Abstract 3049: Synergistic growth-inhibitory efficacy of LSD1 and BCL-XL inhibitors in JAK2+ AML/MPN cells

Abstract This study explores a potential synergy between Lysine-specific demethylase 1 inhibitors (LSD1i) and BCL-XL inhibitors for acute myeloid leukemias (AML) arising from myeloproliferative neoplasms (MPN). LSD1i prolongs the survival of post-MPN AML murine models (Rampal et al. Blood 2020) and induce apoptosis in AML cell lines via upregulating BAX (Wang et al. Blood, 2019). Our analysis of the RNA-seq and data from the Beat 1.0 AML cohort, CRISPR screen data from Cancer Cell Line Encyclopedia, Public Avana 21Q2 dataset, and multi-omics from post-MPN sAML patients (Rodriguez-Meira et al., Nat Genet. 2023) showed that post-MPN AML exhibited high expression of BCL2L1/BCL-XL (p=0.0026), compared to de novo AML (Wang, ASH 2024, #2749). We explored the synergy between the LSD1i Iadademstat (Selleckchem), and BCL-2/BCL-XL inhibitor, Navitoclax, or the platelet-sparing BCL-XL degrader, DT2216 (Dialectic Therapeutics). JAK2 mutated cell lines, Hel and Set2, and Ruxolitinib-resistant (RR) lines derived from them were utilized. The activities of LSD1i, navitoclax, and DT2216, alone and in combination, were tested using Cell Titer Glo assays of 20, 000 cells at 72 hours. LSD1i as a single agent (0.6-50 nM) reduced viability plateauing at 50-68% in all tested cell lines. Navitoclax and DT2216 effectively reduced cell viability; when combined with 10 nM of LSD1i, IC50 values were significantly lower (Table 1). These findings were next verified using the Annexin 5 flow cytometry at 24 hours co-treatment. All combinations showed a significant increase in apoptosis over either compound alone (Table 1). Synergy was confirmed with SynergyFinder+ software (mean: 18.86-72.47 zip model). In summary, JAK2+-mutant post-MPN AML cell lines and isogenic Ruxolitinib-resistant lines showed sensitivity to BCL-XL inhibitors and a synergistic increased sensitivity to these compounds when combined with low dose LSD1 inhibitor, Iadademstat. Mechanisms behind the synergy are being studied and will be reported. Summary of Glo Titer Assays and Annexin 5 Flow Cytometry Data with mean Synergy Scores Glo Titer Assay Navitoclax DT2216 LSD1i LSD1i+Navitoclax LSD1i+DT2216 Hel Parental IC50 1.3±0.2µM 2±0.8µM Not Reached 6.5±3 nM 0.25±0.08 µM Hel RR IC50 0.5±0.3µM 1.8±0.7µM Not Reached 6±3nM 0.3±0.15 µM Set 2 Parental IC50 0.4±0.4µM 2.5±1 µM Not Reached 6.5±02.5nM 2±1.3 µM Set 2 RR IC50 1±0.2µM 0.6±0.3µM Not Reached 20±9 nM 0.525±0.5µM SynergyFinder+ Glo Titer Hel Parental Hel RR Set 2 Parental Set 2 RR Zip Model Mean Synergy: LSD1i + Navitoclax 68.92 55.32 48.72 69.88 Zip Model Mean Synergy: LSD1i + DT2216 31.42 45.22 19.25 18.86 Annexin-5 Flow Cytometry Navitoclax 10 nM DT2216 1µM LSD1i 5 nM LSD1i + Navitoclax LSD1i + DT2216 Control Hel Parental (Annexin %+) 13.76% 25.4% 12.24% 22.51% 52.9% 9.92% Hel RR (Annexin %+) 32.3% 11.34% 26.37% 26.37% 52.7% 9.04% Set 2 Parental (Annexin %+) 21.36% 29.18% 7.15% 57.9% 46.11% 7.48% Set 2 RR (Annexin %+) 33.20% 45.3% 14.86% 87% 47.8% 12.33% SynergyFinder+ for Annexin-5 Dilutional Series Hel Parental Hel RR Set 2 Parental Set 2 RR Zip Model Mean Synergy: LSD1i + Navitoclax 34.23 32.99 68.97 72.47 Zip Model Mean Synergy: LSD1i + DT2216 58.93 23.44 44.24 20.22 Citation Format: Mark A. Forsberg, Zhe Wang, Sovira Chaudhry, Anna Skwarska, Raajit Rampal, Alexandra Schurer, Kira Gritsman, Guangrong Zheng, Daohong Zhou, Marina Konopleva. Synergistic growth-inhibitory efficacy of LSD1 and BCL-XL inhibitors in JAK2+ AML/MPN cells [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 3049.