/ml was defined as hypovitaminosis D. 25(OH)D was assessed prior to and following tenofovir disoproxil fumarate (TDF). Factors related to 25(OH)D levels were determined by logistic regression analysis.

RESULTS

A total of 158 HIV-HBV-coinfected patients (32% female, median age 43 years) were included. Overall, liver disease was mild with 13.4% having a fibrosis score (FS) of 7.1-14 kPa and 2% with a FS>14 kPa. Median (IQR) duration on TDF was 5 years (4-7). The median estimated glomerular filtration rate was 96.9 ml/min/1.73 m(2). The median (IQR) serum 25(OH)D levels prior to and following TDF were 24.8 ng/ml (21.3-30.6) and 22.8 ng/ml (18.0-27.7), respectively; P≤0.001). The proportion of patients with hypovitaminosis D significantly increased from 72.2% (95% CI 64.7, 78.6) prior to TDF to 84.2% (95% CI 77.7, 89.0) after taking TDF (P=0.01). Factors associated with hypovitaminosis D by multivariate analysis were female sex (adjusted OR 3.8, 95% CI 1.1, 13.7; P=0.038) and duration of antiretroviral therapy (ART)>5 years (OR 3.3, 95% CI 1.2, 8.8; P=0.017). Vitamin D levels were not associated with significant liver fibrosis.

CONCLUSIONS

Although our HIV-HBV-coinfected patients live in the tropics, there was a high prevalence of hypovitaminosis D, especially in female patients and those receiving prolonged ART. Since HIV-HBV-coinfection requires long-term use of the HBV-active drug, TDF, which can also contribute to bone loss, routine vitamin D assessment and supplementation as necessary should be considered.