BIOL-10. MOUSE MODELING OF PEDIATRIC MYCN GLIOMA REVEALS INTRATUMORAL HETEROGENEITY INCLUDING NEURONAL AND OLIGODENDROGLIAL LINEAGE SIGNATURES

Pediatric glioma of the subclass MYCN are highly aggressive tumors with a median age at diagnosis of 8 years and a median survival of only 14 months. Molecularly, they frequently carry (MYCN) amplifications, TP53 mutations or both of these alterations. Due to their rarity, such tumors have only recently been identified as a distinct entity, and both biological as well as clinical details have not been fully addressed. In order to further investigate the biology and treatment options of these tumors, preclinical models are urgently needed. Therefore, we generated a genetically engineered model by breeding hGFAP-cre::Trp53(Fl/Fl)::lsl-MYCN mice, which carry a loss of Trp53 and show aberrant MYCN expression in neural precursors of the central nervous system. All such mice developed aggressive forebrain tumors early in lifetime that mimic their human counterparts regarding histology, DNA methylation, and gene expression. Single cell RNA sequencing revealed a high intratumoral heterogeneity with neuronal and oligodendroglial lineage signatures. To find new treatment options, we performed in vitro high-throughput drug screening on both, mouse and human tumor cells. Among 640 investigated anticancer compounds, Doxorubicin, Irinotecan, and Etoposide effectively suppressed the growth of tumor cells. As FDA-approved chemotherapeutics, these compounds are used for the treatment of other pediatric brain tumors. Repurposing them for the treatment of MYCN-driven high grade glioma could achieve a rapid transition to glioma treatment. We believe that our model will pave the way to improved treatment strategies for patients with these highly aggressive tumors.