Eμ-SOX11CCND1: A Novel Immunocompetent Murine Model of Mantle Cell Lymphoma
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Date
2023-02
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Abstract
Background: Mantle cell lymphoma (MCL) is an incurable B cell malignancy, comprising 5% of non-Hodgkin lymphomas (NHL) diagnosed annually (~5000 cases) and associated with a poor prognosis due to emergence of resistance to immuno-chemotherapy and targeted agents [1]. The average overall survival of patients with MCL is 4-6 years and for most patients who progress on targeted agents, survival remains at a dismal 3-8 months[2]. There is a major unmet need to identify new therapeutic approaches that are well tolerated to improve treatment outcomes and quality of life [3]. Immunotherapy has shown great promise in MCL, with the recent FDA approval of Brexucabtagene autoleucel for relapsed/refractory (R/R) MCL [4]. In order to optimize the preclinical testing of immunotherapy for MCL, immunocompetent mouse models are needed; commonly used patient derived xenografts (PDXs) and cell line derived xenografts (CDXs) models of MCL are made in immune incompetent mice and so therapies related to host immune response cannot be tested. There are currently no published immunocompetent murine models of MCL that accurately recreate human pathology.
The C57BL/6J-Tg(Eµ-sox11-GFP, Eµ-ccnd1) or Eµ-SOX11CCND1 transgenic mouse model utilizes two key genes in MCL to create a new lymphoma model. SOX11 has been shown to be a driver of MCL, with overexpression in 80-90% of cases, and is highly correlated with more aggressive disease [5]. CCND1 overexpression is a hallmark of MCL, where the gene translocation to the IgH promotor is frequently used to diagnose MCL from other NHLs [1]. Here we show this model spontaneously developed MCL-like disease that closely recapitulates MCL in humans, can be utilized as an adoptive transfer model, and can be used to test immunotherapy-based regiments pre-clinically.
Methods: Colonies of Eµ-SOX11, Eµ-CCND1, and Eµ-SOX11/CCND1 mice were bred and monitored via flow cytometry for abnormal expansion of B cells and specifically MCL like CD5+/CD19+ B cells circulating in the blood. Lymphoma cells from a donor mouse were passaged through additional wild type, immune competent C57bl/6J mice through adoptive transfer and 100% of engrafted animals developed MCL-like tumor burden. This model can be utilized as a systemic model of MCL via intravenous tail vein or subcutaneous flank engraftment; both reach early removal criteria by approximately day 21 showing disease pathology consistent with MCL. MCL therapies including the BTK inhibitor ibrutinib, the PRMT5 inhibitor, PRT382, and murine CD19 chimeric antigen receptor T cells (CD19-CAR-T) were tested in this immune-competent model of MCL.
Results: Both the Eµ-SOX11 and Eµ-SOX11CCND1 mice showed aberrant expansion of CD5+/CD19+ B cells starting as early as 10 weeks of age. The Eµ-SOX11CCND1 model showed a higher percent circulating MCL cells (p<0.05) with multiple mice progressing to pathologic levels of expansion. Tumor burden manifested as splenomegaly, cytopenias, and premature death compared to wild-type control animals. This model allowed us to test two targeted therapies of MCL, ibrutinib and PRT382. Ibrutinib, an FDA-approved BTK inhibitor, showed limited survival advantage demonstrating that this model recapitulates the aggressive R/R disease with the poorest prognosis. PRT382, a selective inhibitor of PRMT5, significantly extended survival (18 vs 67 days, p<0.0001) suggesting that PRMT5 inhibition may be a useful treatment in ibrutinib resistant MCL. We also observed an interesting reduction of immunosuppressive marks in the myeloid compartment after two rounds of treatment as determined by spectral flow cytometry. In order to test an immunotherapy, we created murine CD19-specific chimeric antigen receptor-T cells (CD19-CAR-T). One dose of 106 CD19-CAR-T cells improved the median survival by seven days (p<0.01). We hope to improve on this survival advantage by testing CD19-CAR-T and other immunotherapeutic agents in combination with targeted agents like PRT382 that hold the potential for modulating the tumor microenvironment.
Conclusion: These results support the Eµ-SOX11CCND1 as an attractive model to explore how MCL modulates host immunity and test novel targeted agents alone and in combination with immunotherapeutic strategies.
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Health Sciences: 2nd Place (The Ohio State University Edward F. Hayes Advanced Research Forum)
Keywords
Mantle Cell Lymphoma, Mouse model, transgenic model, immunotherapy