This Phase II study aims to evaluate the efficacy and safety of the combination of JSB462 (also known as luxdegalutamide) at 100 mg and 300 mg QD doses + lutetium (177Lu) vipivotide tetraxetan (hereafter referred as AAA617) compared with AAA617 (control) in participants with metastatic Castration Resistant Prostate Cancer (mCRPC) with prior exposure to at least 1 Androgen Receptor Pathway Inhibitor (ARPI) and 0-2 taxane regimens and to select the recommended dose of the combination for phase III. Towards that end, the totality of the efficacy, safety, tolerability and pharmacokinetic (PK) data from participants randomized in the study will be evaluated.