Neural organoid models of the immunological microenvironment of glioblastoma for drug discovery applications

Project Summary/Abstract Glioblastoma (GBM) is the most prevalent primary brain tumor in adults with extremely poor survival rates and largely unchanged standard of care. While there are many challenges to developing better GBM treatments, one of the major challenges is the immune-suppressive environment commonly found within GBM tumors. This immune-suppressive nature results in a tumor that is not suitable for mounting an immune response to GBM cells, rendering emerging immunotherapies ineffective. To address this issue, suitable models that can interrogate the complex interactions between GBM cancer cells and microglia and peripherally derived macrophages would be invaluable for target identification, screening of novel therapeutics and for mode of action studies. Tumor-associated microglia and macrophages are of particular interest due to their primary role in shaping the immunological environment of GBM tumors. Human organoid technology is well-suited for modeling complex, multicellular interactions in a human tissue-like environment. Stem Pharm’s hydrogel-enabled neural organoids allow for incorporation of non-neural populations such as microglia and macrophages in a reproducible, 96-well plate format amenable to screening applications. Therefore, work in this proposal will develop and validate a human in vitro glioblastoma organoid model through incorporation of microglia, macrophages, and patient derived GBM cells in our neural organoids. Specific aims will 1) characterize organoids incorporating GBM, evaluate GBM survival, invasion, and proliferation; and characterize cell-type specific transcriptional responses to GBM and compare them to parent tumors and publicly available data sets. 2) demonstrate immunosuppressive activation of microglia and macrophages within the neural organoid in response to infiltrating GBM cells. Multiplex cytokine panels, co-stimulatory and checkpoint molecule expression, and a direct immunosuppression assay with peripheral blood mononuclear cell-derived T-cells will be used to evaluate microglia and macrophage immunosuppression. Finally, treatment with three small molecules known to modulate macrophage activation will be assessed within the organoids to demonstrate the ability to regulate the microglial and macrophage response to GBM cells. Successful completion of these specific aims will result in a robust in vitro organoid model with novel capabilities to interrogate GBM invasion and subsequent microglia and macrophage immunosuppression. This will provide pharma partners with the ability to study therapies that previously failed due to this immunosuppressive environment, and test new therapeutic approaches. Phase II studies will expand the number of available patient-derived samples to better capture the diversity and heterogeneity of GBM tumors, explore sex-linked differences, and evaluate the effectiveness of CAR-Ts and combination therapies within the GBM model with the goal of bringing better treatment options to patients for this devastating condition.