This study is for patients with advanced or metastatic neuroendocrine prostate cancer. The treatment involves two drugs: **pembrolizumab** (a type of immunotherapy that helps the immune system fight cancer) and **lenvatinib** (a medication that blocks proteins promoting cancer cell growth). Each cycle of treatment lasts 21 days, and you may receive up to 35 cycles. The treatment continues until the cancer progresses, side effects become too severe, or you decide to stop.

To join, you must be 18 or older, have a certain type of prostate cancer, and good organ function. You should not have had specific treatments before. Also, you must agree to use contraception during the study and for 120 days after the last dose.

• **Treatment Duration:** Up to 35 cycles of 21 days each
• **Eligibility:** Must have specific health conditions and not have had certain treatments
• **Requirements:** Agree to use contraception and follow study rules

If you meet the criteria and agree to follow the study guidelines, you may consider participating in this research.