In vitro activity: GS-7340 has a potent anti-HIV activity with IC50 of 0.005 μM. GS 7340 has a half-life of 90 min in human plasma and a half-life of 28.3 min in an MT-2 cell extract at 37°C. the hepatic uptake of GS-7340 isfacilitated by OATP1B1 and OATP1B3, respectively. GS-7340 inhibits HBV reverse transcriptase after being converted to the pharmacologically active form, TFV-DP.

Cell Assay: Tenofovir alafenamide 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.