Abstract PR034: NSD2 inhibition in hormone sensitive prostate cancer synergizes with androgen deprivation therapy to improve tumor response

Abstract Introduction: Therapeutic approaches that target prostate cancer (PCa) cells that persist after androgen deprivation therapy (ADT) represent new opportunities to delay disease progression. The histone methyltransferase NSD2 is implicated in this persistence, showing elevated expression in hormone-sensitive PCa (HSPC) patients receiving ADT and following acute androgen depletion in vitro. We hypothesize that NSD2 is critical to the survival of HSPC cells and can be targeted to improve combinatorial responses to ADT. Methods: We generated stable NSD2 overexpression/shRNA knockdown in three HSPC lines (LNCaP, VCaP, and LAPC4) to define its role in the acute response to androgen depletion (3-10 days). Androgen blockade was achieved by culturing cells in charcoal-stripped serum (CSS) or treating with enzalutamide. Functional assays measured acute changes in apoptosis, senescence, and proliferation at 3, 5, 7 and 10 days. Western blotting was used to determine the expression of NSD2, H3K36me2, c-MYC and p16. For therapeutic validation, we utilized a NSD2-targeted PROTAC degrader UNC8153 combined with darolutamide in patient-derived organoids. The in vivo impact was assessed using NSD2 overexpressing LNCaP xenografts treated with the ADT agent degarelix. RNA-sequencing was performed to define the NSD2-regulated transcriptome. Results: NSD2 overexpression in HSPC cells cultured in CSS abrogated the efficacy of androgen receptor (AR) signaling blockade within 3 days. This overexpression drove a significant increase in global H3K36me2 levels, resulting in increased cellular proliferation and decreased apoptosis and senescence. Furthermore, NSD2-overexpressing LNCaP xenografts treated with the ADT agent degarelix showed markedly larger final tumor burdens and decreased p16 expression compared to ADT-treated controls. Crucially, therapeutic targeting of NSD2 synergistically and rapidly enhanced the efficacy of AR-signaling inhibition in HSPC models. This effect is evident in the acute phase (within 3-10 days post-treatment) when NSD2 suppression via shRNA combined with either CSS culture or enzalutamide treatment significantly augmented the AR blockade. This dual approach led to a marked, early increase in apoptosis and senescence in HSPC cells and a concurrent decrease in proliferation in LNCaP spheroids compared to monotherapy. The use of an NSD2 PROTAC combined with darolutamide achieved a similarly potent reduction in tumor growth and a substantial increase in cell death in patient-derived organoids. Mechanistically, after NSD2 knockdown in CSS, gene sets associated with augmented MYC signaling decreased, which was confirmed by a corresponding decrease in MYC protein expression. Conclusion: NSD2 is an important factor in the initial cellular response to AR-targeted therapy in part through augmenting MYC signaling. These studies provide a rationale for combining ADT with NSD2 inhibition in patients with advanced HSPC. Citation Format: Zachery D. Schultz, Tanaya Purohit, Bing Yang, Kayla Bahr, Erika Heninger, Peter W. Lewis, John M. Denu, David F. Jarrard. NSD2 inhibition in hormone sensitive prostate cancer synergizes with androgen deprivation therapy to improve tumor response [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Innovations in Prostate Cancer Research and Treatment; 2026 Jan 20-22; Philadelphia PA. Philadelphia (PA): AACR; Cancer Res 2026;86(2_Suppl):Abstract nr PR034.