1779P PSMA guided approach for bIoCHEmical relapse after prostatectomy-PSICHE trial

Salvage radiotherapy (SRT) is one of the cornerstone for treatment of biochemical relapse (BR) after radical prostatectomy (RP). One randomized controlled trial suggested that next generation imaging (NGI) may have a significant impact on patients management in this scenario. Nonetheless, how to best manage oligometastatic patients identified by PSMA PET imaging requires additional investigation. PSICHE (NCT05022914) is a prospective multicentric trial aimed to test a [68Ga]Ga- PSMA-11 PET/CT imaging tailored strategy. Patients affected by biochemical relapse post RP (defined as PSA >0.2 ng/ml, <1 ng/ml) underwent [68Ga]Ga-PSMA-11 PET/CT imaging. After staging, management was performed according to a pre-defined algorithm. Observation and re-staging at further PSA progression were proposed to patients with negative PSMA and previous postoperative RT. Prostate bed SRT was proposed to all patients with a negative staging or positive imaging within prostate bed. Stereotactic body radiotherapy (SBRT) to all sites of disease was used for all patients with pelvic nodal recurrence (nodal disease < 2 cm under aortic bifurcation) or oligometastatic disease. Androgen deprivation therapy +/- androgen receptor targeted agent was provided in case of widespread metastatic disease. In the present analysis, we report early biochemical analysis focusing on complete biochemical response (PSA ≤0.2 ng/ml) and biochemical response (PSA ≤50% if compared to baseline value before treatment). Gastrointestinal (GI) or genitourinary (GU) toxicity was assessed according to CTCAE v 4.0. Overall, 110 patients were included in the current analysis. At 3 months after treatment, complete biochemical response and biochemical response were detected in 45.4% and 53.6% of patients, respectively. Seven patients had G1 GI toxicity, GU toxicity was reported in 30 patients (only 3 G2 adverse events, overall). No G>2 toxicity was reported. A PSMA targeted treatment strategy led to promising results and was well tolerated within a prospective multicentric trial.