# 131I-MIBG (iobenguane I-131) therapy

Source: https://onco.cc/drugs/i131-mibg/  
OnCo record `i131-mibg` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

High-dose radioactive MIBG delivers radiation from inside neuroblastoma cells that take up noradrenaline; used for relapsed disease and tested in upfront therapy. A branded high-specific-activity form, Azedra, was approved for phaeochromocytoma and paraganglioma in 2018 and discontinued in 2024.

## Summary

Response rate ~30-40% in relapsed/refractory MIBG-avid neuroblastoma (NANT, COG studies), with myelosuppression requiring stem-cell support at ≥12 mCi/kg. COG ANBL1531 randomised 131I-MIBG added to induction (primary results pending 2026).

High-specific-activity iobenguane I-131 (Azedra, Progenics then Lantheus) was approved by the FDA in July 2018 for adults and children aged 12 and over with iobenguane scan-positive, unresectable, locally advanced or metastatic phaeochromocytoma or paraganglioma requiring systemic therapy, on a single-arm phase 2 study in which a quarter of patients halved their antihypertensive medication for at least six months and most had tumour control; it was the first approved therapy for these tumours. Lantheus discontinued manufacture in 2024, so patients rely on compounded low-specific-activity 131I-MIBG or lutetium-177 dotatate. Myelosuppression, secondary MDS and leukaemia, hypothyroidism and renal toxicity are the main risks; the diagnostic-dose iobenguane (AdreView) is an imaging agent covered under MIBG theranostics.

## Fields

- Kind: Treatment
- Status: established
- Last checked: 2026-09-07
- Also known as: Iobenguane I-131 (therapeutic); 131I-MIBG; Ultratrace iobenguane; iobenguane-i-131
- Tags: nci-list
- Brand: Azedra
- Modality: Radioligand therapy (beta, norepinephrine transporter)
- Mechanism: Norepinephrine transporter uptake of radio-iodinated benzylguanidine; 131I beta emission (2 mm range).
- Approvals: US 2018: Iobenguane scan-positive unresectable, locally advanced or metastatic phaeochromocytoma or paraganglioma in patients 12 and older (Azedra, high-specific-activity form; discontinued 2024)
- Dosing: IV; 12-18 mCi/kg single or tandem doses with autologous stem-cell support; thyroid blockade with potassium iodide

## Notes

- Azedra (the approved high-specific-activity product) and compounded 131I-MIBG are one INN, iobenguane I-131, so both are recorded here; the duplicate record iobenguane-i-131 redirects to this page.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Iobenguane
- Wikipedia: https://en.wikipedia.org/wiki/Iobenguane
- US label (DailyMed): https://dailymed.nlm.nih.gov/dailymed/search.cfm?labeltype=all&query=iobenguane
- NCI drug page: https://www.cancer.gov/about-cancer/treatment/drugs/iobenguanei131

## Connected records

- drugs: [Lutetium-177 dotatate](https://onco.cc/drugs/lutathera/)
- cancers: [High-risk neuroblastoma](https://onco.cc/cancers/neuroblastoma-high-risk/), [Metastatic pheochromocytoma and paraganglioma](https://onco.cc/cancers/metastatic-ppgl/), [Neuroblastoma (paediatric)](https://onco.cc/cancers/neuroblastoma/), [Neuroendocrine tumours](https://onco.cc/cancers/neuroendocrine/), [Pheochromocytoma and paraganglioma (PPGL)](https://onco.cc/cancers/pheochromocytoma-paraganglioma/)
- technologies: [MIBG imaging and 131I-MIBG therapy](https://onco.cc/technologies/mibg-theranostics/), [Radioligand therapy (beta emitters)](https://onco.cc/technologies/radioligand-therapy/)
- companies: [Lantheus](https://onco.cc/companies/lantheus/)
- terms: [MIBG Curie and SIOPEN scores](https://onco.cc/terms/curie-siopen-score/), [Radioiodine therapy (I-131)](https://onco.cc/terms/radioiodine-term/)
- trials: [COG ANBL1531](https://onco.cc/trials/anbl1531/)
- people: [Katherine K. Matthay](https://onco.cc/people/katherine-matthay/)
- key papers: [Efficacy and safety of high-specific-activity 131I-MIBG therapy in advanced pheochromocytoma or paraganglioma](https://onco.cc/key-papers/paper-pryma-high-specific-activity-i131-mibg-ppgl-jnm-2019/)
- roadmaps: [Paediatric oncology roadmap: cooperative-group cures → engineered immunity → drugs developed for children first](https://onco.cc/roadmaps/paediatric-oncology-roadmap/)

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