Tenofovir alafenamide
Tenofovir alafenamide, sold under the brand name Vemlidy, is an antiviral medication used to treat hepatitis B and HIV. It is used for the treatment of chronic hepatitis B virus (HBV) infection in adults with compensated liver disease and is administered in combination with other medications for the prevention and treatment of HIV. The medication is taken orally.
Tenofovir alafenamide is a nucleotide reverse transcriptase inhibitor and a prodrug of tenofovir. Developed by Gilead Sciences based on the protide technology of Chris McGuigan, it is used in the form of tenofovir alafenamide fumarate (TAF). TAF is closely related to the commonly used reverse-transcriptase inhibitor tenofovir disoproxil fumarate (TDF) but offers greater antiviral activity and better distribution into lymphoid tissues. It was approved for use in the United States for HIV in 2015 and for hepatitis B in 2016. Although the US Food and Drug Administration (FDA) has approved tenofovir alafenamide for manufacture as a generic medication, it is currently not available.
Fixed-dose combinations containing tenofovir alafenamide:
Elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide (Genvoya): Approved in the United States and the European Union in November 2015.
Emtricitabine/rilpivirine/tenofovir alafenamide (Odefsey): Approved in the United States in March 2016 and in the European Union in June 2016.
Emtricitabine/tenofovir alafenamide (Descovy): Approved in the United States in April 2016. In October 2019, Descovy was approved in the United States for HIV-1 pre-exposure prophylaxis (PrEP).
Bictegravir/emtricitabine/tenofovir alafenamide (Biktarvy): Approved in the United States in February 2018.
Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (Symtuza): Approved in the European Union in September 2017, in the United States in July 2018, and in Australia in November 2019.
Research
Gilead announced a Phase III clinical trial evaluating a single-tablet regimen combining tenofovir alafenamide with cobicistat, emtricitabine, and elvitegravir.
They also developed a co-formulation of the drug with cobicistat, emtricitabine, and the protease inhibitor darunavir.
A 48-week study comparing elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil (Stribild) to elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide (Genvoya) showed the newer drug’s effects to be non-inferior to the established agent, but at much lower dosages and with a lower incidence of adverse side effects such as impaired kidney function.
The FDA approved the TAF-based treatment regimen for HIV-1 in November 2015, making Genvoya the first TAF-based regimen to receive approval.