Abstract 2683: Investigation to explore how duocarmycin prodrugs bioactivated by cytochrome P450 enzymes can be used in combination therapy to treat breast cancer cells

Abstract Introduction: Breast cancer is the most diagnosed cancer worldwide1 and, among other factors, hormones1 and pollutants2 have been suggested to contribute to disease progression. Due to its role in hormone environmental pollutant metabolism and involvement in breast cancer proliferation and survival, the cytochrome P450 1A1 (CYP1A1) isoform represents an interesting therapeutic target in breast cancer3.The present study builds on our understanding of reengineering the duocarmycin class of compounds4, but with focus on comparing the duocarmycin prodrug ICT2700 as single agent or in combination with the PARP inhibitor Olaparib, to uncover the potential of CYP1A1 and DNA minor groove alkylating agents in treating breast cancer. Methods: Functional CYP1A1 activity was evaluated using the EROD assay in a panel of breast cancer cell lines (MCF-7, T47D, MDA-MB-468, MDA-MB-231, MDA-MB-436), using as a control the isogenic cell line pair CHO and CHO1A1. CYP1A1 activity was also measured after serum starving the cells (0% FBS) for 24 and 48 hours. MTT assay was performed to measure the potency of the active duocarmycin CI-MI, ICT2700 and Olaparib in breast cancer cells, alone and in combination. DNA damage was measured using γH2AX as a marker, while cell cycle analysis was performed using FACS after exposing the cells to ICT2700 and Olaparib, alone and in combination. Results: The ICT2700 prodrug is activated, in part, by CYP1A1 which activity was shown to increase as a response to acute nutrient stress. Moreover, both the cytotoxic CI-MI and ICT2700 compounds were shown to enhance cell kill when combined with Olaparib in MDA-MB-468 and T47D breast cancer cells. Conclusion: The current investigation represents a promising starting point to study the activity of duocarmycin prodrugs such as ICT2700 in combination with other drugs such as Olaparib or modalities such as radiation therapy; the latter research is ongoing and will be reported at the meeting. References: 1. WHO. Breast Cancer 2021. https://www.who.int/news-room/fact-sheets/detail/breast-cancer. 11/16/2022. 2. Haghighi NJ, Malehi AS, Ghaedrahmat Z. Dioxins Exposure and the Risk of Breast Cancer: A Systematic Review and Meta-Analysis. Jundishapur Journal of Health Sciences 2021;13. 3. Rodriguez M, Potter DA. CYP1A1 regulates breast cancer proliferation and survival. Mol Cancer Res 2013;11:780-92. 4. Sheldrake HM, Travica S, Johansson I, Loadman PM, Sutherland M, Elsalem L, et al. Re-engineering of the Duocarmycin Structural Architecture Enables Bioprecursor Development Targeting CYP1A1 and CYP2W1 for Biological Activity. Journal of Medicinal Chemistry 2013;56:6273-77. Citation Format: Enrica Denasio, Steven D. Shnyder, Goreti R. Morais, Stewart G. Martin, Klaus Pors. Investigation to explore how duocarmycin prodrugs bioactivated by cytochrome P450 enzymes can be used in combination therapy to treat breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2683.