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Depletion of Mouse Cells from Human Tumor Xenografts Significantly Improves Downstream Analysis of Target Cells

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic ...

Oncotest GmbH

Receptor-targeted therapies have become standard in the treatment of various lymphomas. In view of its unparalleled specificity for the malignant B-cell clone, the B-cell receptor (BCR) on B cell lymphoma cells is a potential therapeutic target. We have used two BCR epitope mimicking peptides binding to the Burkitt's lymphoma cell lines CA46 and SUP-B8. We proved their functionality by demonstrating calcium flux and BCR-mediated endocytosis upon peptide receptor binding. Toxicity experiments in vitro via cross-linking of the BCR with tetramerized epitope mimics lead to apoptosis in both cell lines but was far more effective in SUP-B8 cells. We established a SUP-B8-based disseminated Burkitt's lymphoma model in NOD/SCID mice. Treatment of tumor-bearing mice with tetramerized epitope mimics had significant anti-tumor effects in vivo. We conclude that peptide-mediated, BCR-targeted therapy is a promising approach which may be explored and further developed for application in highly aggressive lymphoma.

Anti-tumor activity of a B-cell receptor-targeted peptide in a novel disseminated lymphoma xenograft model.

We systematically analyzed multiple myeloma (MM) cell lines and patient bone marrow cells for their engraftment capacity in immunodeficient mice and validated the response of the resulting xenografts to antimyeloma agents.

Intratibial injection of human multiple myeloma cells in NOD/SCID IL-2Rγ(null) mice mimics human myeloma and serves as a valuable tool for the development of anticancer strategies.

A technology that visualizes tumor stem cells with clinically relevant tracers could have a broad impact on cancer diagnosis and treatment. The AC133 epitope of CD133 currently is one of the best-characterized tumor stem cell markers for many intra- and extracranial tumor entities. Here we demonstrate the successful noninvasive detection of AC133(+) tumor stem cells by PET and near-infrared fluorescence molecular tomography in subcutaneous and orthotopic glioma xenografts using antibody-based tracers. Particularly, microPET with (64)Cu-NOTA-AC133 mAb yielded high-quality images with outstanding tumor-to-background contrast, clearly delineating subcutaneous tumor stem cell-derived xenografts from surrounding tissues. Intracerebral tumors as small as 2-3 mm also were clearly discernible, and the microPET images reflected the invasive growth pattern of orthotopic cancer stem cell-derived tumors with low density of AC133(+) cells. These data provide a basis for further preclinical and clinical use of the developed tracers for high-sensitivity and high-resolution monitoring of AC133(+) tumor stem cells.

Noninvasive positron emission tomography and fluorescence imaging of CD133+ tumor stem cells.

Cancer stem cells (CSC) drive tumorigenesis and contribute to genotoxic therapy resistance, diffuse infiltrative invasion, and immunosuppression, which are key factors for the incurability of glioblastoma multiforme (GBM). The AC133 epitope of CD133 is an important CSC marker for GBM and other tumor entities. Here, we report the development and preclinical evaluation of a recombinant AC133×CD3 bispecific antibody (bsAb) that redirects human polyclonal T cells to AC133(+) GBM stem cells (GBM-SC), inducing their strong targeted lysis. This novel bsAb prevented the outgrowth of AC133-positive subcutaneous GBM xenografts. Moreover, upon intracerebral infusion along with the local application of human CD8(+) T cells, it exhibited potent activity in prophylactic and treatment models of orthotopic GBM-SC-derived invasive brain tumors. In contrast, normal hematopoietic stem cells, some of which are AC133-positive, were virtually unaffected at bsAb concentrations effective against GBM-SCs and retained their colony-forming abilities. In conclusion, our data demonstrate the high activity of this new bsAb against patient-derived AC133-positive GBM-SCs in models of local therapy of highly invasive GBM.

Kerstin Klingner

In vivo Tumorbiology

Oncotest GmbH

Depletion of Mouse Cells from Human Tumor Xenografts Significantly Improves Downstream Analysis of Target Cells

Kerstin Klingner

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}In vivo Tumorbiology

Oncotest GmbH

Depletion of Mouse Cells from Human Tumor Xenografts Significantly Improves Downstream Analysis of Target Cells

In vivo Tumorbiology