What question did this study set out to answer?

To assess and compare urinary radioactivity and detection rates of two PSMA-PET radiopharmaceuticals in patients with biochemical recurrence of prostate cancer.

February 25, 2026Open Access

An intra-patient contemporaneous comparison of 18F-piflufolastat and 18F-flotufolastat urinary radioactivity and pelvic region detection rates in men with low PSA biochemical recurrence of prostate cancer after radical prostatectomy

Key Points

To assess and compare urinary radioactivity and detection rates of two PSMA-PET radiopharmaceuticals in patients with biochemical recurrence of prostate cancer.
Conducted a multicentre, intra-patient comparator study with PSMA-PET radiopharmaceuticals.
Enrolled patients with low PSA biochemical recurrence ≥6 months post-prostatectomy.
Performed PET/CT scans after administration of both radiopharmaceuticals.
Evaluated urinary radioactivity and detection rates by two blinded readers.
Significantly higher median bladder SUVmean was observed with 18F-piflufolastat (29.0) compared to 18F-flotufolastat (10.9; p < 0.001).
Detection rate for 18F-piflufolastat was 27.3% while 18F-flotufolastat had a detection rate of 45.5%.
Region-level detection rates in the prostate bed for both agents were similar, with slight advantages for 18F-flotufolastat in lymph nodes and extra-pelvic sites.
Among patients with PSA ≤0.2 ng/mL, 38.1% had positive scans with 18F-piflufolastat versus 52.4% with 18F-flotufolastat.

Abstract

This prospective, multicentre, intra-patient comparator study assessed urinary radioactivity, and patient-level and region-level detection rates (DR) with PSMA-PET radiopharmaceuticals, 18F-piflufolastat (18F-DCFPyL) and 18F-flotufolastat (18F-rhPSMA-7.3) in patients with biochemical recurrence (BCR) of prostate cancer to evaluate the hypothesis that lower urinary radioactivity is observed with 18F-flotufolastat. Patients with low PSA (≤0.5 ng/mL) BCR ≥6 months post-prostatectomy with undetectable PSA post-surgery, scheduled for standard-of-care 18F-piflufolastat PSMA-PET were enrolled. Patients underwent PET/CT 60 minutes post-18F-piflufolastat (9 mCi) administration, and a second PET/CT on the same scanner 1–10 days later, 60 minutes post-18F-flotufolastat (8 mCi) administration. The primary endpoint was the difference in urinary radioactivity (SUVmean) between the radiopharmaceuticals. Secondary endpoints included patient-level and region-level DR for each radiopharmaceutical, assessed by two blinded readers (a third resolved disagreements, allowing majority reads). Fifty-five evaluable patients (mean PSA, 0.28 ng/mL) were enrolled. Median bladder SUVmean was significantly higher with 18F-piflufolastat (29.0; interquartile range, 18.9–40.8) than 18F-flotufolastat (10.9; interquartile range, 6.0–18.5; p < 0.001 Wilcoxon signed-rank test). Majority read patient-level DR were 27.3% (15/55) for 18F-piflufolastat and 45.5% (25/55) for 18F-flotufolastat. Region-level DR for 18F-piflufolastat and 18F-flotufolastat, were 10.9% (6/55) and 18.2% (10/55) in the prostate bed, 14.5% (8/55) and 16.4% (9/55) in pelvic lymph nodes, and 7.3% (4/55) and 21.8% (12/55) in extra-pelvic sites. Among patients with PSA ≤0.2 ng/mL, 38.1% (8/21) and 52.4% (11/21) had positive 18F-piflufolastat and 18F-flotufolastat scans, respectively. This intra-patient comparator shows 18F-flotufolastat has significantly lower urinary radioactivity than 18F-piflufolastat, which may help to optimise image assessment in regions close to the urinary tract. Trial registration, clinicaltrials.gov: NCT06604442. Registered September 2024.

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