Mouse Models of Human Mantle Cell Lymphoma for the Study of Disease Biology and for Pre-Clinical Assessment of Experimental Treatment Approaches.

Abstract 2759

Mantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin lymphoma associated with poor prognosis. MCL animal models for the study of disease biology and for the testing of novel agents are scarce. We established and characterized various in vivo models of metastatic blastoid human MCL by tail vein injection of five MCL cell lines (Jeko-1, HBL-2, Mino, Rec-1, Granta-519) into the NOD.Cg-Prkdc^scidIl2rg^tm1Wjl/SzJ immunodeficient mice. Untreated animals were then observed to evaluate differences in the pattern of lymphoma growth and overall survival (OS) between different cell lines. We analyzed infiltration of selected murine organs (i.e. bone marrow [BM], spleen, liver, brain, kidneys, and enlarged lymph nodes [LN]) by immunohistochemistry (IHC) (CD20, Ki-67) at four different time-points related to OS. Extent of organ infiltration with human MCL cells was estimated using the Image-Pro Plus 5.1 software within 20 samples from different organ areas. Subsequently, we analyzed gene expression of Jeko-1 and Mino cells obtained from the xenografted animals (in vivo growing cells) compared to the cells cultured in vitro (controls).MCL cells isolated from various murine organs (the BM, liver, spleen, and LN) or in vitro cultured cells were magnetically sorted by CD45-microbeads. Gene expression analyses were carried out using Illumina BeadChips, and the data were functionally clustered with DAVID Bioinformatics tool. In addition, differences in surface expression of selected antigens were compared between in vivo vs. in vitro grown MCL cells by flow cytometry. Finally, we evaluated the anti-tumor activity of single-agent chemotherapy agents (cytarabine, fludarabine, bendamustine, and cisplatin), monoclonal antibodies (rituximab, ofatumumab, bevacizumab) or targeted agents (bortezomib, temsirolimus) in Jeko-1 and Mino bearing mice. Tumor engraftment was achieved in all the cell lines tested. The median overall survival (OS) of mice xenografted with 1–10×10⁶ MCL cells ranged from 22 to 55 days depending on the cell line used. The principal site of engraftment and proliferation niche for all MCL cell lines was the bone marrow. MCL cells disseminated to other murine organs including the spleen, liver and brain. Development of enlarged lymph nodes (peripheral, intraabdominal) and/or extranodal MCL masses (subcutaneous tumors) were associated with Mino, while infiltration of the ovaries was inconstant finding in Jeko-1 xenografted mice. Mice xenografted with Jeko-1, HBL-2 and Granta-519 showed leukemization of peripheral blood before death. Gene expression studies of Jeko-1 and Mino in vivo growing cells revealed that the genes from the “B-cell receptor signaling” and the “oxidative-phosphorylation” pathways were the most upregulated or downregulated, respectively. In vivo growing Jeko-1 cells showed upregulation of CD31/PECAM, CD37, CD38, CD44, CD164, and downregulation of podoplanin and CXCR4. In vivo growing Mino cells had upregulation of CD23, but downregulation of CD37, CD40, CD44, CD54, CD138, CXCR4, CCR7 and podoplanin. Both Jeko-1 and Mino cells isolated from the BM (but not from the spleen, liver or LN) were significantly more sensitive to cytarabine (2–4 fold) and cisplatin (2 fold) than in vitro growing controls. Single-agent therapy of Jeko-1 and Mino bearing mice with either a chemotherapy agent, monoclonal antibody, or targeted agent resulted in significant prolongation of OS compared to untreated controls. Treatment of Jeko-1 and HBL2 bearing mice with single-agent cisplatin, single-agent cytarabine or combination of both agents revealed that the therapy with single-agent cisplatin was associated with the longest prolongation of OS. Moreover, IHC analyses of the BM, spleen and liver of the treated animals confirmed the most profound suppression of both MCL infiltration (CD20) and proliferation rate (Ki-67) in the single-agent cisplatin cohort compared to the other cohorts. In summary, the mouse models can be used for the study of MCL biology, as well as for preclinical assessment of experimental therapy of MCL including agents that cannot be properly tested in vitro (e.g. monoclonal antibodies, pro-drugs, anti-angiogenic agents, inhibitors of B-cell receptor signaling etc.).