Switching to Tenofovir Alafenamide Fumarate in Chronic Hepatitis B Patients Who Had Detectable HBV DNA during Treatment with Entecavir

Nucleos(t)ide analogues (NAs) suppress hepatitis B virus (HBV) replication, but the risk of hepatocellular carcinoma still remains. The presence of detectable HBV DNA in the serum during NA therapies for chronic hepatitis B patients has been reported to be associated with the risk of hepatocellular carcinoma. In this study, we investigated the antiviral effect of switching from entecavir (ETV) to tenofovir alafenamide fumarate (TAF) in chronic hepatitis B patients who had detectable HBV DNA in the serum at least once within a year. Among a total of 77 cases in 7 hospitals that switched NAs from ETV to TAF, 23 patients with detectable HBV DNA in a year before switching were analyzed. When the detection frequencies of HBV DNA in the 1st and 2nd years after switching to TAF were analyzed, they were significantly lower than those in the year before switching (68.8% vs. 34.1% for the 1st year and 21.3% for the 2nd year, P < 0.001 for both). The HBsAg decline tended to be larger after switching than before (−2.5% vs. −3.0% for 1st year and −3.1% for 2nd year), but the difference was not significant. One patient died of a cardiovascular event 11 months after the treatment switch, but no adverse effects due to TAF including renal function were observed. In conclusion, it was suggested that switching from ETV to TAF might be effective to suppress the HBV DNA level further in patients whose HBV DNA is detectable, even if at a very low level.