A Phase 2/3 Prospective Multicenter Study of the Diagnostic Accuracy of Prostate-Specific Membrane Antigen PET/CT with 18F-DCFPyL in Prostate Cancer Patients (OSPREY).

PSMA-targeted PET/CT has the potential to improve the detection and localization of prostate cancer (PCa). OSPREY was a prospective trial designed to determine the diagnostic performance of 18F-DCFPyL-PET/CT for detecting sites of metastatic PCa.

Two patient populations underwent 18F-DCFPyL-PET/CT: Cohort A enrolled men with high-risk PCa undergoing radical prostatectomy with pelvic lymphadenectomy. Cohort B enrolled patients with suspected recurrent/metastatic PCa on conventional imaging. Three blinded central readers evaluated the 18F-DCFPyL-PET/CT scans. Diagnostic performance of 18F-DCFPyL-PET/CT was based on imaging results compared to histopathology. In Cohort A, detection of pelvic nodal disease (with specificity and sensitivity as co-primary endpoints) and of extra-pelvic metastases were evaluated. In Cohort B, sensitivity and PPV for PCa within biopsied lesions were evaluated.

385 patients were enrolled. In Cohort A (N=252 evaluable), 18F-DCFPyL-PET/CT had median specificity of 97.9% (95% CI: 94.5%-99.4%) and median sensitivity of 40.3% (28.1%-52.5%, not meeting prespecified endpoint) among three readers for pelvic nodal involvement; median PPV and NPV were 86.7% (69.7%-95.3%) and 83.2% (78.2%-88.1%), respectively. In Cohort B (n=93 evaluable, median PSA 11.3 ng/mL), median sensitivity and PPV for extra-prostatic lesions were 95.8% (87.8%-99.0%) and 81.9% (73.7%-90.2%), respectively.

The primary endpoint for specificity was met while the primary endpoint for sensitivity was not. The high PPV observed in both cohorts indicates that 18F-DCFPyL-positive lesions are likely to represent disease, supporting the potential utility of 18F-DCFPyL-PET/CT to stage men with high-risk PCa for nodal or distant metastases, and reliably detect sites of disease in men with suspected metastatic PCa.

The Journal of urology. 2021 Feb 26 [Epub ahead of print]

Kenneth J Pienta, Michael A Gorin, Steven P Rowe, Peter R Carroll, Frédéric Pouliot, Stephan Probst, Lawrence Saperstein, Mark A Preston, Ajjai S Alva, Akash Patnaik, Jeremy C Durack, Nancy Stambler, Tess Lin, Jessica Jensen, Vivien Wong, Barry A Siegel, Michael J Morris

The James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins University School of Medicine, Baltimore, MD., The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD., University of California San Francisco, San Francisco, CA., CHU de Quebec and Laval University, Quebec City, QC., Jewish General Hospital, Montreal, QC., Yale School of Medicine, New Haven, CT., Brigham and Women's Hospital/Dana-Farber Cancer Institute, Boston, MA., University of Michigan, Ann Arbor, MI., Section of Hematology/Oncology, Department of Medicine, The University of Chicago, Chicago, IL., Memorial Sloan Kettering Cancer Center, New York, NY., Progenics Pharmaceuticals, Inc., New York, NY., Mallinckrodt Institute of Radiology and Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri.