Development and characterization of anti-CXCR4 chimeric antigen receptor T cells.

Acute Myeloid Leukemia (AML) and Acute Lymphoblastic Leukemia (ALL) are aggressive hematologic malignancies characterized by dysregulation of normal hematopoiesis and acquisition of stem-like, self-renewing properties leading to oncogenesis. Current treatments primarily rely on toxic chemotherapies with or without hematopoietic stem cell transplantation (HSCT). These are associated with significant short- and long-term side effects and sub-optimal outcomes across treatment of both AML and ALL. Improved HSCT methods are needed that can both eliminate leukemic cells and improve outcomes. The C-X-C chemokine receptor type 4 (CXCR4) plays a key role in both normal hematopoiesis and leukemogenesis by attracting and retaining cells in the bone marrow niche. It has been targeted using antibody or drug-based approaches leading to clinical trials and therapeutics across indications. In the context of chimeric antigen receptor (CAR) T cells, it has been expressed as a co-receptor to improve bone marrow homing and amplify tumor eradication. Here, we confirm high CXCR4 expression across AML and ALL using publicly available tumor transcriptomic datasets. Subsequently, we report the development of anti-CXCR4 CAR-T cells that demonstrate potent activity against a panel of leukemic cell lines in vitro without activity against other T cells. We observe decreased CXCR4 protein expression in CAR-positive populations indicating a potential pathway for T cell survival. Our findings support the potential of anti-CXCR4 CAR-T cells as a broadly applicable strategy for eliminating both AML and ALL, with possible extension to hematopoietic stem and progenitor cells, unlocking the potential of this strategy as a dual HSCT-conditioning and anti-leukemia agent.