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. Author manuscript; available in PMC: 2019 Jul 1.
Published in final edited form as: Mol Cancer Ther. 2018 Apr 25;17(7):1486–1493. doi: 10.1158/1535-7163.MCT-17-1041

Figure 2. The cytotoxic activity of αTac PE24 immunotoxins is significantly and specifically lower than αTac PE38 immunotoxins.

Figure 2

Immunotoxins targeting either Tac or the TfR containing either the PE38 or PE24 toxins were tested for cytotoxicity on the HUT-102 (A and B) or the KARPAS-299 (C and D) cell lines in a cell growth inhibition assay. (A) αTac-dsFv-PE38 and αTac-dsFv-PE24 were tested on the HUT-102 cell line. While αTac-dsFv-PE38 had an average IC50 of 0.1 pM, αTac-dsFv-PE24 exhibited an IC50 that was 34-fold lower (3.4 pM). (B) In contrast, targeting PE38 and PE24 immunotoxins against the TfR on the same HUT-102 cells yields a very similar IC50 for αTfR-dsFv-PE38 and αTfR-dsFv-PE24 (IC50s of 0.77 pM and 0.32 pM, respectively). This difference was also seen when αTac-dsFv-PE38, αTac-dsFv-PE24, αTfR-dsFv-PE38, and αTfR-dsFv-PE24 were tested on KARPAS-299 cells (C and D) (IC50s of 0.23 pM, 10.3 pM, 0.64 pM and 0.93 pM, respectively). Representative graphs are shown. Each assay contained four replicates for each data point and the assays were repeated three times.