IDDF2019-ABS-0169 A phase 3 study comparing switching from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF) with continued TDF treatment in virologically-suppressed patients with chronic hepatitis B (CHB): week 48 efficacy and safety results

Abstract

Background TAF has shown efficacy non-inferior to TDF with improved renal and bone safety in viremic CHB patients at Weeks 48 and 96. We evaluated efficacy and safety in stable, virally-suppressed patients who were switched from TDF to TAF vs. continued TDF for an additional year. Methods CHB patients on TDF for ³48 weeks with HBV DNA Results 488 patients were randomized and treated. At baseline the groups were similar: median age 52 y, 71% male, 82% Asian, 68% HBeAg-negative, median ALT 23 U/L, median eGFRCG90.5 mL/min; 45% and 50% had low BMD by T scores at hip and spine, respectively. Median (Q1, Q3) duration of prior TDF was 222 (145, 305) weeks. Key efficacy/safety results are summarized (table 1). TAF demonstrated non-inferior efficacy to TDF with a similar rate (0.4%) of having HBV DNA ³20 IU/mL at Week 48. TAF resulted in hip/spine BMD increases with less impact on bone turnover makers; switching from TDF to TAF resulted in eGFRCG increases and decreased tubular function markers. Rates of ³Grade 2 adverse events (AEs) and serious AEs were low and similar between groups. No viral resistance was observed. Conclusions Virologically-suppressed CHB patients who were switched to TAF demonstrated noninferior efficacy to continued TDF with improved bone and renal safety.