PROJECT SUMMARY My long-term career goal is to develop an independent research program focused on evaluation of novel cellular therapies designed to improve long-term outcomes for pediatric patients with high-risk malignancies. This K08 application describes a career development plan and research proposal that will provide me with the requisite structured mentorship, coursework, hands-on clinical research experience and protected time necessary to develop into a successful independent clinical investigator. My research plan centers on the hypothesis that novel CD19-CAR T-cell approaches, including allogeneic platforms and/or enhancement of autologous strategies, can overcome limitations of autologous CAR T-cell therapy and improve patient outcomes. To test this hypothesis, I will conduct a Phase I clinical trial (MEMCAR19; NCT04881240) evaluating an allogeneic CD19-CAR T-cell product using donor memory T-cells to minimize risk of graft-versus-host-disease (Aim 1). I will assess the in vivo characteristics of these CAR T cells through intensive correlative studies conducted in conjunction with my collaborators, to further our understanding of CAR T-cell biology and inform upon future therapeutic approaches (aka ‘reverse translation’; Aim 2). Additionally, I will develop a new clinical trial evaluating a novel CAR T-cell product intended to induce sustained remission through dual-antigen targeting (CD19/22) and enhanced CAR T-cell persistence through epigenetic modifications (DNMT3A knockout) (entitled: PERSIST; Aim 3). Importantly, while this research focuses on pediatric patients with relapsed and/or refractory B-cell hematologic malignancies, the knowledge gained from this work will provide valuable insights into CAR T-cell biology that can be translated to approaches for other high-risk malignancies. To support my transition to an independent investigator, I have developed a robust mentorship and advisor team, with complimentary areas of expertise and a strong track record of successful research and mentorship of junior investigators. My mentors, advisors, and I have devised a comprehensive career development plan, which includes: i) acquisition of formal training in clinical trial design, including coursework in biostatistics and a Masters in Clinical Investigations, ii) expansion of my training in immunology through targeted workshops, and iii) advancement of my leadership skills. The rigorous training provided by this award will prepare me for a career dedicated to improving cellular therapies for pediatric patients with historically incurable diseases. Upon completion of this K08 Award, I expect to have gained the necessary training in advanced clinical and transitional research methods to support my transition to an independent investigator. Likewise, I expect to have generated sufficient data to justify the development of additional cellular therapy studies through future clinical R01 applications.