Theranostic radiopharmaceuticals: established agents in current use.

Although use of the term "theranostic" is relatively recent, the concept goes back to the earliest days of nuclear medicine, with the use of radioiodine for diagnosis and therapy of benign and malignant thyroid disease being arguably the most successful molecular radiotherapy in history. A diagnostic scan with ¹²³ I-, ¹²⁴ I-, or a low activity of ¹³¹ I-iodide is followed by therapy with high activity ¹³¹ I-iodide. Similarly, adrenergic tumours such as phaeochromocytoma and neuroblastoma can be imaged with ¹²³ I-metaiodobenzylguanidine and treated with ¹³¹ I-metaiodobenzylguanidine. Bone scintigraphy can be used to select patients with painful bone metastases from prostate cancer who may benefit from treatment with beta- or alpha-particle emitting bone seeking agents, the most recent and successful of which is ²²³ Ra radium chloride. Anti-CD20 monoclonal antibodies can be used to image and treat non-Hodgkins lymphoma, though this has not been as commercially successful as initially predicted. More recently established theranostics include somatostatin receptor targeting peptides for diagnosis and treatment of neuroendocrine tumours with agents such as ⁶⁸ Ga-DOTATATE and ¹⁷⁷ Lu-DOTATATE, respectively. Finally, agents which target prostate-specific membrane antigen are becoming increasingly widely available, despite the current lack of a commercial product. With the recent licensing of the somatostatin peptides and the rapid adoption of ⁶⁸ Ga- and ¹⁷⁷ Lu-labelled prostate-specific membrane antigen targeting agents, we have built upon the experience of radioiodine and are already seeing a great expansion in the availability of widely accepted theranostic radiopharmaceuticals.