Background:

Tenofovir alafenamide (GS-7340) is an investigational oral prodrug of Tenofovir. Tenofovir is a HIV-1 nucleotide reverse transcriptase inhibitor.

Tenofovir alafenamide (GS-7340) antiviral activities are similar across all cell types, ranging from 5 to 7 nM, while the CC50 varies from 4.7 to 42 μM for MT-4 and MT-2 cells, respectively. The antiviral activity of TAF is evaluated against a panel of HIV-1 and HIV-2 isolates, including HIV-1 group M subtypes A to G, as well as group N and O isolates. Overall, for the 29 primary HIV-1 isolates tested in PBMCs, TAF EC50s range from 0.1 to 12 nM, with a mean EC50 of 3.5 nM compared to a mean EC50 of 11.8 nM for AZT, which is used as an internal control. For the HIV-2 isolates, the mean EC50s are 1.8 nM for TAF and 6.4 nM for AZT[2].

Tenofovir alafenamide (GS-7340) hemifumarate is an amidate prodrug of Tenofovir with good oral bioavailability and increases plasma stability compared to Tenofovir disoproxil fumarate (TDF)[1].

参考文献:
[1]. Babusis D, et al. Mechanism for effective lymphoid cell and tissue loading following oral administration of nucleotide prodrug GS-7340. Mol Pharm. 2013 Feb 4;10(2):459-66.
[2]. Ruane PJ, et al. Antiviral activity, safety, and pharmacokinetics/pharmacodynamics of tenofovir alafenamide as 10-day monotherapy in HIV-1-positive adults. J Acquir Immune Defic Syndr. 2013 Aug 1;63(4):449-55.