Study of 225Ac-PSMA-617 in Men With PSMA-positive Prostate Cancer

This study tests actinium-225 (225Ac-PSMA-617), a radioactive drug that targets a protein found on prostate cancer cells called PSMA. It delivers radiation directly to the cancer cells. The study is for men with prostate cancer that has stopped responding to other treatments and whose cancer is confirmed to express PSMA on a special PET scan. **You may be eligible if...** - You are 18 or older with a confirmed prostate cancer diagnosis - A PSMA PET scan done within the last 28 days shows your cancer is PSMA-positive - Your overall health/functional status is adequate (ECOG 0–2) - Your organ function (liver, kidneys, bone marrow) meets study requirements **You may NOT be eligible if...** - Your PET scan shows areas of PSMA-negative disease (meaning the cancer doesn't have enough of the target protein in certain areas) - You have specific types of PSMA-negative metastases above a certain size - You do not meet organ function requirements Talk to your doctor to see if this trial is right for you.