Testing the Safety and Effectiveness of Radiation-based Treatment (Lutetium Lu 177 Dotatate) for Metastatic Prostate Cancer That Has Neuroendocrine Cells

This phase II trial studies how well lutetium Lu 177 dotatate works in treating patients with prostate cancer with neuroendocrine differentiation that has spread to other places in the body (metastatic). Neuroendocrine differentiation refers to cells that have traits of both hormone-producing endocrine cells and nerve cells. These cells release hormones into the blood in response to a signal from the nervous system. Hormones are biological substances that circulate through the bloodstream to control the activity of other organs or cells in the body. Lutetium Lu 177-dotatate is a radioactive drug. It binds to a protein called somatostatin receptor, which is found on some neuroendocrine tumor cells. Lutetium Lu 177-dotatate builds up in these cells and gives off radiation that may kill them. It is a type of radioconjugate and a type of somatostatin analog. Treatment with Lutetium Lu 177 dotatate may shrink the tumor in a way that can be measured in patients with metastatic prostate cancer with neuroendocrine differentiation.

PRIMARY OBJECTIVE: I. Evaluate the objective response rate at 6 months for patients treated with lutetium Lu 177 dotatate using Prostate Cancer Working Group (PCWG) 3 criteria. SECONDARY OBJECTIVES: I. Evaluate the 6-month radiographic progression-free survival of neuroendocrine-differentiated prostate cancer treated with lutetium Lu 177 dotatate. II. Determine if the change in fludeoxyglucose (FDG)-positron emission tomography (PET) signal from pre-treatment to after 2 doses of lutetium Lu 177 dotatate correlates with objective response rate. EXPLORATORY OBJECTIVES: I. Evaluate the potential to perform patient-specific dosimetry of lutetium Lu 177 dotatate using gamma imaging to predict treatment response and renal toxicity. II. Perform gene expression analysis of circulating tumor cells to identify pre-treatment biomarkers of response and signatures of resistance at the time of progression. OUTLINE: Patients receive lutetium Lu 177 dotatate intravenously (IV) over 30 minutes. Cycles repeat every 6 weeks (Q6W) for up to 4 cycles in the absence of disease progression or unacceptable toxicity. Patients also receive gallium Ga 68-dotatate IV during screening then undergo positron emission tomography (PET)/computed tomography (CT) scan at baseline and collection of blood throughout the trial. Patients are followed up at 6 weeks after last dose lutetium Lu 177 dotatate and then every 3 months for 2 years after removal from study or until death, whichever occurs first.