Engineering Interferon-γ-Enhanced Chimeric Antigen Receptor Macrophages via Lipid-Assisted Polymeric Nanoparticles for Cancer Immunotherapy.

Chimeric antigen receptor macrophages (CAR-Ms) are promising in solid tumor therapy due to their tumor-penetrating property and antigen-specific phagocytosis. However, current CAR-M therapy is limited by the low ex vivo proliferation of macrophages and the complexity of the engineering process. Generating CAR-Ms in vivo can overcome these challenges but still faces an M2-like pro-tumor phenotype polarized by immunosuppressive tumor microenvironment. Herein, we devise macrophage-preferential ionizable cationic lipid-assisted polymeric nanoparticles (iCLANs) to co-deliver mRNAs encoding interferon-γ (IFN-γ) and a CAR molecule, denoted as iCLANmCAR+mIFN-γ, enabling in vivo engineering of CAR-Ms with a sustained M1-like phenotype. iCLANmCAR+mIFN-γ can coexpress IFN-γ and CAR in tumor-associated macrophages, thereby producing CAR-Ms capable of maintaining antitumor phenotype to effectively engulf tumor cells in an antigen-specific manner. Intravenous injection of iCLANmCAR+mIFN-γ in EGFRvIII+ breast tumor and CD19+ B-cell lymphoma models directly generates EGFRvIII CAR-Ms or CD19 CAR-Ms within tumors, resulting in significant tumor growth inhibition and remodeling of the immunosuppressive tumor microenvironment. This study provides an efficient strategy for in vivo engineering of M1-like CAR-Ms for cancer therapy.