Abstract P10: B-cell lymphoma CRISPR screens: NSD2 loss confers EZH2 inhibition resistance, while AEBP2 is a specific genetic dependency

Abstract Introduction The characterization of the mutational landscape of human cancers over the past 30 years has resulted in the rise of targeted cancer therapies. This era of precision oncology aims to enable cancer patients to receive therapies that are specific, efficacious, and result in fewer toxicities. A major challenge however is the emergence of drug resistance. Predicting resistance mechanisms using in vitro models can help to plan rational clinical trials using combination approaches and avoiding treating specific subtypes of cancers that are unlikely to respond. Here, we apply CRISPR screens in non-Hodgkin lymphoma (NHL) to predict resistance mechanisms and genetic synergies to EZH2 inhibitor (EZH2i) treatment. Materials and Methods Genome-wide CRISPR-Cas9 screens were performed in EZH2 ‘change-of-function’ mutant and EZH2 wild-type patient-derived NHL cell lines, treated with either EZH2i or vehicle control. Validatory cell competition assays were then performed using individual CRISPR sgRNAs targeting specific genes of interest, including AEBP2 and NSD2. These sgRNAs were tagged with a green fluorescence protein enabling the identification of the knock-out population using flow cytometry. An additional CRISPR screen using a PRC2 ‘tiled’ approach was also performed in the NHL cell lines to elucidate the essential domains within PRC2 proteins. Clonal knock out cells were generated using CRISPR and CUT 2024 Mar 4-6; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2024;5 (2Suppl): Abstract nr P10.