Abstract 1671: Targeting histone H3K27 demethylase for anti-tumor activity: Monotherapy and combination with ceralasertib in non-small cell lung carcinoma

Abstract Lung cancer is the leading cause of cancer-related deaths worldwide, with non-small cell lung carcinoma (NSCLC) accounting for 85% of cases and associated with poor prognosis. The lysine-specific demethylase KDM6A, responsible for removing H3K27 trimethylation at gene promoters and enhancers, is frequently mutated in various cancers. While KDM6A is predominantly considered as a tumor suppressor gene, recent studies suggusted it may support oncogenic transcriptional regulation. To investigate the role of KDM6A in tumorigenesis, we utilized CRISPR-Cas9/sgRNA to knock out (KO) KDM6A in NCI-H1975 NSCLC cells. Phenotypic assessments demonstrated cell cycle arrest with inhibitory effects in cell proliferation with KDM6A-depleted NCI-H1975 cells. RNA sequencing in conjunction with CUT&RUN revealed KDM6A target genes involved in cell cycle regulation, DNA replication, and DNA damage repair pathways, which were further validated using RT-qPCR and CUT&RUN-qPCR. Immunofluorescence confirmed the effects of KDM6A loss on DNA replication and DNA damage-induced repair mechanisms. These findings support our hypothesis that KDM6A is a highly pleiotropic factor in tumorigenesis, playing a critical role in regulating DNA replication-associated gene activation and facilitating the repair of replication stress-induced DNA damage. Notably, loss of KDM6A induced hyperactivation of checkpoint signaling pathways such as the ATR-CHK1 axis, suggesting KDM6A-depleted tumor cells attemption to alleviate replication stress to avoid apoptosis. To evaluate the therapeutic potential of KDM6A along with inhibition of the KDM6A-depletion-induced ATR-CHK1 pathway, ceralasertib (formerly AZD6738), an oral selective ATR inhibitor, was combined with KDM6A depletion for in vivo evaluation. Introducing KDM6A depletion significantly reduced NCI-H1975 tumor volume compared to the control group, demonstrating anti-tumor activity. Consistent with in vitro cell-based assays, the combination therapy of ceralasertib with KDM6A depletion showed enhanced tumor growth inhibition and regression in the NCI-H1975 xenograft model. Our findings reveal a pro-oncogenic role of KDM6A in sustaining tumor maintenance through engagement in DNA replication and repair pathways. Targeting KDM6A alone emerges as a promising therapeutic strategy for NSCLC. Furthermore, combining KDM6A depletion with ceralasertib significantly enhances anti-tumor activity by disrupting the ATR-CHK1 checkpoint signaling pathway, leading to an enhanced anti-tumor activity. Citation Format: Pony Yu-Ling Lee, Kun-Yuan Lin, Chao-Di Chang, Shan-Yun Cheng, Ya-Wen Hung, Chih-Chieh Yang, Yu-Hsien Chang, Chien-Chang Shen, Shu-Ping Wang. Targeting histone H3K27 demethylase for anti-tumor activity: Monotherapy and combination with ceralasertib in non-small cell lung carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1671.