FDA Clears Tenofovir Alafenamide (Vemlidy) for Chronic HBV

Megan Brooks

November 11, 2016

The US Food and Drug Administration has approved tenofovir alafenamide (Vemlidy, Gilead Sciences) 25 mg once daily, for treatment of adults with chronic hepatitis B virus (HBV) infection with compensated liver disease, the company announced.

Gilead Sciences' tenofovir disoproxil fumarate (Viread) has potent antiviral activity in patients with chronic HBV infection, but long-term use has been associated with renal side effects and reduced bone mineral density in some patients.

Vemlidy is a targeted prodrug of tenofovir that has antiviral efficacy similar to that of Viread at a dose less than one tenth that of Viread, the company notes.

"Data show that because Vemlidy has greater plasma stability and more efficiently delivers tenofovir to hepatocytes compared to Viread, it can be given at a lower dose, resulting in less tenofovir in the bloodstream," the company explains in a news release.

"Clinical trials demonstrated Vemlidy is efficacious with improved renal and bone safety parameters compared to Viread, representing an important development for people living with this chronic disease," Calvin Pan, MD, of NYU Langone Medical Center, New York City, and investigator in the Vemlidy clinical trials, said in the release.

Vemlidy's approval was based on 48-week data from two international phase 3 studies (Study 108 and Study 110) among 1298 treatment-naive and treatment-experienced adults with chronic HBV infection.

Study 108 randomly assigned and treated 425 HBeAg-negative patients with either Vemlidy or Viread; Study 110 randomly assigned and treated 873 HBeAg-positive patients with either Vemlidy or Viread.

In both studies, Vemlidy proved noninferior to Viread, as determined on the basis of the percentage of patients with chronic hepatitis B with plasma HBV DNA levels lower than 29 IU/mL at 48 weeks of therapy.

In an integrated analysis of both studies, patients receiving Vemlidy had improvements in certain bone and renal laboratory parameters compared to patients treated with Viread. Patients taking Vemlidy also had numerically higher rates of normalization of blood serum alanine aminotransferase levels.

Both drugs were generally well tolerated; rates of discontinuation because of adverse events were around 1%. The most commonly reported adverse events in both studies included headache, abdominal pain, fatigue, cough, nausea, and back pain. The rates of these events were similar for patients taking Vemlidy or Viread.

Vemlidy carries a boxed warning citing risks for lactic acidosis/severe hepatomegaly with steatosis and posttreatment severe acute exacerbation of hepatitis B.

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