Abstract A33: HIF2 in Pediatric High-Grade Glioma and Its Targeting

Abstract Pediatric high-grade gliomas (pHGGs) represent a very dismal disease that is needing new innovative compound for treatment. Despite the past discovery of histone H3 driver mutations, we are not able for instance to stop this induced process on epigenetic remodulation. Therefore, there is since a decade proactive works aimed to discover new targetable proteins in these tumors. In our recent previous works in pHGGs, we highlighted HIF2alpha as a biomarker of worse prognosis and outcome and a key in treatment resistance. Therefore, this new project was designed to determine in several patient-derived cell lines (5 PDCLs) the presence of HIF2alpha, its role and its induction in normoxic and hypoxic microenvironment concomitantly by immunofluorescence and Western blot assessments and RNA sequencing analyses. Complementary ChipSeq was also performed using HIF2 antibodies to determine its role as a transmission factor. Specific promoters were involved. After the confirmation of its frequent presence in multiple PDCLs initiated from thalamic pHGGs and DIPG, we used allosteric inhibitors to target HIF2alpha. Surprisingly, this protein was expressed constantly in hypoxic and normoxic conditions and specifically in PDCLs bearing stem cell features. Specific expression associations were established between stemness markers and HIF2alpha. To go further, we tested specific HIF2A inhibitors, which were having an impact on cell proliferation and on the decrease of the target itself. In conclusion, HIF2 seem to be a major biomarker in pHGGs that might be targeted, and it is a useful new opportunity for pHGGs treatments. Citation Format: Quentin Fuchs, Anne Florence Blandin, Isabelle Lelong Rebel, Marina Pierrevelcin, Monique Dontenwill, Natacha Entz-Werlé. HIF2 in pediatric high-grade glioma and its targeting [abstract]. In: Proceedings of the AACR Special Conference on the Advances in Pediatric Cancer Research; 2019 Sep 17-20; Montreal, QC, Canada. Philadelphia (PA): AACR; Cancer Res 2020;80(14 Suppl):Abstract nr A33.