Developing CAR-T cells to target immunosuppressive ganglioside GD3 in ovarian cancer 4664

Abstract Description Ovarian cancer (OC) is the fifth leading cause of death in women in the US and the most lethal gynecological malignancy worldwide. Previous studies from our lab have shown that OC cells shed high concentrations of the immunosuppressive lipid, ganglioside GD3. Thus, we hypothesize that targeting GD3-expressing cells will enhance anti-tumor immune responses by eliminating GD3+ OC cells and stromal cells within the tumor microenvironment. We have generated anti-GD3 CAR constructs featuring the costimulatory domains: CD28, 41BB, or a combination of CD28 and 41BB. We characterized the anti-GD3 CAR-T cells by flow cytometry and examined activation and exhaustion markers. To assess specificity, we examine responses of the CAR-T cells to soluble antigen and found that anti-GD3 CAR-T cells exhibit minimal activation in response to soluble GD3. In contrast, anti-GD3 41BB CAR-T selectively eliminate anti-GD3+ OC, but not GD3- OC cells. These anti-GD3 41BB CAR-T also secreted high levels of IFN-g following recognition of target cells in a dose dependent manner. Studies by our group and other has shown that MDSC and cancer associated fibroblasts can upregulate GD3 expression and produce immunosuppressive factors. Future studies will evaluate the ability of anti-GD3 41BB CAR-T to infiltrate and kill tumor associated GD3+ cells using multicellular 3D organoid cultures. Collectively, these studies will determine the effectiveness of anti-GD3 CAR strategies for the treatment of OC. Funding Sources “This work was supported in part by R01AI061061, the Maryland Department of Health’s Cigarette Restitution Fund Program – CH-649-CRF, and the National Cancer Institute - Cancer Center Support Grant (CCSG) - P30CA134274.” Topic Categories Vaccines and Immunotherapy (VAC)