Radioablation +/- hormonotherapy for prostate cancer oligorecurrences (Radiosa trial): Potential of imaging and biology (AIRC IG-22159)

Background: Prostate cancer (PCa) is the second most common cancer among men. New imaging-modalities have increased the diagnosed patients with limited number of metastasis after primary curative therapy, introducing so-called oligometastatic state. Stereotactic body radiotherapy (SBRT) is emerging as a low-toxicity treatment to erase PCa localizations and postpone androgen deprivation therapy (ADT). A deeper understanding of the predictive role of biomarkers is desirable for a targeted treatment selection and surveillance programs. The aims of the RADIOSA trial are: Compare SBRT +/- ADT for oligorecurrent-castration-sensitive PCa (OCS-PCa) in terms of efficacy, toxicity and Quality of Life (QoL).Develop biology/imaging based prognostic tool that allows identifying OCS-PCa subclasses. Methods This is a randomized phase II clinical trial, recruiting 160 OCS-PCa in 3years, with progression-free survival (PFS) as primary endpoint. Three tasks will be developed: Randomized clinical study (3years for accrual and 2years for follow-up and data analysis);Imaging study, including imaging registration and METastasis Reporting and Data System (MET-RADS) criteria;Pre-clinical study, development of a biobank of blood samples for the analysis of neutrophil-to-lymphocyte ratio and preparatory for a subsequent miRNA profiling.We aim to determine which arm is justified for testing in a subsequent Phase III trial. A decision-tree algorithm, based on prognosis, biological phenotype and imaging profile, will be developed. Discussion Recruiting will start in July 2019. SBRT will allow obtaining excellent PFS, local control, QoL and low toxicity. In SBRT arm, ADT deferral will allow for a drug-holiday, delaying the detrimental impact on QoL. A sufficient number of blood samples will be collected to perform biological patient profiling. A stratification tool will be established with an analysis of morphological and functional imaging, based on the use of MET-RADS criteria.So, in conclusion, RADIOSA aims to define the optimal management of bone/nodal PCa relapses in a SBRT regimen. This study will increase our knowledge on low-burden metastatic PCa in the era of high precision and high technology personalized medicine, offering highly effective therapy in terms of clinical outcome and cost-effectiveness. Trial registration The RADIOSA study was prospectively registered at clinicaltrials.gov (NCT03940235, May 2019).