In vitro activity: GSK1265744 inhibits HIV replication with EC50 of 0.22 nM and 0.34-1.3 nM against HIV-1 Ba-L and NL432, respectively. GSK1265744 produces cytotoxicity with CC50 of 6.4, 5.0, 9.2, and 13 μM in proliferating IM-9, U-937, MT-4, and Molt-4 cell lines, respectively.

Kinase Assay: The inhibitory concentrations of GSK1265744 is measured in a strand transfer assay using recombinant HIV IN. A complex of integrase and biotinylated donor DNA–streptavidin-coated SPA beads is formed by incubating 2 μM purified recombinant integrase with 0.66 μM biotinylated donor DNA–4 mg/mL streptavidin-coated SPA beads in 25 mM sodium MOPS pH 7.2, 23 mM NaCl, and 10 mM MgCl2 for 5 minutes at 37°C. These beads are spun down and preincubated with diluted INSTIs for 60 minutes at 37°C. Next, [3H]-labeled target DNA substrate is added to give a final concentration of 7 nM substrate, and the strand transfer reaction is incubated at 37°C for 25 to 45 minutes, which allowed for a linear increase in strand transfer of donor DNA to radiolabeled target DNA. The signal is read using a Wallac MicroBeta scintillation plate reader.

Cell Assay: Using resistance passage experiments, integrase enzyme assays, and cellular assays with site-directed molecular (SDM) HIV clones resistant to other classes of anti-HIV-1 agents and earlier integrase strand transfer inhibitors, results showed that GSK1265744 efficiently inhibited HIV replication through inhibiting HIV integrase