P-02.01 Developing new and effective strategies for adoptive T- cell therapy in pediatric gliomas

<h3>Background</h3> Tumors of the central nervous system (CNS) are the most common form of childhood malignancy, and remain the leading cause of cancer-related morbidity and mortality among children. Cancer immunotherapy holds a lot of potential as a targeted therapy designed with high affinity to locate specifically the tumor cells and act directly on them, however, its applicability in the context of gliomas seems limited, in part, by the lack of ubiquitously expressed tumor antigens. our studies identified a previously uncharacterized biomarker, a mitochondrial protein that is highly expressed in pediatric gliomas that holds potential for serving as a novel CAR target with a dual function for cancer immunotherapy in pediatric gliomas. <h3>Materials and Methods</h3> The aim of this project is to contribute to the state of art of immunotherapy in pediatric gliomas. This will be done in different directions, First by screening different pediatric models that potentially express our novel biomarker, second by improving the efficacy of our specific CAR-T cells enabling monitoring their pathway and biodistribution utilizing gold nanoparticles (GNPs). Lastly, by Integrating CAR-T administration with targeted inhibitors to investigate potential synergistic effects against pediatric gliomas. <h3>Results</h3> We have developed elegant immunocompetent mouse models of pediatric brain tumors by cloning mutations/fusions found in human pediatric patients into Cre/loxP-inducible lentiviral vectors. We validated the expression of our novel antigen on the surface of different pediatric models by using flow cytometry analysis. Next, we generated specific CAR-T cells against this antigen and validated their specificity and functional activity. This was done by evaluating the ability to stimulate the engineered T cells and their target killing capacity. Untransduced (UT) lymphocytes were used as controls in all the experiments. Notably, while the specific CAR-T cells were able to exert their cytotoxic effect, proliferate and secrete IFN-g when co-cultured with glioma cells, UT T cells showed little to no response. Altogether, these results support the potential anti-angiogenic effect of these CARs. <h3>Conclusions</h3> We are currently assessing the efficacy of these CAR’s <i>in vivo</i> using our pediatric models. In addition we are monitoring the CAR-T cell migration and infiltration (biodistribution) using gold nanoparticles (GNPs) that can be tracked using CT screening. Our studies identified a previously uncharacterized biomarker, which is highly expressed in pediatric gliomas that holds potential for serving as a novel CAR-T target for cancer immunotherapy in pediatric gliomas. O. Zohar: None.