Abstract 4998: Integrative analyses in pediatric osteosarcomas to understand the role of GD2 associated to activated mTor for macrophage targeting

Abstract

Abstract Osteosarcoma is the most common primary malignant bone tumor in children and young adults. Its immune environment was described as predominantly involving M2 macrophages or osteoclasts. Previous studies were observing ganglioside GD2 expression on the osteosarcoma cell surface. Even more and more publications are deciphering the role of hypoxic biomarkers and its metabolic cell impact. Nevertheless, no links were, for instance, described clearly between mTor-HIF1 pathway and the macrophages in osteosarcomas through GD2 targeting. The aim of the study was to understand the role of all those molecular partners in osteosarcoma models. Material and methods: A cohort of 35 patients was explored to determine the expression by immunohistochemistry, as well as semi-quantitative PCR of several hypoxic and macrophages' biomarkers. Additionally, in 2D and 3D in vitro osteosarcoma models, analyses using metabolomics, western blotting, immunofluorescent imaging and RNA sequencing were performed to understand functional interactions between patient-derived osteosarcoma cells and the M2 macrophages. Endly, drug screening studies were testing 3D models (integrating matrix and hypoxic microenvironment) to assess efficacy of combinations using dinutuximab, mTor and HIF inhibitors. Results: Osteosarcoma samples are highly expressing CD163 and CD68 macrophage markers, as well as activated mTORC1 and GD2. Hypoxic biomarkers, when overexpressed, were statistically linked to a worst patient outcome. For macrophages and GD2 markers, a low expression was mostly linked to metastatic disease or poor response to chemotherapy. Specific metabolomic changes through glutaminolysis were frequently present and associated to a transcriptomic signature combining metabolism changes and specific immune macrophage environment. The targeting by dinutuximab associated to hypoxia inhibition was having a clear effect on osteosarcoma cell proliferation decrease, when associated to macrophages in 3D models mimicking osteosarcoma tumors. Conclusion: Macrophage immune environment is a key component of pediatric osteosarcomas and can be targeted in association with hypoxia inhibitors in 3D models recreating the osteosarcoma immune environment and bone matrix. Citation Format: Marina Pierrevelcin, Isabelle Lelong-Rebel, Quentin Fuchs, Monique Dontenwill, Natacha Entz-Werle. Integrative analyses in pediatric osteosarcomas to understand the role of GD2 associated to activated mTor for macrophage targeting [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4998.