A Study of JNJ-101556143 With Best Supportive Care in Participants With Metastatic Prostate Cancer

The purpose of this study is to evaluate how well JNJ-101556143 plus Best Supportive Care (BSC) improves overall survival (the length of time a participant remains alive) compared with placebo plus BSC in participants with metastatic androgen pathway modulation-resistant prostate cancer (mAPMR). mAPMR is an advanced form of prostate cancer that has spread to other parts of the body and no longer responds to hormone treatments designed to block male hormones (androgens).

Inclusion Criteria: * Have histologically confirmed adenocarcinoma of the prostate. Primary (or pathologic evidence of conversion to) small cell carcinoma, carcinoid tumor, mixed neuroendocrine carcinoma, large cell neuroendocrine carcinoma, or sarcoma of the prostate is disallowed * Progressive metastatic androgen pathway modulation-resistant prostate cancer (mAPMR) defined as having a Prostate-Specific Antigen (PSA) level greater than or equal (\>=) 10 nanograms per milliliter (ng/mL) and at least one of the following: (a) PSA progression defined as at least 2 consecutive increases in PSA value over a previous reference value measured at least 1 week apart. (b) Progressive disease or new lesion(s) in the lymph nodes, bones, or viscera on conventional imaging (computed tomography \[CT\]/magnetic resonance imaging \[MRI\]) as defined by response evaluation criteria in solid tumors version 1.1 (RECIST v1.1) and/or on bone scan per Prostate Cancer Working Group 4 (PCWG4) while on Androgen Deprivation Therapy (ADT) (either surgically \[bilateral orchiectomy\] or with medication) * Participants should have had all life-prolonging therapies for which they are clinically eligible in the opinion of the investigator and to which they have access * Prior bilateral orchiectomy or medical castration (receiving ongoing ADT with a Gonadotropin-Releasing Hormone (GnRH) analog \[agonist or antagonist\]) with castrate level of serum testosterone (less than \[\