The pharmacophore for activity against KB-V1 cells was tested against the 60 compounds previously identified in a bioinformatic analysis for compounds that were predicted to be selectively active against P-gp expressing cells. The activities of two available compounds, the thiosemicarbazone 27, and 30, are given. a). Querying the structural database for compounds that satisfy at least AH1X (X = thiosemicarbazone) identified the seven NSC isatin-β-thiosemicarbazones shown in Figure 1 from which the pharmacophore was partially derived, and the three remaining thiosemicarbazones in the set: 27, 28 and 29, shown over the site features demonstrating the good fit of structural features of these molecules with the pharmacophore. b). Querying the structural database for compounds that satisfy at least three out of seven sites, including AH1R2, but not the thiosemicarbazone feature (X), gave a further 13 non-thiosemicarbazone NSC compounds from our dataset that appear to satisfy the structural criteria for selectively killing KB-V1 cells. Two examples are shown; 30 and 31.