PhD Student The University of Hong Kong, Hong Kong
Abstract: Immunotherapy has shown promising efficacy in lymphoma and leukemia, but clinical trials for solid tumors have yielded disappointing results. Chimeric antigen receptor (CAR) macrophage therapy holds potential for solid tumors due to its superior infiltration capabilities compared to CAR-T cells. In this study, we leveraged the robustness of cord blood hematopoietic stem cells (CB-HSCs) as an ideal source of CAR-macrophages. We validated the large-scale expansion of macrophages, their in vitro sustainability over two weeks, and their robust phagocytosis capacity from HSCs. Furthermore, we demonstrated that DNA-PK inhibition enhanced AAV-CRISPR mediated knock-in at the AAVS1 loci in CB-HSCs by a factor of 1.5, and the knock-in efficiency could reach 80% by droplet digital PCR detection. Additionally, aGPC3 CAR macrophages successfully engrafted into Huh-7 luciferase-bearing mice and demonstrated significant tumor burden reduction. Subsequently, we observed sustained macrophage presence in the liver post-injection into tumor-bearing mice for four weeks, as confirmed by immunohistochemistry staining. Notably, no cytotoxicity was observed in the mouse organs. Finally, we identified IL-12 and IL-18 primed NK cells, which secrete IFNg, as potential to reinvigorate bystander cells. Our findings demonstrate the robustness of CB-HSCs as a reliable source for immunotherapy and the potential of aGPC3 CAR macrophages to effectively eliminate liver cancer-bearing mice with satisfactory safety. This study presents CB-HSC as an off-the-shelf source of CAR macrophages and tumor microenvironment remodeling in solid cancer.
