Inhibition of Serotonin Synthesis May Have Antitumor Activity? Long‐Term Efficacy in a Patient with Gastrointestinal Neuroendocrine Tumor

• Published in: The oncologist (Dayton, Ohio) Vol. 24; no. 7; pp. e597 - e599
• Main Authors: Molina‐Cerrillo, Javier, Grande, Enrique, Alonso‐Gordoa, Teresa
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-07-2019
• Subjects: Brief Communications
• ISSN: 1083-7159; 1549-490X
• DOI: 10.1634/theoncologist.2018-0776

In this article, we propose, based on a clinical case, the potential antitumor effect related to the inhibition of serotonin in neuroendocrine tumors (NETs). Currently, the only drug that exists for the symptomatic treatment of carcinoid syndrome refractory to somatostatin analogues is telotristat, based on its pivotal study, the TELESTAR trial. Based on the existing preclinical rationale, it seems that the inhibition of serotonin may have an antitumoral role in NETs. Briefly, serotonin may act as an autocrine growth factor of NETs, and it may also play an immunomodulatory role by enhancing macrophage polarization to an immunotolerant M2 phenotype. To our knowledge, this rationale for the possible antitumor effect of serotonin in NETs has not yet been published in the literature.
The treatment of choice for patients with carcinoid syndrome is based on somatostatin analogs. This brief communication presents the case of a patient with a neuroendocrine tumor who participated in the TELESTAR trial and reports on the effectiveness of telotristat ethyl for improved control of diarrhea associated with carcinoid syndrome refractory to somatostatin analogs. Moreover, the article explains the rationale for potential antitumor effects related to inhibition of serotonin synthesis in neuroendocrine tumors.