The FDA has approved tenofovir alafenamide 25 mg (Vemlidy, Gilead Sciences), a prodrug of tenofovir, as a once-daily treatment for adults with chronic hepatitis B virus (HBV) infection with compensated liver disease. The approval was based on positive 48-week data from two international phase 3 studies involving 1,298 treatment-naïve and treatment-experienced adults.
A total of 425 HBeAg-negative patients and 873 HBeAg-positive patients were treated with either tenofovir alafenamide or tenofovir disoproxil fumarate (TDF) (Viread, Gilead Sciences) in Studies 108 and 110, respectively. HBeAg, a hepatitis B viral protein, indicates active viral replication. Both studies met their primary endpoint of noninferiority to TDF, based on the percentage of patients with plasma HBV DNA levels below 29 IU/mL after 48 weeks of therapy.
Tenofovir alafenamide has demonstrated antiviral efficacy similar to and at a dose less than one-tenth that of TDF 300 mg. Data have shown that because tenofovir alafenamide has greater plasma stability and more efficiently delivers tenofovir to hepatocytes compared with TDF, it can be given at a lower dose, resulting in less tenofovir in the bloodstream. As a result, tenofovir alafenamide improved renal and bone laboratory safety parameters compared with TDF, according to Gilead.
The labeling for tenofovir alafenamide includes a boxed warning regarding the risks of lactic acidosis/severe hepatomegaly with steatosis and of post-treatment severe acute exacerbation of hepatitis B.
Source: Gilead Sciences; November 10, 2016.