[18F]Fluciclatide PET Imaging of Pazopanib Response

Positron emission tomography (PET) is a non-invasive imaging tool for monitoring functional and metabolic responses of biological events with specific radiotracer in vivo. The PET tracer \[18F\]Fluciclatide is an 18F radiolabeled small peptide containing the RGD (arginine-glycine-aspartate) tri-peptide, which preferentially binds with high affinity to αvβ3 and αvβ5 integrins. αvβ3-integrins are expressed at low levels on epithelial cells and mature endothelial cells but are expressed at high levels on activated endothelial cells in the neo-vasculature of a range of tumors and it also may regulate angiogenesis. If pazopanib acts mainly on active angiogenetic tumors, the quantitative uptake of \[18F\]Fluciclatide can be used to predict the effect of this antiangiogenic drug. The investigators expected the baseline tumor uptake in \[18F\]Fluciclatide to be able to predict treatment response, and planned a study of \[18F\]FluciclatidePET for patients with metastatic RCC who received pazopanib systemic therapy.