Abstract 356: Pre-clinical investigations utilizing Bcl2 inhibitors in glioblastoma

Abstract

Abstract Glioblastoma (GBM) is a lethal malignant cancer of the central nervous system. The multimodal management approach does not extend survival beyond 2 years. Due to diverse variability in subpopulations of patients with glioma, treatment benefits are not uniform with apoptosis evasion being a key attribute of treatment resistance in GBM. Antiapoptotic protein, Bcl-2, Bcl-xL, and Mcl-1, are frequently upregulated in acquired chemo resistant cancer cells. Here in, we investigated the anti-proliferative effects of disrupting “Bcl-2-regulated pathways” in GBM. Of note, accessibility of FDA approved Bcl-2 inhibitors with known safety profile, makes it a biologically relevant target where intra- and inter-patient heterogeneity can be overcome successfully. Western Blot (WB) analysis was performed to compare the Bcl-2 family expression in human GBM cell lines (LN229, T98G, DI321, SA21). RT-PCR data was obtained for Bcl-2 family mRNA expression profile in present GBM cell lines. IC50s were determined for afore mentioned cell lines using MTS assay for Temozolomide (TMZ, alkylating agent), Bcl-2 inhibitor ABT199, Bcl-xL inhibitor A1331852, Mcl-1 inhibitor AZD5991, and BTK inhibitor Ibrutinib. Further, synergistic activity of TMZ, ABT199, A1331852, AZD5991 and Ibrutinib in several permutations. All experiments were performed with an n of 3/5. Our data suggests upregulation of antiapoptotic Bcl-2 family proteins in GBM cells including GSCs (DI321) and patient derived cells (SA21). There was significant decrease in viability of these cells when treated with ABT199 and A-1331852 (p< 0.0001) as compared to TMZ as a single agent. Other combinations ABT199+AZD5991 (p< 0.0001), AZD5991+A-1331852 (p< 0.0001) and TMZ+ABT (p<0.0002) also shows anti-tumor activity. Alternatively, we observed increased sensitivity in TMZ-resistant GBM cells against these drugs using MTS assay. GBM is an aggressive malignancy with 100% recurrence over time. Our preclinical data suggests synergism of Bcl-2 protein inhibitors in GBM cells, both TMZ-naïve and TMZ-resistant. Our ongoing research is investigating the biological relevance of Bcl-2 in conjugation with other tumor suppressor proteins, in vitro and in vivo. Citation Format: Srishti Kala, Leland Earp, Sonikpreet Aulakh. Pre-clinical investigations utilizing Bcl2 inhibitors in glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 356.