Inclusion Criteria:

          1. Participant is able and willing to provide informed consent (≥18 years), or informed
             consent is obtained by the parent or legal guardian for minor participants, with the
             minor providing age appropriate assent, according to local law and regulations;

          2. Life expectancy ≥ 12 weeks;

          3. Known high-risk neuroblastoma with failure to respond to standard therapy (combination
             chemotherapy with or without radiation and surgery), or development of PD at any time;

          4. Adequate recovery from acute toxic effects of any prior therapy, as deemed by the
             Investigator or treating Sub-Investigator;

          5. Adequate liver function as defined by the following laboratory values obtained within
             28 days prior to administration of 64Cu-SARTATE: Aspartate aminotransferase (AST) and
             alanine aminotransferase (ALT) < 3.0 x upper limit of normal (ULN);

          6. Adequate renal function;

          7. Adequate laboratory parameters: Absolute neutrophil count > 1.0 x 109/L; Platelet
             count > 50 x 109/L; Serum bilirubin <1.5 x ULN;

          8. Karnofsky or Lansky performance status ≥50;

          9. All participants must have a hematopoietic stem cell product available (minimum CD34+
             cell dose is ≥2 x 106 cells/kg);

         10. Sexually active participants of reproductive potential must practice an effective
             method of birth control while participating on this study, to avoid possible damage to
             the fetus. Abstinence is considered acceptable;

         11. 64Cu-SARTATE uptake on the 4 hour scan (SUVmax) of any lesion equal to or higher than
             that of the liver in order to move on to the therapy phase of the study.

        Exclusion Criteria:

          1. Participants with disease of any major organ system that would compromise their
             ability to tolerate therapy, as deemed by the Investigator or treating
             Sub-Investigator;

          2. Any other active malignancy, or a history of prior malignancy within the past 3 years;

          3. History of cardiac failure as evidenced by: dyspnea at rest, exercise intolerance,
             oxygen requirement, clinically significant cardiac dysfunction;

          4. Planned administration of chemotherapy, anti-cancer cytokine therapy, immunotherapy,
             radiotherapy or other investigational agents within 2 weeks prior to the
             administration of 64Cu-SARTATE and 4 weeks prior to the administration of
             67Cu-SARTATE;

          5. Administration of therapeutic dose of 131I-MIBG within 8 weeks prior to the
             administration of 64Cu-SARTATE;

          6. EBRT to both kidneys or a single functioning kidney within 12 months prior to the
             administration of 64Cu-SARTATE;

          7. Administration of any investigational agents within 28 days prior to administration of
             64Cu-SARTATE;

          8. Treatment with long acting somatostatin analogues (administered within 28 days prior
             to the administration of 64Cu-SARTATE), or short acting somatostatin analogues
             (administered within 24 hours prior to the administration of 64Cu-SARTATE);

          9. Known sensitivity or allergy to somatostatin analogues;

         10. Previous PRRT;

         11. Female participants who are pregnant or lactating;

         12. Participants who are on hemodialysis;

         13. QTc interval ≥ 0.45 seconds as measured by Screening ECG;

         14. Participants with uncontrolled infection(s);

         15. Any medical condition which the Investigator feels may interfere with the procedures
             or evaluations of the study;

         16. Participants 12 month and younger will be excluded from cohorts where the planned
             single or cumulative administered activity is modelled to deliver a radiation dose to
             the marrow that exceeds 2 Gy.