TMIC-16. INTRATUMORAL THROMBOSIS INITIATES HYPOXIA AND NECROSIS TO DRIVE TUMOR PROGRESSION THROUGH DRAMATIC TUMOR MICROENVIRONMENTAL ALTERATION

Abstract

Abstract All GBM molecular subsets share the common trait of accelerated progression following necrosis which cannot be adequately explained by cellular proliferation arising from accumulated genetic alterations. We suggest that development of necrosis is much more than a passive phenomenon related to rapid growth but rather is a driving force behind TME restructuring responsible for sustaining accelerated expansion. Current tumor models fail to adequately mimic the magnitude of post-necrotic restructuring within the microenvironment and remain overly reliant on post-mortem analyses, obligating researchers to extrapolate causal relationships between necrosis and progression phenomena during tumor evolution. In GBM (WHO grade 4), the most malignant primary brain tumor, vascular pathology and central necrosis precede rapid, radial expansion. Mechanisms enabling selective fitness within a hypoxic/anoxic GBM setting remain poorly understood. Nanostring GeoMX spatial profiling demonstrates M1-like TAM enrichment in non-necrotic human samples and M2-like TAMs in perinecrotic regions. Our immunocompetent RCAS/tv-a model aptly captures events seen in human gliomas, exposing dynamic temporal and spatial changes that facilitate GBM progression, incorporating unique microenvironmental stressors typically absent from GBM animal models, specifically emerging central necrosis. Simultaneously, our in vitro models scrutinize how hypoxia-dependent signaling between GBM cells, microglia and monocytes alter TAM accumulation and function in the TME. TAMs increase dramatically with the onset of necrosis, with a preferential localization to the hypoxic zone in the perinecrotic niche, which supports their survival. Flow cytometry on digested pre- and post-necrotic GBMs, showed increased TAM accumulation at 6 weeks vs. 2 weeks (necrosis emerges in week 4-5). Our in vivo data along with in silico analysis of Ivy GAP and TCGA datasets suggests GBM cells within the peri-necrotic niche attract and polarize TAMs through MIF secretion, necrotic DAMP (adenosine, S100B) release, and arginase secretion to suppress T cells.