Phase I Dose-escalation Study of Fractionated 177Lu-PSMA-617 for Progressive Metastatic CRPC

Phase I dose escalation study with 177Lu-PSMA-617 using dose fractionation regimen will be performed in patients with documented progressive metastatic CRPC. The cumulative 177Lu dose \[100 mCi (3.7 GBq) - 600 mCi (22.2 GBq)\] will be escalated in up to 6 different dose levels (3 + 3 study design). Additional 10 subjects will be enrolled at the MTD dose level to further assess safety and tolerability and to obtain a preliminary assessment of efficacy. The study will enroll adult males 18 years of age or older with documented progressive metastatic CRPC. The primary objectives are: - To determine the dose limiting toxicity (DLT) of fractionated dose of 177Lu-PSMA-617 - To determine the maximal tolerated and recommended phase II dose of 177Lu-PSMA-617 in a 2-week dose-fractionation regimen Subjects will receive the following study interventions: 1. 177Lu-PSMA-617 \[50mCi (1.85GBq) - 300mCi (11.1GBq)\] intravenous X2 doses, 2 weeks apart (Visit 1 and 2) 2. 68Ga-PSMA-HBED-CC \[5 ±2mCi or 185 ±74MBq\] intravenous during screening and at 12 weeks with standard imaging Subjects will be on this study from screening to end of study (day 85). The treatment phase comprises of 8 visits over 12 weeks. Patients will be followed until death for survival assessment. Patients removed from study for unacceptable adverse events will be followed until resolution or stabilization of the adverse event. All tests and procedures performed on this study are routine and standard of care except: 68Ga-PSMA-HBED-CC PET/CT scan, administration of investigational agent 177Lu-PSMA-617, research blood samples (CTCs for research, cell-free DNA sample), and PSMA testing on archive tissue.