PSMA PET parameters predict biochemical recurrence in high-risk prostate cancer after neoadjuvant hormonal therapy

PURPOSE: To investigate the relationship between [F]PSMA-1007 PET parameters and biochemical recurrence-free survival (BCR-FS) in high-risk primary prostate cancer patients receiving neoadjuvant hormonal treatment. METHODS: This prospective randomized, double-blind, placebo-controlled phase II trial included 89 high-risk primary prostate cancer patients who received a pelvic [F]PSMA-1007 PET/MRI prior to and following neoadjuvant hormonal treatment. Patients were randomly assigned to neoadjuvant hormonal treatment with degarelix + apalutamide (n = 45) or degarelix + matching placebo (n = 44) for 3 months followed by radical prostatectomy and extended pelvic lymph node dissection. The following [F]PSMA-1007 PET parameters were determined on the pre- and posttreatment [F]PSMA-1007 PET: (i) semi-quantitative [F]PSMA-1007 PET parameters such as SUV, SUV, PSMA-expressing volume and total lesion activity, and their absolute and relative differences; (ii) number of pelvic lymph node, distant and extraprostatic (i.e. pelvic lymph node and distant) metastases determined on [F]PSMA-1007 PET; (iii) [F]PSMA-1007 PET-based response criteria (aPERCIST and RECIP 1.0); (iv) molecular imaging TNM-stage as determined by PROMISE V2. RESULTS: 35% of included patients developed BCR within a median follow-up time of 38 months. Multivariate regression analyses revealed that PSMA-expressing volume posttreatment, the number of distant metastases pretreatment and miN1 + miN2 vs. miN0 pretreatment were significant predictors of BCR-FS with hazard ratios of 1.184 (95% CI 1.070-1.309, p = 0.0010), 5.820 (95% CI 2.498-13.561, p < 0.0001) and 4.024 (95% CI 1.740-9.307, p = 0.0011), respectively. CONCLUSION: Our results indicate that [F]PSMA-1007 PET might be used to aid in patient stratification for determining which patients would benefit from additional (neo)adjuvant treatment.