BSCI-19 A LENTIVIRAL CRISPR SCREEN FOR EPIGENETIC MODULATORS OF ANTIGENS TARGETED BY CAR T CELLS IN GLIOBLASTOMA

Glioblastoma (GBM) is the most common adult brain tumor and is very difficult to treat. One promising treatment strategy is CAR T cell therapy, in which T cells are used to target and kill cancer cells. However, CAR T cell therapy is not always effective, and more work is needed to realize its potential. One strategy for improving the efficacy of CAR T cell therapy is to increase the expression of targeted antigens on the surface of cancer cells. Our goal in these studies is to identify pathways that could be modulated to increase expression of the targeted antigens. Focusing on epigenetic proteins, we performed a lentiviral CRISPR screen in the human GBM cell line LN18. A lentiviral library was used to knock out various epigenetic genes in these cells in vitro. Following transduction, we use flow cytometry to examine surface expression of antigens currently being targeted in GBM clinical trials of CAR T cells, e.g. - GD2, B7-H3, etc. Cells with increased expression of the antigens of interest were selected using FACS. Genomic DNA was isolated from these cells and sequencing was performed to determine which epigenetic genes had been knocked out. Results showed multiple genes contributing to increased surface expression of targeted antigens. Future studies will determine whether small molecule inhibitors of the identified epigenetic pathways selectively induce up-regulation of these antigens in GBM cells in vivo.