The overall goal of this project is to develop targeted probes for imaging receptors for vascular endothelial growth factor (VEGF) in tumor angiogenesis. Overexpressed VEGF receptors play the crucial role in the onset and progression of tumor angiogenesis and therefore, these receptors are the primary targets of tremendous efforts to develop inhibitors of angiogenesis. However, these receptors are not being used as biomarkers in prescribing or monitoring anti-angiogenic therapy, because there are no non-invasive methods for assessment of their prevalence. Thus, non-invasive imaging of VEGF receptors addresses unmet clinical needs and might lead to evidence-based selection of patient for anti-angiogenic therapy, and design of personalized treatment regiments. In addition, since VEGF receptors are reportedly overexpressed in tumor and contiguous host vasculature at the onset of malignant growth, VEGF receptor imaging might be used for early diagnostics and discrimination between benign and malignant lesions. In Phase I of this project we have developed novel VEGF-based probes for near-infrared fluorescent (NIRF) and single photon emission computed tomography (SPECT) imaging of VEGF receptors that are suitable for clinical development. Site-specific conjugation of contrast agents to appropriately designed VEGF yielded probes that bind to VEGF receptors on endothelial cells as effectively as parental VEGF. We established that our VEGF-based probes undergo receptor-mediated internalization and accumulate in tumor and host endothelial cells overexpressing VEGF receptors. Importantly, using inactivated VEGF-based probes that lost the ability to bind to VEGF receptors, we evaluated a contribution of non-specific mechanisms to probe accumulation in tumor vasculature. Our targeted imaging probes are based on a novel single-chain (sc) VEGF that provides fora significant improvement in expression, refolding, and purification, relative to a conventional VEGF with two subunits linked via disulfide bonds. Site-specific conjugation of contrast agents to scVEGF via our proprietary humanized cysteine containig tag (Cys-tag) ensures homogeneity of the imaging probes. Taking together, our Phase I results open the road to clinical development of VEGF-based probes for selective and specific imaging of VEGF receptors in tumor vasculature. In Phase II, we will establish safety of scVEGF-based probes, develop scalable GLP production of conjugates and characterize utility of these probes for predicting/monitoring responses to a specific inhibitor of VEGF receptors and for early diagnostic of malignant lung lesions. We expect that Phase II results will establish scVEGF-based imaging probes as viable candidates for clinical development. In Phase II of this project we will undertake crucial steps in pre-clinical development of novel targeted probes for molecular imaging of specific receptors that play crucial role in the onset and growth of tumor vasculature and are the primary targets for therapeutic development. Results obtained in the Phase I of this project established 1) feasibility of constructing targeted probes, using a novel proprietary technology, and 2) feasibility of obtaining early and dynamic information about the status of these receptors. Thus, clinical development of these targeted imaging probes open new opportunities for evidence-based selection of patients for specific therapeutic treatments, timely monitoring responses to anti-cancer therapies, for early cancer diagnostics, and discrimination between benign and malignant lesions. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Small Business Innovation Research Grants (SBIR) - Phase II (R44)
Project #
2R44CA113080-02A2
Application #
7271615
Study Section
Special Emphasis Panel (ZRG1-SBIB-S (10))
Program Officer
Menkens, Anne E
Project Start
2005-02-08
Project End
2009-08-31
Budget Start
2007-09-28
Budget End
2008-08-31
Support Year
2
Fiscal Year
2007
Total Cost
$545,177
Indirect Cost
Name
Sibtech, Inc.
Department
Type
DUNS #
966566465
City
Brookfield
State
CT
Country
United States
Zip Code
06804
Blankenberg, Francis G; Levashova, Zoia; Goris, Michael G et al. (2011) Targeted systemic radiotherapy with scVEGF/177Lu leads to sustained disruption of the tumor vasculature and intratumoral apoptosis. J Nucl Med 52:1630-7
Biswal, Nrusingh C; Gamelin, John K; Yuan, Baohong et al. (2010) Fluorescence imaging of vascular endothelial growth factor in tumors for mice embedded in a turbid medium. J Biomed Opt 15:016012
Anderson, Christopher R; Rychak, Joshua J; Backer, Marina et al. (2010) scVEGF microbubble ultrasound contrast agents: a novel probe for ultrasound molecular imaging of tumor angiogenesis. Invest Radiol 45:579-85
Levashova, Zoia; Backer, Marina; Hamby, Carl V et al. (2010) Molecular imaging of changes in the prevalence of vascular endothelial growth factor receptor in sunitinib-treated murine mammary tumors. J Nucl Med 51:959-66
Blankenberg, Francis G; Levashova, Zoia; Sarkar, Susanta K et al. (2010) Noninvasive assessment of tumor VEGF receptors in response to treatment with pazopanib: a molecular imaging study. Transl Oncol 3:56-64
Tedesco, Maureen M; Terashima, Masahiro; Blankenberg, Francis G et al. (2009) Analysis of in situ and ex vivo vascular endothelial growth factor receptor expression during experimental aortic aneurysm progression. Arterioscler Thromb Vasc Biol 29:1452-7