Abstract 6037: Kinome crispr cas9 screening in breast cancer organoids derived from Ghanaian patients
Authors: Rowdo Florencia P. Madorsky , Ackermann Sarah , Oppong Joseph K. , Kyei Ishmael , Tang Colin , Newman Lisa , Elemento Olivier , Dow Lukas E. , Martin M. Laura , Davis Melissa B. 
Published: June 2022

Abstract
Breast cancer is a polygenic genetic disease caused by multifaceted factors which are often unique for each individual patient. In our prior studies we have demonstrated that west African ancestry is associated with more aggressive breast tumor phenotypes. Precision medicine approaches to cancer treatment exploit genetic differences to tailor therapy options that are specific to individual patients/groups. We hypothesize that shared genetic susceptibilities to cancer, which are harbored within populations of common ancestry, may translate to options for targeted therapies. Specifically, we will investigate whether genetic manipulation of kinases in Patient-Derived Tumor Organoids (PDTO) from West African breast cancer patients uncover novel drug targets in a genetic background that has not been investigated in this context to date. PDTO are three-dimensional cellular models grown in culture ex vivo from the tumor tissues obtained from patients retaining cell-cell and cell-matrix interactions. We established and characterized PDTO from Ghanaian patients and optimized the experimental conditions to perform a lentiviral-based CRISPR-Cas9 loss-of-function mutation screen targeting kinases in breast cancer organoids. We analyzed which kinases are essential for tumor viability or directly impact the response to current therapy/drugs. Tumor specimens were collected in Ghana from breast cancer patients and PDTO were stablished in Weill Cornell Medicine (USA). These PDTO were characterized by IHC, targeted panel sequencing and RNA-seq and biobanked. We established stable Cas9-expressing PDTO and we confirmed Cas9 expression by Western Blot and its activity by reporter-based assays, confirming that at least 80% of the cells present Cas9 activity. We performed a Kinome CRISPR Cas9 screen with 2 PDTO. The screening was performed in the presence of DMSO (vehicle to identify essential genes), a MEK inhibitor or an EGFR inhibitor. Preliminary analysis of the screening revealed efficient depletion of the positive controls as well as of previously proposed pan-cancer essential kinases, including CHEK1, ATR and AURKA. Additional analysis and validation of potential novel targets is currently ongoing. Conclusions: We successfully established the conditions to identify potential new therapeutic targets in PDTO derived from Ghanaian patients. Our Kinome Crispr Screen identified known as well as previously unknown essential kinases for breast cancer.
Citation Format: Florencia P. Madorsky Rowdo, Sarah Ackermann, Joseph K. Oppong, Ishmael Kyei, Colin Tang, Lisa Newman, Olivier Elemento, Lukas E. Dow, M. Laura Martin, Melissa B. Davis. Kinome crispr cas9 screening in breast cancer organoids derived from Ghanaian patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6037.