TAF for Hepatitis B?: A Top HIV Clinical Development of 2016

Top 10 Clinical Developments of 2016
1. Donald Trump6. Return of the Antibodies
2. Switch Frenzy7. Is an Unexpected Low HIV RNA Level Real?
3. 2-Drug ART8. Dolutegravir and the Central Nervous System
4. Is HIV PrEP at a Tipping Point?9. TAF in Hepatitis B
5. Start ART Now10. New HIV infections in U.S. Are Down -- a Bit

It is fortuitous for people living with both HIV and Hepatitis B (HBV) infections that tenofovir disoproxil fumarate (TDF, Viread) and emtricitabine (FTC, Emtriva) are effective against both viruses. Trouble can brew, though, when for one reason or another, such as a change in renal function, the TDF needs to be stopped. Until this year, for co-infected patients, jettisoning TDF meant adding the anti-HBV agent entecavir to the new TDF-less antiretroviral regimen. It is no surprise, then, that when tenofovir alafenamide fumarate (TAF, Vemlidy) was first shown to be effective against HIV, many wanted to know whether it would also be as good as TDF for HBV.

The answer is, yes. In two trials in HBV mono-infected patients, one for HBeAg-negative (N=425) and the other for HBeAg-positive patients (N=873), participants were randomized to TAF 25 mg versus TDF 300 mg daily. At 48 weeks, there was no significant difference between the two treatments in the proportion with a plasma HBV DNA level less than 29 IU/mL in either study.

A smaller, single-arm study enrolled 72 patients with HIV and HBV co-infection who were all switched to the single tablet elvitegravir/cobicistat/FTC/TAF (Genvoya). At enrollment, 96% were on TDF and 86% had an undetectable HBV DNA level. At 48 weeks, 92% had an undetectable HBV DNA level and HIV suppression was maintained, while renal and bone indices improved.

The Bottom Line

Evidence that TAF is as effective as TDF for treating HBV is welcome news for those infected with both viruses. While in the U.S. HIV-HBV co-infection is not common, it is in many other regions, including Asia and Africa. These data are, therefore, comforting to the few patients in our practice who have suppressed HIV and HBV and now or later need to switch from TDF. The larger impact will be where HBV is endemic and, for those people, TAF's demonstrated ability to treat HBV is a big deal.

What are some other top clinical developments of 2016? Read more of Dr. Wohl's picks.

David Alain Wohl, M.D., is a professor in the Division of Infectious Diseases at the University of North Carolina at Chapel Hill, director of the North Carolina AIDS Training and Education Center and site leader of the University of North Carolina Chapel Hill AIDS Clinical Research Site.