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

The current status of somatostatin analogs in the treatment of neuroendocrine tumors and future perspectives

INTRODUCTION

Somatostatin analogs (SSAs) were developed as antisecretory agents to palliate hormonal symptoms in patients with functioning neuroendocrine tumors (NETs). Their antiproliferative activity has been established in the phase 3 PROMID and CLARINET trials. SSAs currently represent the standard first-line therapy for the majority of well-differentiated G1/G2 gastroenteropancreatic NETs as well as for pulmonary NETs.

AREAS COVERED

An update on the clinical applications of established SSAs for the treatment of NETs is provided. Perspectives on emerging nonpeptide SSAs such as paltusotine and innovative formulations of octreotide (CAM2029) are included.

EXPERT OPINION

SSAs represent the cornerstone of treatment for both functioning and nonfunctioning NETs. While standard-dose SSAs have a defined place in the therapeutic algorithm of well-differentiated NETs, uncertainties remain on how to best integrate above-label doses of SSAs in the treatment sequence, particularly when tumor control is the goal. Octreotide and lanreotide appear to be clinically interchangeable, and no signs of superiority of one agent over the other has been observed so far. Whether SSAs may be exploited in the maintenance setting following more aggressive treatments, whether continuing SSAs beyond-progression after first-line therapy could be an effective treatment strategy, and whether new-generation SSAs such as pasireotide could overcome resistance to established SSAs are key areas of investigation.

Comparative analysis of international guidelines on the management of advanced non-functioning well-differentiated pancreatic neuroendocrine tumors

This review presents a comprehensive comparative analysis of international guidelines for managing advanced, non-functioning, well-differentiated pancreatic neuroendocrine tumors (panNETs). PanNETs, which represent a significant proportion of pancreatic neuroendocrine neoplasms, exhibit diverse clinical behaviors and prognoses based on differentiation, grading, and other molecular markers. The varying therapeutic strategies proposed by different guidelines reflect their distinct emphases and regional considerations, such as the ESMO guideline's focus on advanced disease management and the ENETS guidance paper's multidisciplinary approach. This review examines the most recent guidelines from ESMO, NCCN, ASCO, ENETS, and NANETS, analyzing the recommendations for first-line therapies and subsequent treatment pathways in different clinical scenarios. Significant variations are observed in the recommendations, particularly concerning the choice and sequence of systemic therapies, the role of tumor grading and the Ki-67 index in therapeutic decisions, and the integration of regional regulatory and clinical practices. The analysis highlights the need for a tailored approach to managing advanced NF panNETs, advocating for flexibility in applying guidelines to account for individual patient circumstances and the evolving evidence base. This work underscores the complexities of managing this patient population and the critical role of a multidisciplinary team in optimizing treatment outcomes.

Metabolic Tumor Volume on 18-Fluorodeoxyglucose Positron Emission Tomography as a Prognostic Marker of Survival in Patients With Locally Advanced or Metastatic Neuroendocrine Neoplasms Treated With 177Lutetium-DOTA-Octreotate Peptide Receptor Radionuclide Therapy

OBJECTIVE

We investigated metabolic tumor volume (MTV) and total lesion glycolysis (TLG) on pre-treatment FDG-PET as prognostic markers for survival in patients with metastatic neuroendocrine neoplasms (NENs) receiving peptide receptor radionuclide therapy (PRRT).

METHODS

A retrospective review of patients with metastatic NENs receiving PRRT was undertaken. Pre-treatment FDG-PET images were analyzed and variables collected included MTV and TLG (dichotomized by median into high vs low). Main Outcomes were overall survival (OS) and progression-free survival (PFS) by MTV and TLG (high vs low).

RESULTS

One hundred five patients were included. Median age was 64 years (50% male). Main primary NEN sites were small bowel (43.8%) and pancreas (40.0%). Median MTV was 3.8 mL and median TLG was 19.9. Dichotomization formed identical cohorts regardless of whether MTV or TLG were used. Median OS was 72 months; OS did not differ based on MTV/TLG high versus low (47.4 months vs not reached; hazard ratio, 0.43; 95% confidence interval [CI], 0.18-1.04; P = 0.0594). Median PFS was 30.4 months; PFS differed based on MTV/TLG high versus low (21.6 months vs 45.7 months; hazard ratio, 0.35; 95% CI, 0.19-0.64; P = 0.007).

CONCLUSIONS

Low MTV/TLG on pre-treatment FDG-PET was associated with longer PFS in metastatic NEN patients receiving PRRT.

Efficacy and tolerability of somatostatin analogues according to gender in patients with neuroendocrine tumors

As the incidence of neuroendocrine tumors has been rising, gender differences in epidemiology and clinical behavior have emerged, and interest into a gender-driven management of these tumors has grown with the aim to improve survival and quality of life of these patients. Somatostatin Analogues represent the first line of systemic treatment of both functional and non-functional neuroendocrine tumors, through the expression of somatostatin receptors (SSTRs) in the tumor cells, and proved effective in controlling hormonal hypersecretion and inhibiting tumor growth, improving progression-free survival and overall survival of these patients. Aim of the present review is to investigate any differences by gender in efficacy and safety of SSTS-targeted therapies, that represent the mainstay treatment of neuroendocrine tumors, as they emerge from studies of varying design and intent. Although preclinical studies have provided evidence in favor of differences by gender in tumor expression of SSTR, as well as of the role of sex hormones and related receptors in modulating SSTRs expression and function, the clinical studies conducted so far have not shown substantial differences between males and females in either efficacy or toxicity of SSTR-targeted therapies, even if with sometimes inconsistent results. Moreover, in most studies gender was not a predictor of response to treatment. Studies specifically designed to address this issue are needed to develop gender-specific therapeutic algorithms, improving patients' prognosis and quality of life.

Methodology of the SORENTO clinical trial: a prospective, randomised, active-controlled phase 3 trial assessing the efficacy and safety of high exposure octreotide subcutaneous depot (CAM2029) in patients with GEP-NET

BACKGROUND

The current standard of care (SoC) for the initial treatment of unresectable or metastatic well-differentiated gastroenteropancreatic neuroendocrine tumours (GEP-NET) requires initiation of first-generation somatostatin receptor ligand (SRL) therapy, octreotide and lanreotide, which provide safe and efficacious tumour/symptom control in most patients. However, disease progression can occur with SoC SRL treatment and the optimal dose response of SRL remains unknown. Octreotide subcutaneous depot (CAM2029) is a novel, long-acting, high-exposure formulation that has shown greater bioavailability and improved administration than octreotide long-acting release (LAR) with a well-tolerated safety profile. Retrospective data have highlighted a potential benefit of high-exposure SRL for improved disease control in patients who did not adequately respond to the current SoC SRL treatment. This trial will investigate the efficacy and tolerability of CAM2029 compared to the current SoC, including octreotide LAR and lanreotide autogel (ATG).

METHODS

SORENTO is a prospective, multicentre, randomised, active-controlled, open-label phase 3 trial aiming to demonstrate superiority of treatment with 20 mg octreotide subcutaneous depot (CAM2029) every 2 weeks (Q2W) compared to treatment with the Investigator's choice of SRL therapy at standard doses for tumour control (octreotide LAR 30 mg or lanreotide ATG 120 mg every 4 weeks [Q4W]) as assessed by progression-free survival (PFS) in approximately 300 patients with unresectable/metastatic and well-differentiated GEP-NET. Upon confirmation of disease progression (determined by a Blinded Independent Review Committee [BIRC] and defined as per RECIST 1.1), patients may enter an open-label extension treatment period with once weekly dosing, to investigate the effects of higher frequency dosing. Overall survival follow-up will end a maximum of 2 years after primary analysis. The primary endpoint will be analysed after 194 confirmed PFS events.

DISCUSSION

This is the first trial investigating the efficacy of CAM2029 versus SoC SRL therapy using a head-to-head, superiority trial design. It is expected to be the first trial to investigate the efficacy of increased dosing frequency of a high-exposure SRL. A BIRC will limit bias and measurement variability and ensure high-quality efficacy data. Additionally, inclusion of patients with well-differentiated Grade 3 NET may elucidate treatment strategies for this rarely investigated patient population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05050942. Registered on 21st September 2021.

Long-acting somatostatin analogs and well differentiated neuroendocrine tumors: a 20-year-old story

PURPOSE

The specific indications of somatostatin analogs (SSAs) in patients with neuroendocrine tumor (NET) emerged over the time. The objective of this review is to summarize and discuss the most relevant data concerning long-acting SSAs in NET.

METHODS

A narrative review was performed including publications focusing on therapy with the long-acting octreotide, lanreotide, and pasireotide in patients with NET.

RESULTS

Long-acting SSAs confirm to be a manageable and widely used tool in patients with NET. Both long-acting octreotide and lanreotide are safe as the short-acting formulations, while patient compliance and adherence is further improved. Together with some randomized phase-3 trials, many retrospective and prospective studies have been performed in the last 20 years revealing a variable but substantial impact on progression free survival, not only in gastroenteropancreatic but also in lung and unknown primary NETs. The most frequent tumor response to SSAs is stable disease, but an objective response can be observed, more frequently by using high-dose schedules and in MEN1-related pancreatic NETs. Low tumor burden, low tumor grade (G1 and low G2), good performance status and use as first-line therapy are the main predictive factors to SSAs in NET patients. Pasireotide has been evaluated in few studies. This compound remains a promising SSA and would deserve to be further evaluated as a potential additional indication in NET therapy.

CONCLUSIONS

Long-acting SSAs are an effective and safe initial therapy of patients with well differentiated NET, allowing tumor growth as well as symptoms control for long-time in selected patients.

Targeting neuroendocrine tumors with octreotide and lanreotide: Key points for clinical practice from NET specialists

Octreotide and lanreotide are the two somatostatin analogs (SSA) currently available in clinical practice. They have been approved first to control the clinical syndrome (mainly carcinoid syndrome) associated with functioning neuroendocrine tumors (NET) and later for tumor growth control in advanced low/intermediate grade NET. Although evidence regarding their role, especially as antiproliferative therapy, has been increasing over the years some clinical indications remain controversial. Solicited by AIOM (Italian Association of Medical Oncology) a group of clinicians from various specialties, including medical oncology, endocrinology, and gastroenterology, deeply involved in NET for their clinical and research activity, addressed eight open questions, critically reviewing evidence and guidelines and sharing clinical take-home messages. The questions regarded the use of long-acting octreotide and lanreotide in the following settings: functioning and non-functioning NET refractory to label dose, first-line metastatic pulmonary NET, combination with other therapy with an antiproliferative intent, maintenance in NET responding to other therapies, adjuvant treatment, Ki-67-related cut-off, somatostatin receptor imaging, safety, and feasibility. The level of evidence is not absolute for the majority of these clinical contexts, so it is recommended to distinguish routine versus sporadic utilization in very selected cases. Mention of such specific issues by the main European guidelines (ENETS, European Neuroendocrine Tumor Society, and ESMO, European Society for Medical Oncology) was explored and their position reported. However, different clinical decisions on single patients could be made if the case is carefully discussed within a NET-dedicated multidisciplinary team.

The Role of Somatostatin Analogues in the Control of Diarrhea and Flushing as Markers of Carcinoid Syndrome: A Systematic Review and Meta-Analysis

BACKGROUND

Somatostatin analogues (SSAs) are the cornerstone of treatment for carcinoid syndrome (CS)-related symptoms. The aim of this systematic review and meta-analysis is to evaluate the percentage of patients achieving partial (PR) or complete response (CR) with the use of long-acting SSAs in patients with CS.

METHODS

A systematic electronic literature search was conducted in PubMed, Cochrane, and Scopus to identify eligible studies. Any clinical trials reporting data on the efficacy of SSAs to alleviate symptoms in adult patients were considered as potentially eligible.

RESULTS

A total of 17 studies reported extractable outcomes (PR/CR) for quantitative synthesis. The pooled percentage of patients with PR/CR for diarrhea was estimated to be 0.67 (95% confidence interval (CI): 0.52-0.79, I₂ = 83%). Subgroup analyses of specific drugs provided no evidence of a differential response. With regards to flushing, the pooled percentage of patients with PR/CR was estimated to be 0.68 (95% CI: 0.52-0.81, I₂ = 86%). Similarly, no evidence of a significant differential response in flushing control was documented.

CONCLUSIONS

We estimate there is a 67-68% overall reduction in symptoms of CS associated with SSA treatment. However, significant heterogeneity was detected, possibly revealing differences in the disease course, in management and in outcome definition.

The Antiproliferative Activity of High-Dose Somatostatin Analogs in Gastro-Entero-Pancreatic Neuroendocrine Tumors: A Systematic Review and Meta-Analysis

Background: The antiproliferative activity of a high dose of somatostatin analogs (HD-SSA) in treating gastro-entero-pancreatic neuroendocrine neoplasms (GEP-NENs) remains under debate. Methods: A systematic review and proportion meta-analysis were made. The primary endpoint was the efficacy measured as incidence density ratio (IDR) at one year. The secondary endpoints were the disease control rate (DCR) and severe adverse events (SAEs). The heterogeneity (I2), when high (>50%), was interpreted by performing a univariate metaregression analysis, analyzing as covariates: type and design of the study, location (Europe or USA), sample size, grading according to 2017 WHO, the metastatic disease rate, previous therapy including surgery, and quality of the study. Results: A total of 11 studies with 783 patients were included. The IDR was 62 new progressions of 100 patients treated with HD-SSA every one year. The heterogeneity was high. The study’s year, type and design, primary tumor, grading, previous treatments, and quality of the studies did not influence the IDR. The IDR was significantly higher in USA centers and studies with more than 50 patients. The IDR was lower when a high rate of metastatic patients was present in the studies. The DCR was 45%. The heterogeneity was high. The DCR was lower in USA studies and in prospective trials. Conclusion: Given the limited efficacy of HD-SSA in preventing the disease progression in unresectable GEP-NENs after failure of standard dose SSA, the use of this therapeutic approach is advisable in selected cases when other antiproliferative treatments are not feasible.

Therapeutic strategies for patients with neuroendocrine neoplasms: current perspectives

INTRODUCTION

Neuroendocrine neoplasms (NENs) are a heterogeneous group of malignancies mainly arising in the gastroenteropancreatic (GEP) and bronchopulmonary systems, with steadily increasing incidence. The therapeutic landscape has widened and the therapeutic strategy should be based on new sequences and combinations, still debated.

AREAS COVERED

Herein, we provide an overview of current approved pharmacological treatments in patients with NENs, with the aim to summarize evidence of efficacy of the main different options in GEP and pulmonary NENs, principally focusing on somatostatin analogs (SSAs), targeted therapy with everolimus and sunitinib, peptide receptor radionuclide therapy (PRRT) and chemotherapy. We discuss biological rationale and toxicities, including current indications according to differentiation and placement in the therapeutic algorithm, clinical trials, and combinations. Furthermore, we recommend areas for further research.

EXPERT OPINION

Therapeutic management of patients with NENs represents a challenge for clinicians and the identification of effective sequences and combinations is of utmost importance. Major efforts should be directed to early identify and overcome resistance and to limit toxicity. The progress in the therapeutic management of NENs grows faster and the choice of the best approach should be based on randomized clinical trials, as well as on long-term, real-world data.

High-Dose Somatostatin Analogs for the Treatment of Neuroendocrine Neoplasms: where are we Now?

OPINION STATEMENT

Neuroendocrine tumors (NET) represent a complex and heterogeneous group of malignancies arising from the diffuse endocrine cells and other cells derived from the neural crest. Advanced disease is observed at diagnosis in more than one-third of patients. Somatostatin analogs (SSA) are the cornerstone in advanced well-differentiated NET treatment. Unfortunately, most patients will eventually develop resistance to SSA treatment by different mechanisms that are not fully understood. In some cases of refractory carcinoid syndrome or progressive disease, the increase of SSA dose may help to reach out a symptomatic and/or tumor growth control. The clinical evidence behind above-label SSA administration is limited and should be individualized and discussed patient by patient. Some questions regarding high-dose SSA use are unsolved, such as the optimal dose to use, the frequency of administration, or the need of deepen molecular understanding that could help to adequately select patients for this approach.

Therapeutic strategies for gastroenteropancreatic neuroendocrine neoplasms: State-of-the-art and future perspectives

Although gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have always been considered rare tumors, their incidence has risen over the past few decades. They represent a highly heterogeneous group of neoplasms with several prognostic factors, including disease stage, proliferative index (Ki67), and tumor differentiation. Most of these neoplasms express somatostatin receptors on the cell surface, a feature that has important implications in terms of prognosis, diagnosis, and therapy. Although International Guidelines propose algorithms aimed at guiding therapeutic strategies, GEP-NEN patients are still very different from one another, and the need for personalized treatment continues to increase. Radical surgery is always the best option when feasible; however, up to 80% of cases are metastatic upon diagnosis. Regarding medical treatments, as GEP-NENs are characterized by relatively long overall survival, multiple therapy lines are adopted during the lifetime of these patients, but the optimum sequence to be followed has never been clearly defined. Furthermore, although new molecular markers aimed at predicting the response to therapy, as well as prognostic scores, are currently being studied, their application is still far from being part of daily clinical practice. As they represent a complex disease, with therapeutic protocols that are not completely standardized, GEP-NENs require a multidisciplinary approach. This review will provide an overview of the available therapeutic options for GEP-NENs and attempts to clarify the possible approaches for the management of these patients and to discuss future perspectives in this field.

Somatostatin and Somatostatin Receptors: From Signaling to Clinical Applications in Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) are heterogeneous neoplasms which arise from neuroendocrine cells that are distributed widely throughout the body. Although heterogenous, many of them share their ability to overexpress somatostatin receptors (SSTR) on their cell surface. Due to this, SSTR and somatostatin have been a large subject of interest in the discovery of potential biomarkers and treatment options for the disease. The aim of this review is to describe the molecular characteristics of somatostatin and somatostatin receptors and its application in diagnosis and therapy on patients with NENs as well as the use in the near future of somatostatin antagonists.

Efficacy and safety of high-dose lanreotide autogel in patients with progressive pancreatic or midgut neuroendocrine tumours: CLARINET FORTE phase 2 study results

INTRODUCTION

This prospective, single-arm, phase 2 study assessed the efficacy and safety of lanreotide autogel (LAN) administered at a reduced dosing interval in patients with progressive neuroendocrine tumours (NETs) after LAN standard regimen.

METHODS

Patients had metastatic or locally advanced, grade 1 or 2 midgut NETs or pancreatic NETs (panNETs) and centrally assessed disease progression on LAN 120 mg every 28 days. They were treated with LAN 120 mg every 14 days for up to 96 weeks (midgut cohort) or 48 weeks (panNET cohort). The primary end-point was centrally assessed progression-free survival (PFS). PFS by Ki-67 categories was analysed post hoc. Secondary end-points included quality of life (QoL) and safety.

RESULTS

Ninety-nine patients were enrolled (midgut, N = 51; panNET, N = 48). Median (95% CI) PFS was 8.3 (5.6-11.1) and 5.6 (5.5-8.3) months, respectively. In patients with Ki-67 ≤ 10%, median (95% CI) PFS was 8.6 (5.6-13.8) and 8.0 (5.6-8.3) months in the midgut and panNET cohorts, respectively. Patients' QoL did not deteriorate during the study. There were no treatment-related serious adverse events and only two withdrawals for treatment-related adverse events (both in the panNET cohort).

CONCLUSIONS

In patients with progressive NETs following standard-regimen LAN, reducing the dosing interval to every 14 days provided encouraging PFS, particularly in patients with a Ki-67 ≤ 10% (post hoc); no safety concerns and no deterioration in QoL were observed. Increasing LAN dosing frequency could therefore be considered before escalation to less well-tolerated therapies.

Health-related quality of life and treatment effects in patients with well-differentiated gastroenteropancreatic neuroendocrine neoplasms: A systematic review and meta-analysis

Introduction

Gastroenteropancreatic neuroendocrine neoplasms (GEPNENs) are often diagnosed in an advanced stage. As the optimal sequence of therapy remains largely unclear, all treatment‐related outcomes, including health‐related quality of life (HRQoL) prospects, should be assessed according to patients' preferences.

Methods

A targeted search was performed in PubMed and EMBASE to identify studies on treatment effect and HRQoL, measured using the EORTC QLQ‐C30 tool, in patients with advanced, well‐differentiated GEPNENs. Study quality was assessed, and meta‐analyses were performed for global health status/QOL and tumour response.

Results

The search yielded 1,322 records, and 20 studies were included, examining somatostatin analogues (SSA), peptide receptor radionuclide therapies (PRRT), chemotherapy, SSA‐based combination therapies, and targeted therapies. Global HRQoL was stable, and rates for disease stabilisation were moderate to high across all treatments. Meta‐analyses for global health status/QOL after SSA treatment were not significant (mean difference: –0.3 [95% CI: −1.3 to 0.7]). The highest pooled overall tumour response rate was 33% (95% CI: 24–45%) for PRRT. The highest pooled clinical benefit rate was 94% (95% CI: 65–99%) for chemotherapy.

Conclusion

All treatments appeared beneficial for disease stabilisation while maintaining stable global health status/QOL. High‐quality HRQoL reporting was lacking. HRQoL should be a central outcome next to well‐established outcomes.

Carcinoid Syndrome and Hyperinsulinemic Hypoglycemia Associated with Neuroendocrine Neoplasms: A Critical Review on Clinical and Pharmacological Management

The carcinoid syndrome (CS) and hyperinsulinemic hypoglycemia (HH) represent two of the most common clinical syndromes associated with neuroendocrine neoplasms (NENs). The former is mainly related to the serotonin secretion by a small bowel NEN, whereas the latter depends on an insulin hypersecretion by a pancreatic insulinoma. Both syndromes/conditions can affect prognosis and quality of life of patients with NENs. They are often diagnosed late when patients become strongly symptomatic. Therefore, their early detection and management are a critical step in the clinical management of NEN patients. A dedicated and experienced multidisciplinary team with appropriate therapeutic strategies is needed and should be encouraged to optimize clinical outcomes. This review aims to critically analyze clinical features, evidence and treatment options of CS and HH and therefore to improve their management.

Drug Development in Neuroendocrine Tumors: What Is on the Horizon?

OPINION STATEMENT

Neuroendocrine neoplasms (NENs) constitute a heterogenous group of malignancies. Translational research into NEN cell biology is the cornerstone for drug development strategies in this field. Somatostatin receptor type 2 (SSTR2) expression is the hallmark of well-differentiated neuroendocrine tumors (NETs). Somatostatin analogs and peptide receptor radionuclide therapy (PRRT) form the basis of anti-SSTR2 treatment onto new combination strategies, antibody-drug conjugates and bispecific antibodies. Classical pathways involved in NET development (PI3K-Akt-mTOR and antiangiogenics) are reviewed but new potential targets for NET treatment will be explored. Epigenetic drugs have shown clinical activity in monotherapy and preclinical combination strategies are more than attractive. Immunotherapy has shown opposite results in different NEN settings. Although the NOTCH pathway has been targeted with disappointing results, new strategies are being developed. Finally, after years of solid preclinical evidence on different genetically engineered oncolytic viruses, clinical trials for refractory NET patients are now ongoing.

Versatile Functions of Somatostatin and Somatostatin Receptors in the Gastrointestinal System

Somatostatin (SST) and somatostatin receptors (SSTRs) play an important role in the brain and gastrointestinal (GI) system. SST is produced in various organs and cells, and the inhibitory function of somatostatin-containing cells is involved in a range of physiological functions and pathological modifications. The GI system is the largest endocrine organ for digestion and absorption, SST-endocrine cells and neurons in the GI system are a critical effecter to maintain homeostasis via SSTRs 1-5 and co-receptors, while SST-SSTRs are involved in chemo-sensory, mucus, and hormone secretion, motility, inflammation response, itch, and pain via the autocrine, paracrine, endocrine, and exoendocrine pathways. It is also a power inhibitor for tumor cell proliferation, severe inflammation, and post-operation complications, and is a first-line anti-cancer drug in clinical practice. This mini review focuses on the current function of producing SST endocrine cells and local neurons SST-SSTRs in the GI system, discusses new development prognostic markers, phosphate-specific antibodies, and molecular imaging emerging in diagnostics and therapy, and summarizes the mechanism of the SST family in basic research and clinical practice. Understanding of endocrines and neuroendocrines in SST-SSTRs in GI will provide an insight into advanced medicine in basic and clinical research.

Antiproliferative Effect of Above-Label Doses of Somatostatin Analogs for the Management of Gastroenteropancreatic Neuroendocrine Tumors

BACKGROUND

Above-label doses of somatostatin analogs (SSAs) are increasingly utilized in the management of inoperable/metastatic gastroenteropancreatic neuroendocrine tumors (GEP-NETs), progressing on standard 4-weekly regimens.

OBJECTIVE

To evaluate the antiproliferative effect of 3-weekly SSA administration in a retrospective GEP-NET cohort.

METHODS

Patients with advanced GEP-NET, treated with long-acting release (LAR) octreotide 30 mg or lanreotide Autogel 120 mg at a 3-weekly interval, after disease progression on standard 4-weekly doses, were retrospectively identified. Clinicopathologic and treatment response data were collected. Progression-free survival (PFS; dose escalation to radiographic progression or death) was estimated with the Kaplan-Meier method. Factors associated with PFS were identified with the Cox proportional-hazards model.

RESULTS

The inclusion criteria were fulfilled by 105 patients. Octreotide LAR was administered to 60 (57%) and lanreotide Autogel to 45 (43%). Indications for dose escalation were breakthrough carcinoid symptoms (58%), radiographic progression (35%) and/or increasing biomarkers (11%). Diarrheal and/or flushing symptomatic improvement was identified in 37/67 cases (55%) and 30/55 cases (55%) with available data, respectively. The disease control rate (radiographic partial response or stable disease) was achieved in 53 patients (50%). Median PFS was 25.0 months (95% CI 16.9-33.1). Patients with radiographic progression <12 months from 4-weekly SSA initiation had worse PFS after dose escalation (7.0 vs. 17.0 months, p = 0.002). In multivariate analysis, pancreatic NETs, a Ki-67 index ≥5% and multiple extrahepatic metastases were independently associated with inferior PFS.

CONCLUSIONS

Above-label doses of SSAs may offer a considerable prolongation of PFS and could be utilized as a bridge to other more toxic treatments. Patients with small bowel/colorectal primaries, a Ki-67 index <5% and absence of/limited extrahepatic metastases are more likely to benefit from this approach.

Use of octreotide long acting repeatable (LAR) as second-line therapy in advanced neuroendocrine tumors in different clinical settings: an Italian Delphi survey

BACKGROUND

Somatostatin receptor ligands including octreotide LAR are first-line therapy in locally advanced or metastatic NETs that are nonresectable and well differentiated and are recommended as first-line therapy in functioning and in G1/low G2 nonfunctioning NETs. However, several questions remain that are not adequately addressed in current guidelines regarding its use in clinical scenarios in which the tumor progresses. These include use of nonconventional doses or schedules of octreotide LAR in tumors with hormonal symptoms or showing clinical-radiological progression, administration in combination with everolimus, peptide receptor radionuclide therapy, and chemotherapy, following first-line treatment with octreotide LAR.

METHODS

An expert panel was gathered to obtain consensus using Delphi methodology on a series of statements regarding further administration of octreotide LAR after its use in first-line therapy in these settings in patients who experience disease progression.

RESULTS

Consensus was reached for 8 of the 10 statements proposed in the above clinical scenarios; consensus was not achieved for two statements.

CONCLUSIONS

The present statements aim to fill current gaps in treatment guidelines by providing recommendations based on expert consensus in clinical settings in which patients progress following first-line therapy with octreotide LAR.

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.

Biliary Stone Disease in Patients with Neuroendocrine Tumors Treated with Somatostatin Analogs: A Multicenter Study

BACKGROUND

Somatostatin analogs (SSAs) are the mainstay of neuroendocrine tumor (NET) treatment. Biliary stone disease is reported as a common side effect of SSAs, with a frequency ranging from 10% to 63%. Studies on SSA-treated patients for acromegaly report an increased incidence of biliary stone disease compared with the general population, whereas data on patients with NETs are few. Guidelines are based on weak evidence, thus resulting in conflicting recommendations. The aim of the study is to evaluate biliary stone disease incidence, complications, and risk factors in a large population of SSA-treated patients with NETs.

MATERIALS AND METHODS

A retrospective analysis of a prospectively collected database was performed. Patients with a diagnosis of NET in seven dedicated centers from 1995 to 2017 were included at the time of SSA start.

RESULTS

A total of 754 SSA-treated patients were evaluated. Patients with history of cholecystectomy or with known biliary stone disease were excluded; 478 patients were included. Among them, 118 patients (24.7%) received prophylactic ursodeoxycholic acid (UDCA). During the study period, 129 patients (27.0%) developed biliary stone disease; of them, 36 (27.9%) developed biliary complications. On multivariate analysis, primary gastrointestinal (GI)-NET (hazard ratio [HR] 1.76) and related surgery (HR 1.58) were independent risk factors for biliary stone disease.

CONCLUSION

We report a high incidence of biliary stone disease particularly in GI-NET or GI surgery. UDCA prophylaxis does not seem to have a protective role. Our data suggest that all patients with primary GI-NET or undergoing abdominal surgery should be considered for prophylactic cholecystectomy; no conclusion could be drawn on the indication of prophylactic cholecystectomy in patients with primary pancreatic or thoracic NET for whom abdominal surgery is not planned.

IMPLICATIONS FOR PRACTICE

The results of this study confirm an increased rate of gallstones development and related complications in patients with neuroendocrine tumors (NETs) treated with somatostatin analogs (SSAs). NETs of the gastrointestinal (GI) tract and related surgery are independent risk factors for biliary stone disease development. Therefore, all patients with primary GI-NET or undergoing abdominal surgery should be considered for prophylactic cholecystectomy. Data on other subgroups are not exhaustive, and management also evaluating additional clinical features (life expectancy, surgical and anesthesiological risks) should be considered. Prophylactic treatment with ursodeoxycholic acid does not seem to be a protective factor for SSA-related biliary stone disease.

Nonconventional Doses of Somatostatin Analogs in Patients With Progressing Well-Differentiated Neuroendocrine Tumor

PURPOSE

To evaluate the antiproliferative activity and safety of nonconventional high doses of somatostatin analogs (HD-SSA) in patients with well-differentiated gastroenteropancreatic (GEP) neuroendocrine tumors (NET) with radiological disease progression according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria on a previous treatment.

METHODS

A retrospective analysis of prospectively maintained databases from 13 Italian NET-dedicated centers was performed. Main inclusion criteria were: well-differentiated G1 or G2 GEP-NET, progressive disease on a previous treatment, and subsequent treatment with HD-SSA (either by increased administered dose [dose intensity] or shortened interval between administrations [dose density]). Main endpoints were progression-free survival (PFS) and safety.

RESULTS

Of 198 patients, 140 matched inclusion criteria and were included in the analysis. Overall, median PFS was 31 months. Use of HD-SSA as second-line treatment was associated with reduced risk for progression or death compared with third- or further-line treatment (HR: 2.12; P = 0.004). There was no difference in PFS between HD-SSA by increased dose density (N = 133; 95%) or intensity (N = 7; 5%). Partial response according to RECIST criteria was observed in 12 patients (8.6%), and stable disease was achieved in 106 (75.7%) patients. Adverse events occurred in 21 patients (15.0%), 2 of whom had grade 3 biliary stone disease. No patients discontinued HD-SSA treatment due to adverse events.

CONCLUSIONS

HD-SSA is an active and safe treatment option in patients with progressive well-differentiated GEP-NET. The high rate of objective responses observed deserves prospective validation in ad hoc clinical trials.

Long-Acting Somatostatin Analogue Safety Monitoring Protocol for Outpatients With Neuroendocrine Tumors

Somatostatin analogues (SSAs) are widely used in the long-term treatment of neuroendocrine tumors (NETs) and have a relatively favorable safety profile. However, SSAs are associated with specific side effects that are important to monitor. Currently, there is no standardized safety monitoring protocol for health-care professionals to use as a reference when initiating patients on long-acting SSAs. With the expansion of SSA use from symptomatic control to include antiproliferative tumor treatment in patients with NETs, it is increasingly important that patients taking these medications are properly monitored. The purpose of this analysis was to develop a comprehensive, practical SSA safety monitoring protocol for patients with NETs in the outpatient setting. This strategy was based on side effect frequencies that were reported and the monitoring parameters used in influential clinical and safety trials. Based on our assessment, we consider monitoring gallbladder imaging, laboratory tests (including blood chemistry, thyroid-stimulating hormone, hemoglobin A1c, and stool studies), vital signs, and physical examinations as the most important parameters when evaluating the safety of long-term SSA therapy. Due to the frequency at which patients experienced diarrhea as a side effect in clinical trials, questions about urgency, frequency, timing, consistency, odor, and color of bowel movements should be asked as part of the follow-up visits every 6 months to help differentiate between drug-induced vs. disease-associated causes. This broad monitoring strategy for patients receiving long-term SSAs was developed specifically for patients with NETs; however, the use of this protocol could be expanded to other indications in the future.

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.

Therapy With 177Lu-DOTATATE: Clinical Implementation and Impact on Care of Patients With Neuroendocrine Tumors

OBJECTIVE. The purpose of this article is to enhance knowledge of the clinical implementation of peptide receptor radionuclide therapy (PRRT) and its impact on care of patients with neuroendocrine tumors. CONCLUSION. Most well differentiated and some moderately and poorly differentiated neuroendocrine tumors express large numbers of somatostatin receptors on their cell surfaces. PRRT targets these cells with ¹⁷⁷Lu-DOTATATE, which is a medium-energy beta emitter. Since this agent received U.S. Food and Drug Administration approval in 2018, tremendous effort has been exerted at institutions throughout the United States toward proper implementation of this promising therapy. This review summarizes clinical implementation of PRRT and its impact on patient care.

When and How to Use Somatostatin Analogues

Long-acting depot formulations of the currently available somatostatin analogues are considered the first-line treatment for control of hormonal excess by hormone-producing neuroendocrine tumors of the gastrointestinal tract and pancreas. These drugs are currently also considered the first-line treatment for tumor control of both hormone-producing and non-hormone-producing neuroendocrine tumors of the gastrointestinal tract and pancreas. These drugs need coupling and interaction with specific somatostatin receptor subtypes, which are expressed on the cells of neuroendocrine tumors of the gastrointestinal tract and pancreas.

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.

Open issues on G3 neuroendocrine neoplasms: back to the future

The recent recognition that grade 3 (G3) neuroendocrine neoplasms (NENs) can be divided into two different categories according to the histopathological differentiation, that is G3 neuroendocrine tumors (NETs) and G3 neuroendocrine carcinomas (NECs) has generated a lot of interest concerning not only the diagnosis, but also the differential management of such new group of NENs. However, several issues need to be fully clarified in order to put G3 NETs and G3 NECs in the right place. The aim of this review is to focus on those issues that are still undetermined starting from the current knowledge, evaluating the available evidence and the possible clinical implications.

Robotic enucleation of benign pancreatic tumors

Robot-assisted enucleation provides the dual benefits of a minimally-invasive technique and pancreatic parenchymal conservation to selected patients with functional pancreatic neuroendocrine tumors (F-pNETs) and serous cystadenomas. Insulinomas, the most common F-pNETs, are ideal candidates for enucleation when <2 cm given the 80% probability of being benign. Current evidence suggests enucleation for the following: benign, isolated lesions with a distance between tumor and main pancreatic duct ≥3 mm (no focal stricture or dilation), insulinomas, gastrinomas <2 cm, and nonfunctional pancreatic neuroendocrine tumors (NF-pNETs) <1-2 cm and low Ki67 mitotic index. Minimally-invasive enucleation is an imaging-dependent procedure that requires recognizable anatomic landmarks for successful completion, including tumor proximity to the pancreatic duct as well as localization relative to major structures such as the gastroduodenal artery, bile duct, and portal vein. Tumor localization often mandates intraoperative ultrasound aided by duplex studies of intratumoral blood flow and frozen section confirmation. Five patients have undergone robot-assisted enucleation at Beth Israel Deaconess Medical Center between January 2014 and January 2017 with median tumor diameter of 1.3 cm (0.9-1.7 cm) located in the pancreatic head [2] and tail [3]. Surgical indications included insulinoma [2] and NF-pNETs [3]. Median operative time was 204 min (range, 137-347 min) and estimated blood loss of 50 mL. There were no conversions to open or transfusions. Robotic enucleation is a safe and feasible technique that allows parenchymal conservation in a minimally-invasive setting, reducing operative time and length of stay with equivalent pathological outcomes compared to open surgery.

Somatostatin analogs in the treatment of neuroendocrine tumors: current and emerging aspects

INTRODUCTION

Neuroendocrine tumors (NETs) harbor somatostatin receptors and there is a strong rationale for using somatostatin analogs (SSAs) for treatment of NETs. Areas covered: This article discusses i) pharmacology of somatostatin and its analogs; ii) antisecretory and anti-proliferative effects of SSAs in NETs; iii) efficacy and safety of emerging therapeutic regimens with first generation SSAs administered at either high doses or in combination with antineoplastic drugs; iv) efficacy and safety of pasireotide and chimeric molecules; v) efficacy of radionuclide therapy of NETs using SSAs. Expert opinion: SSAs are the first-line medical therapy for functioning and non-functioning well-differentiated NETs. In patients not responder to first generation SSAs, the increase of drug dose over the conventional regimens, the combination of SSAs with other biotherapies or molecular targeted therapies, the switch to pasireotide or the use of SSAs in radionuclide therapy may improve the therapeutic success.