Humanised PDX models 16:00 - 17:05

Preclinical rodent models for immune-oncology and related research areas have become more and more relevant, as researchers globally appreciate their versatility and direct relevance for such scientific questions. In this workshop, we will give an overview over traditional and state-of-the-art immunodeficient rodent models and their applications for various indications. Classical immunodeficient mice as well as novel humanized immune system mice will be presented and put into comparison. We will further give an exclusive insight into our proprietary humanization pipeline to shed light on this complex technical process. Recent data and proof-of-concept studies from JANVIER LABS users from industry and academia will be shown to demonstrate the robustness and reproducibility of data obtained using JANVIER LABS` immunodeficient and humanized mice. Finally, we will present our brand-new services in the realm of immunoprofiling of mouse innate and adaptive immune cell populations to assist you in accelerating your immune-oncology research programs and obtaining highly relevant preclinical data. In the following discussion, our experts will be happy to address your questions and further elaborate on these topics

Humanized patient-derived tumor xenografts are powerful tools for dissecting lympho-host interactions and discovering new immune-based strategies for human DLBCLs

DLBCL is the most common Non-Hodgkin lymphoma (NHL), comprising different biological and molecular entities, with a ~60% curable rate. Despite introducing a battery of novel regimens, there is still an unmet clinical need for novel treatments of DLBCLs. Although intrinsic defects drive lymphomas' tumorigenesis, the microenvironments' role has emerged as a critical element to their pathogenesis. Testing immunotherapies in clinical settings is financially demanding, time-consuming, and often limited in scope. Immunocompetent mouse models have been successfully used to test new compounds. To this end, it has become mandatory to establish in vivo models that closely reproduce not only human cancers but also their interactions with an intact human immune system. Fully humanized mice have emerged as powerful platforms to address these questions.

Here, humanized mice (HuMice) were generated in different strains of preconditioned immunodeficient mice by injecting cord blood/adult CD34+ hematopoietic stem cells (HSC). Reconstituted HuMice were characterized over time by multicolor flow cytometry, immunohistochemistry, and genomics (BCR and TCR repertoire was evaluated using RNA/DNA based NGS assays). To assess host-lymphoma responses, HuMice were challenged with diffuse large B cell lymphoma (DLBCL) patient-derived tumor xenografts (PDTX). Immune reconstitution partially controlled the lymphoma growth, but tumor eradication was only rarely achieved. Remarkably, DLBCL-PDTX challenges resulted in a significant expansion of humanized T-cells, with often a remarkable expansion of circulating CD8+, TILs, and lymphoid elements. Notably, TILs displayed an exhausted phenotype (TIGIT, PD-1, and Lag-3 positive), and did not expand in in-vitro. Dynamic T cell receptor clonotyping proved a robust TCR representation and the clonal expansion of unique populations within lymphoma infiltrating tissues.

Our data demonstrate a robust reconstitution in HuMice, which elicit effective anti-lymphoma responses. PDTX humanized models represent a powerful tool to rapidly and effectively test new and/or combination strategies to overcome the chemo-resistance of DLBCL.

Alex Martínez-Sabadell^1,2,#, Macarena Román¹, Irene Rius Ruiz^1,2, Beatriz Morancho¹, Marta Escorihuela¹, Christian Klein³, Marina Bacac³, Joaquín Arribas^1,2,5,6,7,*, Enrique J. Arenas^1,2,#,*

¹ Preclinical Research Program and 2CIBERONC, Vall d’Hebron Institute of Oncology (VHIO), Barcelona, 08035, Spain.
³ Roche Innovation Center Zurich, Roche Pharma Research & Early Development, pRED, Zurich, Switzerland.
⁴ Department of Biochemistry and Molecular Biology, Universitat Autónoma de Barcelona, Campus de la UAB, 08193, Bellaterra, Spain.
⁵ Cancer Research Program, IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain.
⁶ Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010, Barcelona, Spain.
^# These authors contributed equally
^* These authors jointly supervised this work

Introduction

Elimination of cancer cells by effector immune cells represents the culmination of a complex cascade of events, and disruption of any of those events may result in resistance. T cell-engaging therapies, such as T cell bispecific antibodies (TCBs) or chimeric antigen receptors (CARs), are raising extraordinary expectations as future treatments for virtually all cancers. Encouraging these expectations, TCBs and CARs have been recently approved to treat some hematologic malignancies. In contrast, TCBs and CARs against solid tumors tested to date, have failed to show clinical efficacy. This failure prompted intense research and the subsequent identification of mechanisms of primary and acquired resistance. All these mechanisms impinge on the ability of T cells to reach cancer cells and/or on the inhibition of T cells. However, little is known about putative intrinsic mechanisms of resistance of cancer cells. That is, mechanisms deployed by tumor cells to resist killing by fully active and correctly engaged T cells.

Objective: To identify novel mechanisms of acquired resistance to T cell redirection therapies and how to overcome it.

Material and Methods

Using HER2+ cell lines and patient-derived xenografts (PDXs) and a TCB targeting HER2, we generated in vitro and in vivo acquired resistant models to HER2-TCB. This resistance was obtained after coculturing in vitro with peripheral blood mononuclear cells (PBMCs) or in vivo in fully humanized mice with CD34+ cells obtained from cord blood, both from healthy donors.

Results and Discussion

Here we demonstrate that disruption in interferon-gamma (IFN-gamma) signaling in cancer cells is a mechanism of intrinsic resistance to killing by fully active, correctly engaged, T lymphocytes. Importantly, we have identified that the kinase JAK2, which transduces the signal initiated by IFN-gamma, is the component preferably disrupted to acquired resistance across all models used.

Conclusion

These results unveil a novel mechanism of resistance to T cell based therapies, and imply the potential use of JAK2 and IFN-gamma response as a surrogate biomarker of response to immunotherapies. In addition, they open the avenue for the screening for therapies that can overcome deficient interferon-gamma response or restore JAK2 levels, which are promising potential candidates to increase the benefits of immunotherapies. Currently we are identifying novel genes and drugs in order to overcome resistance to immunotherapies by using a genome wide CRISPR screening and a drug screening, respectively, which will allow to characterize in depth a mechanism of resistance to redirected lymphocytes and will allow to design novel and more efficacious immunotherapy-based strategies for the treatment of different cancers.