Abstract 5117: CK2 inhibiton exhibits synergistic effect in acute lymphoblastic leukemia

Abstract Survival for pre-B cell Acute lymphoblastic leukemia (B ALL) has improved greatly, however. High risk (HR) subgroups continue to result in significant mortality and morbidity of pediatric oncology patients. Pediatric T-cell acute lymphoblastic leukemia (T-ALL) is a lethal disease, often associated with high-risk clinical features. T-ALL therapy has made less improvement than B ALL and continues to represent a significant number of high-risk outcomes. Novel treatment strategies are required to overcome chemotherapy resistance and improve morbidity for HR B ALL. The development of treatments that can overcome chemotherapy resistance is essential for improving survival in T-ALL. Deletions of IKZF1, resulting in decreased IKAROS function, are present in High-risk ALL patients. Casein kinase 2 (CK2), a protein kinase upregulated in ALL, phosphorylates IKAROS preventing DNA binding reducing transcriptional regulation in ALL patients. Past studies have shown that pharmacologic inhibition of CK2 with CX-4945 rescues IKAROS function as a transcriptional regulator. Receptor tyrosine kinase c-KIT is transcriptionally regulated by IKAROS and is often upregulated in cancer. The purpose of this study was to determine whether restoration of IKAROS via CX-4945 would act in a synergistic manner with c-KIT inhibitor imatinib in ALL.Methods/results B-ALL Nalm6 cells were treated with imatinib over 72-hours to establish the half-maximal inhibitory concentration (IC50). The IC50 was used to determine the concentration range of imatinib to be used in combination with CX-4945 in a 72-hour synergy analysis of cytotoxicity.. Cell viability was measured using WST-1 cell proliferation assay. The data were analyzed using Calcusyn and synergy was defined as a combination index below 0.85. The study was repeated to determine a more precise range of synergy. The cytotoxicity of single drug c-KIT inhibitor, Imatinib, in Nalm6 B-ALL yielded an IC50 of 25uM while CK2 inhibitor CX-4945 resulted in 4uM. When a combination was administered with a constant dose of CX-4945 at 4uM and varying concentrations of imatinib, synergy was observed at multiple dose combinations. Conclusion: The data shows that CK2 inhibitor, CX-4945, and c-KIT inhibitor, imatinib, exhibit a synergistic therapeutic effect. Imatinib is indicated for use in Philadelphia positive (Ph+) acute lymphoblastic leukemia so future studies will include testing CX-4945/imatinib synergy in Ph+ BALL where we expect to see more potent synergistic effect. Citation Format: Daniel Gary Bogush, Joseph Schramm, Katarina Dovat, Yali Ding, Chingakham Singh, Sinisa Dovat. CK2 inhibiton exhibits synergistic effect in acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5117.