The risk of HCC development is low in pre-cirrhotic patients, but remains high in patients with cirrhosis. Disclosures: The following people have nothing to disclose: Suut Gokturk, Rafet Basar, Ali Riza Ucar, Barbaros Hayrettin Basgoze, Mustafa Altinkaynak, Pinar Buyukballi, Busra Alpaslan, Bulent Baran, Asli Cifcibasi Ormeci, Ozlem Mutluay Soyer, Sami Evir-gen, Baris Bakir, Filiz Akyuz, Cetin Karaca, Kadir Demir, Fatih Besisik, Sabahat-tin BTK signaling pathway inhibitor Kaymakoglu Background/Aims: Entecavir (ETV) is approved for the treatment of adults with chronic hepatitis B (CHB). The purpose of Study AI463-028 was to support ETV dose selection in pediatric subjects. Safety and

efficacy of ETV in pediatric CHB subjects is being evaluated in ongoing clinical trials. Methods: Adult dosing, scaled to body surface area (BSA), was extrapolated to determine ETV dosing in pediatric subjects (>2-l 8 years old [yo]) using a weight-based algorithm (0.015 mg/kg up to a maximum dose of 0.5 mg). Dose selection was designed to achieve a median exposure (AUC[TAU]) across each of three age groups (A: >2-<6 yo [n=7], B: >6-≦12 yo [n=9], and C: >12-≦18 yo [n=8]) within ±30% of the median exposure

obtained in adults (1 8.7 ng.h/mL). Subjects in each of the three age cohorts NSC 683864 had pharmacokinetics (PK) samples drawn at selected times. Individual subject PK parameters were derived by noncompartmental methods using a validated PK program. Results: Target median exposure (13.1-24.3 ng.h/mL) was achieved in all three age cohorts (17.0, 20.5, and 15.4 ng.h/mL, respectively). ETV clearance (CLT/F) increased as age increased, CLT/F normalized to body weight decreased with increasing age. ETV BSA-normalized CLT/F was independent of age. Conclusions: medchemexpress ETV dosing using a weight-based algorithm (0.015 mg/kg up to a maximum dose of 0.5 mg) provided comparable exposures in pediatric subjects compared with historical exposures in adults receiving 0.5 mg/day (AUC[TAU]

geo.mean [CV] at day 14: 14.78 ng.h/mL1). 1. Yan JH, et al. J Clin Pharmacol. 2006 Nov;46(1 1): 1250-8. Disclosures: Deirdre A. Kelly – Consulting: Sanofi Pasteur; Grant/Research Support: BMS, Astellas, Acitllion, MSD, Roche Nanda Kerkar – Advisory Committees or Review Panels: Gilead Inc. Maureen M. Jonas – Advisory Committees or Review Panels: Gilead Sciences; Consulting: Novartis; Grant/Research Support: Bristol Myers Squibb, Roche, Merck Schering Plough Philip Rosenthal – Advisory Committees or Review Panels: Ikaria, Gilead, Merck, General Electric; Consulting: Roche; Grant/Research Support: Roche, Bristol MyersSquibb, Gilead, Vertex Peter Ackerman – Employment: Bristol-Myers, Squibb Marc Bifano – Employment: Bristol-Myers Squibb The following people have nothing to disclose: Mei-Hwei Chang Background/Aims: Tenofovir disoproxil fumarate (TDF) has high antiviral efficacy in treatment-naïve patients with chronic hepatitis B virus (HBV) infection.