Testing the Addition of an Anti-cancer Drug, Triapine, to the Usual Radiation-Based Treatment (Lutetium Lu 177 Dotatate) for Neuroendocrine Tumors

Inclusion Criteria: * Metastatic, histologically confirmed well-differentiated neuroendocrine tumor with positive dotatate scan (gallium-68 or copper-64) within 6 months. Lesions on dotatate scan (gallium-68 or copper-64 dotatate scan) will be considered positive if the maximum standard uptake value (SUVmax) is \> 2 times SUV mean of normal liver parenchyma * Failure of at least one prior systemic cancer treatment, including somatostatin analogs * Patients must have progressive disease based on RECIST criteria, version 1.1 evidenced with CT scans/MRI obtained within 24 months from enrollment * Patients must have measurable disease per RECIST 1.1 * No prior exposure to peptide receptor radionuclide therapy * Recovered from adverse events of previously administered therapeutic agents to grade 1 or less toxicity according to Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 * Archival tissue no longer than 6 months old should be present, otherwise baseline research biopsy is needed for WES * Age \>= 18 years. Because no dosing or adverse event data are currently available on the use of triapine in combination with lutetium Lu 177 dotatate in patients \< 18 years of age, children are excluded from this study, but will be eligible for future pediatric trials * Eastern Cooperative Oncology Group (ECOG) performance status 0,1, or 2 (Karnofsky \>= 60%) * Leukocytes \>= 2,000/mcL * Absolute neutrophil count \>= 1,500/mcL * Platelets \>= 75,000/mcL * Total bilirubin =…