Standard of Care +/- 177Lu-PSMA-617 In de Novo mHSPC Patients With Poor PSA Response (PEACE6-Poor Responders)

The study plans to enroll 500 patients over 63 months who will be randomized (1:1) to receive either: (i) Control arm: SoC (ADT+ ARSI (second-generation androgen receptor signaling inhibitors) +/- RT or ADT+ ARSI +/- RT) or (ii) Experimental arm: 177Lu-PSMA-617 + SoC (ADT+ ARSI +/- RT or ADT+ docetaxel + ARSI +/- RT). Response to treatment will be assessed according to the Prostate Cancer Clinical Trials Working Group 3 (PCWG3) criteria. Treatment will be continued at least until castration-resistant prostate cancer (CRPC) stage is reached, defined by evidence of cancer progression (either a confirmed PSA rise or a radiographic progression) with serum testosterone being at castrated levels (\<0.50 ng/mL). This systemic treatment may be continued after CRPC is reached, based on patient benefit and the investigator's opinion. Treatment may also be terminated at the initiative of either the patient or the investigator for any reason that would be beneficial to the patient, including: unacceptable toxicity, intercurrent conditions that preclude continuation of treatment, or patient request. At the end of treatment period, the follow-up period will last for 102 months (8.5 years). The overall trial duration, including the follow-up, is expected to last 18.5 years.