ARTO (ClinicalTrials.gov identifier: NCT03449719) is a multicenter, phase II randomized clinical trial testing the benefit of adding stereotactic body radiation therapy (SBRT) to abiraterone acetate and prednisone (AAP) in patients with oligometastatic castrate-resistant prostate cancer (CRPC).
All patients were affected by oligometastatic CRPC as defined as three or less nonvisceral metastatic lesions. Patients were randomly assigned 1:1 to receive either AAP alone (control arm) or AAP with concomitant SBRT to all the sites of disease (experimental arm). Primary end point was the rate of biochemical response (BR), defined as a prostate-specific antigen (PSA) decrease ≥50% from baseline measured at 6 months from treatment start. Complete BR (CBR), defined as PSA < 0.2 ng/mL at 6 months from treatment, and progression-free survival (PFS) were secondary end points.
One hundred and fifty-seven patients were enrolled between January 2019 and September 2022. BR was detected in 79.6% of patients (92% v 68.3% in the experimental v control arm, respectively), with an odds ratio (OR) of 5.34 (95% CI, 2.05 to 13.88; P = .001) in favor of the experimental arm. CBR was detected in 38.8% of patients (56% v 23.2% in the experimental v control arm, respectively), with an OR of 4.22 (95% CI, 2.12 to 8.38; P < .001). SBRT yielded a significant PFS improvement, with a hazard ratio for progression of 0.35 (95% CI, 0.21 to 0.57; P < .001) in the experimental versus control arm.
The trial reached its primary end point of biochemical control and PFS, suggesting a clinical advantage for SBRT in addition to first-line AAP treatment in patients with metastatic castration-resistant prostate cancer.
Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2023 Sep 21 [Epub ahead of print]
Giulio Francolini, Andrea Gaetano Allegra, Beatrice Detti, Vanessa Di Cataldo, Saverio Caini, Alessio Bruni, Gianluca Ingrosso, Rolando Maria D'Angelillo, Anna Rita Alitto, Matteo Augugliaro, Luca Triggiani, Silvana Parisi, Gaetano Facchini, Marco Banini, Gabriele Simontacchi, Isacco Desideri, Icro Meattini, Richard K Valicenti, Lorenzo Livi, ARTO Working Group members
Radiation Oncology Unit, Oncology Department, Azienda Ospedaliero Universitaria Careggi, Firenze, Italy., Department of Biomedical, Experimental and Clinical Sciences "M. Serio", University of Florence, Florence, Italy., Cancer Risk Factors and Lifestyle Epidemiology Unit, Institute for Cancer Research, Prevention and Clinical Network (ISPO), Florence, Italy., Radiation Oncology Unit, Department of Oncology and Hematology, University Hospital of Modena, Modena, Italy., Radiation Oncology Section, Department of Medicine and Surgery, University of Perugia, Perugia, Italy., Radiation Oncology, Department of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy., UOC di Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy., Unit of Radiotherapy, Azienda USL-IRCCS di Reggio Emilia, Reggio Emilia, Italy., Università degli Studi di Brescia, Department of Radiation Oncology, Brescia University, Brescia, Italy., Radiation Oncology Unit, Department of Biomedical, Dental Science and Morphological and Functional Images, University of Messina, Messina, Italy., Medical Oncology Unit, SM delle Grazie Hospital, Pozzuoli, Italy., Department of Radiation Oncology, UC Davis, Davis, CA.