Empowering IL-2 therapy development: A novel humanized mouse model with functional IL-2 and IL-15 receptors

The efficacy of immuno-oncology therapies, particularly those involving cytokines like IL-2 and IL-15, is often limited by their species-specificity and complex receptor interactions, which are poorly recapitulated in wild-type mice. To establish a robust preclinical platform for evaluating novel human-specific immunotherapies and their combinations, we developed a comprehensive seven-gene humanized mouse model. The B-hPD-1 plus/hIL2/hIL2RA/hIL2RB/hIL2RG/hIL15/hIL15RA mouse model was engineered on a C57BL/6 background by co-integrating seven key human genes: PD-1, IL2, IL2RA, IL2RB, IL2RG, IL15, and IL15RA. Humanization and cell surface expression of the encoded proteins were confirmed via flow cytometry. The IL2 and IL15 were detected by ELISA. Comprehensive immune cell profiling was performed. The model's functionality was validated in vivo using syngeneic tumor models treated with human IL-2 (hIL-2), an anti-human PD-1 antibody (Ketruda), and their combination. Flow cytometry and ELISA confirmed successful expression of the membrane proteins and the secreted protein, respectively. Immune phenotyping demonstrated the presence of key lymphocyte populations capable of responding to human cytokines. In therapeutic studies, monotherapy with hIL-2 or Ketruda significantly inhibited tumor growth compared to control groups. Notably, the combination of hIL-2 and Ketruda resulted in superior, synergistic antitumor efficacy, significantly outperforming either agent alone. Ongoing histopathological (H&E) and clinical pathology (hematology and serum biochemistry) analyses to date indicate no overt toxicity, supporting the model's utility for safety and efficacy assessments. We have successfully developed and validated a novel seven-gene humanized mouse model that robustly expresses human PD-1, IL-2, IL-15, and their complete receptor complexes. This model supports functional in vivo evaluation of human-specific mono- and combination therapies, as demonstrated by the enhanced efficacy of hIL-2 plus anti-PD-1. It represents a unique and powerful preclinical tool for the screening and mechanistic study of next-generation immunotherapies, including cytokines, checkpoint inhibitors, and their synergistic combinations.