A Study of JNJ-69086420, an Actinium-225-Labeled Antibody Targeting Human Kallikrein-2 (hK2) for Advanced Prostate Cancer

Inclusion Criteria: * For Part 1, Part 2, Part 3: Metastatic castration resistant prostate cancer (mCRPC) with histologic confirmation of adenocarcinoma (adenocarcinoma with small-cell or neuroendocrine features is allowed) with prior exposure to at least one androgen receptor (AR) targeted therapy (for example \[e.g.\], abiraterone acetate, enzalutamide, apalutamide, darolutamide). In addition: Part 1: prior taxane or other chemotherapy is acceptable but not required. Part 2a: prior taxane or other chemotherapy required, Part 2b: no prior taxane or other chemotherapy, Part 2c: mCRPC that has progressed after prior treatment with lutetium Lu-177 vipivotide tetraxetan, with or without prior chemotherapy, Part 3: prior taxane or other chemotherapy is acceptable but not required \& For Part 4a: metastatic HSPC, For Part 4b: disease that can be treated with less than or equal to (\<=) 5 radiation fields and no visceral metastases * Parts 1, 2 \& 3: Prior orchiectomy or medical castration, or, for participants who have not undergone orchiectomy, must be receiving ongoing androgen deprivation therapy with a gonadotropin releasing hormone (GnRH) analog (agonist or antagonist) prior to the first dose of study drug and must continue this therapy throughout the treatment phase. This criterion does not apply to Part 4 * Palliative radiotherapy (e.g. soft tissue lesions) must be completed greater than (\>) 2 weeks prior to start of study drug except for palliative radiotherapy for pain …