A Study of JNJ-87189401 Combined With JNJ-78278343 for Advanced Prostate Cancer

This study is testing a combination of two experimental cancer drugs — JNJ-87189401 and JNJ-78278343 — in patients with advanced prostate cancer that has stopped responding to standard hormone-based treatments. The study is in early phases to assess safety and find the right dosing. **You may be eligible if...** - You have been diagnosed with prostate adenocarcinoma (the most common type of prostate cancer) - Your cancer is measurable or evaluable on scans - Your testosterone has been suppressed to castrate levels (through surgery or ongoing hormone therapy) - You are in good enough health to carry out daily activities (ECOG 0-1) **You may NOT be eligible if...** - You have active autoimmune disease - You have pure small cell, carcinoid, or large cell neuroendocrine prostate cancer (mixed types may be permitted) - You have significant heart, liver, or kidney problems - You have had certain prior treatments that would conflict with the study drugs Talk to your doctor to see if this trial is right for you.