ESTRO 2025 - Abstract Book

S1907

Clinical - Urology

ESTRO 2025

940

Mini-Oral PERSIAN TRIAL (NCT03449719): Apalutamide and stereotactic body radiation therapy in patients affected by hormone-sensitive prostate cancer Giulio Francolini 1 , Vanessa Di Cataldo 1 , Pietro Garlatti 1 , Saverio Caini 2 , Alessio Bruni 3 , Nicola Simoni 4 , Matteo Augugliaro 5 , Cinzia Iotti 5 , Luca Tagliaferri 6 , Roberto Iacovelli 7 , Chiara Ciccarese 8 , Nicola Battelli 9 , GIanluca Ingrosso 10 , Angelo Porreca 11 , Marco Trovò 12 , Giuseppe Fornarini 13 , Giuseppe C Iorio 14 , Umberto Ricardi 14 , Alessia Guarneri 15 , Cinzia Ortega 16 , Michele Sisani 17 , Mattia F Osti 18 , Veronica Mollica 19 , Alfio Di Grazia 20 , Lorenzo Livi 1 1 Radiation oncology, Azienda Ospedaliero Universitaria Careggi, Università di Firenze, Florence, Italy. 2 Cancer Risk Factors and Lifestyle Epidemiology Unit, Institute for Cancer Research, Prevention and Clinical Network (ISPO), Florence, Italy. 3 Radiation Oncology Unit, Department of Oncology and Hematology, University Hospital of Modena, Modena, Italy. 4 Radiotherapy Unit, Azienda Ospedaliera Universitaria, Parma, Parma, Italy. 5 Unit of Radiotherapy, Azienda USL-IRCCS di Reggio Emilia, Reggio Emilia, Italy. 6 Radiotherapy Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 7 Medical oncology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, rome, Italy. 8 Medical Oncology, Fondazione Policlinico A. Gemelli IRCCS, Rome, Italy. 9 Medical oncology Unit, Macerata Hospital, Macerata, Italy. 10 Department of Radiation Oncology, University of Perugia, Perugia, Italy. 11 Department of Oncological Urology, Veneto Institute of Oncology (IOV) IRCCS, Padua, Italy. 12 Department of Radiation Oncology, University General Hospital, udine, Italy. 13 Medical Oncology Unit 1, IRCCS Ospedale Policlinico San Martino, Genoa, Italy. 14 Department of Oncology, Radiation Oncology, University of Turin, Turin, Italy. 15 Radiation Oncology, Candiolo Cancer Institute, FPO-IRCCS, Turin, Italy. 16 Division of Oncology, Institute for Cancer Research and Treatment, Alba Brà, Italy. 17 Medical Oncology Unit, San Donato Hospital, Arezzo, Italy. 18 Radiotherapy Department, St. Andrea Hospital, Sapienza University of Rome, Rome, Italy. 19 Medical Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy. 20 Radiation oncology, Humanitas Istituto Clinico Catanese, Catania, Italy Purpose/Objective: Apalutamide showed to provide significant overall survival improvement when added to standard androgen deprivation therapy (ADT) in metastatic hormone sensitive prostate cancer (mHSPC) [1]. In metastatic castrate resistant prostate cancer (mCRPC), addition of stereotactic body radiotherapy (SBRT) to abiraterone acetate, another androgen receptor pathway inhibitor (ARPI), showed to provide significant benefit in terms of clinical outcomes [2]. Nonetheless, there is no current evidence to support addition of SBRT to ARPIs in HSPC scenario. Testing the benefit of this approach in patients with oligometastatic HSPC undergoing apalutamide and ADT is the aim of the ongoing PERSIAN trial. Material/Methods: PERSIAN trial-NCT05717660, is a randomized phase II trial including patients with metachronous oligometastatic HSPC with < 5 metastatic sites. Subjects were randomized to ARM A (Control: apalutamide+ADT) or ARM B (Treatment: apalutamide+ADT+SBRT on all sites of metastatic disease detected by conventional imaging). Patients with visceral metastases or de novo metastatic disease were excluded from the trial. Here is presented a first interim analysis exploring rate of complete biochemical response (PSA<0.2 ng/ml) at 3 months after treatment start. Results: Currently, 96.6% (174 patients) of the final target sample size have been enrolled. A minimum follow up of 3 months was reached in 87 of these. Control vs treatment arm had a complete biochemical response rate of 91.1% vs 92.9% (OR 1.27, 95% CI 0.27-6.03, p=0.76). No association between biochemical response and presence of bone metastatic lesions or PSMA lesions undetected by conventional imaging was detected. Presence of PSMA positive lesions undetected by conventional imaging or presence of bone metastatic lesions were not predictive of biochemical response (OR 1.39, 95%CI 0.29-6.67, p=0.678 and OR 0.74, 95%CI 0.08-6.94, p = 0.791 respectively). Significant benefit in the experimental vs control arm was detected in patients with < 3 metastatic sites (OR 5.88, 95%CI 1.13 33.3, p = 0.03).