PRIMARY OBJECTIVE:~I. To estimate the percent change in N-terminal pro B-type natriuretic peptide (NT-proBNP) at 6 month visit from baseline after initiation of study drug in each arm and to compare the percent change between the two study arms.~SECONDARY OBJECTIVES:~I. To evaluate the change in functional capacity from baseline at 3 and 6 month visits as assessed by a 6 minute walk test (6MWT) in each arm.~II. To evaluate changes in echocardiographic parameters (Carcinoid Valvular Heart Disease [CVHD] score, global longitudinal myocardial strain assessment of the left and right ventricle/tricuspid annular plane systolic excursion [TAPSE]) from baseline to 3 and 6 month visits in each arm.~III. To evaluate the change from baseline to 3 and 6 month visits in plasma 5-hydroxyindoleacetic acid (5-HIAA) levels in each arm.~IV. To evaluate the change from baseline to 3 and 6 month visits in high sensitivity troponin T in each arm.~V. To evaluate the change from baseline to 3 and 6 month visits in health related quality of life with using the MD Anderson Symptom Inventory (MDASI) in each arm.~VI. To evaluate compliance of medications.~OUTLINE: Patients are randomized to 1 of 2 arms.~ARM A: Patients receive telotristat ethyl orally (PO) three times daily (TID) and somatostatin analog therapy (SSA) for 6 months in the absence of disease progression or unacceptable toxicity.~ARM B: Patients receive placebo PO TID and SSA for 6 months in the absence of disease progression or unacceptable toxicity.~After completion of study treatment, patients are followed up for 30 days.
This phase III trial compares the effect of telotristat ethyl and the current standard of care somatostatin analog therapy or somatostatin analog therapy alone in treating patients with neuroendocrine tumor that has spread to other places in the body (metastatic). Telotristat ethyl and somatostatin analog therapy may help to control carcinoid syndrome and carcinoid heart disease.