Abstract 5254: Xenograft-derived 3D cultures of hematological maligancies ex vivo and in vivo as a model system to investigate efficacy of antitumor compounds

Abstract

Abstract Hematological malignancies account for a notable proportion of cancers worldwide, and the heterogeneity and biological characteristics induce unique therapeutic challenges. A panel of 20 hematological cell lines comprising different entities like leukemia (acute lymphoblastic ALL; acute myeloid AML; chronic myeloid CML), Hodgkin-, and non-Hodgkin-lymphoma (NHL), as well as multiple myeloma (MM) was established for ex vivo anti-tumor efficacy profiling using a clonogenic assay. These 3D cell culture assays often mimic the in vivo scenario better than 2D cell culture assays. Tumor cells were injected into the flanks of NOD/SCID mice to obtain subcutaneous tumor xenografts, which were kept at low passages (n <3). These xenografts served as starting material to prepare single cell suspensions for ex vivo analysis, or to carry out in vivo efficacy tests with either subcutaneous or disseminated growing tumors. Twenty four cytotoxic and targeted drugs were tested for their ex vivo chemosensitivity. The drugs showed diverse patterns of selectivity and potency: vincristine, doxorubicin, cytarabine, and bortezomib exhibited activity with IC50 values in the nanomolar range (mean IC50 = 1 - 100nM), not limited to their respective clinical application, but also in other tumor entities, such as in ALL and AML in case of bortezomib. IC50 values of prednisolone and dexamethasone were in the micromolar range (mean IC50 = 22 - 58µM) in cell lines of ALL (CCRF-CEM, MOLT-4), AML (NOMO-1), NHL (DAUDI, U-937), and MM (IM-9). All-trans-retinoic acid (mean IC50 = 1.3µM) as well as interferon-gamma-1b (mean IC50 = 0.43µM) showed specific activity patterns with pronounced growth inhibition in cell lines of AML (KG-1, NOMO-1, OCI-AML2), CML (EM-2), and MM (L-363). IC50 values of tyrosine kinase inhibitors imatinib and nilotinib showed strong correlation (spearman coefficient: 0.76, p <0.001) with selectivity mainly for bcr-abl-positive cells. In vivo follow-up testing confirmed the ex vivo results. E.g. cyclophosphamide that showed strong antitumor activity against the NHL cell line DAUDI ex vivo (IC50 = 0.3µM), also induced tumor remissions of 80% in xenografts. Moreover, antitumor activity of sorafenib in AML cells assessed via clonogenic assay (mean IC50 0.84µM in AML cells vs. mean IC50 4.0µM over all tested entities) could be confirmed in the disseminated in vivo model using HL-60 cells (reduction of 99% vs. untreated control). The presented ex vivo panel screen is of great value for time and cost effective profiling of cytotoxic and targeted anti-cancer agents, which can be confirmed in in vivo tumor models of hematological malignancies, and can thereby guide to more effectively designed in vivo experiments. Diverse activity and resistance patterns ex vivo and in vivo also contribute to create clinical development strategies of standard and novel compounds. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5254. doi:1538-7445.AM2012-5254