Radium-223 for High-Volume Metastatic Hormone Sensitive Prostate Cancer

The trial will enroll competitively up to 50 patients with mHSPC and high volume disease (i.e. ≥4 bone metastatic foci in Tc-99m bone scanning, with at least one focus located outside the pelvis or vertebral bodies in the spine AND/OR visceral metastasis shown on computed tomography or magnetic resonance imaging not including lymph nodes). Patients should have started and be on treatment as per standard of care with first-line triplet therapy consisting of chemical or surgical androgen deprivation therapy (ADT), docetaxel and darolutamide. At least four cycles of docetaxel should have been administered and the last dosing of docetaxel be \< 12 weeks prior the first planned dose of Ra223. Patients should have a good performance status (ECOG PS 0-2 and Charlson score ≤ 3) and have recovered from any prior toxicity from triplet therapy. Previous treatments other than chemotherapy for locoregional disease are acceptable. Additionally to the IMPs and AXMPs, the study includes the administration of at least two doses of a bone protecting agent (zoledronic acid or denosumab) is required before the first administration of Ra223, and the bone protecting agent should have been started at least 6 weeks before the first administration of Ra223. Patients should also start treatment with vitamin D and calcium supplements