Impact of switching to tenofovir alafenamide fumarate in patients with entecavir-treated chronic hepatitis B

Background and aims Tenofovir alafenamide (TAF), a new tenofovir prodrug, has been developed to circumvent the less favorable safety profile of tenofovir disoproxil fumarate (TDF). We investigated reductions in hepatitis B surface antigen (HBsAg) levels in patients with HBV infection who received continuous entecavir (ETV) monotherapy or sequential therapy with ETV and TAF. Methods: This retrospective cohort study included 286 patients who were divided into two groups: continuous ETV monotherapy (ETV group, n = 168) and sequential therapy with ETV and TAF (ETV-TAF group, n = 108). Factors associated with a 90% reduction in HBsAg levels were analyzed by a Cox proportional hazards model using a time-dependent covariate in both groups. Results In the multivariate Cox proportional hazards model, the ETV-TAF group [adjusted hazard ratio (aHR) 2.750; 95% confidence interval (CI), 1.265–3.405; P = 0.0038] and BMI ≤ 25.0 kg/m 2 (aHR 0.520, 95% CI, 0.308–0.875; P = 0.0139) demonstrated a 90% reduction in HBsAg levels. HBsAg levels of patients in the TAF phase in the ETV-TAF group showed greater yearly percent reductions than those in the ETV group and those in the ETV phase in the ETV-TAF group ( P = 0.0361 and P = 0.0022, respectively, Steel–Dwass test). Conclusion HBsAg levels decreased more rapidly after patients switched from ETV to TAF. Switching to TAF may be an effective treatment option to reduce HBsAg levels.