177Lu-PSMA-617 in Metastatic Castration Resistant Prostate Cancer (mCRPC) With Bone Marrow Involvement and Cytopenia

This study is testing a radioactive drug called 177Lu-PSMA-617 (lutetium PSMA) in men with metastatic castration-resistant prostate cancer (cancer that has spread and is no longer controlled by hormone therapy) who also have low blood counts due to cancer invading their bone marrow. **You may be eligible if...** - You are 18 or older - You have prostate cancer confirmed by biopsy that has spread and is no longer responding to hormone therapy - Your PSA is rising and is at least 2.0 ng/mL - You have received at least one prior systemic treatment (beyond hormone therapy) - You have documented cancer cells in your bone marrow causing low blood counts (low hemoglobin or low platelets) - You are on hormone therapy or have had surgical castration **You may NOT be eligible if...** - Your blood counts are too low to be safely treated - You are not able to consent or comply with the study's blood and bone marrow sampling schedule - You have other serious health conditions making treatment unsafe Talk to your doctor to see if this trial is right for you.