ESTRO 2022

Session Item

Sunday

May 08

16:55 - 17:55

Room D1

Urology

Co-Chair: Nejla Fourati, Tunisia;

Chair: , Germany

Session Type: Proffered Papers

Track: Clinical

Journey:

16:55 - 17:05

Early outcomes of a randomized trial of SBRT and Abiraterore in mCPRC: ARTO trial NCT03449719

Giulio Francolini, Italy

Presentation Number: OC-0605

Abstract

Abstract Title:

Early outcomes of a randomized trial of SBRT and Abiraterore in mCPRC: ARTO trial NCT03449719

Authors:

Giulio Francolini¹, Beatrice Detti¹, Vanessa Di Cataldo², Saverio Caini³, Anna Rita Alitto⁴, Silvana Parisi⁵, Chiara Demofonti⁶, Alessio Bruni⁷, Gianluca Ingrosso⁸, Giorgia Timon⁹, Angiolo Tagliagambe¹⁰, Michele Aquilano¹¹, Lucia Pia Ciccone¹¹, Viola Salvestrini¹¹, Giulio Frosini¹¹, Cecilia Cerbai¹¹, Andrea Allegra¹¹, Luca Burchini¹², Isacco Desideri¹³, Monica Mangoni¹⁴, Icro Meattini¹⁴, Lorenzo Livi¹⁴

¹Azienda Ospedaliero Universitaria Careggi, Radiation Oncology Unit Oncology Department, Florence, Italy; ²Istituto Fiorentino di Cura e Assistenza (IFCA), Radiation Oncology CyberKnife Center, Florence, Italy; ³Institute for Cancer Research, Prevention and Clinical Network (ISPRO), Cancer Risk Factors and Lifestyle Epidemiology Unit, Florence, Italy; ⁴Fondazione Policlinico Universitario A. Gemelli IRCCS, U.O.C. di Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Rome, Italy; ⁵University of Messina, Department of Biomedical and Dental Sciences and Morpho-Functional Imaging, Messina, Italy; ⁶Tor Vergata General Hospital, Radiotherapy Unit, Department of Oncology and Hematology, Rome, Italy; ⁷University Hospital of Modena, Radiation Therapy Unit, Department of Oncology and Hematology, Modena, Italy; ⁸University of Perugia, Radiation Oncology Section, Department of Surgical and Biomedical Science, Perugia, Italy; ⁹AUSL-IRCCS di Reggio Emilia, Radiation Oncology Unit, Clinical Cancer Centre, Reggio Emilia, Italy; ¹⁰Azienda Azienda Usl 1 di Massa e Carrara, Struttura Complessa UO Radioterapia, Massa Carrara, Italy; ¹¹University of Florence, Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", Florence, Italy; ¹²University of Florence, Department of Biomedical, Experiemental and Clinical Sciences "Mario Serio", Florence, Italy; ¹³University of Florence, Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", Florence, Italy; ¹⁴University of Florence - Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", Azienda Ospedaliero Universitaria Careggi - Radiation Oncology Unit Oncology Department, Florence, Italy

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Purpose or Objective

A multicentre, randomized trial testing the benefit of stereotactic body radiation therapy (SBRT) addition to abiraterone acetate (AA) in oligometastatic Castrate Resistant Prostate Cancer (CRPC) patients (ARTO, NCT03449719) is currently running in 16 Italian centres. Here we present an early report, exploring efficacy results of SBRT+AA combination after enrollment of 79% of target sample.

Material and Methods

Patients affected by oligometastatic CRPC (<3 non-visceral metastatic lesions) were enrolled in the trial. Patients were randomized 1:1 to receive either AA alone (control arm) or associated with concomitant SBRT on all sites of disease (treatment arm). Primary endpoint is biochemical response, defined as a PSA≥50% from baseline measured within 6 months from treatment start (BR). PSA drop (PSA reduction at 6 months if compared to baseline, expressed as a logarithmic function, logPSA) and complete biochemical response (CBR), defined as PSA at 6 months ≤0.2 ng/ml are secondary endpoints of the trial. All included patients had ≥6 months of follow up.

Results

One hundred twenty-three patients were enrolled in ARTO trial, 98 patients were evaluable for this analysis. 76.5% of patients had BR (82.2% vs. 71.7% in treatment vs. control arm, respectively), with an unadjusted odds ratio (OR) of 1.83 (95%CI 0.69-4.82, p-value 0.22). After adjustment for baseline PSA and metastatic sites (>1 vs. 1), the OR for BR was 2.23 (95%CI 0.74-6.73, p-value 0.15). A nearly significant trend for a lower logPSA at 6 months was detected in treatment vs control arm (beta -0.76, 95%CI -1.58, 0.05, p-value 0.064). 36.7% of patients had CBR (46.7% vs. 28.3% in treatment vs. control arm, respectively) with an unadjusted OR equal to 2.22 (95%CI 0.96-5.12, p-value 0.06), and an adjusted OR equal to 2.31 (95%CI 0.90-5.92, p-value 0.08). Baseline PSA and >1 metastatic sites were non-significantly associated with CBR in multivariable models, with OR equal to 0.92 (95%CI 0.85-1.01, p-value 0.06) and 1.20 (95%CI 0.46-3.09, p-value 0.71), respectively.

Conclusion

Promising efficacy of SBR+AA combination was shown if compared to standard of care alone for oligometastatic CRPC. Even if statistical significance is not yet reached, treatment arm resulted in OR for BR and CBR doubled if compared to control arm. Moreover, PSA drop confirmed this trend. Selection criteria may be further refined, considering that baseline burden of disease was suggested to predict increased outcomes after SBRT. Whole cohort will be enrolled in 2022, final results for primary endpoint may confirm early outcomes in a larger population.