[18F]PT2385 PET/CT in Patients With Renal Cell Carcinoma

HIF2α is an emerging therapeutic target in RCC. Proof-of-principle experiments in mice have demonstrated the feasibility of PET/CT imaging with novel radiotracers, \[11C\] and \[18F\]PT2385, to assess HIF2α expression in RCC. \[18F\]PT2385 has been proposed in this study for practical imaging of HIF2α. This is a non-therapeutic research study. Patients with localized or metastatic RCC will undergo imaging with \[18F\]PT2385. Patients will have the opportunity to ask questions regarding the procedure. A peripheral intravenous line will be placed for \[18F\]PT2385 administration. Patients will be injected with \[18F\]PT2385 intravenously and evaluated by PET/CT. Up to 15 subjects will undergo a dynamic PET scanning and multi-time point whole body imaging to determine the intratumoral tracer kinetics, the optimal time point for whole body imaging, as well as to calculate human dosimetry. In the first 3 subjects, a dynamic scan over the kidneys will be performed for approximately 25 minutes. Upon completion of the dynamic scan, a whole-body scan will be acquired to yield a whole body distribution at approximately 35 minutes. These 3 subjects will be asked to return for delayed whole body images at 120 and 240 minutes post injection. In up to 7 additional subjects, a dynamic scan will be acquired for 55 minutes followed by an immediate whole body scan to yield whole body distribution at approximately 65 minutes. Additional whole-body images will be acquired at 120 and 240 minutes post-injection. The pre-surgical cohort of 5 subjects will receive one PET/CT scan at the optimal time point determined from the first 15 subjects. Subsequently, surgery will be performed, and SUV from the PET scans will be correlated with HIF2α levels by IHC on the surgical specimen. A second cohort of 10 subjects with metastatic RCC will be evaluated. Patients with metastatic disease should all have a previous tissue diagnosis, and this cohort will focus on ccRCC patients. Subjects with metastatic ccRCC will be injected with \[18F\]PT2385 by intravenous (IV) push and will have a whole-body \[18F\]PT2385 PET/CT at a time considered optimal based on imaging studies performed in cohort 1. A mandatory biopsy will be performed, and up to 4 suitable core tissue samples will be obtained. A third cohort of 5 subjects with VHL syndrome and any of the following disease manifestations - RCC, CNS hemangioblastoma, and/or pancreatic neuroendocrine tumor(s)- will be evaluated. Subjects will be injected with \[18F\]PT2385 by IV push and will have a whole-body \[18F\]PT2385 PET at a time considered optimal based on imaging studies performed in the cohort 1. A biopsy is encouraged but not mandatory. If pursued, the biopsy will be performed in a similar fashion as that performed in cohort 2. Future biopsies per standard of care may be utilized for HIF2α and/or other biomarker analyses. Following dosimetry studies, a subset of patients may undergo repeat \[18F\]PT2385 PET studies. Patients in all cohorts will receive standard or experimental treatment for RCC at the discretion of the treating physician. Recently available at UTSW, Positron Emission Tomography/Magnetic Resonance Imaging (PET/MRI) may be used instead of PET/CT at the physician/investigator discretion wherever PET/CT is mentioned. PET/MRI is a novel hybrid technology that combines physiologic information from a PET scan and detailed anatomic images from an magnetic resonance imaging (MRI) scan. PET/MRI has the potential to increase imaging quality/diagnostic accuracy while reducing radiation exposure.