Somatostatin Analog-Based Radiopharmaceuticals for Molecular Imaging and Therapy of Neuroendocrine Tumors

Somatostatin receptors (SSTRs) are overexpressed in a wide variety of cancers such as neuroendocrine tumors (NETs), but the expression in normal cells is relatively low. Therefore, SSTRs serve a potential target for molecular imaging and therapeutic applications of NETs. This review presents the development of somatostatin analog-labeled with gamma-emitting radionuclides such as 111In, 99mTc, and 123I for the visualization of NETs via single-photon emission tomography (SPECT). Additionally, the development of somatostatin analog-radiolabeled with positron emitting radionuclide such as 68Ga for the molecular imaging of NETs with positron emission tomography (PET) is also presented herein. Moreover, this review describes 177Lu-, 90Y-, and 111In-labeled somatostatin analogs as peptide receptor radionuclide therapy (PRRT) agents for the therapeutic application of NETs. These radiolabeled-somatostatin analogs showed promising results with good images quality and high tumor uptake. These results highlight the potential application of radiopharmaceuticals-based somatostatin analogs for the molecular imaging and targeted treatment of NETs.