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Yuen, Man-Fung,Lee, Sung-Hack,Kang, Hyang-Mi,Kim, Chung Ryeol,Kim, John,Ngai, Vincent,Lai, Ching-Lung American Society for Microbiology 2009 Antimicrobial agents and chemotherapy Vol.53 No.5
<B>ABSTRACT</B><P>LB80380, a dipivoxil ester prodrug of LB80331 (metabolite, LB80317), is a novel antiviral agent for chronic hepatitis B (CHB). The pharmacokinetics of LB80331/LB80317 were evaluated in two clinical studies and a study with mice. The clinical studies were dose-escalating pharmacokinetic studies with six healthy subjects per single-dose group and six CHB patients per repeated-dose group. The mouse study was designed to measure the amounts of the phosphorylated portions of LB80331 and LB80317 in the liver. In healthy subjects receiving a single dose of LB80380, the plasma level of LB80331 increased as the dose increased. Although a high-fat diet delayed the time to the maximum concentration in plasma (<I>T</I>max) of LB80331, the area under the concentration-time curve from time zero to infinity was similar between the subjects in the fasted group and those in the group who consumed a high-fat diet. In CHB patients, the mean <I>T</I>max of LB80331 was 1.0 to 2.0 h postdosing at steady state. The steady-state plasma concentration of LB80331 declined in a monoexponential manner, and the apparent elimination half-life was 2.5 to 3.3 h. The steady-state plasma concentration of LB80317 was maximum at 3 to 8 h postdoing and declined in a monoexponential manner; the apparent elimination half-life was 45 to 62 h at the 30- to 240-mg doses, while LB80317 was measurable in plasma only at higher doses of 120 and 240 mg after the administration of the first dose of LB80380. Forty percent of the amount of LB80331/LB80317 in the mouse liver was detected as the phosphorylated form. In conclusion, LB80380 is rapidly absorbed and converted to LB80331. LB80317 has a long half-life at steady-state, supporting the use of a once-daily dosing regimen. The ingestion of a high-fat diet delays the rate of absorption of LB80380 without affecting the extent of absorption.</P>
Yuen, Man-Fung,Han, Kwang-Hyub,Um, Soon-Ho,Yoon, Seung Kew,Kim, Hye-Ryon,Kim, John,Kim, Chung Ryeol,Lai, Ching-Lung Wiley Subscription Services, Inc., A Wiley Company 2010 Hepatology Vol.51 No.3
<P>We aimed to determine the antiviral activity and safety of a new nucleotide analogue, LB80380, in chronic hepatitis B (CHB) patients with lamivudine-resistant virus. Sixty-five patients with lamivudine-resistant virus were randomized to receive five ascending daily doses (30, 60, 90, 150, 240 mg) of LB80380. LB80380 was given together with lamivudine for the first 4 weeks, followed by 8 weeks of LB80380 monotherapy. This was then followed by 24 weeks of adefovir. Hepatitis B virus (HBV) DNA levels, serology, liver biochemistry, and safety were monitored. The extent of the HBV DNA reduction at week 12 was dose-dependent. The mean reduction from baseline was 2.81, 3.21, 3.92, 4.16, and 4.00 log<SUB>10</SUB> copies/mL for the five ascending dose groups. The dose-proportionate effect was statistically significant (P < 0.001) with a decrease of HBV DNA levels by an average of 1.54 log<SUB>10</SUB> copies/mL for every 1-unit increase in log<SUB>10</SUB> dose of LB80380. In 93.4% of patients, HBV DNA decreased by >2 log<SUB>10</SUB> copies/mL, and 11.5% of patients had undetectable HBV DNA levels (<300 copies/mL) by week 12. HBV DNA suppression was maintained during the 24 weeks of adefovir treatment. Hepatitis B e antigen seroconversion and normalization of alanine aminotransferase were seen in 14.6% and 24.6% of patients, respectively, at week 12; 44.6% of patients experienced mild and self-limiting adverse events, none of which were attributed to the study drug. Conclusion: LB80380 at doses of up to 240 mg is safe, well tolerated, and effective at reducing viral load in CHB patients with lamivudine-resistant virus for a period of 12 weeks. (HEPATOLOGY 2010.)</P>
Detoxification: A Novel Function of BRCA1 in Tumor Suppression?
Kang, Hyo Jin,Hong, Young Bin,Kim, Hee Jeong,Rodriguez, Olga C.,Nath, Raghu G.,Tilli, Elena M.,Albanese, Christopher,Chung, Fung-Lung,Kwon, Sang Hoon,Bae, Insoo Oxford University Press 2011 Toxicological sciences Vol.122 No.1
<P>Our studies found that BRCA1 levels negatively correlate with DNA adducts induced by Benzo(a)pyrene (BaP). Pulse-chase experiments showed that the increase in BaP-induced DNA adducts in BRCA1 knockdown cells may not be associated with BRCA1’s function in nucleotide excision repair activity; rather, it may be associated with its function in modulating transcriptional regulation. BRCA1 knockdown in MCF-10A cells significantly attenuated the induction of CYP1A1 following BaP treatment indicating that the increase in BaP-induced adducts in BRCA1 knockdown cells is not CYP1A1 dependent. However, our study shows that BRCA1 defective cells may still be able to biotransform BaP by regulating other CYP enzymes, including CYP1B1. Knockdown of BRCA1 also severely affected the expression levels of two types of uridine diphosphate glucorunyltransferase (UGT1A1 and UGT1A9) and NRF2. Both UGTs are known as BaP-specific detoxification enzymes, and NRF2 is a master regulator of antioxidant and detoxification genes. Thus, we concluded that the increased amount of BaP-induced DNA adducts in BRCA1 knockdown cells is strongly associated with its loss of functional detoxification. Chromatin immunoprecipitation assay revealed that BRCA1 is recruited to the promoter/enhancer sequences of UGT1A1, UGT1A9, and NRF2. Regulation of UGT1A1 and UGT1A9 expression showed that the induction of DNA adducts by BaP is directly affected by their expression levels. Finally, overexpression of UGTs, NRF2, or ARNT significantly decreased the amount of BaP-induced adducts in BRCA1-deficient cells. Overall, our results suggest that BRCA1 protects cells by reducing the amount of BaP-induced DNA adducts possibly via transcriptional activation of detoxification gene expression.</P>