Abstract 343P
Background
Research on PSMA PET/CT and pending FDA approval are predominantly aimed towards biochemical recurrence, rather than presurgical staging. Studies on the latter indication have almost exclusively investigated biopsy-proven cancers. We herein present the first in-man clinical evaluation of a novel 18 F-labelled PSMA ligand, Florastamin, in screening for prostate cancer.
Methods
We recruited twenty men with PSA levels between 3 (the threshold for biopsy) and 20 n/mL. A dose of 267-370 MBq (8-10 mCi) 18 F-Florastamin was administered. Whole-body images were acquired at 90 minutes postinjection, followed by an additional pelvic PET/CT acquisition 30 minutes later. Conventional imaging (MRI) was performed within one week of, usually preceding, the PET/CT. PET/CT findings were compared to preoperative diagnostic MRI and correlated with final biopsy pathology. Diagnostic performance of the two modalities and both timepoints were compared on a per-patient, per-lobe and per-segment basis. Inter-rater agreement was also measured for three readers.
Results
Twenty patients, who had a median PSA of 8.02 ng/mL (range 3.24-18.6) were enrolled in this study. Twelve patients were biopsy-proven with prostate cancer, of which four were low-risk and eight were intermediate risk. PET/CT visual analysis identified abnormal 18 F-Florastamin uptake in at least one primary prostatic tumor focus in 10/12 patients at 90 minutes and 11/12 patients at 120 minutes. The per-segment sensitivity, specificity and accuracy was 50%, 99.3% and 93.1% for MRI with the best performing threshold of ≥ 4, and 85%, 99.3% and 97.5% for 18 F-Florastamin at 60 minutes, respectively. Delayed imaging showed comparable accuracy, with detection an additional true-positive lesion. The inter-rater agreement was substantial to almost perfect.
Conclusions
18 F-Florastamin is a promising PET tracer that correctly identifies foci of cancer within the prostate with a higher accuracy than conventional imaging (MRI), and may be helpful in stratification of patients with low to intermediate PSA levels to better assess the need for an invasive biopsy. In our cohort, triage with 18 F-Florastamin PET/CT would have reduced unnecessary biopsies in 9/20 (45%) patients.
Clinical trial identification
KCT0004609.
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
FutureChem.
Disclosure
All authors have declared no conflicts of interest.