IMMU-24. IMMUNOTHERAPEUTIC NANOTECHNOLOGY TARGETING IDO1 FOR PEDIATRIC DIFFUSE INTRINSIC PONTINE GLIOMA

BACKGROUND: Research on adult high-grade gliomas has shown a targetable pathway through the inflammation-induced expression of indoleamine 2,3 dioxygenase (IDO1) and its recognized ability to suppress the anti-tumor immune response. Our project delineates the role of indoleamine 2,3 dioxygenase 1 (IDO1) in pediatric diffuse intrinsic pontine glioma (DIPG) and develops small inhibitory (si)RNA oligonucleotides and spherical nucleic acids (SNAs) aimed at therapeutically inhibiting the gene expression of immunosuppressive IDO1. SNAs composed of nanoparticles have been shown to transverse cellular membranes, exhibit stability in physiological environments, escape from degradation, and create precise targeting in brain tumors, and therefore make it a fundamental step for the investigation and targeting of IDO1. OBJECTIVE: Our specific aims are to: (1) confirm the gene expression IDO1 in different human DIPG cell lines; (2) generate and characterize siRNA oligonucleotides targeting human IDO1 in vitro; and (3) generate and characterize gold nanoparticles for targeted inhibition of IDO1. DESIGN/METHOD: Unique patient-derived DIPG cell lines were grown in culture, stimulated with proinflammatory cytokine IFNγ, and treated with increasing concentrations of IDO1 targeted siRNAs and SNAs. Cells were analyzed for mRNA, protein, enzymatic levels, cell viability and apoptosis. RESULTS: IDO1 is expressed in multiple human pediatric DIPG cell lines. Custom siRNA targeting IDO1 among exons 9-10 results in a significant decrease in overall IDO1 expression in multiple DIPG cell lines. SNA generation for targeting IDO1 is ongoing, with preliminary results demonstrating a robust ability to inhibit IDO1 expression in multiple cells lines while maintaining stability and precise targeting.