IL-12 CAR T cell Immunotherapy for Heterogeneous Brain Tumors

Glioblastoma (GBM) is the most common and deadly primary malignant brain tumor with a median survival of <20 months. Despite aggressive standard of care therapies, GBM remains lethal. Alternatively, immunotherapy in the form of adoptively transferred T cells expressing chimeric antigen receptors (CARs) has emerged as a promising approach to targeting brain tumors. Preclinically, CARs for GBM-specific epidermal growth factor receptor variant III (EGFRvIII; CARvIII) have been successful combined with total body irradiation (TBI) in treating tumors exclusively expressing EGFRvIII. While effective at the bench, this model does not translate clinically; therefore, next generation immunotherapy aims to enhance CARs to secrete immunomodulatory factors to better treat GBM. This work spans the development and success of this new CAR “armored” to secrete IL-12, a stimulatory cytokine that enhances T cell persistence and function, to treat orthotopic heterogeneous GBM.Chapters 1 and 2 provide an overview of GBM. Detailed in these chapters are the current clinical standard of care, immune privilege of the brain, and various immunotherapies under active preclinical and clinical investigation. Chapter 3 details the history of adoptive T cell therapy in the context of brain tumors. Specifically, it focuses on existing CAR T cell therapies for GBM. Chapter 4 summarizes the next generation of “armored” CARs currently being developed. In Chapter 5 we present the development of a new CAR T therapy and demonstrate, for the first time, its efficacy in treating an in vivo, heterogeneous brain tumor. Chapter 6 summarizes the data gathered from our single-cell sequencing of immune cells collected from CAR-treated, tumor-bearing brains and flow cytometry. Additionally, we briefly evaluated the toxicity of our CAR treatment. In Chapter 7, we evaluate numerous in vivo, immunological depletion models to better understand the mechanism of action of our CAR therapy. To conclude, Chapter 8 contains closing remarks on the current state of CAR T cell therapy and future directions. To summarize, we have engineered a fourth-generation CAR T cell that can cure homogeneous and kill heterogeneous brain tumors in immunocompetent mice without host lymphodepletive preconditioning through reprogramming endogenous immune cells in the tumor microenvironment.