SN38-oligonucleotide Au-NPs exhibit toxicity against Ewing sarcoma cells in vivo. TC71 xenotransplanted tumors were injected with PBS (n = 4), Survivin Au-NPs 75 nM (n = 4), SN38-Survivin Au-NPs 75 nM (n = 5), or SN38-EWS/FLI1 Au-NPs 75 nM (n = 5). After 48 h, the tumors were excised, dissociated, and stained with annexin-V antibody and a viability dye followed by flow cytometry. The annexin-V and annexin-V/viability dye positive populations were then used to calculate the percentage of viable TC71 cells. The data are normalized to tumors injected with PBS. ***, P < 0.0001 and *, <0.05 when comparing PBS with SN38-Survivin Au-NP and SN38-EWS/FLI1 Au-NP injected tumors, respectively.