Interim analyses from the PROSPET-BX trial: [G8Ga]PSMA PET/CT vs. mpMRI in patients with suspicion of prostate cancer and previous negative biopsy.

Abstract

282 Background: Herein we present the results of the interim analyses of our prospective trial (Identifier: NCT05297162), designed to compare [68Ga]PSMA PET/CT with mpMRI in men with a high suspicion of prostate cancer (PCa) after at least one previous negative biopsy. Methods: From April 2022 until September 2023, overall, 94 patients were screened, 78 were enrolled and 64 completed all study investigations. Inclusion criteria: PSA>4.0ng/ml; free-to-total PSA ratio <20%; progressive rise of PSA levels in two consecutive samples; at least one previous negative biopsy; negative digital rectal examination. [68Ga]PSMA PET/CT and 3T mpMRI were performed within one month, followed by TRUS-fusion prostate biopsy. Target lesions were defined based on PI-RADS v2.1 for mpMRI and Primary Score, SUVmax and SUVratio for [68Ga]PSMA PET/CT, then correlated to pathology findings. Results: Median age was 64 years (range 51-83) and median PSA 10.4 ng/ml (range 4.3-25,9). Most patients (76.6%) had one previous negative biopsy. According to re-biopsy results, 10 patients presented with clinically significant PCa (csPCa), 4 with GS 6, while the majority had a negative biopsy (78%). mpMRI results were: 40 patients with PI-RADS 2 (62.5%), 3 with PI-RADS 3 (4.7%), 15 with PI-RADS 4 (23.4%), and 6 with PI-RADS 5 (9.4%). Primary scores were: 45 score 1-2 (70%), and 19 score 3-5. PI-RADS and Primary scores were significantly correlated (P=0.0006). Median SUVmax and SUVratio were 3.7 and 1.35 for benign versus 8.9 and 3 for malignancy, respectively (P<0.001). ROC analyses identified optimal cut-off points for csPCA, with SUVmax>7.48 (AUC 0.756; 95%CI 0.633-0.855) and SUVratio>2.79 (AUC 0.748; 95%CI 0.624-0.848). PI-RADS, Primary score, SUVmax and SUVratio proved significantly associated to biopsy results. When combining [68Ga]PSMA PET/CT with mpMRI data, the detection rate was 90% for csPCa, and the combination of both modalities could spare 87.5% of unnecessary re-biopsies. Conclusions: In these interim results, [68Ga]PSMA PET/CT parameters predict biopsy results as mpMRI in patients who are candidates to re-biopsy; the combination of both modalities can spare most unnecessary re-biopsies, by granting a 90% detection rate for csPCa. Clinical trial information: NCT05297162 .