[18]F-Fluciclatide for Kidney Cancer Imaging Studies and Treatment

Background: \- The experimental contrast agent \[18\]F-Fluciclatide is being tested for cancer treatment imaging studies. It is designed to show tumors in which new blood vessels are growing. Imaging studies with \[18\]F-Fluciclatide may help predict how well a tumor will respond to therapy that will prevent the growth of new blood vessels. Researchers will test \[18\]F-Fluciclatide before beginning treatment and after the first treatment cycle. Participants may also have a third scan with \[18\]F-Fluciclatide between 2 and 7 days after starting treatment to look for changes in blood vessel growth early after starting therapy. Objectives: \- To test the safety and effectiveness of \[18\]F-Fluciclatide in predicting cancer treatment outcomes. Eligibility: \- Individuals at least 18 years of age who will have kidney cancer treatment to stop tumor blood vessel growth. Design: * Participants will be screened with a physical exam and medical history. Blood and urine samples will be collected. Tumor imaging studies and biopsies will be performed before starting the study. * Participants will have two positron emission tomography (PET) and computed tomography (CT) scans. \[18\]F-Fluciclatide will be used for each scan. One scan will happen before the start of cancer treatment, and the second will happen after the first treatment cycle. * Participants may also have an optional third PET/CT scan with \[18\]F-Fluciclatide. This scan will take place 2 to 7 days after beginning therapy. * Depending on the location of the tumor, some participants may have an optional magnetic resonance imaging scan to look for changes in tumor blood flow and size. These scans will be done within 3 weeks of each \[18\]F-Fluciclatide PET/CT scan. * The scans will be monitored with regular blood tests and vital signs. * Participants will be followed for up to 1 year after the study to look for overall disease response to therapy.