This medical study is exploring if high doses of testosterone can help men with a type of prostate cancer that has changes in specific genes (ATM, CDK12, or CHEK2). These genes are related to DNA repair, which is how cells fix themselves. The study is looking at whether people with these gene changes respond well to the treatment. Men with metastatic castration-resistant prostate cancer (mCRPC), which is a type of cancer that has spread and doesn't respond to hormonal therapy, may be eligible to participate. Participants will receive testosterone treatment until the cancer worsens or they can't tolerate it. Progress will be checked using scans and blood tests. Men interested in joining must be over 18, have specific gene changes, and meet other criteria. They cannot participate if they have certain other health issues, like brain or liver problems. The study involves frequent visits and checks for safety and side effects.

• Eligible participants will receive high dose testosterone until the cancer progresses.
• Safety and side effects will be monitored with regular check-ups and tests.
• Participants must have specific gene changes and not have other major illnesses.