Study On The Hepatotoxicity And Its Mechanism(s) Of Anti-HBV Compound Bay41-4109

During the drug developmental process, undesired hepatotoxicty has been a major reason for compound failure, thus becomes a great concern for pharmatoxicologists. In order to reduce drug candidate attrition at the preclinical stage, new technologies such as toxicogenomics and metabonomics are being used in attempt to predict the toxicity of drug candidate, to find the biomarkers related to the toxicity and to study the mechanisms. Bay41-4109 is a novel nonnucleosidic inhibitor of HBV nucleocapsid maturation that possesses in vitro and in vivo antiviral activity. It has potential for future therapeutic regimens to combat chronic HBV infection. However, the toxicity of Bay41-4109 including toxic feature, toxic target organ and toxic mechanism haven't been characterized, and there is little data to evaluate the development perspective of Bay41-4109. In this study, traditional toxic experiments and '-omics' techniques have been applied together to explore the hepatotoxicity and its mechanisms of Bay41-4109 in order to offer some toxicological information for development as a novel anti-HBV drug. At the same time, the application of transcriptomics and metabonomics in hepatotoxicity study of CYP450 inducer was discussed.Clinical signs of toxicity in Beagle dog when Bay41-4109≥100mg/kg included: salivation, emesis, depressed, decreased food appetite, reduced motility, female were found more serious than male. Serum biochemistry profiles displayed a trend of increase in Tchol. Slightly vacuolization and focal necroses of hepatocytes were found both in dogs and rats and the deformation and swelling even vacuolation of mitochondria were also found inside the cells. Total CYP450 content and activities of BROD, PROD and EMND were significantly elevated after multiple induction withBay41-4109, indicating that Bay41-4109 was a strong inducer of CYP450 similar to that of Phenobarbital. Therefore, the apparent NOAEL for Bay41-4109 in Beagle dogs is deduced as 30mg/kg, and liver is one of its toxic target organs. cDNA microarray analysis showed the genes up- or down-regulated in rat liver induced by Bay41-4109 were functionally related to xenobiotics metabolism and fatty, amino acid, energy metabolism, and the alterations of the I , II, III phase metabolic enzymes were consistent with Phenobarbital. The further study on gene expression profile of HepG2 cells treated with Bay41-4109 also revealed significant alterations in genes involved in fatty, energy metabolism and transport, cell cycle and so on. These observations all provided evidence that mitochondrial inability and fatty acid, energy metabolism disorder might contribute to the hepatotoxicity of Bay41-4109. The hepatotoxicity was probably mediated by CAR as well as that of Phenobarbital.An integrated metabonomics study using high-resolution lH NMR spectroscopy has been applied to investigate the biochemical composition of urine, serum, liver tissue aqueous extracts (acetonitrile/water) and liver tissue lipidic extracts (chloroform/methanol) obtained from Bay41-4109 treated rats. The results showed the biochemical profiles of high-dose group might reflect the hepatotoxicity of Bay41-4109 more exactly. The elevation in the level of 3-HB, lactate, 2-hydroxy-acetol, hydroxymaleic acid and d-glucose was found in the urine, and the levels of VLDL/LDL(CH2)n, VLDL/LDL-CH3, 3-HB, lactate, pyruvate, taurine, in serum were increased significantly in high-dose group. The predominant changes identified in liver tissue aqueous extracts included an increase in the signal intensities of lactate, 3-amino-isovalerate, pyruvate, taurine, choline, TMAO and a reduction in the intensities of trytophan and d-glucose. In liver tissue chloroform/methanol extracts, there was a remarkably increase in many of the lipid signals including the triglyceride terminal methyl, methylene groups, and CH2CO, N+(CH3)3, CH2OPO2, CH2OCOR. The results revealed an increased rates of fatty acid oxidation, glycogenolysis and glycolysis which was consistent with the results from cDNA microarray. The analysis of the time-course of metabonome changes in urine after Bay41-4109 dosing indicated that lactate,...