Leukemia-targeting NK cell nanoengagers effectively promote robust NK activation and potent anti-acute myeloid leukemia response.

Natural killer (NK) cells are key components of innate immunity, playing a pivotal role in tumor recognition and eradication, and numerous NK cell-based immunotherapeutic approaches have been extensively investigated for cancer treatment. Here, we develop leukemia-targeting NK cell nanoengagers, termed AaLS/aCD16Nb/aCD13Nb, by simultaneously displaying NK cell-engaging nanobodies (aCD16Nb) and acute myeloid leukemia (AML)-targeting nanobodies (aCD13Nb) on lumazine synthase (AaLS) protein nanoparticles. The AaLS/aCD16Nb/aCD13Nb nanoengagers effectively bind to both NK cells and AML cells, thereby facilitating selective engagement of NK cells with leukemic targets. Through this targeted engagement, the AaLS/aCD16Nb/aCD13Nb nanoengagers promote NK cell activation, leading to enhanced interferon gamma (IFN-γ) production and robust AML cell killing in vitro. Furthermore, in AML-engraft mouse models, administration of the AaLS/aCD16Nb/aCD13Nb nanoengagers significantly reduce leukemic burden across multiple tissues, with pronounced effects in the bone marrow niche, and extend overall survival in two independent AML (U937 and THP-1) engrafted models. Collectively, our study demonstrates that this dual-ligand-displaying nanoengager platform represents a promising and potent anti-leukemic strategy, offering a multifunctional protein nanoparticles-based approach for AML immunotherapy that may be broadly adaptable to other malignancies.