Abstract
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Objectives: PET tracers targeting the prostate specific membrane antigen (PSMA) have shown promise to detect prostate cancer recurrence and metastases that are occult on conventional imaging. However, most studies reported to date are retrospective or involve a small number of subjects. The objective of this prospective study was to evaluate the lesion detection rate, safety, and impact on management of [18F]DCFPyL PET/CT for prostate cancer imaging.
Methods: An interim analysis of the first 208 [18F]DCFPyL PET/CT patient scans done in an investigator-initiated clinical trial (clinicaltrials.gov identifier NCT03181867) was conducted. The inclusion criteria were: (1) known prostate cancer with biochemical recurrence after initial curative therapy with radical prostatectomy with PSA > 0.4 ng/mL followed by an additional measurement showing increase; (2) known prostate cancer with biochemical recurrence after initial curative therapy by radiation therapy with a PSA level > 2.0 ng/mL above nadir after radiation therapy; (3) castration resistant prostate cancer with minimum PSA of 2.0 ng/mL and castrate levels of testosterone (<1.7 nmol/L); (4) findings on other examinations that are suspicious but not conclusive for metastatic disease. The participants underwent [18F]DCFPyL PET/CT after informed consent was obtained. The localization and number of lesions was recorded as well as uptake of the five most active lesions. Referring physicians completed a pre- and post-test survey to determine impact on management.
Results: Two hundred and eight subjects were evaluated. The lesion detection rates were: 60% (PSA 0.2 to <0.5), 83% (0.5 to <1.0), 73% (1.0 to <2.0), 94% (≥2.0). Many subjects had few lesions: 38.5% (1 lesion), 9.6% (2 lesions), 6.7% (3 lesions). By ANOVA analysis, the number of lesions was significantly related to PSA, but there was a large overlap in PSA ranges for number of lesion categories. Total lesion uptake was also significantly related to PSA values. There were no adverse events during scans. Twenty-two subjects reported mild adverse events after the scan; all resolved completely. Treatment intent changed in 64.4%, disease stage changed in 66.7%, and management plans changed in 87.8% following [18F]DCFPyL PET/CT imaging.
Conclusions: [18F]DCFPyL is a safe and sensitive radiopharmaceutical for the detection of prostate cancer. It also improved decision making for referring physicians and changed management for the majority of participants.