Abstract A005: Preclinical evaluation of novel immune cell therapies, check point inhibitors, and immune cell engagers in humanized mouse models
Authors: Stecklum Maria , Wulf-Goldenberg Annika , Brzezicha Bernadette , Alcaniz Joshua , Smits Glenn , Walther Wolfgang , Hoffmann Jens 
Published: December 2023

Background The preclinical evaluation of novel immune therapies requires humanized mouse models with functional human immune cells. In previous studies we have demonstrated, that either peripheral blood mononuclear cells (PBMC), subsets of PBMCs like T- and NK-cells or hematopoietic stem cells (HSC) can be used to establish a humanized immune system with functional T-, B-, and NK cells, as well as monocytes and dendritic cells in immunodeficient mice. By xenotransplantation of cell-line-derived (CDX) or patient-derived (PDX) tumors on humanized mice, we successfully generated a full human tumor-immune-cell model for different disease entities. Finally, we validated the functionality of these models using checkpoint inhibitors like Ipilimumab (Ipi), Nivolumab (Nivo), Pembrolizumab (Pembro), cell therapies, and immune cell engagers.

Methods HSC-humanized mice were generated by i.v. transplantation of CD34+ stem cells to immunodeficient 1st and 2nd generation NOG mice. Engraftment of immune cells was monitored by FACS analysis of blood samples. PBMC or isolated T- or NK-cell preparations were used to humanize mice by single or multiple i.v. injections. CDX and PDX from different entities were s.c. (i.e. lymphoma) and/or i.v. (leukemia) transplanted on those humanized mice. Tumor growth of orthotopic models was followed up by BLI measurement. Blood and tumor samples were analysed by for immune cell infiltration and activation.

Results The transplanted HSCs engrafted in mice and established a functional human immune system with proliferation and differentiation. The 2nd generation NOG mice are showing an increased total engraftment and lineage specific differentiation of cells. The selected CDX and PDX tumors successfully engrafted on humanized mice without significant differences in tumor growth compared to non-humanized mice. Check point inhibitor treatments (Ipi, Nivo, or Pembro) induced tumor growth delay in selected models. BLI measurement is a suitable method to follow up systemic disease models and treatment effects over time. We identified a set of CDX and PDX models without interference with parallel injection of PBMC, T- or NK-cell preparations for the evaluation of immune cell engagers and other cell therapies.

Conclusions We established human tumor-immune-cell models of different entities using CDX or PDX in combination with different donor derived immune cell subsets as effector cells. We demonstrated successful engraftment of HSC on different immunodeficient mouse strains, generating mice with a functional human hematopoiesis. These models have been successfully used for preclinical evaluation of novel check point inhibitors, cell therapies and immune cell engagers. Our human tumor-immune-cell models allow preclinical translational research on tumor immune biology as well as evaluation of new therapies, drug combinations, as well as biomarker identification and validation in subcutaneous and orthotopic models.

Citation Format: Maria Stecklum, Annika Wulf-Goldenberg, Bernadette Brzezicha, Joshua Alcaniz, Glenn Smits, Wolfgang Walther, Jens Hoffmann. Preclinical evaluation of novel immune cell therapies, check point inhibitors, and immune cell engagers in humanized mouse models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A005.