Radioactive Drug (177Lu-DOTATATE) for the Treatment of Locally Advanced, Metastatic, or Unresectable Rare Endocrine Cancers

PRIMARY OBJECTIVE: I. Objective response rate (ORR) by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 determined by Ia. Computed tomography (CT) or Ib. Magnetic resonance imaging (MRI). SECONDARY OBJECTIVES: I. To estimate progression-free survival at 1-year. II. To correlate blood pressure control and change/discontinuation of antihypertensive medications with tumor responses in patients with pheochromocytomas and paragangliomas (PHPGs). III. To correlate plasma metanephrines and chromogranin A with tumor responses in patients with PHPGs. IV. To correlate calcitonin, carcinoembryonic antigen, and chromogranin A with tumor responses in patients with medullary thyroid carcinoma (MTCs). V. To correlate pituitary hormones (depending on particular tumor, e.g. prolactin for prolactinomas, insulin-like growth factor (IGF-1) for acromegaly, adrenocorticotropic hormone (ACTH) and 24-hour urine free cortisol for Cushing disease, and chromogranin A with tumor responses in patients with functional pituitary carcinomas). VI. To correlate calcium, intact parathyroid hormone (iPTH), and chromogranin A with tumor responses in patients with parathyroid carcinoma. VII. Toxicity assessment by the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE 5.0). VIII. To correlate tumor responses with tumor uptake score in somatostatin receptor scintigraphy, overall prognosis and responsiveness to lutetium Lu 177 dotatate (177Lu-DOTATATE). IX. To determine the percentage of tumors that demonstrate uptake on diagnostic 68Gallium-DOTATATE positron emission tomography (PET)/CT that would make treatment with 177Lu-DOTATATE feasible. EXPLORATORY OBJECTIVES: I. To evaluate pituitary function in all patients to look for possible radiation late effects on the pituitary gland. II. To estimate best biochemical response for specific tumor markers in patients with non-measurable disease. III. To correlate biochemical response in patients with non-measurable disease with RECIST 1.1 tumor response criteria for patients with non-measurable disease. OUTLINE: Patients receive 177Lu-DOTATATE intravenously (IV) over 30 minutes every 8-16 weeks. Treatment continues for up to 52 weeks in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up at week 72 and then every 24 weeks for up to 5 years.