Antiviral therapy with nucleos(t)ide analogues (NAs) has revolutionized the management of chronic hepatitis B (CHB) in the last two decades.1 Entecavir (ETV), a nucleoside analogue, is one of the first-line NAs recommended by all international treatment guidelines.2-4 As hepatitis B surface antigen (HBsAg) seroclearance rarely occurs, most patients require long-term, if not life-long, NA therapy. Hence, the safety of NAs requires careful scrutiny. In clinical trials, nephrotoxicity may occur in a small proportion of patients receiving nucleotide analogues. We previously demonstrated that tenofovir disoproxil fumarate (TDF) was associated with mild renal impairment in a minority of patients; those treated with entecavir (ETV) had a similar risk compared to untreated patients.5
Tenofovir alafenamide (TAF), a novel prodrug of tenofovir (TFV), has been approved for the treatment of chronic hepatitis B virus (HBV) infection. TAF has been shown to be a potent inhibitor of HBV replication at a low dose, with high intracellular concentration and more than 90% lower systemic TFV concentration than tenofovir disoproxil fumarate (TDF). TAF has been approved in the clinical practice guidelines in the west. Since its availability in Asia in 2017, there have been evolving data concerning its positive impact on renal safety as shown in registration trials.
