Type 1 Innate Lymphoid Cells: Mechanisms and Anti-AML Potential - PROJECT SUMMARY Acute myeloid leukemia (AML) is an aggressive, devastating cancer with limited treatment options. AML progresses rapidly and presents significant treatment challenges due to its immunosuppressive tumor microenvironment , which impairs immune cell function. Group 1 innate lymphoid cells (ILCs), including natural killer (NK) cells and ILC1s, play key roles in immunity. ILC1s reside in tissues and were initially believed to function primarily by secreting cytokines such as IFN-γ, TNF-α, and GM-CSF. However, their anti-tumor activity has been largely unknown. In 2022, we addressed this gap and published our discovery in Nature Immunology as a cover story. We found that ILC1s isolated from AML patients are functionally impaired, whereas ILC1s from healthy mice are significantly more potent. Healthy ILC1s induce the death of leukemia stem cells (LSCs), block LSC differentiation into leukemia progenitor cells, and promote the transition of LSCs into non-leukemic lymphoid progenitors. Mechanistically, normal ILC1s target LSCs by secreting IFN-γ and engaging receptor-ligand interactions (e.g., DNAM-1–CD155 and IL-7 receptor–IL-7). Despite identifying key features of ILC1s and their role in inhibiting LSCs, important questions remain unanswered. It is still unclear how ILC1s develop in vivo under normal or AML conditions, and the mechanisms through which ILC1s induce LSC death and differentiation in humans are largely unexplored. Moreover, the therapeutic potential of ILC1s remains unknown. We hypothesize that ILC1s possess strong anti-LSC activity and unique developmental pathways, offering a novel approach to control or treat AML and potentially prevent its relapse. The goals of this project are to elucidate the mechanisms of ILC1 anti-tumor activity, characterize their developmental pathways, and explore their therapeutic applications. In Aim 1, we will dissect the mechanisms by which ILC1s induce LSC death (e.g., via pyroptosis) and drive M1 polarization of LSC-differentiated myeloid cells in humans. In Aim 2, we will characterize ILC1 developmental pathways in both normal and AML conditions. Leveraging our expertise in developing adoptive cellular therapies, including chimeric antigen receptor (CAR) NK cells for AML, in Aim 3, we will study novel FLT3-targeting CAR ILC1s that we generated. FLT3 is highly and selectively expressed on AML blasts and LSCs, making it an ideal target. We will generate allogeneic, off-the-shelf, ready-to-use FLT3- CAR ILC1s from umbilical cord blood CD34⁺ cells or by converting NK cells into ILC1s, which we demonstrated. These CAR ILC1s will be tested for their anti-AML efficacy in preclinical models and compared to unmodified ILC1s. Additionally, we will combine ILC1s or FLT3-CAR ILC1s with NK cells and an FDA-approved tyrosine kinase inhibitor, which upregulates FLT3 expression on AML cells. Finally, we propose to reprogram endogenous ILC1s by treating them with IL-7 to enhance their activity. A deeper understanding of ILC1 development and function, anticipated through the completion of this study, holds significant promise. The knowledge gained could lay the groundwork for diverse therapeutic strategies that have the potential to reduce mortality in AML patients.
