Analysis of targeted biological therapies in a genetically engineered mouse model of sarcoma

The development of effective drugs in the treatment of sarcomas is limited by the lack of reliable animal models of sarcomas. This is especially true for drugs that target not only tumor cells but also the interaction between tumor cells and their host microenvironment. Bevacizumab and sunitinib are promising new biological agents that inhibit tumor angiogenesis (or new blood vessel formation) and tumor growth. We recently described an inducible, genetically engineered mouse model of sarcoma where intramuscular delivery of an adenovirus expressing Cre recombinase into mice with conditional mutations in K-ras and p53 results in high-grade sarcomas of the extremity…  Read More »

Development of a high throughput screening assay for Ewing sarcoma oncoprotein

Ewing’s sarcoma presents a unique opportunity to develop tumor specific targeted therapy due to a pathognomonic chromosomal translocation. Proper function of EWS-FLI1, protein product of this chromosomal translocation, is required for tumor cell survival. We will develop a cell-based High Throughput Screening assay. We will generate Ewing’s cell-lines expressing two fluorescent proteins. GFP will be expressed from an EWS-FLI1 regulated promoter and RFP from an unrelated negative control promoter. In this dual color HTS assay, a small molecule library will be screened for inhibiting GFP but not RFP, which will provide lead compounds for novel Ewing’s sarcoma therapies.

CSF1 inhibitors in soft tissue tumors

Our recent microarray collaborative studies demonstrate that tenosynovial giant cell tumor and aggressive soft tissue leiomyosarcomas express macrophage colony stimulating factor, which appears to represent a key factor driving these neoplasms. New drugs inhibit this target, but appropriate models which include a tumor-host macrophage interaction are lacking. We recently found that primary tumor renal subcapsular xenografts can attract host macrophages and seek to establish if this model can serve as a preclinical assay for an anti-CSF1 targeted treatment strategy in these diseases.

Mechanisms of tumor progression and kinome targeting in peripheral nerve sheath tumors

Tyrosine kinases (TK) are central regulators of signaling pathways that control critical activities in cells. A breakthrough in therapy for cancers associated with activating mutations in TKs is the development of imatinib mesylate for the treatment of CML and GIST tumors. Our hypothesis is that novel kinase oncogenic mutations might be implicated in the pathogenesis of tumor progression in peripheral nerve sheath tumors (PNST) and therefore potential targets to molecular inhibition. MPNSTs are highly aggressive neuroectodermal mesenchymal neoplasms, for which no effective cytotoxic or targeted chemotherapy is currently available. Our aim is to perform high throughput mutational analysis of 15…  Read More »

Predicting treatment response of soft tissue sarcomas to neoadjuvant therapy by imaging proliferation with a FLT-PET/CT scan: a pilot study

Although metabolic imaging with F18-fluorodeoxyglucose positron emission tomography(FDG-PET) is more sensitive than standard size-based criteria(RECIST) at monitoring response to therapy in high-grade soft tissue sarcomas(STS), its limited specificity restricts its utility as a functional bio-marker. Hypothesis: Imaging proliferation with 18F-fluorodeoxythymidine-positron-emission-tomography(FLT-PET) will provide a more accurate assessment of response in patients with high-grade STS. Aims: 1.  Evaluate the ability of changes in FLT uptake and size to predict histopathologic response to systemic neoadjuvant therapy. 2.  Compare change in FLT uptake with immunohistochemical markers of proliferation, cell-cycle-progression and apoptosis. 3.  Correlate changes in FLT uptake, size and histopathology with recurrence and survival.

Evaluation of flow cytometry for the detection of circulating Ewing sarcoma cells

Approximately 25% of patients with Ewing sarcoma have circulating EWS fusion transcripts using RT-PCR. RT-PCR has several practical disadvantages. This study will evaluate a flow cytometry method we developed to detect circulating Ewing sarcoma cells. The primary aims are: 1.  To establish the feasibility of this method and 2.  To compare this method to RT-PCR results. Twenty patients with Ewing sarcoma will enroll. Blood and bone marrow will be evaluated for circulating tumor cells using flow cytometry and RT-PCR. The flow cytometry and RT-PCR results will be compared to determine whether this method merits further evaluation in larger studies.

A mouse model to examine human osteosarcoma therapeutic options

Osteosarcoma, while relatively rare in humans (about 1000 cases per year in the U.S.), represents a continuing challenge to oncologists. Current chemotherapy regimens have a 60-70% five year survival rate. Thus, there is a need for more effective, less toxic therapies. We have extensively characterized a mouse osteosarcoma model to test therapies that may be transferable to human osteosarcomas. In this application, we propose a “proof of principle” experiment to show that downregulating the CSF-1 receptor (highly upregulated in mouse and human osteosarcomas) by siRNA and small molecule inhibitor approaches will result in significant inhibition of osteosarcoma growth in vivo.