Shortened interval of long-acting octreotide administration is effective in patients with well-differentiated neuroendocrine carcinomas in progression on standard doses

Resistance of neuroendocrine tumours to somatostatin analogs

INTRODUCTION

A common feature shared by most neuroendocrine tumors (NETs) is the expression on their surface of somatostatin receptors (SSTRs) that are essential for their pathophysiological regulation, diagnosis, and management. The first-generation synthetic somatostatin analogs (SSAs), octreotide and lanreotide, constitute the cornerstone of treatment for growth hormone secreting pituitary adenomas and functioning, progressive functioning, and non-functioning gastro-entero-pancreatic (GEP-NETs). SSAs exert their mechanism of action through binding to the SSTRs; however, their therapeutic response is frequently attenuated or diminished by the development of resistance. The phenomenon of resistance is complex implicating the presence of additional epigenetic and genetic mechanisms.

AREAS COVERED

We aim to analyze the molecular, genetic, and epigenetic mechanisms of resistance to SSA treatment. We also summarize recent clinical data related to the development of resistance on conventional and non-conventional modes of administration of the first-generation SSAs and the second-generation SSA pasireotide. We explore mechanisms used to counteract the resistance to SSAs using higher doses or more frequent mode of administration of SSAs and/or combination treatments.

EXPERT OPINION

There is considerable heterogeneity in the development of resistance to SSAs that is tumor-specific necessitating the delineation of the underlying pathophysiological processes to further expand their therapeutic applications.

Somatostatin Analogue Therapy in MEN1-Related Pancreatic Neuroendocrine Tumors from Evidence to Clinical Practice: A Systematic Review

Neuroendocrine neoplasms (NENs) are relatively rare and complex tumors that can be sporadic or hereditary, as in the context of multiple endocrine neoplasia type 1 (MEN1) where patients display a 70% lifelong risk of developing a pancreatic NENs (pNENs). To date, specific personalized treatment for pNENs in patients with MEN1 are lacking. The aim of this study was to systematically analyze the efficacy and safety of somatostatin analogue (SSA) treatment in patients affected by MEN1-related pNENs. We performed a systematic review of the literature, searching for peer-reviewed articles on SSA (octreotide or lanreotide) treatment in MEN1 associated with pNENs. We selected 20 studies with a pooled population of 105 MEN1 patients with pNENs. Females were 58.5%, median age was 44 years (18-73). TNM stage at diagnosis was stage I-II in 84.8% and stage IV in 15.2%. The overall response rate (SD+PR+CR) was achieved in 88.3% of cases, with stable disease in 75.6% and objective response in 12.7% of patients. The safety profile was favorable with both SSA agents. SSAs appear to be an effective and safe treatment option for MEN1-related pNEN, either at localized or advanced stages.

Current status of medical treatment for gastroenteropancreatic neuroendocrine neoplasms and future perspectives

Neuroendocrine neoplasms (NENs) constitute a heterogeneous group of tumors. In this review, we summarize the results of various clinical trials that have been conducted to investigate the efficacy and safety of various therapeutic options for NENs. Based on the encouraging results obtained from these trials, various therapeutic options have been established for the treatment of NENs, including somatostatin analogs (SSAs), molecularly targeted drugs and cytotoxic agents. In addition, peptide receptor radionucleotide therapy has recently been evaluated for the treatment of various NENs. We also discuss the approach for selecting the appropriate drugs and sequence of treatment with the various drug classes, as recommended by different treatment guidelines. Finally, we discuss the scope for future research in this field, especially into the merits of combination therapy with molecularly targeted drugs plus SSAs, along with ongoing studies.

Medical Treatment of Advanced Pancreatic Neuroendocrine Neoplasms

Pancreatic neuroendocrine neoplasms (panNENs) are relatively rare but their incidence has increased almost sevenfold over the last four decades. Neuroendocrine neoplasms are classified according to their histologic differentiation and their grade. Their grade is based on their Ki-67 proliferation index and mitotic index. Their prognosis is highly variable according to these elements and treatments also vary according to their classification. Surgery is the only curative treatment for localized and advanced panNENs and offers a better prognosis than non-surgical treatments. In the case of an advanced panNEN without the possibility of resection and/or ablation, medical treatment remains the cornerstone for improving survival and preserving quality-of-life. PanNENs are considered as chemosensitive tumors, unlike midgut neuroendocrine tumors. Thus, panNENs can be treated with chemotherapy, but targeted therapies and somatostatin analogs are also treatment options. The scarcity and heterogeneity of NENs make their management difficult. The present review aims to clarify the medical treatments currently available for advanced panNENs, based on their characteristics, and to propose a treatment algorithm.

Targeted Systemic Treatment of Neuroendocrine Tumors: Current Options and Future Perspectives

Neuroendocrine tumors (NETs) originate from the neuroendocrine cell system in the bronchial and gastrointestinal tract and can produce hormones leading to distinct clinical syndromes. Systemic treatment of patients with unresectable NETs aims to control symptoms related to hormonal overproduction and tumor growth. In the last decades prognosis has improved as a result of increased detection of early stage disease and the introduction of somatostatin analogs (SSAs) as well as several new therapeutic options. SSAs are the first-line medical treatment of NETs and can control hormonal production and tumor growth. The development of next-generation multireceptor targeted and radiolabelled somatostatin analogs, as well as target-directed therapies (as second-line treatment options) further improve progression-free survival in NET patients. To date, however, a significant prolongation of overall survival with systemic treatment in NET has not been convincingly demonstrated. Several new medical options and treatment combinations will become available in the upcoming years, and although preliminary results of preclinical and clinical trials are encouraging, large, preferrably randomized clinical studies are required to provide definitive evidence of their effect on survival and symptom control.

Gamma-Aminobutyric Acid Levels in the Anterior Cingulate Cortex of Perimenopausal Women With Depression: A Magnetic Resonance Spectroscopy Study

Objective

The anterior cingulate cortex (ACC) is associated with the processing of negative emotions. Gamma-aminobutyric acid (GABA) metabolism plays an important role in the pathogenesis of mental disorders. We aimed to determine the changes in GABA levels in the ACC of perimenopausal women with depression.

Methods

We recruited 120 perimenopausal women, who were followed up for 18-24 months. After reaching menopause, the participants were divided into a control group (n = 71), an anxiety group (n = 30), and a depression group (n = 19). The participants were examined using proton magnetic resonance spectroscopy (MRS). TARQUIN software was used to calculate the GABA concentrations in the ACC before and after menopause. The relationship of the GABA levels with the patients' scores on the 14-item Hamilton Anxiety Scale and 17-item Hamilton Depression Scale was determined.

Results

GABA decreased with time. The postmenopausal GABA levels were significantly lower in the depression group than in the anxiety group and were significantly lower in both these groups than in the normal group. The postmenopausal GABA levels were significantly lower than the premenopausal levels in the normal, anxiety, and depression groups (P = 0.014, <0.001, and <0.001, respectively). The premenopausal GABA levels did not significantly differ between the normal vs. anxiety group (P = 0.907), normal vs. depression group (P = 0.495), and anxiety vs. depression group. The postmenopausal GABA levels were significantly lower in the depression group than in the anxiety group and were significantly lower in both these groups than in the normal group, normal vs. anxiety group (P = 0.022), normal vs. depression group (P < 0.001), and anxiety vs. depression group (P = 0.047).

Conclusion

Changes in GABA concentrations in the anterior cingulate cortex are related with the pathophysiological mechanism and symptoms of perimenopausal depression.

Carcinoid Syndrome: Updates and Review of Current Therapy

OPINION STATEMENT

Carcinoid syndrome (CS) is a complex disorder caused by functional neuroendocrine tumors (NETs). This debilitating disease is characterized by hyper-secretion of biologically active substances eliciting major hormonal symptoms burden and fibrotic changes that are often challenging for management. There have been a number of insights that have substantially advanced treatments since the introduction of somatostatin analogs (SSAs). Second-line treatments are needed in a substantial proportion of patients with advanced disease that have uncontrolled hormone secretion on the highest labeled doses of SSAs. International guidelines suggest several available options including dose escalation of SSAs, interferon alpha, everolimus, radionuclide therapy, liver-directed therapies, and the novel tryptophan hydroxylase 1 inhibitor, telotristat ethyl. The clear preference of one second-line therapy over the other is not stated since their relative and long-term efficacy are largely unknown, and standardized approach of hormonal response assessment is lacking in the literature. In the clinical setting, the treatment of CS is guided in conjunction with patients' performance status, tumor origin, grade, stage, and growth rate, with regard to both anti-hormonal, as well as anti-proliferative effect. There is an unmet need for further well-designed randomized placebo-controlled and head-to-head studies that systematically assess CS symptom control and biochemical response following a specific intervention.

Evidence-Based Policy in Practice: Management of Carcinoid Syndrome Diarrhea

Carcinoid syndrome causes substantial morbidity and reduces quality of life and survival. In a recent clinical trial, 97% of patients reported bowel movement-related issues, abdominal pain, flushing, and low energy. Combining somatostatin analogs with elotristat ethyl provides a new option for managing refractory CS symptoms. Health care providers should consider strategies that take advantage of approved dosing for patients with CS-related diarrhea.

Somatostatin Analogues in the Treatment of Neuroendocrine Tumors: Past, Present and Future

In recent decades, the incidence of neuroendocrine tumors (NETs) has steadily increased. Due to the slow-growing nature of these tumors and the lack of early symptoms, most cases are diagnosed at advanced stages, when curative treatment options are no longer available. Prognosis and survival of patients with NETs are determined by the location of the primary lesion, biochemical functional status, differentiation, initial staging, and response to treatment. Somatostatin analogue (SSA) therapy has been a mainstay of antisecretory therapy in functioning neuroendocrine tumors, which cause various clinical symptoms depending on hormonal hypersecretion. Beyond symptomatic management, recent research demonstrates that SSAs exert antiproliferative effects and inhibit tumor growth via the somatostatin receptor 2 (SSTR2). Both the PROMID (placebo-controlled, prospective, randomized study in patients with metastatic neuroendocrine midgut tumors) and the CLARINET (controlled study of lanreotide antiproliferative response in neuroendocrine tumors) trial showed a statistically significant prolongation of time to progression/progression-free survival (TTP/PFS) upon SSA treatment, compared to placebo. Moreover, the combination of SSA with peptide receptor radionuclide therapy (PRRT) in small intestinal NETs has proven efficacy in the phase 3 neuroendocrine tumours therapy (NETTER 1) trial. PRRT is currently being tested for enteropancreatic NETs versus everolimus in the COMPETE trial, and the potential of SSTR-antagonists in PRRT is now being evaluated in early phase I/II clinical trials. This review provides a synopsis on the pharmacological development of SSAs and their use as antisecretory drugs. Moreover, this review highlights the clinical evidence of SSAs in monotherapy, and in combination with other treatment modalities, as applied to the antiproliferative management of neuroendocrine tumors with special attention to recent high-quality phase III trials.

Carcinoid syndrome: update on the pathophysiology and treatment

Approximately 30-40% of patients with well-differentiated neuroendocrine tumors present with carcinoid syndrome, which is a paraneoplastic syndrome associated with the secretion of several humoral factors. Carcinoid syndrome significantly and negatively affects patients' quality of life; increases costs compared with the costs of nonfunctioning neuroendocrine tumors; and results in changes in patients' lifestyle, such as diet, work, physical activity and social life. For several decades, patients with neuroendocrine tumors and carcinoid syndrome have been treated with somatostatin analogues as the first-line treatment. While these agents provide significant relief from carcinoid syndrome symptoms, there is inevitable clinical progression, and new therapeutic interventions are needed. More than 40 substances have been identified as being potentially related to carcinoid syndrome; however, their individual contributions in triggering different carcinoid symptoms or complications, such as carcinoid heart disease, remain unclear. These substances include serotonin (5-HT), which appears to be the primary marker associated with the syndrome, as well as histamine, kallikrein, prostaglandins, and tachykinins. Given the complexity involving the origin, diagnosis and management of patients with carcinoid syndrome, we have undertaken a comprehensive review to update information about the pathophysiology, diagnostic tools and treatment sequence of this syndrome, which currently comprises a multidisciplinary approach.

Improved survival with higher doses of octreotide long-acting release in gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) represent a heterogeneous group of tumors that is associated with an indolent course. Octreotide has a positive effect on disease stabilization in well-differentiated midgut NETs, but a meaningful survival analysis was not possible due to insufficient events. Higher doses of octreotide long-acting release (LAR) are often used in clinical practice for control of carcinoid symptoms and our objective was to determine if dose of octreotide correlates with survival. We reviewed all patients with advanced GEP NETs who initiated treatment with octreotide LAR between 2000 and 2013 in a large, representative Canadian province. We compared overall survival in patients who received low (< 30 mg) compared to high (≥ 30 mg) doses of octreotide. A total of 170 patients were identified. Baseline characteristics in the low- and high-dose groups were similar: median age 62/63 years, 50/58% were male, 46/48% originated from the small bowel, and 74/66% had liver metastases at diagnosis. The median time from diagnosis to treatment initiation was 5.5 and 6.0 months. Octreotide LAR was initiated with the intent of symptom management (71%), disease stabilization (23%), or biomarker control (6%). Median overall survival (OS) was better in the high-dose group, 66 months compared to 22 months (multivariate HR 0.5, p < 0.01). Age ≥ 65 (HR 1.9, p < 0.01), ECOG ≥ 2 (HR 2.7, p < 0.01), and pancreatic NETs (HR 1.7, p = 0.03) were all predictors of worse survival. Our findings suggest that octreotide may confer survival benefits in GEP NETs. Further prospective studies are warranted to validate the impact of high-dose octreotide on outcomes.

Treatment options for PNET liver metastases: a systematic review

BACKGROUND

Pancreatic neuroendocrine tumors (PNETs) are rare pancreatic neoplasms. About 40-80% of patients with PNET are metastatic at presentation, usually involving the liver (40-93%). Liver metastasis represents the most significant prognostic factor. The aim of this study is to present an up-to-date review of treatment options for patients with liver metastases from PNETs.

METHODS

A systematic literature search was performed using the PubMed database to identify all pertinent studies published up to May 2018.

RESULTS

The literature search evaluated all the therapeutic options for patients with liver metastases of PNETs, including surgical treatment, loco-regional therapies, and pharmacological treatment. All the different treatment options showed particular indications in different presentations of liver metastases of PNET. Surgery remains the only potentially curative therapeutic option in patients with PNETs and resectable liver metastases, even if relapse rates are high. Efficacy of medical treatment has increased with advances in targeted therapies, such as everolimus and sunitinib, and the introduction of radiolabeled somatostatin analogs. Several techniques for loco-regional control of metastases are available, including chemo- or radioembolization.

CONCLUSIONS

Treatment of patients with PNET metastases should be multidisciplinary and must be personalized according to the features of individual patients and tumors.

Systematic literature review of the antitumor effect of octreotide in neuroendocrine tumors

AIM

To provide a comprehensive examination of the existing evidence of the antitumor effect of long-acting octreotide in neuroendocrine tumors (NETs).

METHODS

A systematic literature review of clinical trials and observational studies was conducted in PubMed, EMBASE, and Cochrane through January 18, 2017. Conference abstracts for 2015 and 2016 from 5 scientific meetings were also searched.

RESULTS

Of 41 articles/abstracts identified, 13 unique studies compared octreotide with active or no treatment. Two of the 13 studies were clinical trials; the remaining were observational studies. The phase 3 Placebo-Controlled, Double-Blind, Prospective, Randomized Study of the Effect of Octreotide long-acting repeatable (LAR) in the Control of Tumor Growth in Patients with Metastatic Neuroendocrine Midgut Tumors clinical trial showed that long-acting octreotide significantly prolonged time to tumor progression compared with placebo in patients with functionally active and inactive metastatic midgut NETs; no statistically significant difference in overall survival (OS) was observed, possibly due to the crossover of placebo patients to octreotide. Retrospective observational studies found that long-acting octreotide use was associated with significantly longer OS than no octreotide use for patients with distant metastases although not for those with local/regional disease.

CONCLUSION

The clinical trial and observational studies with informative evidence support long-acting octreotide’s antitumor effect on time to tumor progression and OS. This review showed the rarity of existing studies assessing octreotide’s antitumor effect and recommends that future research is warranted.

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.

Octreotide long-acting repeatable in the treatment of neuroendocrine tumors: patient selection and perspectives

Over the past three decades, the incidence and prevalence of neuroendocrine tumors have gradually increased. Due to the slow-growing nature of these tumors, most cases are diagnosed at advanced stages. Prognosis and survival are associated with location of primary lesion, biochemical functional status, differentiation, initial staging, and response to therapy. Octreotide, the first synthetic somatostatin analog, was initially used for the management of gastrointestinal symptoms associated with functional carcinoid tumors. Its commercial development over time led to long-acting repeatable octreotide acetate, a long-acting version that provided greater administration convenience. Recent research demonstrates that octreotide’s efficacy has evolved beyond symptomatic management to targeted therapy with antitumoral effects. This review examines the history and development of octreotide, provides a synopsis on the classification, grading, and staging of neuroendocrine tumors, and reviews the evidence of long-acting repeatable octreotide acetate as monotherapy and in combination with other treatment modalities in the management of non-pituitary neuroendocrine tumors with special attention to recent high-quality Phase III trials.

Advances and Current Concepts in the Medical Management of Gastroenteropancreatic Neuroendocrine Neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are rare and heterogeneous group of tumors presenting as localised or metastatic disease and in a subset with distinct clinical syndromes. Treatment is aimed at controlling the functional syndrome, eradicating the tumor, and/or preventing further tumor growth. Surgery is the treatment of choice in removing the primary tumor and/or reducing tumor burden but cannot be applied to all patients. Somatostatin analogs (SS-analogs) obtain control of functional syndromes in the majority of GEP-neuroendocrine tumors (NETs); phase III trials have shown that SS-analogs can be used as first-line antiproliferative treatment in patients with slow-growing GEP-NETs. The role of the recently approved serotonin inhibitor, telotristat ethyl, and gastrin receptor antagonist, netazepide, is evolving. Streptozotocin-based chemotherapy has been used for inoperable or progressing pancreatic NENs but the orally administered combination of capecitabine/temozolomide is becoming more popular due to its better tolerability and potential effect in other GEP-NENs. Phase III trials have shown efficacy of molecular targeted therapies in GEP-NETs and of radionuclide treatment in patients with midgut carcinoid tumors expressing somatostatin receptors. Most patients will develop disease progression necessitating further therapeutic options. A combination of currently available treatments along with the molecular signature of each tumor will guide future treatment.

Anti-tumoral effects of somatostatin analogs: a lesson from the CLARINET study

Octreotide and lanreotide, the first-generation somatostatin analogs, successfully control hormone hyperproduction, and related syndromes, in patients with acromegaly and neuroendocrine tumors. However, their anti-tumor effect, rather evident in large number of pituitary adenomas in acromegalic patients, has been hypothesized for a long time in patients with neuroendocrine tumors as well, although a significant tumor shrinkage has rarely been observed. However, the recent publication of the CLARINET study has strengthened the evidence, already emerged with the PROMID trial, that the long-term treatment with the first-generation long-acting somatostatin analogs may exert an anti-tumor activity on G1 and G2 enteropancreatic neuroendocrine tumors, as well. After the publication, majority of international guidelines have updated their algorithms in line with these results and this class of drugs obtained the indication as anti-tumor agents in the majority of patients with neuroendocrine tumors.

Escalated-dose somatostatin analogues for antiproliferative effect in GEPNETS: a systematic review

BACKGROUND/PURPOSE

Somatostatin analogues are the cornerstone of systemic therapy for metastatic well-differentiated gastroenteropancreatic neuroendocrine tumours for both hormonal control and antiproliferative effect. Dose escalation of somatostatin analogues is often utilized in clinical practice, but small studies have yielded mixed results. The aim of this study was to systematically determine the efficacy and safety of escalated-dose somatostatin analogues in the above setting.

METHODS

Eligible trials (using more than 30 mg octreotide or 120 mg lanreotide/28 days) were identified from MEDLINE, EMBASE, other databases and conference proceedings. Demographics, disease control rate, objective response rate, biochemical response, improvement in symptoms and toxicity were abstracted. Trials were synthesized qualitatively.

RESULTS

Eighteen studies (1002 patients) were identified. The risk of bias was moderate for objective response outcomes, but high for the outcomes of symptom control and toxicity due to open-label trial designs. Disease control rates ranged from 30 to 100%, but response rates were modest (at 0-14%). Rates of biochemical improvement (27-100%) and symptom improvement (23-100%) ranged widely depending on the population studied and the definition of response. The most common toxicities were fatigue, diarrhoea, abdominal discomfort and cholelithiasis, with no severe or unexpected toxicities compared to standard-dose somatostatin analogues.

CONCLUSIONS

The current evidence indicates that escalated-dose somatostatin analogues are well-tolerated in patients with gastroenteropancreatic neuroendocrine tumours, with significant rates of disease control but low rates of tumour response. It was difficult to judge the exact rate of biochemical response or symptomatic improvement. There is a need for large, prospective studies investigating the role of escalated-dose somatostatin analogues in the treatment of metastatic gastroenteropancreatic neuroendocrine tumours.

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.

Somatostatin receptor expression indicates improved prognosis in gastroenteropancreatic neuroendocrine neoplasm, and octreotide long-acting release is effective and safe in Chinese patients with advanced gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine neoplasm (GEP-NEN) is known to overexpress somatostatin receptors (SSTRs), most commonly SSTR2 and SSTR5. The expression of SSTRs on tumor cells forms the basis for somatostatin analog treatment of patients with NEN. The present study detected the expression of SSTR2 and SSTR5 in GEP-NEN and investigated the efficacy and safety of octreotide long-acting release (LAR) in the treatment of advanced gastroenteropancreatic neuroendocrine tumors (GEP-NET) in China. The present study reported that functionality of the pancreas, G1 and G2 grading, NET classification and Tumor-Node-Metastasis stages I and II were associated with higher SSTR2 positive expression. Similarly, SSTR5 was increased in pancreatic and well-differentiated tumors. SSTR2 and SSTR5 positive expression predicted improved survival in GEP-NEN patients. The median overall survival of patients treated with octreotide LAR was not reached. The median time to progression was 20.2 months, with the objective response rate being 5.6% and the stable disease rate being 79.6%. A total of 25.9% of the patients experienced adverse drug reactions. In conclusion, the present study demonstrated that SSTR2 and SSTR5 are heterogeneously expressed in GEP-NEN. Both markers may serve as potential prognostic factors. Octreotide LAR is effective and safe in the treatment of Chinese patients with advanced GEP-NET.

Somatostatin analogues according to Ki67 index in neuroendocrine tumours: an observational retrospective-prospective analysis from real life

Somatostatin analogues (SSAs) have shown limited and variable antiproliferative effects in neuroendocrine tumours (NETs). Whether tumour control by SSAs depends on grading based on the 2010 WHO NET classification is still unclear. The aim of this study is to evaluate the efficacy of long-acting SSAs in NETs according to Ki67 index.

An observational Italian multicentre study was designed to collect data in patients with gastro-entero-pancreatic or thoracic NETs under SSA treatment. Both retrospective and prospective data were included and they were analysed in line with Ki67 index, immunohistochemically evaluated in tumour samples and graded according to WHO classification (G1 = Ki67 index 0-2%, G2 = Ki67 index 3-20%, G3 = Ki67 index > 20%).

Among 601 patients with NET, 140 with a histologically confirmed gastro-entero-pancreatic or thoracic NET or NET with unknown primary were treated with lanreotide autogel or octreotide LAR. An objective tumour response was observed in 11%, stability in 58% and progression in 31%. Objective response and tumour stability were not significantly different between G1 and G2 NETs. Progression free survival was longer but not significantly different in G1 than G2 NETs (median: 89 vs 43 months, p = 0.15). The median PFS was significantly longer in NETs showing Ki67 < 5% than in those showing Ki67 ≥5% (89 vs 35 months, p = 0.005).

SSA therapy shows significant antiproliferative effects in well differentiated low/intermediate-proliferating NETs, not only G1 but also in G2 type. A Ki67 index of 5% seems to work better than 3% to select the best candidates for SSA therapy.

Octreotide and Lanreotide in Gastroenteropancreatic Neuroendocrine Tumors

Neuroendocrine tumors are heterogeneous, rare malignancies that arise most commonly in the gastrointestinal tract and pancreas. They often secrete vasoactive substances resulting in carcinoid syndrome and the tumor cells exclusively express somatostatin receptors. Octreotide and lanreotide are the two synthetic somatostatin analogs used for the control of carcinoid symptoms and tumor progression in advanced inoperable disease. Recent pivotal trials (PROMID and CLARINET studies) established their antitumor activity. We discuss the available data to support their use as symptom controlling and antiproliferative agents. This article also reviews the guidelines (National Comprehensive Cancer Network and North American Neuro Endocrine Tumor Society), cost-analysis (suggesting the cost-effectiveness of lanreotide autogel compared to higher doses of octreotide long acting release formulation in refractory patients), and future directions of somatostatin analogs in the management of patients refractory to conventional doses of octreotide and lanreotide.

Treatment of symptomatic neuroendocrine tumor syndromes: recent advances and controversies

INTRODUCTION

Neuroendocrine tumors(NETs), once thought rare, are increasing in frequency in most countries and receiving increasing-attention. NETs present two-treatment problems. A proportion is aggressive and a proportion has a functional, hormone-excess-state(F-NET), each of which must be treated. Recently, there have been many advances, well-covered in reviews/consensus papers on imaging-NETs; new, novel anti-tumor treatments and understanding their pathogenesis. However, little attention has been paid to advances in the treatment of the hormone-excess-state. These advances are usually reported in case-series, and case-reports with few large studies. In this paper these advances are reviewed. Areas covered: Advances in the last 5-years are concentrated on, but a review of literature from the last 10-years was performed. PubMed and other databases (Cochrane, etc.) were searched for F-NET-syndromes including carcinoid-syndrome, as well as meeting-abstracts on NETs. All advances that controlled hormone-excess-states or facilitated-control were covered. These include new medical-therapies [serotonin-synthesis inhibitors(telotristat), Pasireotide, new agents for treating ACTHomas], increased dosing with conventional therapies (octreotide-LAR, Lanreotide-Autogel), mTor inhibitors(everolimus), Tyrosine-kinase inhibitors(sunitinib),cytoreductive surgery, liver-directed therapies (embolization, chemoembolization, radioembolization, RFA), peptide radio-receptor-therapy(PRRT) and ¹³¹I-MIBG, ablation of primary F-NETs. Expert opinion: Although many of the newer therapies controlling the hormone-excess-states in F-NETs are reported in relatively few patients, all the approaches show promise. Their description also generates some controversies/unresolved areas,such as the order of these new treatments, their longterm-efficacy, and effectiveness of combinations which may require large,controlled studies.

Update on management of midgut neuroendocrine tumors

Midgut neuroendocrine tumors are typically indolent but can be fatal when advanced. They can also cause significant morbidity due to the characteristic carcinoid syndrome. Somatostatin analogs continue to be the mainstay of treatment given their antiproliferative properties, as well as inhibitory effects on hormones that cause carcinoid syndrome. There have been several recent advances in the systemic therapy of these tumors including consolidation of somatostatin analogs as the cornerstone of therapy, completion of pivotal trials with mTOR inhibitors, and the establishment of novel approaches including peptide receptor radionuclide therapy and oral inhibitors of peripheral tryptophan hydroxylase in tumor and symptom control, respectively. In this review article, the recent advances are summarized and an updated approach to management is proposed.

Multidisciplinary management of advanced lung neuroendocrine tumors

The optimal clinical management of aggressive/advanced lung neuroendocrine tumors (NETs) is still debated, due to their rarity and the lack of prospective randomized studies. Results derive from retrospective mono-Institutional series, and few dedicated prospective trials, recently designed, are still ongoing. In low-grade tumors [bronchial carcinoids (BCs)] surgery, whenever feasible, remains the mainstay of treatment, and chemo/radiotherapy (RT) should be reserved to progressive diseases (PD). In case of resected N1-N2 BCs, a "watch and see" policy associated with a close clinical/radiological follow-up is recommended. Somatostatin analogs (SSA) seem to be effective in controlling BCs associated endocrine syndromes, while SSA antiproliferative effect has also been reported in the past. Targeted therapy with new drugs (Everolimus) seems to be very promising, but further trials are needed. Surgery alone is not sufficient to treat high-grade NETs: adjuvant CT is required also in early stages. Platinum-Etoposide regimen demonstrated to be the most effective; irinotecan and other biological drugs are considered very promising. In conclusion, the management of advanced lung NETs should be individualized by multidisciplinary teams which include Medical and Radiation Oncologists, Surgeons, Pathologists, Pulmonologists, Endocrinologists, Interventional Radiologists, and the prognosis is mainly dependent on tumor grade and its anatomical extent.

Gastrointestinal neuroendocrine tumors treated with high dose octreotide-LAR: A systematic literature review

AIM: To review literature on efficacy and safety of octreotide-long-acting repeatable (LAR) used at doses higher than the Food and Drug Administration (FDA)-approved 30 mg/mo for treatment of neuroendocrine tumors (NETs).

METHODS: We searched PubMed and Cochrane Library from 1998-2012, 5 conferences (American Society of Clinical Oncology, Endocrine Society, European Neuroendocrine Tumor Society, European Society for Medical Oncology, North American Neuroendocrine Tumor Society) from 2000-2013 using MeSH and keyterms including neuroendocrine tumors, carcinoid tumor, carcinoma, neuroendocrine, and octreotide. Bibliographies of accepted articles were also searched. Two reviewers reviewed titles, abstracts, and full-length articles. Studies that reported data on efficacy and safety of ≥ 30 mg/mo octreotide-LAR for NETs in human subjects, published in any language were included in the review.

RESULTS: The search identified 1086 publications, of which 238 underwent full-text review (20 were translated into English); 17 were included in the review. Studies varied in designs, subjects, octreotide-LAR regimens, and definition of outcomes. Eleven studies reported use of higher doses to control symptoms and tumor progression, although symptom severity and formal quality-of-life analysis were not quantitatively measured. Ten studies reported efficacy, describing 260 subjects with doses ranging from 40 mg/mo or 30 mg/3 wk up to 120 mg/mo. Eight studies reported expert clinical opinion that supported dose escalation of octreotide-LAR up to 60 mg/mo for symptom control and suggested increased doses may be effective at preventing tumor progression. Eight studies reported safety; there was no evidence of increased toxicity associated with doses of octreotide-LAR > 30 mg/mo.

CONCLUSION: As reported in this review, octreotide-LAR at doses > 30 mg/mo is being prescribed for symptom and tumor control in NET patients. Furthermore, expert clinical opinion provided support for escalation of somatostatin analogs for refractory hormonal symptoms.

Therapy for metastatic pancreatic neuroendocrine tumors

BACKGROUND

Pancreatic neuroendocrine tumors (pNETs) are frequently malignant (50-80%, except for insulinoma) and may show an aggressive course with metastases to the liver as well as more distant sites. These heterogeneous neoplasms include functioning tumors, which secrete a variety of peptide hormones, and non-functioning tumors (up to 90% of pNETs), which often show metastases at the time of diagnosis.

METHODS

A PubMed search was performed for English-language publications from 1995 through December 2012. Reference lists from studies selected were manually searched to identify further relevant reports. Manuscripts comparing different therapeutic options and advances for metastatic pNETs were selected.

RESULTS

The therapeutic options for metastatic pNETs are expanding and include surgery, which remains the only curative approach, liver-directed therapies, and medical therapy. In selected cases also liver transplantation (OLT) may be considered. The option of OLT for metastatic disease is unique to neuroendocrine tumors. Recently, novel promising targeted therapies have been proposed for progressive well-differentiated pNETs.

CONCLUSIONS

The best therapeutic approach for pNETs is still matter of debating. However, since pNETs often show a more indolent behavior compared to other malignancies, the preservation of the quality of life of the patient and the personalization of the therapy according to tumor's and patient's features are mandatory.

Clinical benefits of above-standard dose of octreotide LAR in patients with neuroendocrine tumors for control of carcinoid syndrome symptoms: a multicenter retrospective chart review study

BACKGROUND

Octreotide LAR is used in patients for control of carcinoid syndrome (CS) and other symptoms of hormone hypersecretion. The aim of this study was to examine reasons for octreotide LAR dose escalation and observe CS symptom improvement in patients with neuroendocrine tumors (NETs) who underwent octreotide LAR dose escalation at three cancer referral centers.

METHODS

Medical records for patients with diagnosis of carcinoid or pancreatic NET who had received one dose or more of octreotide LAR above 30 mg every 4 weeks from 2000 to 2012 were reviewed. Reasons for dose escalation and symptomatic outcomes were abstracted for each patient 3 months prior to and up to 12 months following the dose escalation.

RESULTS

Of the evaluated 239 NET patients, 53% were male, mean age at first dose escalation was 60 years (standard deviation [SD]: 11 years), and mean time from octreotide LAR initiation to first dose escalation was 1.7 years (SD: 2.0 years). The primary reasons reported for dose escalation were carcinoid or hormonal syndrome (62%) or radiographic progression (28%). The most common dose changes at the first dose escalation were 40 mg every 4 weeks (71%) and 60 mg every 4 weeks (18%). Of 90 patients in whom flushing was reported prior to first dose escalation, 73 (81%) were reported to have experienced improvement or resolution of their symptoms following the dose escalation. Of 107 patients who were reported to have experienced diarrhea before the first dose escalation, 85 (79%) were reported to have experienced improvement or resolution after first dose escalation.

CONCLUSION

The goal of improved symptom control is a common reason for dose escalation of octreotide LAR. This study suggests that escalation to above the standard dose of octreotide LAR of 30 mg every 4 weeks may result in improved CS symptom control.

Somatostatin analogs therapy in gastroenteropancreatic neuroendocrine tumors: current aspects and new perspectives

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare tumors that present many clinical features secreting peptides and neuroamines that cause distinct clinical syndromes such as carcinoid syndrome. However most of them are clinically silent until late presentation with mass effects. Surgical resection is the first line treatment for a patient with a GEP-NET while in metastatic disease multiple therapeutic approaches are possible. GEP-NETs are able to express somatostatin receptors (SSTRs) bounded by somatostatin (SST) or its synthetic analogs, although the subtypes and number of SSTRs expressed are very variable. In particular, SST analogs are used frequently to control hormone-related symptoms while their anti-neoplastic activity seems to result prevalently in tumor stabilization. Patients who fail to respond or cease to respond to standard SST analogs treatment seem to have a response to higher doses of these drugs. For this reason, the use of higher doses of SST analogs will probably improve the clinical management of these patients.