301 Inhibition of lysine-specific histone demethylase 1A (KDM1A/LSD1) attenuates DNA double strand break repair and enhances efficacy of temozolomide in glioblastoma

OBJECTIVES/GOALS: Glioblastoma (GBM) patients face a poor prognosis. Glioma stem cells (GSCs), a chemo resistant GBM subpopulation, possess enhanced DNA repair and elevated levels of epigenetic modifier KDM1A. This study aims to establish the significance of KDM1A in DNA repair and determine the potential of novel KDM1A inhibitor NCD38 to enhance TMZ efficacy in GSCs. METHODS/STUDY POPULATION: Patient derived GSCs were obtained via IRB-approved protocol from patient samples at UT Health San Antonio. KDM1A knockdown and knockout cells were generated by transduction of validated KDM1A-specific shRNA or gRNA, respectively. Brain bioavailability of KDM1A inhibitor NCD38 was established using LS-MS/MS. Effect of combination of KDM1A knockdown, knockout, or inhibition with TMZ was studied using cell viability, neurosphere, and self-renewal assays. Mechanistic studies were conducted using CUT&Tag-seq, RNA-seq, immunofluorescence, comet, Western blotting, RT-qPCR, homologous recombination (HR) or non-homologous end-joining (NHEJ) DNA repair reporter assays. In vivo efficacy of KDM1A knockdown or inhibitor alongside TMZ treatment was determined using orthotopic murine GBM models. RESULTS/ANTICIPATED RESULTS: KDM1A knockdown, knockout, or inhibition increased efficacy of TMZ in reducing cell viability and self-renewal of GSCs. Pharmacokinetic studies demonstrated KDM1A inhibitor NCD38 is readily brain penetrable. CUT&Tag-seq studies revealed KDM1A is enriched at DNA repair gene promoters. RNA-seq studies suggest KDM1A inhibition reduces DNA double strand break repair gene expression, with these findings validated using RT-qPCR and Western blotting. Knockdown, knockout, or inhibition of KDM1A attenuated HR and NHEJ-mediated DNA repair capacity. Immunofluorescence and comet assay support findings of increased DNA damage in NCD38/TMZ combination treated GSCs. Importantly, KDM1A knockdown or inhibition enhanced efficacy of TMZ and significantly improved survival of orthotopic GBM tumor-bearing mice. DISCUSSION/SIGNIFICANCE: Our results show compelling evidence that KDM1A is essential for DNA repair in GSCs and that KDM1A inhibition sensitizes GBM to TMZ via attenuation of DNA repair pathways. These findings suggest combination of KDM1A inhibitor NCD38 with TMZ could serve as a promising novel therapeutic strategy that can be translated to improve GBM patient outcomes.