Switching to tenofovir alafenamide in virally-suppressed chronic hepatitis B patients with renal/hepatic impairment

Background/purpose: Tenofovir alafenamide (TAF) has demonstrated non-inferior efficacy to tenofovir disoproxil fumarate (TDF) with improved bone and renal safety across diverse populations, including those with mild renal or hepatic impairment. We evaluated TAF efficacy and safety in a subset of Taiwanese chronic hepatitis B (CHB) patients enrolled in a phase 2, multicentre study (NCT03180619) of patients with more advanced renal or hepatic impairment. Methods: In a sub-analysis of virally-suppressed (hepatitis B virus DNA <20 IU/mL) adult Taiwanese CHB patients with renal (chronic kidney disease stage ≥1) or hepatic (Child-Turcotte-Pugh Class B or C) impairment, all participants received open-label TAF 25 mg once daily for 96 weeks. Efficacy was evaluated based on proportion of patients with viral suppression and normal alanine aminotransferase levels. Incidence of adverse events (AEs) and laboratory abnormalities were considered over 96 weeks, alongside renal function parameters, hip and spine bone mineral density (BMD) and fasting lipid changes. Results: Of 124 patients treated in the phase 2 study, 33 (27 %) were from Taiwan. All sub-analysis participants (renal impairment, n = 22; hepatic impairment, n = 11) achieved virologic response after 24 weeks of TAF; of the 28 patients who completed the study, 96 % (n = 27) maintained suppression through Week 96. One AE in each group, and no serious AEs, were related to study treatment. Following TAF switch, renal function and BMD remained stable or improved slightly over 96 weeks. Conclusion: Consistent with overall population results, TAF demonstrated high efficacy and favourable safety and tolerability in Taiwanese CHB patients with renal or hepatic impairment. Trial registration: NCT03180619/GS-US-320-4035.