PROJECT SUMMARY Chimeric antigen receptor (CAR) T cell therapy is a novel form of cellular immunotherapy in which the antigen specificity of T cells is redirected using synthetic receptors. CD19-CAR T cells have achieved complete responses in up to 90% of patients with acute lymphoblastic leukemia. However, many malignancies do not possess a single, highly expressed tumor-associated antigen (TAA) such as CD19. Furthermore, CD19-negative relapses have been frequently encountered following CD19-CAR T cell therapy, suggesting that multi-antigen- targeting approaches will be needed to reduce relapse. Acute myeloid leukemia (AML) is the most common acute leukemia in adults and the majority of patients will die from their disease. We and others are evaluating CAR T cells to treat AML. However, AML exhibits heterogeneous expression of TAAs and many of these TAAs are expressed on hematopoietic progenitor cells (HPCs), increasing the risk of antigen-negative AML immune escape and bone marrow toxicity following AML-targeting CAR T cell therapy, respectively. Additionally, AML employs many active immune-suppressive strategies that may inhibit CAR T cells. To overcome these challenges, I have recently developed a novel viral co-transduction and sorting system to allow generation and purification of T cells with multiple transgenes such as multiple CARs, immune- stimulating molecules, safety switches, and secreted cytokines. Preliminary data suggest that multi-functional CAR T cells can be engineered to overcome antigen-negative leukemia escape and immune suppression mechanisms. I hypothesize that this novel sorting system can be used to engineer T cells to overcome AML TAA heterogeneity and immune suppressive strategies. Aim 1 will investigate CAR T cells simultaneously targeting a set of AML TAAs and predicted to avoid toxicity to HPCs. CAR T cells engineered to overcome AML- induced immune suppression will also be evaluated. In Aim 2 the goal is to target a set of TAAs expressed by both AML and HPCs as part of a pre-transplant CAR T cell immunotherapy strategy. During the award period, the candidate will conduct research at Memorial Sloan Kettering Cancer Center under the mentorship of Dr. Marcel van den Brink and an Advisory Committee. He will obtain the critical skills he needs to become a tenure-track physician-scientist running his own academic laboratory developing synthetic biology approaches to improve cellular therapies and successfully competing for independent NIH funding. He will cultivate a detailed and comprehensive skill set for syngeneic, xenograft, and humanized mouse models of cellular immunotherapy, build upon an existing knowledge base of molecular construct design and cellular gene modification by mastering multiplexed CRISPR/Cas9 gene disruptions and site-specific gene integration, and develop proficiency in genomic analysis to better define T cell activation and exhaustion states and to identify novel targets for gene therapy.

NARRATIVE Acute myeloid leukemia (AML) is the most common form of acute leukemia in adults and most patients will die from their disease. Chimeric antigen receptor (CAR) T cell therapy is a novel form of cellular immunotherapy that has demonstrated great success in acute lymphoblastic leukemia, but translation of CAR T cell therapy to AML is complicated by (1) heterogeneous target antigen expression in AML, (2) expression of some target antigens on normal bone marrow cells in addition to AML, and (3) active immune-suppressive strategies employed by AML. The goals of this project are to generate multi-antigen-specific CAR T cells to eliminate AML by mitigating escape of antigen-negative leukemia, to identify sets of AML target antigens that are either non- myelosuppressive when targeted or that are myeloablative and can facilitate donor hematopoietic cell engraftment, and to further engineer CAR T cells to overcome AML-induced immune suppression.