Control of carcinoid syndrome with everolimus

Efficacy, safety and unmet needs of evolving medical treatments for carcinoid syndrome

This review reports on the currently available medical treatment options for the control of symptoms due to carcinoid syndrome in patients with neuroendocrine tumors. The efficacy and adverse events (AEs) of approved drugs such as somatostatin analogues (SSA), telotristat ethyl (TE) and interferon-alpha, are reviewed. Somatostatin analogues remain the standard treatment of carcinoid syndrome based on the high expression of somatostatin receptors and the resulting inhibition of secretion of bioactive compounds; their use is associated with relatively mild AEs, involving mainly the gastrointestinal system, and being usually transient. Although dose escalation of SSA remains an unapproved option, it is clinically implemented to alleviate symptoms in refractory carcinoid syndrome and supported by the most recent guidelines. The side effects associated with the increased dose are in general mild and consistent with standard dose of SSA. Telotristat ethyl, an oral inhibitor of tryptophan hydroxylase, the rate-limiting enzyme in serotonin biosynthesis, represents a rather novel innovative treatment option in patients with carcinoid syndrome suffering from diarrhea and complements the standard therapy of SSA. Given the low toxicity profile, TE may be considered an early add-on treatment to SSA in patients with uncontrolled carcinoid syndrome. However, further prolonged follow-up of patients treated with TE may be needed to exclude potential AEs, such as liver toxicity or depressed mood, in patients with long-term treatment. Interferon alpha is a cytokine with direct inhibitory effect on hormone secretion and tumor cell proliferation and an approved therapy in carcinoid syndrome but is associated with significant AEs in the majority of the patients requiring frequently dose reduction. The finding of a more favorable tolerability of pegylated interferon needs to be confirmed in a prospective study.

Medical Management of Gastroenteropancreatic Neuroendocrine Tumors

The increased incidence and prevalence of neuroendocrine tumors (NETs) over the past few decades has been accompanied by an improvement in overall survival. There are differences in the management of small bowel NETs versus pNETs. The management of all patients with NETs must be individualized based on patient characteristics as well tumor-related factors. This article reviews the role of somatostatin analogues, historical results with chemotherapy in gastroenteropancreatic NETs (GEPNETs), and more recent evidence for the use of cytotoxic chemotherapy in GEPNETs. The article also discusses molecular targeted therapies approved for use in GEPNETs and some ongoing clinical trials.

Management of carcinoid syndrome: a systematic review and meta-analysis

Carcinoid syndrome (CS) is a debilitating disease caused by functional neuroendocrine tumors. Several treatment options are available to alleviate the hormonal symptoms, but their relative efficacy is unknown. Online databases were searched for publications on the treatment of CS symptoms. Independent reviewers assessed relevant publications for study quality and outcome. Meta-analysis of the outcomes of the intervention on CS-related symptoms was stratified by the type of treatment. We found 3682 therapeutic interventions on CS-specific outcomes were collected from 93 studies. Overall, the study qualities were poor with only six randomized controlled clinical trials. The somatostatin analogs octreotide and lanreotide induced symptomatic improvement in 65-72% and biochemical response in 45-46% of patients. An increase in dose or frequency or interclass switch led to a reduction of flushes and/or diarrhea in 72-84% of cases. Retrospective, institutional series showed that liver-directed therapy can improve symptoms in 82% of CS patients with a liver-dominant disease. The serotonin synthesis inhibitor telotristat ethyl reduced bowel movements in 40% of patients with diarrhea refractory to somatostatin analogs. Interferon-alpha controlled CS symptoms in 45-63% of cases. Favorable response has been noted after radionuclide therapy in subgroup analyses of studies not specifically involving CS patients. Chemotherapy and everolimus did not induce a significant response in the CS. We conclude that several treatment lines can be offered to patients suffering from the carcinoid syndrome. Initiation of randomized controlled trials with a primary outcome on carcinoid syndrome symptoms is strongly recommended.

Management of carcinoid syndrome: a systematic review and meta-analysis

Carcinoid syndrome (CS) is a debilitating disease caused by functional neuroendocrine tumors. Several treatment options are available to alleviate the hormonal symptoms, but their relative efficacy is unknown. Online databases were searched for publications on the treatment of CS symptoms. Independent reviewers assessed relevant publications for study quality and outcome. Meta-analysis of the outcomes of the intervention on CS-related symptoms was stratified by the type of treatment. We found 3682 therapeutic interventions on CS-specific outcomes were collected from 93 studies. Overall, the study qualities were poor with only six randomized controlled clinical trials. The somatostatin analogs octreotide and lanreotide induced symptomatic improvement in 65–72% and biochemical response in 45–46% of patients. An increase in dose or frequency or interclass switch led to a reduction of flushes and/or diarrhea in 72–84% of cases. Retrospective, institutional series showed that liver-directed therapy can improve symptoms in 82% of CS patients with a liver-dominant disease. The serotonin synthesis inhibitor telotristat ethyl reduced bowel movements in 40% of patients with diarrhea refractory to somatostatin analogs. Interferon-alpha controlled CS symptoms in 45–63% of cases. Favorable response has been noted after radionuclide therapy in subgroup analyses of studies not specifically involving CS patients. Chemotherapy and everolimus did not induce a significant response in the CS. We conclude that several treatment lines can be offered to patients suffering from the carcinoid syndrome. Initiation of randomized controlled trials with a primary outcome on carcinoid syndrome symptoms is strongly recommended.

Everolimus in the treatment of neuroendocrine tumors: efficacy, side-effects, resistance, and factors affecting its place in the treatment sequence

INTRODUCTION

Since the initial approval of everolimus in 2011, there have been a number of important changes in therapeutic/diagnostic modalities as well as classification/staging systems of neuroendocrine tumors (NETs), which can significantly impact the use of everolimus in patients with advanced NETs. Areas covered: The efficacy of everolimus monotherapy and combination therapy demonstrated in clinical studies involving patients with advanced NETs are reviewed. Several factors affecting everolimus use are described including: the development and routine use of NET classification/staging systems; widespread use of molecular imaging modalities; side effects; drug resistance; and the availability of other treatment options. Furthermore, the current position of everolimus in the treatment approach is discussed, taking into account the recommendations from the recent guidelines. Expert opinion: Although everolimus demonstrated its high efficacy and tolerability in the RADIANT trials and other clinical studies, there still remain a number of controversies related to everolimus treatment in the management of NETs. The synergistic anti-growth effect of other agents in combination with everolimus or its effect on overall survival have not been established. The appropriate order of the use of everolimus in the treatment of advanced NETs still remains unclear, which needs to be defined in further studies and will be addressed in the new guidelines.

Carcinoid-syndrome: recent advances, current status and controversies

PURPOSE OF REVIEW

To review recent advances and controversies in all aspects of carcinoid-syndrome.

RECENT FINDINGS

Over the last few years there have been a number of advances in all aspects of carcinoid syndrome as well as new therapies. These include new studies on its epidemiology which demonstrate it is increasing in frequency; increasing insights into the pathogenesis of its various clinical manifestations and into its natural history: definition of prognostic factors; new methods to verify its presence; the development of new drugs to treat its various manifestations, both initially and in somatostatin-refractory cases; and an increased understanding of the pathogenesis, natural history and management of carcinoid heart disease. These advances have generated several controversies and these are also reviewed.

SUMMARY

There have been numerous advances in all aspects of the carcinoid-syndrome, which is the most common functional syndrome neuroendocrine tumors produce. These advances are leading to new approaches to the management of these patients and in some cases to new controversies.

Telotristat ethyl: proof of principle and the first oral agent in the management of well-differentiated metastatic neuroendocrine tumor and carcinoid syndrome diarrhea

INTRODUCTION

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.

METHODS

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.

DISCUSSION

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.

FUTURE DIRECTIONS

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.

Diagnosing and Managing Carcinoid Heart Disease in Patients With Neuroendocrine Tumors: An Expert Statement

Carcinoid heart disease is a frequent occurrence in patients with carcinoid syndrome and is responsible for substantial morbidity and mortality. The pathophysiology of carcinoid heart disease is poorly understood; however, chronic exposure to excessive circulating serotonin is considered one of the most important contributing factors. Despite recognition, international consensus guidelines specifically addressing the diagnosis and management of carcinoid heart disease are lacking. Furthermore, there is considerable variation in multiple aspects of screening and management of the disease. The aim of these guidelines was to provide succinct, practical advice on the diagnosis and management of carcinoid heart disease as well as its surveillance. Recommendations and proposed algorithms for the investigation, screening, and management have been developed based on an evidence-based review of the published data and on the expert opinion of a multidisciplinary consensus panel consisting of neuroendocrine tumor experts, including oncologists, gastroenterologists, and endocrinologists, in conjunction with cardiologists and cardiothoracic surgeons.

Refractory carcinoid syndrome: a review of treatment options

Carcinoid syndrome (CSy) is a constellation of symptoms that may commonly present in patients with well differentiated neuroendocrine tumors (NETs), with somatostatin analogs (SSAs) being the first-line option for symptom management. However, symptomatic progression eventually occurs and in this scenario of a refractory CSy; several treatment options have been studied such as dose escalation of SSA, interferon and liver-directed therapies. Nevertheless, recent phase III trials have contributed to the understanding and management of this condition. We performed a comprehensive review of interventional studies examining refractory CSy to provide the evidence for current treatment options and propose a treatment sequence.

Efficacy and Safety of Everolimus in Extrapancreatic Neuroendocrine Tumor: A Comprehensive Review of Literature

BACKGROUND

Everolimus, an oral mTOR (mammalian target of rapamycin) inhibitor, is currently approved for the treatment of progressive pancreatic neuroendocrine tumors (NETs). Although promising, only scattered data, often from nondedicated studies, are available for extrapancreatic NETs.

PATIENTS AND METHODS

A systematic review of the published data was performed concerning the use of everolimus in extrapancreatic NET, with the aim of summarizing the current knowledge on its efficacy and tolerability. Moreover, the usefulness of everolimus was evaluated according to the different sites of the primary.

RESULTS

The present study included 22 different publications, including 874 patients and 456 extrapancreatic NETs treated with everolimus. Nine different primary sites of extrapancreatic NETs were found. The median progression-free survival ranged from 12.0 to 29.9 months. The median time to progression was not reached in a phase II prospective study, and the interval to progression ranged from 12 to 36 months in 5 clinical cases. Objective responses were observed in 7 prospective studies, 2 retrospective studies, and 2 case reports. Stabilization of the disease was obtained in a high rate of patients, ranging from 67.4% to 100%. The toxicity of everolimus in extrapancreatic NETs is consistent with the known safety profile of the drug. Most adverse events were either grade 1 or 2 and easy manageable with a dose reduction or temporary interruption and only rarely requiring discontinuation.

CONCLUSION

Treatment with everolimus in patients with extrapancreatic NETs appears to be a promising strategy that is safe and well tolerated. The use of this emerging opportunity needs to be validated with clinical trials specifically designed on this topic.

IMPLICATIONS FOR PRACTICE

The present study reviewed all the available published data concerning the use of everolimus in 456 extrapancreatic neuroendocrine tumors (NETs) and summarized the current knowledge on the efficacy and safety of this drug, not yet approved except for pancreatic NETs. The progression-free survival rates and some objective responses seem promising and support the extension of the use of this drug. The site-by-site analysis seems to suggest that some subtypes of NETs, such as colorectal, could be more sensitive to everolimus than other primary NETs. No severe adverse events were usually reported and discontinuation was rarely required; thus, everolimus should be considered a valid therapeutic option for extrapancreatic NETs.

Symptomatic Control of Neuroendocrine Tumours with Everolimus

Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, increases progression-free survival in patients with advanced neuroendocrine tumours. Patients with neuroendocrine tumours and symptomatic carcinoid have inferior health-related quality of life than those without symptoms. We aimed to evaluate the effect of everolimus on symptomatic control of neuroendocrine tumours. Fifteen patients with metastatic neuroendocrine disease pre-treated with depot octreotide received combination everolimus and octreotide (midgut = 8, pancreatic = 3, other = 4). Reasons for initiation of everolimus were progressive disease (PD) by response evaluation criteria in solid tumours (n = 5), worsening syndromic symptomology (n = 5), or both (n = 5). Symptomatic and objective response and toxicity were evaluated using standard criteria. 7/10 patients who were syndromic had improvements in symptomology, with a mean duration of symptom control 13.9 months (range 1-39). All 10 symptomatic patients had non pancreatic neuroendocrine (pNET) primaries, and with everolimus, 6/10 had reduced stool frequency, 3/7 had a reduction of asthenia, and 5/7 had reduced frequency and severity of flushing. Sixty percent of patients experienced any grade toxicities, including the following: 40% grade 1/2 stomatitis, 7% grade 3/4 stomatitis, 20% grade 1/2 rash, 13% diarrhoea, and one case of pneumonitis. In this cohort of 15 patients, we demonstrated that 70% of non pNET individuals with common carcinoid syndrome symptoms resistant to depot octreotide had improvement in these symptoms on institution of everolimus, with meaningful durations of symptom control. Although this data is observational, to our knowledge, this represents the largest analysis of carcinoid syndrome control with combined everolimus and octreotide.

Raised circulating Neurokinin A predicts prognosis in metastatic small bowel neuroendocrine tumours. Lowering Neurokinin A indicates improved prognosis

Background

Assessing prognosis is important in patients with neuroendocrine tumours of the small bowel as disease progression and survival is variable. We previously identified raised Neurokinin A as an independent indicator of poor prognosis and have shown that prognosis worsens when circulating Neurokinin A rises ≥50 ng/L. In the present study we have examined survival in relation to Neurokinin A concentrations.

Methods

Patients in whom Neurokinin A rose ≥50 ng/L between January 1989 and December 2010 were identified. All circulating Neurokinin A concentrations were recorded and survival was followed up to 31 December 2014 or to death.

Results

Median survival, from the date when Neurokinin A was first ≥50 ng/L was 11.1 (2.0–117.8) months if Neurokinin A remained ≥50 ng/L and 72.4 (4.8–152.6) months when Neurokinin A was reduced below 50 ng/L and controlled below that concentration for ≥3 months (P < 0.001). Survival was significantly better for patients attending the neuroendocrine tumour specialist clinic than for those not attending (P = 0.009). Comparing patients identified during 1989–2000, and those during 2001–2010, Neurokinin A was successfully reduced in the earlier period in 30.3% patients with median survival 23.2 (2.0–152.6) months and this improved in 58.1% with median survival of 43.3 (2.0–141.1) months in the later period (P = 0.019). Significance was greater between the earlier and later periods when only patients attending the neuroendocrine tumour clinic were compared (P = 0.016).

Conclusions

Circulating Neurokinin A ≥ 50 ng/L is a strong indicator of poor prognosis when Neurokinin A remains above this concentration. Lowering Neurokinin A below 50 ng/L indicates a significant improvement in prognosis (P < 0.001). This prognostic indicator reflects improved treatment and survival in more recent years.

[Neuroendocrine tumors: the age of targeted therapies]

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are the second most prevalent group of advanced gastrointestinal tract tumors. Resources invested in research on this patient population have exponentially increased in recent years, and this has become one of the most attractive fields for oncological research. Several proangiogenic proteins have been found to be overexpressed in GEP-NETs, including vascular endothelial growth factor and its receptors and the more closely related intracellular signaling pathways such as the epidermal growth factor pathway, type I insulin-like growth factor receptor, and the PI3K-(PTEN)-AKT-mTOR pathway. The recent results of the three most important Phase III studies in GEP-NETs have allowed for approval of two targeted agents, sunitinib and everolimus, for the treatment of patients with pancreatic neuroendocrine tumors after decades of minimal advances in this population.