Telotristat ethyl in carcinoid syndrome: Safety and efficacy in the TELECAST phase 3 trial

Marianne Pavel, David J. Gross, Marta Benavent, Petros Perros, Raj Srirajaskanthan, Richard R.P. Warner, Matthew H. Kulke, Lowell B. Anthony, Pamela L. Kunz, Dieter Hörsch, Martin O. Weickert, Pablo Lapuerta, Wenjun Jiang, Kenneth Kassler-Taub, Suman Wason, Rosanna Fleming, Douglas Fleming, Rocio Garcia-Carbonero

Research output: Contribution to journalArticlepeer-review

106 Scopus citations

Abstract

Telotristat ethyl, a tryptophan hydroxylase inhibitor, was efficacious and well tolerated in the phase 3 TELESTAR study in patients with carcinoid syndrome (CS) experiencing >4 bowel movements per day (BMs/day) while on somatostatin analogs (SSAs). TELECAST, a phase 3 companion study, assessed the safety and efficacy of telotristat ethyl in patients with CS (diarrhea, flushing, abdominal pain, nausea or elevated urinary 5-hydroxyindoleacetic acid (u5-HIAA)) with <4 BMs/day on SSAs (or >1 symptom or >4 BMs/day if not on SSAs) during a 12-week double-blind treatment period followed by a 36-week open-label extension (OLE). The primary safety and efficacy endpoints were incidence of treatment-emergent adverse events (TEAEs) and percent change from baseline in 24-h u5-HIAA at week 12. Patients (N = 76) were randomly assigned (1:1:1) to receive placebo or telotristat ethyl 250 mg or 500 mg 3 times per day (tid); 67 continued receiving telotristat ethyl 500 mg tid during the OLE. Through week 12, TEAEs were generally mild to moderate in severity; 5 (placebo), 1 (telotristat ethyl 250 mg) and 3 (telotristat ethyl 500 mg) patients experienced serious events, and the rate of TEAEs in the OLE was comparable. At week 12, significant reductions in u5-HIAA from baseline were observed, with Hodges-Lehmann estimators of median treatment differences from placebo of -54.0% (95% confidence limits, -85.0%, -25.1%, P < 0.001) and -89.7% (95% confidence limits, -113.1%, -63.9%, P < 0.001) for telotristat ethyl 250 mg and 500 mg. These results support the safety and efficacy of telotristat ethyl when added to SSAs in patients with CS diarrhea (ClinicalTrials.gov identifier: NCT02063659).

Original languageEnglish
Pages (from-to)309-322
Number of pages14
JournalEndocrine-Related Cancer
Volume25
Issue number3
DOIs
StatePublished - Mar 2018

Keywords

  • 5-HIAA
  • Carcinoid syndrome
  • Metastatic neuroendocrine tumor
  • Serotonin
  • Somatostatin analog

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