Abstract PR003: Lineage plasticity dictates responsiveness to anti-GD2 therapy in neuroblastoma

Abstract Epigenetic dysregulation is frequently observed in the disease pathology of pediatric cancers, including neuroblastoma, the most common extracranial solid tumor in pediatric patients. Neuroblastoma tumors co-opt developmentally linked adrenergic or mesenchymal super-enhancer landscapes that rewire their transcriptional programs. Here, we describe that the lineage commitment to a mesenchymal epigenetic state is an important mechanism of resistance to anti-GD2 therapy through loss of GD2 antigen, a ganglioside glycolipid expressed on the cell surface. Low GD2 expression was significantly correlated with the mesenchymal state in a large panel of neuroblastoma cell lines and a forced adrenergic-to-mesenchymal transition conferred downregulation of GD2 and resistance to anti-GD2 antibody. Mechanistically, low-GD2 expressing cell lines demonstrated significantly reduced expression of the ganglioside synthesis enzyme ST8SIA1 (GD3 synthase), resulting in a bottlenecking of GD2 synthesis. Genome-wide CRISPR/Cas9 screening to identify regulators of GD2 in neuroblastoma revealed that the ablation of the polycomb repressive complex 2 (PRC2) significantly upregulates GD2 expression in GD2-low cells. Pharmacologic inhibition of EZH2 resulted in epigenetic rewiring of mesenchymal neuroblastoma cells into an adrenergic-like state, re-expressed ST8SIA1, and restored surface expression of GD2 and sensitivity to anti-GD2 antibody. These data identify developmental lineage as a key determinant of sensitivity to anti-GD2 based immunotherapies and credential PRC2 inhibitors for clinical testing in combination with anti-GD2 antibody to enhance outcomes for children with neuroblastoma. Citation Format: Nathaniel W. Mabe, Min Huang, Daniel A. Schaefer, Guillermo N. Dalton, Giulia Digiovanni, Gabriela Alexe, Anna C. Geraghty, Delan Khalid, Marius M. Mader, Michal Sheffer, Miles H. Linde, Nghi Ly, Maria Caterina Rotiroti, Benjamin A. H. Smith, Marius Wernig, Carolyn R. Bertozzi, Michelle Monje, Constantine Mitsiades, Ravindra Majeti, Ansuman T. Satpathy, Kimberly Stegmaier, Robbie G. Majzner. Lineage plasticity dictates responsiveness to anti-GD2 therapy in neuroblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Epigenomics; 2022 Oct 6-8; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_2):Abstract nr PR003.