Treatment of Patients With Progressive mCRPC With 177Lu-PSMA-617

The study begins with a first cohort of three participants, each receiving a dose of 100 millicuries (mCi). After administration, participants are monitored for any dose-limiting toxicities (DLTs) during a predefined observation window. If fewer than two participants experience a DLT in a given cohort, the dose will be escalated for the next group. The dose escalation schedule is structured as follows: the second cohort receives 130 mCi (a 30% increase), the third cohort receives 162.5 mCi (a 25% increase), and the fourth cohort receives 200 mCi, a dose that is already FDA-approved and clinically accepted for mCRPC. This stepwise escalation continues until the 200 mCi dose is reached, or until two or more DLTs are observed in any cohort. If that occurs, escalation stops immediately, and the maximum tolerated dose is considered to be the previous lower dose. This becomes the optimal tolerated dose (OTD). After identifying the OTD, additional participants will be enrolled for treatment.