Abstract 3314: AML patients characterized by BH3 profiling and the response to venetoclax-based regimen

Abstract Venetoclax (VEN), a selective BCL-2 inhibitor, has dramatically changed acute myelogenous leukemia (AML) treatment. The AML patient respond heterogenous to VEN-based therapy and frequently require additional conjugated treatment. BCL-2 family, crucial in apoptosis regulation, comprises three categories: anti-apoptotic protein, pro-apoptotic protein, and BH3-only sensitizers which bind to specific anti-apoptotic proteins at resting state. By exposing cells to various synthesized BH3-only peptides and measuring cytochrome c release, we are able to detect the cells dominate anti-apoptotic proteins, namely BCL-2 family dependency. This method, known as BH3 profiling, has been validated by multiple studies as a way to correlate the cells response to different BH3 inhibitors in cell lines and primary samples (Bhatt et al. Cancer Cell 2020). In this study, we performed BH3 profiling on samples collected from 52 patients on VEN-based treatments, including 40 patients achieved response (28 CR, 7 CRi, 2 CRp, 1 CR with MRD, 2 CR then relapse), 12 non-response (NR). We exposed the primary cells to peptides of hBIM and PUMA (general priming, all anti-apoptotic proteins), HRK-Y (priming BCL-XL), mBAD (priming of BCL-W in addition to BCL2- and BCL-XL), MS-1 and mNoxaA (priming MCL-1), FS-1 (priming of BFL-1), and BCL-2 inhibitor Veneotoclax (priming BCL-2) for 1 hour, and then measure the cytochrome C by flow cytometry. The priming was defined as CytC loss by median fluoresce intensity relative to Alamethicin and DMSO controls. AML dependency on anti-apoptotic proteins is heterogenous, as reflected by varying responses to BH3-only peptides. 69.23% (36 out of 52) of the samples showed intact apoptotic capacity with more than 50% priming to hBIM. 43.15% (24/52) of samples depended on BCL-2, as indicated by more than 40% priming to VEN, while 34.62% (18/52) depended on BCL-XL, as indicated by more than 40% priming to HRK-Y. In addition, 51.92% (27/52) had a dependency on MCL-1 (more than 40% priming to MS-1), and 25.00% (13/52) were dependent on BFL-1 (more than 40% priming to FS-1). Overlapping co-dependencies were also observed. Among the 24 samples with BCL-2 dependency, 16 also depended on MCL-1, 10 on BCL-XL, 9 on BFL-1, and 6 were co-dependent on BCL-2, MCL-1, BCL-XL and BFL1. Comparing the samples from patients who achieved response with who did not, response samples had higher priming capacity, as shown by greater median CytC release in response to hBIM (p=0.0378). Non-CR samples exhibited higher dependency on non-BCL-2 proteins, with greater priming to peptides mNoxaA (p=0.0893), MS-1 (p=0.0153), and FS-1 (p=0.0147). In summary, AML shows heterogenous and co-dependent relationships withc multiple anti-apoptotic proteins. Patients who responded to VEN-based therapy typically retain the apoptotic capacity and show lower co-dependency on MCL-1 and BFL-1. Citation Format: Qi Tatarata, Zhe Wang, Lina Han, Tapan Kadia, Courtney DiNardo, Marina Konopleva. AML patients characterized by BH3 profiling and the response to venetoclax-based regimen [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 3314.