Efficacy and safety of high-specific-activity 131I-MIBG therapy in advanced pheochromocytoma or paraganglioma
A purified radioactive form of MIBG, taken up by adrenaline-producing tumour cells, let a quarter of patients halve their blood pressure medication for at least six months and shrank tumours in about one in five, leading to the first approved radiopharmaceutical for these tumours.
Overview
Open-label single-arm multicentre phase 2 study of high-specific-activity iobenguane I-131 in patients with MIBG-avid unresectable or metastatic pheochromocytoma or paraganglioma, given as up to two therapeutic doses; 68 patients received at least one dose.
About a quarter of patients achieved the primary endpoint of at least a 50 percent reduction in antihypertensive medication for six months or more, objective responses occurred in about 22 percent, and most patients had disease control; myelosuppression was the main toxicity. The FDA approved the product (Azedra) in 2018.
- At least a 50 percent reduction in antihypertensive medication for six months or longer in about a quarter of patients.
- Objective tumour response in about 22 percent; myelosuppression was the main adverse effect.
Radionuclide therapy is a standard option for MIBG-avid metastatic pheochromocytoma and paraganglioma; somatostatin receptor targeted lutetium therapy is the alternative for SSTR-avid disease.
- Single-arm study with a blood pressure medication endpoint rather than survival.
- The commercial product was later withdrawn from the US market for business reasons, limiting access.