Heme Oxygenase 1‐Targeted Hybrid Nanoparticle for Chemo‐ and Immuno‐Combination Therapy in Acute Myelogenous Leukemia

Acute myelogenous leukemia (AML) is a fatal blood cancer with high patient mortality. Daunorubicin and cytarabine are first‐line chemotherapy for AML, with bone marrow transplantation in most cases. Recently, cancer immunotherapy has been challenged in AML and leukemia‐niche myeloid cells are promising targets for the AML immunotherapy. Heme oxygenase 1 (HO1) is an antioxidative and cytoprotective enzyme inducing chemo‐resistant AML and has been focused as an immune checkpoint molecule in tumor microenvironments. Herein, lipid‐polymer hybrid nanoparticle (hNP) is loaded with tin mesoporphyrin (SnMP), a HO1‐inhibitor, and non‐covalently modified with an engineered antibody for leukemic cell‐targeted delivery. HO1‐inhibiting T‐hNP (T‐hNP/SnMP) enhances chemo‐sensitivity in human leukemia cells. In a human AML‐bearing orthotopic mouse model, intravenously injected T‐hNP not only actively targets to human leukemia cells but passively targets to CD11b+ myeloid cells in a bone marrow niche. The T‐hNP/SnMP enhances the chemo‐therapeutic effect of daunorubicin and boosts immune response by reprogramming bone marrow myeloid cells resulting from the recruitment of the monocyte‐lineage and induction of inflammatory genes. The ex vivo study demonstrates an enhanced immune response of HO1‐inhibited bone marrow CD11b+ myeloid cells against apoptotic leukemia cells. Collectively, HO1‐inhibiting dual cell‐targeted T‐hNP/SnMP has a strong potential as a novel therapeutic in AML.