Abstract 478: Development of an orthotopic model for human malignant bone diseases in immunocompromised NOD.Cg-PrkdcscidIl2rgtmlwjl/szj(NSG) mice

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Bone is the third most common site for metastatic disease in cancer. The continuity of bone tissue relies on the delicate balance between osteoblasts and osteoclasts and the formation and resorption of new bone tissue. The presence of cancer cells disturbs this equilibrium and can lead to aberrant new bone formation or destruction. In Ewing's sarcoma (ES) the 3-year event free survival in patients with osseous metastases or bone marrow infiltration is less than 20%, which accounts for 10% of patients. Clinically, the morphological changes to bone caused by ES differ from those of other cancer types such as prostate cancer (CaP). To better address the interaction between ES and bone, we have developed a preclinical orthotopic bone model. Intrafemoral (i.f.) transplantation is a technically feasible and convenient method for the study of cancer types associated with bone or bone marrow. Cells are injected directly into the bone marrow cavity of the femur via the knee. ES cell lines TC-71 and VH-64 and the CaP cell line PC3M were injected into the right femur of NSG mice at varying cell doses. The course of the disease was tracked using Computed Tomography (CT) and 2-[18F]fluoro-2-deoxy-D-glucose-Positron Emission Tomography (FDG-PET); a final MR documented the tumor before dissection. Areas of interest, identified by imaging of the mice, were taken for histopathology and data were compared to clinical imaging and histopathology of patients. Seven weeks post injection, CT images of mice transplanted with the ES cell line VH-64 showed development of structures identified as sunray spicules. The ES cell line TC-71 did not initiate the development of such structures, but the transplanted femurs appeared mottled and thickened compared to the left femur in the same mouse matching the permeative growth of ES in human patients. 66% of PC3M transplanted mice developed a pathological fracture of the right femur. In addition to palpable tumors in the thigh, all experimental mice had developed metastases at distant sites including liver and lungs. Histological analysis of the right femurs confirmed the findings of CT, and both ES cell lines were shown to have induced new bone formation. A review of ES patient images and histopathology shows that a considerable number of patients present with new bone formation, demonstrating the good concordance and clinical relevance of our proposed model. As 20% of ES arise in the diaphysis of the femur and patients develop lung or bone metastases, this i.f. model better reflects the situation in patients than subcutaneous or i.v. models do. All implanted animals developed bone tumors, suggesting that this preclinical model may be useful for studies of ES and primary metastasis in CaP. In addition to examining the biology of bone malignancies the model can be used to study new drugs disturbing the interaction between cancer cells and the bone microenvironment. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 478.