Abstract 7228: Long-term humanization of NOG mice and next-generation NOG strains to induce lineage-specific differentiation of immune cells for assessment of novel immune cell therapies, check point inhibitors, and immune cell engagers for translational immuno-oncology research

Abstract Background: The preclinical evaluation of novel immune therapies requires humanized immune system (HIS) mouse models. In previous studies we have demonstrated that either peripheral blood mononuclear cells (PBMC), subsets of PBMCs like T and NK cells or CD34+ hematopoietic stem cells (HSC) can be used to establish a HIS model. With the development of next-generation NOG mice, lineage-specific differentiation of immune cell sub-populations of interest can be supported. Transplantation of cell line-derived (CDX) or patient-derived (PDX) tumor xenografts on HIS mice provides a full model for human tumors for the investigation of checkpoint inhibitors (CPI), as well as novel cell therapies and immune cell engagers. Methods: HSC-humanized mice were generated by i.v. transplantation of CD34+ stem cells to immunodeficient mice. For humanization, NOG mice and next-generation NOG strains were used: NOG, NOG-EXL, hIL-2 NOG, hIL-6 NOG and FcResolv™ NOG mice were compared to each other for lineage-specific differentiation using single donors or a mixed HSC donor pool. Long-term survival was monitored and engraftment of immune cells was analyzed by FACS of blood every four weeks. After termination, spleen, bone marrow and thymus was also screened for human immune cells. In humanized NOG mice, CDX and PDX from different entities were s.c. transplanted and used to evaluate CPI. Results: Humanized hIL-2 NOG mice showed significantly decreased survival after HSC transplantation in comparison to the other mouse strains and had to be sacrificed within the first 6-8 weeks after HSC transplantation. In the other mouse strains, transplanted HSCs engrafted and differentiated mainly into B and T cells. NOG-EXL mice displayed the highest engraftment, with up to 80% of human cells in the blood, including a higher portion of myeloid cells after 8 to 12 weeks. Humanized NOG, hIL-6 NOG and FcResolv™ NOG mice showed the longest survival rate with over 400 days for single donor transplantation. In humanized NOG mice, selected CDX and PDX tumors successfully engrafted without significant differences in tumor growth compared to non-humanized mice. CPI treatments with Nivolumab or Ipilimumab induced tumor growth delay in selected models. Conclusions: Next-generation NOG mouse strains are characterized by a lineage-specific differentiation of immune cells depending on integrated human cytokines. Furthermore, we established a human tumor-immune-cell model for NOG mice using different entities of CDX or PDX in combination with CPI. Our human tumor-immune cell models allow preclinical translational studies on tumor immune biology as well as evaluation of new therapies, drug combinations and biomarker identification and validation. Citation Format: Maria Stecklum, Louise Baskin, Jens Hoffmann. Long-term humanization of NOG mice and next-generation NOG strains to induce lineage-specific differentiation of immune cells for assessment of novel immune cell therapies, check point inhibitors, and immune cell engagers for translational immuno-oncology research [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7228.