Abstract B027: EZH2 and Menin inhibition induce neuronal differentiation and GD2 expression in neuroblastoma

Abstract Neuroblastoma is the most common extracranial pediatric tumor and accounts for about 15% of childhood cancer deaths. It arises from precursors of the peripheral sympathetic nervous system. GD2 is a disialoganglioside that is highly expressed on the surface of neuroblastoma cells, but has limited expression in healthy tissues, making the GD2 antigen a strong candidate for targeted cancer therapy. Current integration of anti-GD2 immunotherapy has significantly improved patient outcomes, but nearly half of these patients will eventually relapse, in part due to resistance developed from antigen escape. Here, we show that GD2 expression in GD2-low neuroblastoma cells can be increased through genetic knockout or pharmacological inhibition of several proteins involved in the epigenetic regulation of transcription, including EZH2, DOT1L, and Menin. Furthermore, the combination of either knockout or inhibition of EZH2 and Menin together increased GD2 expression to a greater extent than single drug treatment. Integrated transcriptomics and epigenomics identified that combined EZH2 and Menin inhibition induced a neuronal differentiation of cells through regulation of bivalent promoters, which are characterized by the presence of both H3K27me3 and H3K4me3 histone marks. This combination increased the transcription of the ganglioside biosynthetic enzyme ST8SIA1 (GD3 synthase), which is regulated by a bivalent promoter, rendering cells sensitive to anti-GD2 therapy. Combined treatment with the EZH2 inhibitor tazemetostat and Menin inhibitor revumenib in an orthotopic neuroblastoma tumor model also increased GD2 expression more than each single agent. Increased GD2 was sustained for 30 days after discontinuing the drugs. This suggests that the combination of epigenetic therapy may be a promising mechanism to restore sensitivity to anti-GD2 immunotherapy in low GD2 expressing tumors. Our early findings identify targeting epigenetic regulation as a mechanism of increasing GD2 expression, thus providing a therapeutic strategy for overcoming resistance to current immunotherapy regimens. Citation Format: Silvi Salhotra, Nathaniel W Mabe, Susu Zhang, Gabriela Alexe, Giulia Digiovanni, Kathleen Engel, Daniel Schaefer, Guillermo N Dalton, Melinda Soeung, Robbie G Majzner, Kimberly Stegmaier. EZH2 and Menin inhibition induce neuronal differentiation and GD2 expression in neuroblastoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Discovery and Innovation in Pediatric Cancer— From Biology to Breakthrough Therapies; 2025 Sep 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl_2):Abstract nr B027.