Abstract 110: Quantitative high throughput screening as a tool to identify novel therapies in bladder cancer

Abstract

Abstract Introduction: Bladder cancer (CaB) is the 4th most common cancer among men in the US. It is the most expensive malignancies to treat from diagnosis to death. No new pharmacological agents have been approved for treatment of bladder cancer since the approval of BCG in 1990. Thus, there is an urgent need for development of new treatment therapies. Quantitative high throughput screening (qHTS) of representative cancer lines with oncology drugs may identify new treatments or re-purpose already existing therapies for different disease. We utilized this technique to identify new therapies in two primary bladder lines (T24 and UMUC3) and their metastatic lines (T24T, SLT3 and FL3 of T24 and LUL-2 for UMUC3). Methods: We screened 7 bladder cancer cell lines against 1,912 oncology drugs using a 48 hour cell proliferation assay with an ATP−based readout (CellTiterGlo) to determine activity and potency of compounds in a dose response manner. One of the candidate drugs inhibitory in all cell lines tested is flavopiridol, a pan CDK inhibitor. We further characterized the mechanism of action and in vivo effects of flavopiridol using various cell based assays and mouse xenograft studies. Results: The initial screen identified 95 compounds active in 7 cell lines. The top 50 compounds were further analyzed for molecular size of >200 g/mol and TPSA<90. This identified mitomycin C and 8 novel compounds. Further testing revealed Flavopiridol to be most consistent with qHTS data having IC50 of 100-300nM in all the cell lines tested. Flavopiridol induces G2/M arrest; however, very little apoptosis was seen suggesting cytostatic rather than cytotoxic mechanism of flavopiridol action. Flavopiridol showed dose dependent inhibition of migration, invasion and colony formation in CaB cell lines tested. Xenograft studies in rapidly growing UMUC-3 cells showed slowing of tumor growth but not complete reduction indicating cytostatic mechanism of flavopiridol. However, in slow growing cells, 5637, 5/8 treated mice showed complete tumor reduction. Conclusions: qHTS can identify novel compounds. Flavopiridol seems to be a very effective inhibitor both in vitro and in vivo. Physical properties of Flavopiridol are most suited for intravesical use which may lead to it being an effective inhibitor of CaB in the bladder at higher doses without any/few systemic toxicities. Studies are underway to elucidate the use of flavopiridol as a single intravesical agent. Citation Format: Reema Railkar, Thomas Sanford, L. Spencer Krane, Piyush K. Agarwal. Quantitative high throughput screening as a tool to identify novel therapies in bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 110. doi:10.1158/1538-7445.AM2017-110