Have histologically confirmed adenocarcinoma of the prostate
Have disease that is metastatic at the time of screening by computed tomography (CT) or magnetic resonance imaging (MRI) and 99m\^Tc bone scan as determined by the investigator
Participants must receive ongoing androgen deprivation therapy (ADT) with a gonadotropin releasing hormone (GnRH) analog throughout the treatment or have had prior bilateral orchiectomy, and have serum testosterone less than or equal to (\<=) 50 nanogram per deciliter (ng/dL) (\<= 1.73 nanomoles per Liter \[nmol/L\]) at screening
Have progressed by PSA or CT/MRI or 99m\^Tc bone scan on at least 1 novel androgen receptor pathway inhibition (ARPI) but no more than 2 different ARPI for any stage of disease. Must have discontinued ARPI before randomization into the study
Have an eastern cooperative oncology group (ECOG) performance status of 0 to 1
You may not be if
Known history of either brain or leptomeningeal prostate cancer metastases
Participants with known breast cancer gene 1/2 (BRCA 1/2) mutations (germline or somatic) who have not received treatment with a poly (ADP-ribose) polymerase (PARP) inhibitor, unless not available or contraindicated
Prior or concurrent second malignancy (other than the disease under study)
Received cytotoxic chemotherapy for prostate cancer in any setting
Received prior treatment with human kallikrein 2 (KLK-2) directed therapies
