An 18F-Labeled PSMA Ligand for PET/CT of Prostate Cancer: First-in-Humans Observational Study and Clinical Experience with 18F-JK-PSMA-7 During the First Year of Application

Abstract

In preclinical trials, the recently developed tracer 2-methoxy-¹⁸F-DCFPyL (¹⁸F-JK-prostate-specific membrane antigen [PSMA]-7) has shown favorable properties regarding clinical performance and radiochemical accessibility. The aim of this study was to evaluate the clinical utility of ¹⁸F-JK-PSMA-7 for PET/CT imaging of patients with prostate cancer. Methods: In an Institutional Review Board-approved pilot study, the initial clinical utility of PET/CT imaging with ¹⁸F-JK-PSMA-7 was directly compared with ⁶⁸Ga-PSMA-11 PET/CT in a group of 10 patients with prostate cancer. The 2 PSMA tracers were administered to each patient less than 3 wk apart. Next, we analyzed the data of 75 consecutive patients who had undergone clinical ¹⁸F-JK-PSMA-7 PET/CT imaging for tumor localization of biochemical recurrence (BCR). Results: The pilot study in 10 patients who were examined with both PSMA tracers demonstrated that ¹⁸F-JK-PSMA-7 was at least equivalent to ⁶⁸Ga-PSMA-11. All unequivocally ⁶⁸Ga-PSMA-11-positive lesions could be also detected using ¹⁸F-JK-PSMA-7, and in 4 patients additional suspected PSMA-positive lesions were identified (1 patient changed from PSMA-negative to PSMA-positive). In patients with BCR (after prostatectomy or radiotherapy), the capacity of ¹⁸F-JK-PSMA-7 PET/CT to detect at least one PSMA-positive lesion was 84.8%. The prostate-specific antigen (PSA)-stratified detection rate of ¹⁸F-JK-PSMA-7 after prostatectomy varied among 54.5% (6/11 patients; PSA < 0.5 μg/L), 87.5% (14/16 patients; PSA 0.5-2 μg/L), and 90.9% (20/22 patients; PSA > 2 μg/L). Conclusion: The tracer ¹⁸F-JK-PSMA-7 was found to be safe and clinically useful. We demonstrated that ¹⁸F-JK-PSMA-7 was not inferior when directly compared with ⁶⁸Ga-PSMA-11 in a pilot study but indeed identified additional PSMA-avid suspected lesions in oligometastasized patients with BCR. In a subsequent analysis of a clinical cohort of BCR patients, ¹⁸F-JK-PSMA-7 was useful in tumor localization. ¹⁸F-JK-PSMA-7 is recommended for future prospective trials.

Keywords: 18F-JK-PSMA-7; PET imaging; PSMA tracer; prostate cancer.