lx1032 and Neuroendocrine-Tumors

Carcinoid syndrome symptoms significantly reduce quality of life in patients with neuroendocrine tumors. Evidence supporting the use of somatostatin analogues in carcinoid syndrome symptom control dates back 30 years. The introduction of new treatment options for carcinoid syndrome, such as telotristat ethyl in 2017, highlights the need for a review of high-level evidence of new and established systemic treatments.. To examine the efficacy and safety of systemic treatment options for patients with carcinoid syndrome.. A systematic review of English language articles was conducted using PubMed, EMBASE, and the Cochrane Controlled Trials Register using the search terms carcinoid syndrome, clinical trial, clinical study, and prospective study. Additional studies were identified by searching abstracts from oncology or neuroendocrine tumor congresses during the previous year. Prospective, interventional, phase II or III clinical trials or pivotal trials leading to drug approval were included. Studies were required to have >85% of patients with carcinoid syndrome; secondary publications were excluded.. The search identified 233 unique records, of which 12 trials met the criteria for inclusion. Interventions assessed in these trials included short-acting and long-acting octreotide, lanreotide prolonged-release and autogel/depot, short-acting and long-acting pasireotide, telotristat ethyl, everolimus, and peptide receptor radionuclide therapy. Somatostatin analogues provided substantial symptom relief for patients with carcinoid syndrome. For refractory symptoms, an increased dose of somatostatin analogue or addition of telotristat ethyl were valuable options. Interventions were generally well tolerated, with few serious treatment-related adverse events.. By critically evaluating high-level evidence in a rigorous manner, this review highlights the general lack of consensus regarding what defines symptom control in studies of carcinoid syndrome and the need for standardized treatment guidelines for this disease. More prospective trials of treatments for carcinoid syndrome are warranted to assist oncologists with optimizing treatment selection and sequencing in this patient population.

Topics: Antineoplastic Agents; Clinical Trials as Topic; Female; Humans; Male; Malignant Carcinoid Syndrome; Neuroendocrine Tumors; Phenylalanine; Practice Guidelines as Topic; Prospective Studies; Pyrimidines; Quality of Life; Somatostatin; Treatment Outcome

Telotristat ethyl (Xermelo), developed by Lexicon Pharmaceuticals, is an oral tryptophan hydroxylase inhibitor blocking peripheral conversion of tryptophan to serotonin (5-hydroxytryptamine [5-HT]). It was approved by the U.S. Food and Drug Administration (FDA) in February 2017 and by the European Commission in September 2017 for patients with carcinoid syndrome in whom diarrhea is not adequately controlled by somatostatin analogues (SSAs). Diarrhea, secondary to the release of serotonin, is the predominant gastrointestinal symptom in patients with carcinoid syndrome and has a significant impact on patients' quality of life. Telotristat is not meant for all patients with diarrhea and carcinoid syndrome. Prescribing of telotristat for patients with diarrhea refractory to SSAs requires careful consideration and an approach that involves identifying and ruling out other common causes of diarrhea in patients with carcinoid syndrome. Delineating the timing of diarrhea and whether it occurs in patients with stable disease versus cancer progression can help identify the right drug candidates for therapy.

Topics: Clinical Trials as Topic; Diarrhea; Humans; Malignant Carcinoid Syndrome; Neuroendocrine Tumors; Phenylalanine; Pyrimidines; Somatostatin

Metastatic neuroendocrine tumors (NETs) are associated with carcinoid syndrome that is typically characterized by diarrhea, cutaneous flushing and bronchospasm. Treatment with somatostatin analogues (SSA) improves the symptom burden but a significant proportion of patients stop responding to SSA therapy eventually. Novel agents with the potential to effectively control the symptoms are urgently needed.. This article reviews an in-depth analysis of the phase I-III clinical trials determining the clinical rationale for the use of tryptophan hydroxylase inhibitor, telotristat ethyl in patients with well-differentiated metastatic NETs and uncontrolled carcinoid syndrome.. Telotristat ethyl has already been approved for the treatment of inadequately controlled carcinoid syndrome symptoms in metastatic NET patients on SSA therapy. Results from multiple phase I-III clinical studies of telotristat ethyl therapy have reported a significant decrease in the daily bowel movement frequency, increase in quality of life and the subsequent decrease in annual health costs related to carcinoid syndrome symptoms in NET patients.. The associated decrease in urinary 5-hydroxyindoleacetic acid (u5-HIAA) provides evidence that telotristat ethyl effectively decreases serotonin production, and therefore, offers a rationale to investigate this agent to mitigate serotonin-mediated complications in this patient population, especially cardiac valvular disease or mesenteric fibrosis.

Topics: Administration, Oral; Diarrhea; Female; Humans; Male; Malignant Carcinoid Syndrome; Neuroendocrine Tumors; Phenylalanine; Pyrimidines

Many patients with neuroendocrine tumour-related carcinoid syndrome treated with somatostatin analogues (SSA) won't achieve adequate symptom relief with the SSA alone; new treatment options are required. Telotristat ethyl is a tryptophan hydroxylase inhibitor, developed for the treatment of carcinoid syndrome. Areas covered: This review summarises the evidence supporting the role of telotristat ethyl in the management of carcinoid syndrome. Rationale, pharmacodynamics, pharmacokinetics, metabolism, clinical experience, efficacy and toxicity profiles are covered. Expert opinion: The efficacy of telotristat ethyl in producing a statistically-significant and clinically-meaningful reduction in daily bowel movements has been confirmed in phase III clinical trials. Two pivotal trials, TELESTAR and TELECAST, explored the role of telotristat ethyl in the management of patients with carcinoid syndrome refractory to SSAs focusing on patients with ≥4 and <4 daily bowel movements, respectively. In addition, benefit was confirmed in patient-reported outcomes. Based on activity and safe toxicity profile, telotristat ethyl is pending regulatory agencies evaluation and is likely to add to the armamentarium used to treat carcinoid syndrome. Long-term safety and efficacy data will be available from the ongoing TELEPATH study. The impact on carcinoid heart disease, mesenteric fibrosis and other long-term complications of carcinoid syndrome as well as its role earlier in patients' pathways remain investigational.

Topics: Animals; Carcinoid Tumor; Clinical Trials as Topic; Humans; Malignant Carcinoid Syndrome; Neuroendocrine Tumors; Phenylalanine; Pyrimidines; Somatostatin; Tryptophan Hydroxylase

Patients with metastatic neuroendocrine tumors and carcinoid syndrome (CS) may experience chronic, recurring symptoms despite somatostatin analogue therapy. Little is known about the relationship between bowel movement (BM) frequency, patient-reported symptoms and health-related quality of life (QoL). Data from the TELESTAR study were used in exploratory, post hoc analyses to understand the relationship between durable reductions in BM frequency, symptom relief, and health-related QoL.. Patients with metastatic neuroendocrine tumors and CS in the Phase III TELESTAR study were randomized (1:1:1) to receive telotristat ethyl (TE) 250 mg, TE 500 mg, or placebo three times daily (TID) during a 12-week double-blind treatment period (DBTP). All patients received TE 500 mg TID in an open-label extension (OLE) to Week 48. Durable response was predefined. Analyses compared durable responders (DRs) and non-durable responders (NDRs), irrespective of treatment group, at Weeks 12, 24, and 48.. At the start of the DBTP, 135 patients were randomized, 45 patients each to TE 250 mg, TE 500 mg, and placebo. After the 12-week DBTP, 48 of 135 patients were DRs (TE 250 mg, n = 20; TE 500 mg, n = 19; placebo, n = 9). Of the 115 patients who entered the OLE, 35 were DRs initially randomized to TE 250 mg (n = 18) or 500 mg (n = 17), 29 of whom maintained a durable response throughout the OLE. Of the 71 DBTP-NDRs (inclusive of patients initially randomized to placebo), 28 became OLE-DRs. There were 29 NDRs initially randomized to placebo who entered the OLE, 16 of whom became DRs when switched to TE 500 mg. DRs during the DBTP had greater symptom improvements in the DBTP; these improvements continued over the OLE. DBTP-DRs also maintained more meaningful QoL improvements in EORTC QLQ-C30 global health status, nausea and vomiting, pain, diarrhea, and EORTC QLQ-GINET21 gastrointestinal symptoms over the DBTP and OLE periods than DBTP-NDRs.. These results suggest that sustained improvements in BM frequency in patients with CS may have multifaceted, long-term effects on a patient's well-being. ClinicalTrials.gov identifiers: NCT01677910.

Topics: Aged; Diarrhea; Double-Blind Method; Female; Humans; Male; Malignant Carcinoid Syndrome; Neuroendocrine Tumors; Phenylalanine; Pyrimidines; Quality of Life; Treatment Outcome; Tryptophan Hydroxylase

Serotonin, a biologically active amine, is related to carcinoid syndrome in functioning neuroendocrine tumors (NETs). Telotristat ethyl is a novel inhibitor of the tryptophan hydroxylase (TPH), a key enzyme in the production of serotonin. While its use in patients with carcinoid syndrome and uncontrolled diarrhea under somatostatin analogs (SSAs) has been recently approved, in vitro data evaluating its effectiveness are lacking. For this reason, we aimed to evaluate the effect of telotristat as monotherapy, and in combination with SSAs, on proliferation and secretion in a NET cell line model. The human pancreatic NET cell lines BON-1/QGP-1 were used as 2D and 3D cultured models; somatostatin receptor and TPH mRNA expression, as well as the potential autocrine effect of serotonin on tumor cell proliferation using a 3D culture system were evaluated. Telotristat decreased serotonin production in a dose-dependent manner at a clinically feasible concentration, without affecting cell proliferation. Its combination with pasireotide, but not with octreotide, had an additive inhibitory effect on serotonin secretion. The effect of telotristat was slightly less potent, when BON-1 cells were co-treated with octreotide. Octreotide and pasireotide had no effect on the expression of TPH. Telotristat did not have an effect on mRNA expression of somatostatin receptor subtypes. Finally, we showed that serotonin did not have an autocrine effect on NET cell proliferation on the 3D cell model. These results suggest that telotristat is an effective drug for serotonin inhibition, but the effectiveness of its combination with SST2 (somatostatin receptor subtype 2)-preferring SSA should be evaluated in more detail.

Topics: Dose-Response Relationship, Drug; Enzyme Inhibitors; Humans; In Vitro Techniques; Neuroendocrine Tumors; Pancreatic Neoplasms; Phenylalanine; Pyrimidines; Serotonin; Tryptophan Hydroxylase; Tumor Cells, Cultured