CHB subjects with HBV DNA >2 x 1 03 IU/mL and ALT ≦10 x ULN received treatment with TAF at doses of 8, 25, 40, and 120 mg, or TDF 300 mg for 28 days

with 4 weeks off-treatment follow-up. Intensive pharmacokinetics (PK) were performed on Day 1. Results: 51 subjects were enrolled and completed 28 days of dosing. Groups were well matched at baseline (table) and subjects were mostly male and either Asian or Black; 53% were HBeAg-negative. No subject experienced a serious adverse event (SAE), grade 3/4 AE, or discontinued for AE. No subject experienced a renal event (>0.5 mg/dL increase in creatinine from baseline, phosphorus <2 mg/dL, or CrCL <50 mL/min). The kinetics of reduction in serum HBV DNA were similar across all TAF dose groups and comparable to TDF. PK analysis suggested mean reductions in TFV exposures (AUCinf) of 97%, 93%, 81 %, ICG-001 concentration and 32% at TAF doses of 8, 25, 40, and 120 mg, respectively, relative to the mean TFV exposure with TDF. Conclusions: Over 28 days, TAF was safe and well tolerated. Declines in HBV DNA with TAF did not differ by dose and were similar to TDF. Additionally, TAF may have less impact on renal function (CrCL) compared to TDF. Further clinical trials with TAF are warranted in CHB patients.   TAF 8 mg (N=10) TAF 25 mg (N=10) TAF 40 ng (N=ll) TAF 120 mg (N=10) TDF 300 mg (N=10) Results are median (IQR) unless otherwise stated. Disclosures:

Kosh Agarwal – Advisory Committees or Review Panels: Gilead, Novartis, Abbott; Grant/Research Support: Roche, MSD; Speaking and Teaching: BMS, Astellas, Janssen Scott K. Fung – Advisory Committees or Review Panels:

BMS, Vertex, Gilead Sciences; Dabrafenib Grant/Research Support: Gilead Sciences, Hoffman La Roche, Merck; Speaking and Teaching: Gilead Sciences, Hoffman La Roche, Merck, BMS Tuan T. Nguyen – Grant/Research Support: Bristol Myers Squibb, Gilead Sciences, Idenix Pharmaceuticals Incorporation, Globeimmune Pharmaceuticals, Vertex Pharmaceuticals John F. Flaherty – Employment: Gilead Sciences; Stock Shareholder: Gilead Sciences Eileen Lawson – Employment: Gilead Sciences, Inc.; Stock Shareholder: Gilead Sciences, Inc. Mani Subramanian – Employment: Gilead Sciences John G. McHutchison – Employment: Gilead Sciences; Stock Shareholder: Gilead Sciences Edward J. Gane – Advisory Committees or Review Panels: Roche, AbbVie, Novartis, Tibotec, Gilead Sciences, Janssen Chlormezanone Cilag, Vertex, Achillion; Speaking and Teaching: Novartis, Gilead Sciences, Roche Graham R. Foster – Advisory Committees or Review Panels: GlaxoSmithKline, Novartis, Boehringer Ingelheim, Tibotec, Chughai, Gilead, Janssen, Idenix, GlaxoSmithKline, Novartis, Roche, Tibotec, Chughai, Gilead, Merck, Janssen, Idenix, BMS; Board Membership: Boehringer Ingelheim; Grant/Research Support: Chughai, Roche, Chughai; Speaking and Teaching: Roche, Gilead, Tibotec, Merck, BMS, Boehringer Ingelheim, Gilead, Janssen The following people have nothing to disclose: Wendy Cheng, Eric Sicard, Stephen D.