Figure 2.

Structures of SST and synthetic analogs used clinically. (A) The 14 amino acid SST is shown and essential amino acids are in black. The SST synthetic analogs, octreotide (B), and lanreotide (C), which have 8 amino acids, are approved to treat patients with neuroendocrine tumors (NETs) producing hormone-excess states (VIPoma, carcinoid syndrome) and for their anti-proliferative activity in patients with advanced, aggressive NETs. ¹¹¹InDTPA pentetreotide (D) as well as ⁶⁸GaDOTATATE (E) are used for SSTR imaging in patients with NETs. ⁹⁰Y-DOTA (F) and ¹⁷⁷Lu-DOTA (G) -labeled SST analogs are used for their antitumor activity during PRRT by targeting the cytotoxic radiolabel to the tumor.