Pancreatic cancer is a lethal disease. Due to its aggressiveness and our inability to detect pancreatic cancer at an early stage, the disease is often far advanced in patients at the time of diagnosis. The 5-year relative survival rate for all pancreatic cancer stages is only approximately 4%. Chemotherapy and radiotherapy have only modest benefits and surgery for localized disease is only possible in 20% of patients at the time of diagnosis. Currently early detection of pre-invasive and early invasive stages of pancreatic cancer that allows surgical resection offers our best hope for longer survival of patients with pancreatic cancer. Furthermore, early detection of pre-invasive or early stage invasive pancreatic cancer in high-risk patient groups represents a critical unmet need in the cancer diagnostic portfolio. By combining non-invasive, high-resolution ultrasound imaging with the ability to visualize and quantify markers of angiogenesis in early stage cancer at the molecular level, our overall objective is to detect pancreatic cancer at early, still curable stages and eventually decrease mortality in patients with pancreatic cancer. We hypothesize that at pre-invasive and early stage invasive pancreatic cancer, tumor angiogenic vessels [are already present and] can be visualized non-invasively with high sensitivity and specificity by targeted contrast-enhanced ultrasound (molecular ultrasound). We will use novel, clinically translatable microbubbles targeted at human vascular endothelial growth factor receptor type 2 (KDR), which has been shown to be overexpressed on angiogenic vessels in pancreatic cancer.
In specific aim 1 we will test the hypothesis that tumor angiogenesis in human subcutaneous and orthotopic pancreatic cancer xenografts in mice can be visualized by molecular ultrasound using novel, clinically translatable, KDR-targeted contrast microbubbles. We will further demonstrate that the in vivo imaging signal from molecular ultrasound can be quantitatively correlated with the extent of tumor angiogenesis and expression levels of vascular endothelial growth factor receptor type 2 as assessed by ex vivo assays.
In specific aim 2 we will test the hypothesis that screening with molecular ultrasound using clinically translatable, KDR-targeted microbubbles allows detection of pre-invasive and early stage invasive pancreatic cancer in a spontaneous, transgenic, mouse model of pancreatic cancer. In this aim, the optimized imaging protocol from specific aim 1 will be translated into an experimental protocol that mimics a clinical scenario wherein regular ultrasonic screening examinations for patients at high risk of developing pancreatic cancer are performed. In vivo ultrasound imaging signal will also be quantitatively correlated with the presence and magnitude of angiogenesis and VEGFR2 expression in early stage pancreatic cancer in transgenic mice as assessed by ex vivo assays. Since we are exploring a novel ultrasound contrast agent designed for future use in humans, this project will lay the groundwork for clinical translation of molecular ultrasound into patients with pancreatic cancer. In addition, this research will provide further insight into the biology of tumor angiogenesis at early stage pancreatic cancer and will bring a new approach for non-invasive molecular imaging of early stage pancreatic cancer to othe investigators with similar research interests.
Pancreatic cancer is a lethal disease with early detection currently offering the best hope to improve patient survival. Ultrasound, often combined with endoscopy, is among the primary imaging approaches in patients with suspected pancreatic disease. However, ultrasound is not sensitive and specific enough to detect pancreatic cancer at an early stage. In this research application, we develop and test a modified ultrasound imaging technique that can visualize markers at the molecular level that are present at very early stages of pancreatic cancer. We use gas-filled microbubbles as contrast agents to visualize preinvasive and early stage invasive pancreatic cancer in different murine models of pancreatic cancer. The contrast microbubbles used in our research are designed for a future use in humans. Therefore, this project will lay the foundation for a use of molecular ultrasound in patients with pancreatic cancer. Following successful outcome with our current study, we anticipate rapid translation of this technique into the clinic to expand patient survival and improve patient care by diagnosing this deadly disease much earlier.
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