Stereotactic Body Radiation Therapy and Abiraterone Acetate for Patients Affected by Oligometastatic Castrate-Resistant Prostate Cancer: A Randomized Phase II Trial (ARTO)

Author(s): Giulio Francolini, MD1; Andrea Gaetano Allegra, MD2; Beatrice Detti, MD1; Vanessa Di Cataldo, MD1; Saverio Caini, MD3; Alessio Bruni, MD4; Gianluca Ingrosso, MD5; Rolando Maria D’Angelillo, MD6; Anna Rita Alitto, MD7; Matteo Augugliaro, MD8; Luca Triggiani, MD9; Silvana Parisi, MD10; Gaetano Facchini, MD11; Marco Banini, MD12; Gabriele Simontacchi, MD1; Isacco Desideri, MD12; Icro Meattini, MD12; Richard K. Valicenti, MD13; Lorenzo Livi, MD12
Maem Hussein MD

Dr. Maen Hussein's Thoughts

SBRT improves PFS in addition to antiandrogen therapy. The question is, with oligomets, do we need systemic therapy in all patients? Or will SBRT be sufficient?
I encourage our FCS radiation oncologists to provide their input on this study, as well.

PURPOSE

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).

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Author Affiliations

1Radiation Oncology Unit, Oncology Department, Azienda Ospedaliero Universitaria Careggi, Firenze, Italy; 2Department of Biomedical, Experimental and Clinical Sciences “M. Serio”, University of Florence, Florence, Italy; 3Cancer Risk Factors and Lifestyle Epidemiology Unit, Institute for Cancer Research, Prevention and Clinical Network (ISPO), Florence, Italy; 4Radiation Oncology Unit, Department of Oncology and Hematology, University Hospital of Modena, Modena, Italy; 5Radiation Oncology Section, Department of Medicine and Surgery, University of Perugia, Perugia, Italy; 6Radiation Oncology, Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy; 7UOC di Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, Rome, Italy; 8Unit of Radiotherapy, Azienda USL-IRCCS di Reggio Emilia, Reggio Emilia, Italy; 9Università degli Studi di Brescia, Department of Radiation Oncology, Brescia University, Brescia, Italy; 10Radiation Oncology Unit, Department of Biomedical, Dental Science and Morphological and Functional Images, University of Messina, Messina, Italy; 11Medical Oncology Unit, SM delle Grazie Hospital, Pozzuoli, Italy; 12Department of Biomedical, Experimental and Clinical Sciences “M. Serio”, University of Florence, Florence, Italy; 13Department of Radiation Oncology, UC Davis, Davis, CA

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