AbstractBackground and AimTenofovir alafenamide (TAF) is a new prodrug of tenofovir, enabling treatment of patients with hepatitis B virus (HBV) infection at a lower dose than tenofovir disoproxil fumarate (TDF), via more efficient delivery of tenofovir to the hepatocytes. We compared the efficacy and safety of TDF and TAF and investigated switching from TDF to TAF therapy.MethodsConsent for TDF and TAF therapy was obtained from 117 and 67 patients from August 2014 to January 2018. In total, 45 and 14 patients were administered with TDF and TAF, respectively, as naïve therapy, and 36 patients were switched from TDF to TAF. The antiviral effects and renal function safety were assessed.ResultsAt week 48, the antiviral effects on patients receiving TDF and TAF as naïve therapy were similar in terms of reduction of HBV DNA (−5.6 ± 1.8 logIU/ml vs −5.0 ± 1.7 log IU/ml; P = 0.34) and hepatitis B surface antigen (−0.29 ± 0.64 logIU/ml vs −0.15 ± 0.42 logIU/ml; P = 0.71) levels. A significant decrease in the estimated glomerular filtration rate (eGFR) was seen at 48‐week TDF treatment (−5.34 ± 7.69 ml/min/1.73 m2; P < 0.001). Switching from TDF to TAF did not increase the HBV DNA or hepatitis B surface antigen at 24 weeks. Although the eGFR worsened during TDF therapy (−7.32 ± 4.87 ml/min/1.73 m2), it improved significantly at week 4 (+3.93 ± 6.18 ml/min/1.73 m2; P = 0.008) and week 24 (+2.89 ± 4.26 ml/min/1.73 m2; P = 0.020) after switching from TDF to TAF.ConclusionTenofovir disoproxil fumarate and TAF showed adequate antiviral effects as naïve therapies. Furthermore, switching from TDF to TAF therapy contributed to the maintenance of the antiviral effect and recovery of renal dysfunction.