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)

Purpose: Prostate specific membrane antigen-targeted positron emission tomography/computerized tomography has the potential to improve the detection and localization of prostate cancer. OSPREY was a prospective trial designed to determine the diagnostic performance of F-18- DCFPyL-positron emission tomography/computerized tomography for detecting sites of metastatic prostate cancer. Materials and Methods: Two patient populations underwent F-18-DCFPyLpositron emission tomography/computerized tomography. Cohort A enrolled men with high-risk prostate cancer undergoing radical prostatectomy with pelvic lymphadenectomy. Cohort B enrolled patients with suspected recurrent/metastatic prostate cancer on conventional imaging. Three blinded central readers evaluated the F-18-DCFPyL-positron emission tomography/computerized tomography. Diagnostic performance of F-18-DCFPyL-positron emission tomography/computerized tomography was based on imaging results compared to histopathology. In cohort A, detection of pelvic nodal disease (with specificity and sensitivity as co-primary end points) and of extrapelvic metastases were evaluated. In cohort B, sensitivity and positive predictive value for prostate cancer within biopsied lesions were evaluated. Results: A total of 385 patients were enrolled. In cohort A (252 evaluable patients), F-18-DCFPyL-positron emission tomography/computerized tomography 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 end point) among 3 readers for pelvic nodal involvement; median positive predictive value and negative predictive value were 86.7% (69.7%-95.3%) and 83.2% (78.2%-88.1%), respectively. In cohort B (93 evaluable patients, median prostate specific antigen 11.3 ng/ml), median sensitivity and positive predictive value for extraprostatic lesions were 95.8% (87.8%-99.0%) and 81.9% (73.7%-90.2%), respectively. Conclusions: The primary end point for specificity was met while the primary end point for sensitivity was not. The high positive predictive value observed in both cohorts indicates that F-18-DCFPyL-positive lesions are likely to represent disease, supporting the potential utility of F-18-DCFPyL-positron emission tomography/ computerized tomography to stage men with high-risk prostate cancer for nodal or distant metastases, and reliably detect sites of disease in men with suspected metastatic prostate cancer.

Automated summary

The study aimed to evaluate the diagnostic performance of F-18-DCFPyL positron emission tomography/computerized tomography in detecting metastatic sites of prostate cancer. The results showed high specificity and positive predictive value, but moderate sensitivity.