Abstract 1625: Redox homeostasis is a therapeutic vulnerability in lethal neuroendocrine prostate cancer

Abstract Background: Neuroendocrine prostate cancer (NEPC) is an aggressive and lethal subtype of prostate cancer that often develops after second-generation anti-androgen therapies. The current treatment options for NEPC are limited and only produce disappointing results, highlighting the urgent need for novel therapies. Previously, we have found that NEPC cells are vulnerable to BCL2 and GPX4 inhibitors compared to their counterparts, prostate adenocarcinoma (PADC). Here, we aim to determine whether and how combining BCL2 and GPX4 inhibitors would enable optimal therapeutic effects in NEPC. Methods: We conducted drug synergism analyses of BCL2 and GPX4 inhibitors using NEPC cell lines and determined their impacts on the major cell death pathways by performing rescuing experiments. To further determine the molecular mechanisms of BCL2 and GPX4 inhibitors-induced cell death in NEPC, we measured the intracellular reactive oxygen species (ROS) levels and tested the rescuing effects of various antioxidants and reducing agents on cell death. Finally, we determined the in vivo therapeutic efficacy of BCL2 and GPX4 inhibitors in an NCI-H660 cell line-derived xenograft (CDX) tumor model. Results: Our results demonstrate that the BCL2 inhibitor ABT-199 and GPX4 inhibitor C18 synergistically induced apoptosis in NEPC cell lines in a ROS-independent manner. Although N-acetylcysteine (NAC) rescued ABT-199 and C18 cotreatment-induced apoptosis, the CellROX Green assay revealed no significant changes in ROS levels in ABT-199 and C18-cotreated cells. Surprisingly, reducing agents including tris(2-carboxyethyl)phosphine (TCEP) and Dithiothreitol (DTT) strongly rescued cell death induced by ABT-199 and C18 cotreatment. Our findings therefore suggested that the cell-killing effects of ABT-199 and C18 were due to ROS-independent disruption of redox homeostasis. Lastly, our preclinical tumor study showed that the ABT-199 and C18 combinatorial therapy significantly suppressed the tumor growth of NEPC. Conclusions: Our study validated the combination of BCL2 and GPX4 inhibitors as a feasible approach for the treatment of NEPC and suggested that redox homeostasis is a therapeutic vulnerability in NEPC. Citation Format: Mu-En Wang, Wei-Ling Tu, Ji-Hoon Kim, Yi Lu, Alyssa Bawcom, Andrew J. Armstrong, Qianben Wang, Yuzhuo Wang, Jiaoti Huang, Ming Chen. Redox homeostasis is a therapeutic vulnerability in lethal neuroendocrine prostate cancer [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 1625.