[¹⁸F]PSMA-1007 PET for biochemical recurrence of prostate cancer, a comparison with [¹⁸F]Fluciclovine

The objective of this study was to compare the detection rates of [¹⁸F]PSMA-1007 and [¹⁸F]Fluciclovine in early biochemical recurrence (BCR) of prostate cancer, i.e. with low prostate-specific antigen (PSA) levels (0.2-5.0 µg/L).

This was a prospective, single-center (Radboudumc; Nijmegen, The Netherlands), comparative phase II diagnostic imaging study (NCT04239742). The main inclusion criteria were histologically proven adenocarcinoma of the prostate, BCR after radical treatment with two consecutive (rising) PSA values (0.2-5.0 µg/L). Patients underwent both [¹⁸F]PSMA-1007 PET/CT and [¹⁸F]Fluciclovine PET/CT within two weeks. Both scans were blindly scored by three independent nuclear medicine physicians. Hereafter, a result per scan and region was generated by consensus. The primary outcome was to compare the detection rate on a patient and region level. Secondary objectives were to determine detection rate stratified for PSA value, inter-reader agreement, and SUV measurements. For lesion confirmation a composite reference score was established using follow-up data.

Data of fifty patients were included, median age of 71 (IQR: 67-74) years and median PSA value of 0.38 (IQR: 0.30-1.55) µg/L. Detection rates were 68% (34/50) for [¹⁸F]PSMA-1007 and 42% (21/50) for [¹⁸F]Fluciclovine on a patient level (p < 0.001). Detection rates stratified for PSA value of [¹⁸F]PSMA-1007 in comparison with [¹⁸F]Fluciclovine were for PSA 0.2-0.5 µg/L; 60.7% versus 25.0% (p = 0.002); and for PSA ≥ 0.5 µg/L; 77.3% versus 63.6% (p = 0.250). There was a trend for higher inter-reader agreement with [¹⁸F]PSMA-1007. SUV_max (p < 0.001) was significantly higher for [¹⁸F]PSMA-1007 in comparison to [¹⁸F]Fluciclovine.

In patients with early BCR of prostate cancer after radical surgery or radiotherapy, [¹⁸F]PSMA-1007 demonstrated a significantly higher detection rate than [¹⁸F]Fluciclovine. This is particularly relevant since earlier and more accurate detection of a BCR can guide salvage therapy into a tailored strategy which may improve outcomes.

ClinicalTrials.gov, NCT04239742. Registered 02 January 2020, https://clinicaltrials.gov/study/NCT04239742 .