A Prospective Pilot Study of 89Zr-J591/Prostate Specific Membrane Antigen Positron Emission Tomography in Men with Localized Prostate Cancer Undergoing Radical Prostatectomy

Purpose: In this pilot study we explored the feasibility of Zr-89 labeled J591 monoclonal antibody positron emission tomography of localized prostate cancer. Materials and Methods: Before scheduled radical prostatectomy 11 patients were injected intravenously with Zr-89-J591, followed 6 days later by whole body positron emission tomography. Patients underwent surgery the day after imaging. Specimens were imaged by ex vivo micro positron emission tomography and a custom 3 Tesla magnetic resonance scanner coil. Positron emission tomography images and histopathology were correlated. Results: Median patient age was 61 years (range 47 to 68), median prostate specific antigen was 5.2 ng/ml (range 3.5 to 12.0) and median biopsy Gleason score of the 11 index lesions was 7 (range 7 to 9). On histopathology 22 lesions were identified. Median lesion size was 5.5 mm (range 2 to 21) and median Gleason score after radical prostatectomy was 7 (range 6 to 9). Eight of 11 index lesions (72.7%) were identified by in vivo positron emission tomography. Lesion identification improved with increasing lesion size for in vivo and ex vivo positron emission tomography (each p<0.0001), and increasing Gleason score (p=0.14 and 0.01, respectively). Standardized uptake values appeared to correlate with increased Gleason score but not significantly (p=0.19). Conclusions: To our knowledge this is the first report of Zr-89-J591/prostate specific membrane antigen positron emission tomography in localized prostate cancer cases. In this setting Zr-89-J591 bound to tumor foci in situ and positron emission tomography identified primarily Gleason score 7 or greater and larger tumors, likely corresponding to clinically significant disease warranting definitive therapy. A future, larger clinical validation trial is planned to better define the usefulness of Zr-89-J591 positron emission tomography for localized prostate cancer.