IDDF2018-ABS-0108 Improved bone and renal safety at 1 year after switching from TENOFOVIR DISOPROXIL FUMARATE (TDF) to TENOFOVIR ALAFENAMIDE (TAF): results from 2 phase 3 studies in HBEAG-positive and HBEAG-negative patients with chronic hepatitis B (CHB)

Background TAF has shown less bone and renal effects with similar efficacy rates compared to TDF in Phase 3 studies after 96 weeks of double-blind (DB) treatment. We evaluated patients who completed 96 weeks of DB treatment with TAF or TDF and switched to open label (OL) treatment with TAF, including those with 1 year of data (through Week 144) to determine changes in bone mineral density (BMD), creatinine clearance (CrCL), and the maintenance of viral suppression. Methods 1298 CHB patients who were HBeAg-negative or HBeAg-positive were randomised and treated with TAF or TDF. At Week 96, 541 (42%; TAF 361; TDF 180) patients had completed DB treatment with TAF or TDF and switched to OL TAF. Analyses included subjects with values at Week 96 and at Week 144 for creatinine clearance (n=401), spine BMD (n=288) or hip BMD (n=287), HBV DNA (n=394) and ALT normalisation by AASLD criteria (n=398). Results CrCL improved in patients who switched from DB TDF to OL TAF at Week 144 compared to Week 96 (n=122, median (Q1, Q3) change=+3.6 (-4.2,+8.4) ml/min, p Conclusions Patients who switched from TDF to TAF demonstrated continued improvements in BMD and CrCL over 48 weeks of treatment, virologic control was maintained, and rates of ALT normalisation increased.