412 Synergistic Targeting of Lysine-specific demethylase 1 (LSD1) and MAPK Signaling: A Mechanism-Guided Therapeutic Approach for Glioblastoma (GBM)

OBJECTIVES/GOALS: LSD1 is a histone demethylase important in GBM regulation. Our goal is to design a therapeutic strategy for LSD1 inhibitors to meet clinical needs in GBM. Despite the abundance of LSD1 inhibitors, resistance emerges in GBM mouse models. We aim to understand the relevance of proliferative signaling pathways, such as MAPK, in LSD1 inhibitor resistance. METHODS/STUDY POPULATION: Following LSD1 knockdown in GBM cells, we determined differentially expressed genes using RNA-seq and gene set enrichment analysis (GSEA). Kinase signaling processes enriched for LSD1 expression were identified. Utilizing western blot, we assessed LSD1’s impact on MAPK signaling in patient-derived GBM stem cells (GSCs) and pediatric high-grade glioma cell models. Pharmacological evaluation of LSD1 involved five inhibitor candidates. Additionally, we explored LSD1 inhibition in combination with brain penetrant kinase inhibitors, osimertinib and ulixertinib, directed against the epidermal growth factor receptor (EGFR) and MAPK, respectively. The treatment combinations were assessed at multiple concentrations and analyzed using SynergyFinder. RESULTS/ANTICIPATED RESULTS: Pharmacological LSD1 inhibition after 24 hours induced increased phosphorylated ERK1/2 across multiple glioma cell lines. Concurrent LSD1 and EGFR/MAPK inhibition demonstrated improvedin vitro efficacy compared to individual agents. Notably, the combination of Iadademstat (ORY-1001) and osimertinib demonstrated the highest synergy score of 37.2 using the bliss synergy model in the GSC17s. Furthermore, 11 out of the 12 combination treatments tested had a synergistic relationship, with bliss synergy scores greater than 10. DISCUSSION/SIGNIFICANCE: Our study addresses the pressing need for novel therapeutic strategies in GBM. We leveraged pharmacological tools of LSD1 inhibition to determine how they could be used most effectively, revealing kinase inhibition as a promising strategy with demonstrated in vitro efficacy. Future efforts will focus on validating these findingsin vivo.