Abstract 3659: Target validation and structural optimization of selective small molecule survivin inhibitors as potential anti-cancer agents

The anti-apoptotic protein survivin is highly expressed in most human cancer cells, but has very low expression in normal differentiated cells. Thus survivin is widely considered as an attractive cancer drug target. Herein we report the in vitro and in vivo study on a series of novel survivin inhibitors modified from our recently identified hit compound UC-112. NCI 60-cell line screening assay showed that three new analogs with oxyquinoline scaffold had GI50 values within the nanomolar range (513 nM, 646 nM and 891 nM). These new compounds can overcome the P-gp mediated multidrug-resistance in cancer cell lines. Western blot analyses demonstrated the high selectivity for survivin inhibition among other members in the inhibitor of apoptosis protein family. Mechanistic studies such as isothermal calorimetry measurements, survivin protein pull-down assay and fluorescence polarization assay confirm that these novel compounds indeed target survivin and inhibit its function. The most active compound showed excellent aqueous solubility of 148.7 μM (PBS pH7.4), reasonable metabolic stability (half-life) of 51 minutes as tested in human liver microsomes, and no significant inhibitions to major CYP enzymes except one of CYPs. Rat pharmacokinetic studies indicated good pharmacokinetic profiles for this novel scaffold. When tested in an A375 human melanoma xenograft model, this compound effectively suppressed tumor growth and strongly induced cancer cell apoptosis in tumor tissues. Overall, our study has demonstrated that these cell-permeable small molecular survivin inhibitors possessing a novel scaffold could be developed as potent anti-tumor therapeutic agents. Citation Format: Jin Wang, Min Xiao, Duane D. Miller, Wei Li. Target validation and structural optimization of selective small molecule survivin inhibitors as potential anti-cancer agents. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3659. doi:10.1158/1538-7445.AM2015-3659