The U.S. Food and Drug Administration (FDA) has approved telotristat ethyl (Xermelo) for the treatment of adults with carcinoid syndrome diarrhea in combination with somatostatin analog (SSA).1

Approval was based on findings from the multicenter, double-blind, phase 3 TELESTAR trial ( Identifier: NCT01677910), which evaluated the efficacy and safety of telotristat ethyl in combination with SSA therapy in 90 adult patients with well-differentiated metastatic neuroendocrine tumors and carcinoid syndrome diarrhea. Despite the use of SSA therapy at a stable dose for at least 4 months, these patients had 4 to 12 bowel movements per day.

Thirty-three percent of patients randomly assigned to receive telotristat ethyl in combination with SSA therapy had an average reduction of 2 bowel movements per day compared with 4% of those who received placebo plus SSA. The most common adverse events associated with telotristat ethyl include nausea, headache, increased gamma-glutamyl transferase, depression, peripheral edema, flatulence, decreased appetite, and pyrexia.

Continue Reading

Clinicians should monitor patients for severe constipation. Discontinue telotristat ethyl in patients who experience severe constipation and/or severe persistent or worsening abdominal pain.

The recommended dose and schedule of telotristat ethyl is 250 mg taken orally 3 times daily with food. If short-acting octreotide is used in combination with telotristat ethyl, administer the short-acting octreotide at least 30 minutes after administering telotristat ethyl.

RELATED: Efficacy of Osimertinib in Advanced T790M-positive NSCLC

Telotristat ethyl is a first-in-class oral tryptophan hydroxylase inhibitor that targets the overproduction of serotonin inside mNET cells.


  1. FDA approves Lexicon drug Xermelo (telotristat ethyl) 250 mg as first and only oral treatment for carcinoid syndrome diarrhea in cancer patients with metastatic neuroendocrine tumors [news release]. The Woodlands, TX: Lexicon Pharmaceuticals; February 28, 2017. Accessed February 28, 2017.