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.