Iobenguane I-131 (therapeutic)

High-specific-activity iobenguane I-131 (Azedra) 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. Progenics (later 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 were the main risks; the diagnostic-dose iobenguane (AdreView) is an imaging agent covered separately.