Efficacy and Safety of Entecavir 0. 5 mg in Treating Naive Chronic Hepatitis B Virus Patients in Egypt: Five Years of Real Life Experience

Association Analysis of Genetic Variants of Sodium Taurocholate Co-Transporting Polypeptide NTCP Gene (SLC10A1) and HBV Infection Status in a Cohort of Egyptian Patients

Background: Single nucleotide polymorphisms (SNPs) in the SLC10A1 gene, coding for a functional receptor of hepatitis B virus (HBV), sodium taurocholate co-transporting polypeptide (NTCP), may influence the susceptibility, outcome, and disease course of HBV infection in some populations. Aim: to determine the prevalence of SNPs of the NTCP gene, rs2296651 and rs943277, and their relationship with chronic HBV infection in a group of Egyptian patients. Methods: One hundred and thirty seven patients with HBV and 65 healthy controls were enrolled, and the patients were divided into two groups; group I chronic HBV infection (68 patients with normal ALT and minimal or no liver necroinflammation or fibrosis) and group II chronic hepatitis B (69 patients with elevated ALT and moderate or severe liver necroinflammation). They were subjected to full history taking, clinical examination, laboratory investigations, abdominal ultrasound, and liver stiffness measurement using both Echosens® Fibroscan and acoustic radiation force impulse (ARFI). A real time PCR TaqMan 5′ allelic discrimination assay was applied to detect the SNPs in the NTCP gene, rs2296651 and rs943277. Results: On studying the rs2296651 variant, all controls and patients had genotype GG without any significant association with HBV infection or disease progression. However, the rs943277 variant in all controls and 98% of patients had genotype GA, except for two chronic HBV infection patients who had genotype AA, but no significant difference between patients and controls was found. The non-invasive methods for liver fibrosis assessment ARFI, AST/platelet’s ratio (APRI), and fibrosis-4 score (FIB-4) could predict the stages of fibrosis in agreement with Fibroscan with AUCOR 0.8, 0.79, and 0.76, respectively. Conclusion: These findings may suggest that there is no relation between these SNPs of the NTCP gene and the susceptibility or chronicity of HBV infection in the Egyptian population. We also suggest that the use of the non-invasive methods for liver fibrosis assessment, ARFI, FIB-4, and APRI, may decrease the need for liver biopsies in the prediction of significant hepatic fibrosis in chronic HBV patients.

Present and Future Therapies for Chronic Hepatitis B

Chronic hepatitis B (CHB) remains the leading cause of liver-related morbidity and mortality across the world. If left untreated, approximately one-third of these patients will progress to severe end-stage liver diseases including liver failure, cirrhosis, and hepatocellular carcinoma (HCC). High level of serum HBV DNA is strongly associated with the development of liver failure, cirrhosis, and HCC. Therefore, antiviral therapy is crucial for the clinical management of CHB. Current antiviral drugs including nucleoside/nucleotide analogues (NAs) and interferon-α (IFN-α) can suppress HBV replication and reduce the progression of liver disease, thus improving the long-term outcomes of CHB patients. This chapter will discuss the standard and optimization antiviral therapies in treatment-naïve and treatment-experienced patients, as well as in the special populations. The up-to-date advances in the development of new anti-HBV agents will be also discussed. With the combination of the current antiviral drugs and the newly developed antiviral agents targeting the different steps of the viral life cycle or the newly developed agents modulating the host immune responses, the ultimate eradication of HBV will be achieved in the future.

CMCdG, a Novel Nucleoside Analog with Favorable Safety Features, Exerts Potent Activity against Wild-Type and Entecavir-Resistant Hepatitis B Virus

We designed, synthesized, and characterized a novel nucleoside analog, (1S,3S,5S)-3-(2-amino-6-oxo-1,6-dihydro-9H-purin-9-yl)-5-hydroxy-1-(hydroxymethyl)-2-methylene-cyclopentanecarbonitrile, or 4'-cyano-methylenecarbocyclic-2'-deoxyguanosine (CMCdG), and evaluated its anti-hepatitis B virus (anti-HBV) activity, safety, and related features. CMCdG's in vitro activity was determined using quantitative PCR and Southern blotting assays, and its cytotoxicity was determined with a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay, while its in vivo activity and safety were determined in human liver-chimeric mice infected with wild-type HBV genotype Ce (HBV_WT ^Ce) and an entecavir (ETV)-resistant HBV variant containing the amino acid substitutions L180M, S202G, and M204V (HBV_ETV-R ^{L180M/S202G/M204V}). CMCdG potently inhibited HBV production in HepG2.2.15 cells (50% inhibitory concentration [IC₅₀], ∼30 nM) and HBV_WT ^Ce plasmid-transfected Huh7 cells (IC₅₀, 206 nM) and efficiently suppressed ETV-resistant HBV_ETV-R ^{L180M/S202G/M204V} (IC₅₀, 2,657 nM), while it showed no or little cytotoxicity (50% cytotoxic concentration, >500 μM in most hepatocytic cells examined). Two-week peroral administration of CMCdG (1 mg/kg of body weight/day once a day [q.d.]) to HBV_WT ^Ce-infected human liver-chimeric mice reduced the level of viremia by ∼2 logs. CMCdG also reduced the level of HBV_ETV-R ^{L180M/S202G/M204V} viremia by ∼1 log in HBV_ETV-R ^{L180M/S202G/M204V}-infected human liver-chimeric mice, while ETV (1 mg/kg/day q.d.) completely failed to reduce the viremia. None of the CMCdG-treated mice had significant drug-related changes in body weights or serum human albumin levels. Structural analyses using homology modeling, semiempirical quantum methods, and molecular dynamics revealed that although ETV triphosphate (TP) forms good van der Waals contacts with L180 and M204 of HBV_WT ^Ce reverse transcriptase (RT), its contacts with the M180 substitution are totally lost in the HBV_ETV-R ^{L180M/S202G/M204V} RT complex. However, CMCdG-TP retains good contacts with both the HBV_WT ^Ce RT and HBV_ETV-R ^{L180M/S202G/M204V} RT complexes. The present data warrant further studies toward the development of CMCdG as a potential therapeutic for patients infected with drug-resistant HBV and shed light on the further development of more potent and safer anti-HBV agents.