Abstract
1485
Objectives: 18F-FPPRGD2 is a ligand targeting αvβ3, a member of the integrin family. We evaluated 18F-FPPRGD2 PET/CT in patients with metastatic renal cell cancer before and after antiangiogenic therapy. Methods: Seven patients (4 men and 3 women, mean age of 52.5-year-old) were enrolled in this prospective study. All patients had undergone both 18F-FPPRGD2 and 18F-FDG PET/CT within a month prior to starting therapy. We compared detectability using visual assessment and maximum standardized uptake value (SUVmax) for all lesions between the 18F-FPPRGD2 and 18F-FDG PET/CT. We also compared SUVmax of lesions seen on 18F-FPPRGD2 PET/CT before and after the therapy. Mann-Whitney U test and Spearman’s rank correlation coefficient were used as statistical analyses. Results: A total of 60 lesions were detected in this cohort. One primary tumor and one rib metastasis were not identified on 18F-FPPRGD2 or 18F-FDG PET/CT due to urinary excretion of the tracer and adjacent pneumonia, respectively. Visual assessment of 18F-FPPRGD2 and 18F-FDG PET/CT showed high uptake in 57 and 52 lesions, respectively. SUVmax from 18F-FPPRGD2 was significantly lower than that from 18F-FDG (4.4±2.9 vs 7.8±5.6, P<0.001). There was significant correlation between SUVmax measured from 18F-FPPRGD2 and 18F-FDG (R=0.519, P<0.001). Five patients had 18F-FPPRGD2 PET/CT at 1 week after antiangiogenic therapy. SUVmax significantly decreased between before and after antiangiogenic therapy (4.2±3.1 vs 2.7±1.4, P=0.005). Average change in SUVmax between the two 18F-FPPRGD2 PET/CT studies was -26.7±24.8%. Conclusions: 18F-FPPRGD2 PET/CT is a promising tool to detect metastatic renal cell cancer lesions and to monitor effect of antiangiogenic therapy. These results need to be confirmed in larger cohorts.