Switching from entecavir to tenofovir alafenamide versus maintaining entecavir for chronic hepatitis B.

Tenofovir alafenamide (TAF) is a newly developed prodrug of tenofovir (TFV). We divided 48 chronic hepatitis B patients who had taken entecavir (ETV) for ≥2 years into two groups: the ETV continuation (n = 24) and the TAF switching (n = 24) groups, and compared the antiviral effects and safety until 48 weeks after the start of the study. There were no significant differences in the alterations in the serum levels of HBs antigen (HBsAg) level between the ETV continuation and the TAF switching groups at 24 or 48 weeks. We also examined the effect of baseline HBsAg level on the decrease of HBsAg during the treatment; in the TAF switching group, the decrease of HBsAg level at 48 weeks was more significant in patients with low baseline HBsAg (<800 IU/mL) than those with high baseline HBsAg ( >800 IU/mL) (change of HBsAg; - 0.029 vs - 0.132 for high and low baseline HBsAg, respectively, P = .007). Also, the effect on renal function was found to be comparable between the TAF switch group and the ETV continuation group. In this study, switching from ETV to TAF may represent higher efficacy for a decrease of HBsAg than a continuation of ETV among the patients with low baseline HBsAg level.