Somatostatin Receptor 2-Targeting Compounds.

The molecular imaging and treatment of neuroendocrine tumors (NETs) with radiolabeled somatostatin analogs represent a milestone in the development of theranostic compounds. Whole-body scintigraphy with 111In-pentetreotide has revolutionized the diagnosis and staging of NETs and the evaluation of treatment outcomes. At present, diagnostic accuracy with positron-emitting radionuclides is greater than 90%. Peptide receptor radionuclide therapy (PRRT) has become a well-accepted treatment for patients with well-differentiated inoperable or metastatic NETs and disease progression after first-line treatment. Disease control rates (complete or partial remission or stable disease in patients with formerly progressive disease) of up to 95%, with a low incidence of long-term hematologic and renal toxicity, have been reported. In a recently published randomized trial, compared with intensified treatment of midgut NETs with long-acting and repeatable octreotide, PRRT reduced the hazard of disease progression and death by 79%. Upcoming developments in PRRT include the use of somatostatin receptor antagonists and α-emitting radionuclides, which may further enhance treatment outcomes.