New Tenofovir for Hep B Improves Bone and Kidney Safety

Formulation now recommended in updated HBV treatment guidelines

By Liz Highleyman,

Contributing Writer,

MedPage Today

April 24, 2017

AMSTERDAM — Hepatitis B patients who switched to a new formulation of tenofovir showed improvements in bone and kidney safety in a pair of long-running studies, researchers reported here.

Tenofovir alafenamide (TAF, sold as Vemlidy) was as effective as the older tenofovir disoproxil fumarate (TDF) formulation in keeping hepatitis B virus (HBV) in check, Henry Chan, MD, from the Chinese University of Hong Kong said at the International Liver Congress, the annual meeting of the European Association for the Study of the Liver (EASL).

But TAF led to more ALT normalization, less decline in kidney function, and less bone loss than TDF, according to Chan. Patients who switched from TDF to TAF saw improvement in all three areas.

Updated EASL hepatitis B clinical practice guidelines released at the conference recommend TAF as a new treatment option, especially for people at higher risk for bone or kidney problems.

“I think the main advantage in addition to a better safety profile is that TAF doesn’t need dose adjustment for renal function,” said guidelines panel member Maria Buti, MD, from Hospital General Universitari Vall d’Hebron in Barcelona. “For patients with renal alterations, older patients, and patients with comorbidities, it clearly represents an advantage.”

TDF (Viread) is one of the most effective antiviral drugs for hepatitis B, as well as being a widely used antiretroviral for HIV. It is generally considered safe and well tolerated, but it can cause bone loss and kidney problems in some patients.

TAF is a new pro-drug formulation that produces high levels of the active agent (tenofovir diphosphate) in hepatocytes and CD4 T-cells using smaller doses than TDF, which means lower concentrations in circulation and therefore less drug exposure for the kidneys and bones. The FDA approved stand-alone TAF for hepatitis B late last year. Previously it had only been available in coformulations for HIV treatment.

The availability of a safer formulation of tenofovir is important because, although nucleoside/nucleotide antivirals suppress HBV replication, they usually do not lead to a cure and a majority of patients need long-term therapy, according to guidelines panel member Kosh Agarwal, MD, from King’s College Hospital in London.