Synergistic anti-tumor efficacy of mutant isocitrate dehydrogenase 1 inhibitor SYC-435 with standard therapy in patient-derived xenograft mouse models of glioma

Isocitrate dehydrogenase 1 (IDH1) is mutated in >70% of these tumors, making it an attractive therapeutic target. To determine the efficacy of our newly developed mutant IDH1 inhibitor, SYC-435 (1-hydroxypyridin-2-one), we treated orthotopic glioma xenograft model (IC-BT142AOA) carrying R132H mutation and our newly established orthotopic patient-derived xenograft (PDX) model of recurrent anaplastic oligoastrocytoma (IC-V0914AOA) bearing R132C mutation. In addition to suppressing IDH1 mutant cell proliferation in vitro, SYC-435 (15 mg/kg, daily x 28 days) synergistically prolonged animal survival times with standard therapies (Temozolomide + fractionated radiation) mediated by reduction of H3K4/H3K9 methylation and expression of mitochondrial DNA (mtDNA)-encoded molecules. Furthermore, RNA-seq of the remnant tumors identified genes (MYO1F, CTC1 and BCL9) and pathways (base excision repair, TCA cycle II, sirtuin signaling, protein kinase A, eukaryotic initiation factor 2 and a-adrenergic signaling) as mediators of therapy resistance. Overall design: To understand drug model of mechanism of SYC-435, we conducted bulk RNA sequencing analysis of patient-derived xenograft mice model of glioma with SYC-435 treatment, radiation treatement and combination treatment