ATRT-04. UNBIASED METABOLIC PROFILING OF ATYPICAL TERATOID/RHABDOID TUMORS PREDICTS SENSITIVITY TO GLUTAMINE METABOLIC INHIBITORS Free

Atypical teratoid rhabdoid tumors (AT/RT) are deadly tumors of infancy in need of new, targeted therapies to reduce morbidity and improve survival. Molecular analyses have revealed considerable molecular heterogeneity dividing AT/RT into three distinct subgroups. MYC expression is identified in a particularly aggressive subgroup of AT/RT. MYC is challenging to target directly given large, flat, featureless protein-protein binding sites. To identify anomalies that can be targeted in high MYC-expressing AT/RT, we performed unbiased metabolic profiling of each of our 8 AT/RT cell lines using high pressure liquid chromatography mass spectrometry (HPLC-MS). Partial Least Squares-Discriminant Analysis (PLS-DA) identified a distinct metabolic profile in high MYC-expressing cell lines. Further pathway analysis highlighted unique patterns of glutamine utilization in these cell lines. In fact, high-MYC expressing cell lines were more dependent on glutamine for growth and survival (MTS assay, glutamine-free media vs normal media). Due to this dependence on glutamine metabolism, we hypothesized that high-MYC expressing AT/RT would be especially sensitive to glutamine metabolic inhibitors. We showed that the glutamine analogue, 6-diazo-5-oxo-L-norleucine (DON) slowed high-MYC expressing AT/RT cell growth (MTS assay, p<0.001), induced high rates of apoptosis (C-PARP by western blot), and improved survival in orthotopic mouse models (p<0.01 by log-rank test). In contrast, low-MYC expressing models were relatively resistant to DON. Metabolic flux experiments showed that DON inhibited glutamine-dependent synthesis of glutathione, depleting cells of intracellular glutathione. This DON-induced depletion of glutathione sensitized cells to carboplatin, leading to increased AT/RT cell death (cell viability assay, p<0.001 by ANOVA) and extended survival in mice bearing AT/RT orthotopic xenografts (p< 0.001 by log rank test). We aim to translate these findings into a new clinical trial to improve survival in this deadly disease.