211At-MABG in Adults With Advanced Neuroendocrine Cancers

Prior treatment

• Uncontrolled brain metastasis (Participant must be at least 4 weeks since CNS-directed therapy and no longer requiring corticosteroid therapy).
• Anticancer therapy, except hormonal therapy or bone supportive therapies, within 14 days of cycle 1 day 1.

Other illness

• Serious or unstable medical, psychological, or social conditions that, in the opinion of the investigator, would compromise the subject's safety or successful participation in the study.
• Has a known additional malignancy (other than the disease under study) that has required active systemic treatment within the past 2 years AND for which the natural history or recent/ongoing treatment could likely interfere with study endpoints or safety of the study treatment per Investigator and Medical Director assessment.

Other

• Women who are pregnant or breast-feeding will not be eligible for this study.
• Inability to tolerate study procedures in the opinion of the investigator or treating physician.

• Adult patients, at least 18 years of age
• Advanced neuroendocrine cancers requiring systemic therapy and refractory to, ineligible for, declining, or lacking standard treatments.
• I MIBG imaging indicating MIBG-avid disease (radiotracer uptake above background in at least one tumor site) per Investigator/Sub-Investigator assessment.
• Participants must provide written informed consent prior to study-specific procedures.
• ECOG performance status ≤ 2.
• Adequate organ function including:
  • Hemoglobin ≥ 9 g/dL
  • Absolute neutrophil count ≥ 1,500/mm³
  • Platelet count ≥ 75,000/mm³
  • Measured or estimated GFR ≥ 60 mL/min
  • Serum bilirubin ≤ 1.5x upper limit of normal
  • ALT/AST each ≤ 2.5x upper limit of normal
• Life expectancy at least 3 months as judged by treating physician