Development of humanized mouse models for the preclinical evaluation of NK cell-based therapies.

INTRODUCTION: Novel immunotherapeutic strategies engaging human Natural Killer (huNK) cells have emerged as a promising treatment paradigm; however, their accurate preclinical evaluation requires reliable mouse models capable of supporting functional huNK cell engraftment. METHODS: We developed and characterized robust in vivo NK-humanized mouse models using immunodeficient human Interleukin-15 (huIL-15) transgenic (Tg) mice. In vitro amplified huNK cells were used as the source of immune cells. Multiple humanized mouse models were evaluated with optimized protocols. Fcγ receptor knocked-out (FcγR-KO) mice were employed to exclusively model antibody-dependent cellular cytotoxicity (ADCC) potential of huNK cells. A resting period prior to adoptive transfer was also introduced and assessed. RESULTS: Our NK-humanized mouse models were developed using in vitro amplified huNK cells, which facilitated the production of large number of viable and functional huNK cells and allowed the engraftment of greater cohort of mice. We identified several key parameters improving the long-term persistence and proliferation of functional huNK cells that maintain important functional cell surface markers. FcγR-KO mice exclusively modeled the ADCC potential of huNK cells without the confounding contribution of mouse immune cells. The introduction of a pre-transfer resting period improved tolerability and circumvented potential donor-dependent toxicity issues. Engrafted huNK cells were successfully mobilized in vivo by different NK-based therapeutics, including an engineered IL-2 and an ADCC-enhanced monoclonal antibody. DISCUSSION: The NK-humanized huIL-15 Tg mouse models developed here provide a versatile and translationally relevant platform for the evaluation and selection of NK cell-based drug candidates, improving clinical translatability and offering a robust framework for preclinical assessment of novel NK cell immunotherapies.