Modulation of ITK signaling for sustainable adoptive T cell therapy

Project Summary/Abstract CAR-T cell therapy has demonstrated success in curing B cell (CD19+) malignancies and has shown promise in treating lupus. However, the cytotoxic and short-lived nature of CAR-T cells results in severe side effects of immunopathology and reduces the therapeutic values of this costly therapy. There is an urgent need for novel strategies to elicit potent and persistent tumor-specific effector and memory T cell responses and minimize off-target toxicity in CAR-T therapy. This makes our work highly significant. T cell development, function and homeostasis are regulated by T cell receptor (TCR) signals as well as cytokines and are suggested to be proportional to TCR signal strength. Yet, excessive TCR activation and cytokine stimulation can trigger excessive cytotoxic T cell activation causing immunopathology, with rapid exhaustion of anti-tumor immunity. Our preliminary data show that IL-2-inducible T cell kinase (ITK), a key regulator of TCR signaling, negatively regulates CD8+ T cell homeostatic expansion and effector memory functions. The absence of ITK resulted in enhanced effector cell fate programming, antigen sensitivity and anti-tumor immunity of CD8+ T cells in mice. Our pilot experiments show that deletion of ITK in human CAR-T cells also resulted in improved production of CAR-T cells that are significantly more sustainable in vitro, and have adequate tumor killing activity and minimal tissue cytotoxicity. We hypothesize that ITK signaling can be modulated to promote CAR-T cell expansion, survival and long-term anti-tumor activity, while limiting the effector cytotoxicity. We propose two specific aims: (1) determine ITK's role in CAR-T cell expansion, function, and safety; and (2) develop a novel class of CAR molecules containing modulatory domains for ITK signaling inhibition. Our work is innovative, supported by exciting preliminary data that challenge conventional thinking. Validating this hypothesis will unveil ITK's role, relevant signaling pathways, and biomarkers in CAR-T cell production, safety, and efficacy. We also propose developing a novel class of CAR molecules that contain TCR signaling modulators, which will further our understanding of CAR-T cell signaling and enable a handy production of safe, effective and sustainable CAR-T cells. Completion of the proposed work will add to our knowledge of new molecular principles for the design of improved CAR-T cell production, safety and therapeutic efficacy. Our pre-clinical results are directly transferable to understanding human CAR-T cell biology and have the potential of improving of CAR-T therapy.