Understanding the drivers and impact of CAR T cell donor variability - PROJECT SUMMARY The objective of this study is to understand the underlying biological phenomena that drive differences in antitumor activity of CAR T cells generated from different T cell donors. Although CAR T cell therapy is an effective treatment option for several hematological malignancies, there is variation in the success of these treatments between patients. Further, in the lab setting, variation in antitumor efficacy also exists between CAR T cells generated from healthy donor T cells, indicating that differences in efficacy may be due in part to differences in T cell phenotype between donors. Defining T cell phenotypes that drive effective antitumor response in a CAR T cell setting will indicate areas for improvement in CAR T cell therapy for all patients. In my Preliminary Data, I first define the functional attributes that correlate with successful antitumor response. Next, I propose to use identified effective and ineffective CAR T cell donors to investigate the role of different T cell phenotypes (memory, exhaustion, polyfunctionality, IL-9 secretion) in determining CAR T cell function. Finally, I will investigate how baseline CAR T cell functionality impacts the success of additional genetic modifications to further improve these cells. I hypothesize that the success of effective CAR T cell donors is driven by definable T cell phenotypes. Additionally, I hypothesize that variation in T cells between CAR T cell donors will impact the efficacy of genetic modifications to further improve CAR T cells generated from them. I have demonstrated in Preliminary Data that CAR T cells generated from different healthy T cell donors exhibit variable efficacy in in vitro functional assays and in vivo antitumor efficacy. Further, I have demonstrated that functional assays can be performed simultaneous with T cell phenotype analysis to robustly determine correlations between phenotype and function. I plan to expand upon these preliminary studies to test my hypotheses in the following aims. Aim 1 will investigate biological drivers of T cell functional variation, specifically investigating T cell memory, exhaustion, and polyfunctionality. Additionally, I will investigate the role of IL-9 in CAR T cell donor variability, following Preliminary Data indicating that IL-9 secretion is correlated with CAR T cell efficacy. Aim 2 will then determine the impact of CAR T cell donor variability on the success of genetic modifications by testing the impact of a model genetic modification on both effective and ineffective CAR T cell donors. The success of this study will provide new understanding and knowledge of T cell biology and how it impacts the success of CAR T cell therapy. This added knowledge will be translationally impactful by indicating additional mechanisms to improve CAR T cells for all donors. This project will be conducted at St. Jude Children’s Research Hospital, an NCI- designated comprehensive cancer center. The study and training plan proposed herein were carefully designed to train me in foundational and advanced techniques critical to the field of cancer immunotherapy and to further develop my writing, presenting, and mentoring skills.
