The participants receive treatment for 52 weeks, including four cycles of ipilimumab and nivolumab with or without concomitant SBRT (24 Gray in three fractions) to a single soft tissue or bone metastasis, followed by 10 cycles of nivolumab. Participants are followed until progression, death, or for 12 months after the end of treatment.~Biopsies from metastatic sites are collected at baseline, before the third treatment, and at the end of treatment. Blood sampling for immune monitoring and circulating tumor DNA is performed consecutively at baseline and every radiographic assessment.
The goal of this investigator-initiated, single-center, and randomized phase II trial is to investigate the potential synergistic effect of combining stereotactic body radiotherapy of a single soft tissue- or bone metastasis with ipilimumab and nivolumab in patients with mCRPC and perform translational analyses on tissue and blood, searching for predictive biomarkers of efficacy and toxicity.~Participants will be randomized to receive ipilimumab and nivolumab with or without stereotactic body radiotherapy (SBRT).