Abstract B024: Uncovering replication stress vulnerabilities in pediatric low grade gliomas using a genome wide CRISPR-Cas9 knockout screen

Abstract Pediatric low-grade gliomas (pLGGs) are the most common brain tumors in children, comprising approximately 33% of all pediatric brain tumors. These tumors are typically driven by single somatic mutations in the MAPK pathway including genes such as BRAF, FGFR, and NF1. The majority of current therapies target MAPK pathway inhibition, which is often initially effective. However, high tumor rebound rates following treatment discontinuation underscore the urgent need for alternative therapeutic strategies. To identify novel MAPK independent vulnerabilities, we performed a whole genome CRISPR-Cas9 knockout screen in neural stem cells harboring pLGG mutations. Our screen revealed a strong dependence of BRAFV600E mutant cells on proteins involved in replication stress. We hypothesize BRAFV600E mutant cells experience elevated levels of replication fork stalling, making them more reliant on proteins that resolve replication stress. In this study, we are investigating how perturbation of proteins that prevent replication fork collapse and DNA damage affect the survival of BRAFV600E mutant cells. Our goal is to uncover novel therapeutic targets for pLGGs that are not reliant on MAPK inhibition. Citation Format: Joohee Lee, Jenna Robinson, Elisabeth Gonzalez, Kevin Zhou, David Root, Pratiti Bandopadhayay. Uncovering replication stress vulnerabilities in pediatric low grade gliomas using a genome wide CRISPR-Cas9 knockout screen [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Discovery and Innovation in Pediatric Cancer— From Biology to Breakthrough Therapies; 2025 Sep 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl_2):Abstract nr B024.