New and emerging somatostatin therapies for neuroendocrine tumors: "what is in the pipeline".

INTRODUCTION: Somatostatin receptors (SSTRs) play a central role in all aspects of management of neuroendocrine/endocrine-neoplasms (NENs). This includes diagnosis, with radiolabeled SSTR ligands localizing the primary/tumor extent, and confirming their NEN nature. Non-radiolabeled-SSTR agonists are first line for controlling the hormone-excess-state for functional NENs (F-NENs) and for initial cytotoxic treatment of advanced tumor-growth. Radiolabeled-SSTR-ligands treat advanced disease. There is increasing need for improvement, because some patients do not respond to SSTA-therapies, others become resistant, in some current imaging with radiolabeled-SSTAs is negative and the ease of ligand use/availability is a problem. Additionally, newer groups of patients are being considered for possible SSTA-treatment with newer SSTA‑related-compounds.

AREAS COVERED: In this perspective, the authors briefly review recent advances that are resulting in, or may result in, new/emerging SSTAs that show promise for future use in NEN patients.

EXPERT OPINION: This review involves both radiolabeled and non-radiolabeled agents for the future treatment of NENs, strongly supports the conclusion that in the future SSTR‑based-drugs will continue to play prominent roles in all aspects of NEN. Numerous recent studies firmly establish these conclusions, all of which are reviewed here; and they will likely be further supported by additional studies that are in progress and also cited here.