PSMA-PET/CT Registry for Recurrent Prostate Cancer (PREP): Initial findings from a single center.

5064 Background: Several lesion-targeted therapies exist for locally recurrent or limited stage metastatic prostate cancer (PCa) post-radiotherapy (RT) and radical prostatectomy (RP). However, detection of disease sites is limited using conventional imaging (CI) including computed tomography (CT) and bone scan. Prostate specific membrane antigen (PSMA) targeting PET radiopharmaceuticals like [18F]DCFPyL may help detect disease not seen on CI. Our objective was to assess the ability of PSMA targeted PET/CT to detect sites of disease recurrence and impact on patient management. Methods: This multi-center prospective registry study included six Ontario centers. Eligible patients in 1 of 7 clinical cohorts (Table) were identified and approved by Cancer Care Ontario (CCO) to have restaging with PSMA targeted PET/CT. Referring physicians were asked to complete a form indicating whether a change in management strategy would occur based on the PET/CT results. At 6 months post-PET/CT, actual patient management will be confirmed via provincial registries. These interim results are from a single center. Results: 253 patients were enrolled and had a PSMA targeted PET/CT. At baseline, median age was 71 years (range 50-102 years) and median PSA was 2.7 ng/mL (range 0.04-134.0 ng/mL). The majority of patients (n=59; 23.3%) were in cohort 2 (biochemical failure post-RP). In patients with negative CI, PSMA targeted PET/CT detected disease sites in 68.5% (170/248), resulting in a change in management for 67.8% (137/202) overall and 72.1% and 64.3% post-RT and post-RP, respectively. Conclusions: PSMA targeted PET/CT detected occult lesions on CI in the majority of patients enrolled, leading to a high rate of change in management. Our institutional results are in keeping with preliminary results reported for the provincial cohort. Clinical trial information: NCT03718260. [Table: see text]