Abstract A016: Organotypic high-throughput screening identifies the combinatorial treatment of navitoclax and YM155 that target chemoresistant ovarian cancer cells
Authors: Kenny Hilary A. , Ip Carman , kordylewicz Kasjusz , Hoffmann Rachael , Rauch Sarah , Malacrida Beatrice , Balkwill Frances R. , Battistini Chiara , Cavallaro Ugo , Lengyel Ernst 
Published: March 2024

Abstract
The goal of this study was to identify a combination of drugs that targets the entire population of OvCa cells in combination with carboplatin. In preliminary experiments, we found that low proliferating subpopulations of ovarian cancer (OvCa) cells with either a high or very low expression of the enzyme, aldehyde dehydrogenase (ALDH), are resistant to carboplatin. With a semi-automated high-throughput cell-based screen using our 3D organotypic assay (3D HTS), we identified drugs that specifically target cells with high (ALDHhi) and low (ALDHlo) ALDH expression. The ALDHhi and ALDHlo cells were sorted from the parent population and differentially labeled with CMPTX and CMFDA. An equal number of ALDHhi and ALDHlo cells were plated on 3D HTS. This expansion of our 3D HTS platform did not compromise the quality of the adhesion/invasion assay, which was still robust and reproducible with signal-to background ratios of &gt;12-fold and Z’-factor values of &gt;0.45. Approximately 2,000 FDA approved drugs were screened. We then re-tested the 140 active drugs resulting from the primary screen with confirmatory 3D HTS assays, including a measurement of proliferation/viability. To eliminate drugs that are cytotoxic to stromal cells, a counter screen was performed. Our results show that Omipalisib, Verteporfin, CA3, Mitoxantrone, Navitoclax, Venetoclax and YM155 inhibited adhesion/invasion or proliferation/viability of either ALDHlo or both cell populations and were not cytotoxic to the stroma. These 7 active compounds were then tested in a combinatorial drug screen. Navitoclax in combination with Omipalisib, and Navitoclax in combination with YM155 had synergistic activity in adhesion/invasion in both cell populations and did not affect the stroma. YM155 in combination with Omipalisib, and Navitoclax in combination with Omipalisib had synergistic activity in proliferation/viability in both cell populations and did not affect the stroma. Next, the activity of the drug combinations was tested in the entire cell population of OvCa cell lines and primary human OvCa cells. Navitoclax in combination with YM155, and YM155 in combination with Omipalisib inhibited the proliferation/viability of OvCa cells on the 3D HTS and primary human OvCa cell spheroid formation significantly better when directly compared to Navitoclax or Omipalisib treatment alone. Finally, the activity of the drug combinations was tested in combination with carboplatin in vitro and in vivo. The combination of Navitoclax, YM155 and carboplatin inhibited OvCa cell viability/proliferation and tumor number and total tumor weight significantly better than carboplatin treatment alone. These results show that the combination of Navitoclax and YM155 has promise as a therapy for the prevention and treatment of OvCa metastasis.
Citation Format: Hilary A. Kenny, Carman Ip, Kasjusz kordylewicz, Rachael Hoffmann, Sarah Rauch, Beatrice Malacrida, Frances R. Balkwill, Chiara Battistini, Ugo Cavallaro, Ernst Lengyel. Organotypic high-throughput screening identifies the combinatorial treatment of navitoclax and YM155 that target chemoresistant ovarian cancer cells [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A016.