Treatment Strategies for Metastatic Neuroendocrine Tumors of the Gastrointestinal Tract

Investigation of an oncolytic herpes simplex virus as a potential therapeutic agent for gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) present unique challenges due to their heterogeneity and limited treatment options. Oncolytic virotherapy has emerged as a promising therapeutic for other NETs and thus, we sought to investigate the potential of an engineered oncolytic herpes simplex virus (oHSV), M002, for GEP-NETS. We employed an established long-term passage GEP-NET cell line and a unique, human pediatric patient-derived xenograft GEP-NET line. We found the virus to effectively infect, replicate within, and kill both cell lines in vitro. Similar effects were noted in vivo, with M002 decreasing tumor growth and improving overall survival in mice bearing tumors from both the established cell line and human GEP-NET PDX. Overall, these studies provide an evaluation of an oncolytic HSV in GEP-NETs, highlighting its therapeutic potential and considerations for clinical translation.

PD-L1 expression, tumor-infiltrating lymphocytes, and mismatch repair proteins status in digestive neuroendocrine neoplasms: exploring their potential role as theragnostic and prognostic biomarkers

Theragnostic biomarkers are still needed to select patients with digestive neuroendocrine neoplasms (NENs) for an optimal management. The PD-1/PD-L1 pathway plays a pivotal role in T cells activation and host immune response to cancer and PD-L1 expression in tumor and/or immune cells is used to identify patients who would benefit of treatment with immune checkpoint inhibitors. However, its role as a biomarker is still unclear in digestive NENs. We investigated PD-L1 expression in 68 well-characterized digestive NENs (32 NETs, 32 NECs and 4 MiNENs) and TPS and CPS scores were calculated. In addition, tumor infiltrating T-lymphocytes and mismatch repair protein expression (MMR) were evaluated. All results were correlated with clinicopathological features. PD-L1 expression was higher in NECs than in NETs: TPS > 1% and/or CPS > 1 were observed in 16% of NETs, 68.8% of NECs and 50% of MiNENs (p: 0.05). The mean TPS score in positive cases was 6.3% in NETs, 16.2% in NECs and 5% in MiNENs. The CPS score was 4.8 in NETs, 8.1 in NECs and 6 in MiNENs. MMR-deficient neoplasms were more frequently observed in NECs than in NETs (p: < 0.05) as well as intra-tumor immune infiltration (p: 0.00001). No correlation between PD-L1 expression and survival or other clinicopathological parameters was observed. Our results suggest that treatment with immune checkpoint inhibitors may have a potential role only in selected cases, mainly in NECs and MiNENs.

The use of deep learning models to predict progression-free survival in patients with neuroendocrine tumors

Aim: The RAISE project assessed whether deep learning could improve early progression-free survival (PFS) prediction in patients with neuroendocrine tumors. Patients & methods: Deep learning models extracted features from CT scans from patients in CLARINET (NCT00353496) (n = 138/204). A Cox model assessed PFS prediction when combining deep learning with the sum of longest diameter ratio (SLDr) and logarithmically transformed CgA concentration (logCgA), versus SLDr and logCgA alone. Results: Deep learning models extracted features other than lesion shape to predict PFS at week 72. No increase in performance was achieved with deep learning versus SLDr and logCgA models alone. Conclusion: Deep learning models extracted relevant features to predict PFS, but did not improve early prediction based on SLDr and logCgA.

Cell-free RNA for the liquid biopsy of gastrointestinal cancer

Gastrointestinal (GI) cancer includes many cancer types, such as esophageal, liver, gastric, pancreatic, and colorectal cancer. As the cornerstone of personalized medicine for GI cancer, liquid biopsy based on noninvasive biomarkers provides promising opportunities for early diagnosis and dynamic treatment management. Recently, a growing number of studies have demonstrated the potential of cell-free RNA (cfRNA) as a new type of noninvasive biomarker in body fluids, such as blood, saliva, and urine. Meanwhile, transcriptomes based on high-throughput RNA detection technologies keep discovering new cfRNA biomarkers. In this review, we introduce the origins and applications of cfRNA, describe its detection and qualification methods in liquid biopsy, and summarize a comprehensive list of cfRNA biomarkers in different GI cancer types. Moreover, we also discuss perspective studies of cfRNA to overcome its current limitations in clinical applications. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Complete Remission Upon Peptide Receptor Radionuclide Therapy in a G2 Pancreatic Neuroendocrine Tumor

ABSTRACT

We report the case of a 52-year-old man affected with a metastasized neuroendocrine tumor (G2) of the pancreas. After surgical removal, follow-up imaging 36 months later revealed somatostatin receptor-positive liver lesions. Because of disease progression under cold somatostatin analogs 6 months later, peptide receptor radionuclide therapy was performed, that induced complete remission (CR), supporting the notion that "hot" somatostatin analogs can achieve CR even in patients affected with pancreatic G2 neuroendocrine tumor. Of note, such cases exhibiting CR upon peptide receptor radionuclide therapy are extremely rare and further investigations may pool those exceptional treatment responders.

Discrimination of Liver Metastases of Digestive System Neuroendocrine Tumors From Neuroendocrine Carcinoma by Computed Tomography-Based Radiomics Analysis

OBJECTIVE

The aim of the study is to investigate the value of computed tomography (CT) radiomics features to discriminate the liver metastases (LMs) of digestive system neuroendocrine tumors (NETs) from neuroendocrine carcinoma (NECs).

METHODS

Ninety-nine patients with LMs of digestive system neuroendocrine neoplasms from 2 institutions were included. Radiomics features were extracted from the portal venous phase CT images by the Pyradiomics and then selected by using the t test, Pearson correlation analysis, and least absolute shrinkage and selection operator method. The radiomics score (Rad score) for each patient was constructed by linear combination of the selected radiomics features. The radiological model was constructed by radiological features using the multivariable logistic regression. Then, the combined model was constructed by combining Rad score and the radiological model into logistic regression. The performance of all models was evaluated by the receiver operating characteristic curves with the area under curve (AUC).

RESULTS

In the radiological model, only the enhancement degree (odds ratio, 8.299; 95% confidence interval, 2.070-32.703; P = 0.003) was an independent predictor for discriminating the LMs of digestive system NETs from those of NECs. The combined model constructed by the Rad score in combination with the enhancement degree showed good discrimination performance, with AUCs of 0.893, 0.841, and 0.740 in the training, testing, and external validation groups, respectively. In addition, it performed better than radiological model in the training and testing groups (AUC, 0.893 vs 0.726; AUC, 0.841 vs 0.621).

CONCLUSIONS

The CT radiomics might be useful for discrimination LMs of digestive system NECs from NETs.

Carcinoid Syndrome: Preclinical Models and Future Therapeutic Strategies

Carcinoid syndrome represents a debilitating paraneoplastic disease, caused by the secretion of several substances, occurring in about 10-40% of patients with well-differentiated neuroendocrine tumors (NETs). The main signs and symptoms associated with carcinoid syndrome are flushing, diarrhea, hypotension, tachycardia, bronchoconstriction, venous telangiectasia, dyspnea and fibrotic complications (mesenteric and retroperitoneal fibrosis, and carcinoid heart disease). Although there are several drugs available for the treatment of carcinoid syndrome, the lack of therapeutic response, poor tolerance or resistance to drugs are often reported. Preclinical models are indispensable tools for investigating the pathogenesis, mechanisms for tumor progression and new therapeutic approaches for cancer. This paper provides a state-of-the-art overview of in vitro and in vivo models in NETs with carcinoid syndrome, highlighting the future developments and therapeutic approaches in this field.

Chemotherapy in Well Differentiated Neuroendocrine Tumors (NET) G1, G2, and G3: A Narrative Review

Neuroendocrine tumors (NETs) are rare neoplasms with a wide spectrum of clinical behavior, from the long survival of well-differentiated NETs to the dismal prognosis of high-grade neuroendocrine carcinomas (NECs), being G3 NETs a recently recognized intermediate entity. While the role of chemotherapy is well established in NECs, data on NETs mostly derives from small studies, experts' opinions, and extrapolating results from small-cell lung cancer studies. This narrative review aims to summarize available evidence about the use of chemotherapy in the setting of G1-2 NETs and G3 NETs. We performed literature research in PubMed Library for all articles published up to September 2022 about the efficacy of chemotherapy in NETs. Treatment regimens with STZ-5FU, CAPTEM, and anti-metabolite-based treatment are the most active and tolerated in gastroenteropancreatic NETs (GEP-NETs) G1-G2, while platinum-based regimens (FOLFOX/XELOX) and TEM/CAPTEM showed the best activity in thoracic NETs. Solid evidence about chemotherapy efficacy in G3 NETs is still lacking. Literature data support the use of chemotherapy in low-intermediate grade NETs after the failure of other therapies or if tumor shrinkage is needed. Studies assessing G3 NETs independently from NECs are needed to better understand the role of chemotherapy in this setting.

Rechallenge With Additional Doses of 177 Lu-DOTATOC After Failure of Maintenance Therapy With Cold Somatostatin Analogs

ABSTRACT

Here, we report a case of a 52-year-old woman with a well-differentiated, metastasized neuroendocrine tumor (NET G1) of the duodenum. Initial imaging with 68 Ga-DOTATOC revealed multiple sites of disease with intense uptake. Peptide receptor radionuclide therapy (PRRT) with 177 Lu-DOTATOC induced partial remission. Treatment was then switched to cold somatostatin analog as a maintenance therapy. After 2 years of follow-up, progressive disease with multiple lesions in the skeleton was noted. Given the initial response to PRRT, a rechallenge with another 2 cycles of PRRT were given, and the patient had an excellent response to treatment, in particular in the skeleton.

A Nomogram to Accurately Identify Pancreatic Neuroendocrine Tumors Metastasizing to Distant Organs: A Study Based on Two National Population-Based Cohorts From the United States and China

Background:

Distant organ metastasis is the leading cause of death in pancreatic neuroendocrine tumor (pNET) patients. In the present study, we aimed to develop and validate a nomogram that could accurately identify pNET metastasizing to distant organs.

Methods:

The cases extracted from the Surveillance, Epidemiology, and End Results (SEER) program were assigned to the training cohort and validation cohort. The cases from the Chinese Gastrointestinal Neuroendocrine Tumors program were assigned to the external validation cohort. The strategy was developed with the support of a nomogram, and the predictive value of this strategy was evaluated by the receiver operating characteristic (ROC) curve analysis.

Results:

In total, 2024 American cases were involved in the present study. Besides, 1450 and 574 patients were allocated into training and internal validation cohorts, respectively. In addition, 122 Chinese patients were assigned to the external validation cohort. The results of the univariate logistic regression analysis suggested that tumor grade, tumor size, and the number of metastatic lymph nodes were the risk of metastasis to distant organs, and these 3 clinicopathological characteristics were used to develop the nomogram. We observed that the accuracy of the nomogram for predicting metastasis to distant organs was 0.797, 0.819, and 0.837 in the training cohort, internal validation cohort, and external validation cohort, respectively.

Conclusions:

A predictive nomogram was developed and validated, and it showed an acceptable performance in predicting metastasis to distant organs. The results will enable clinicians to identify pNETs, metastasizing to distant organs, and develop an effective individualized therapeutic strategy for these patients.

Establishment of Novel Neuroendocrine Carcinoma Patient-Derived Xenograft Models for Receptor Peptide-Targeted Therapy

Simple Summary

Gastroenteropancreatic neuroendocrine neoplasms (GEP NENs) are a family of rare cancers with rising incidence in recent years. GEP NEN tumor cells are difficult to propagate, and few cellular and patient-derived xenograft (PDX) models are available for testing new therapies and studying the heterogeneous nature of these cancers. Here, we described the establishment and characterization of two novel NEC cellular and PDX models (NEC913 and NEC1452). NEC913 PDX tumors express somatostatin receptor 2 (SSTR2), whereas NEC1452 PDX tumors are SSTR2 negative. As a proof-of-concept study, we demonstrated how these PDX models can be used for peptide imaging experiments targeting SSTR2 using fluorescently labelled octreotide. The NEC913 and NEC1452 PDX lines represent valuable new tools for accelerating the process of drug discovery for GEP NENs.

Abstract

Gastroenteropancreatic neuroendocrine neoplasms (GEP NENs) are rare cancers consisting of neuroendocrine carcinomas (NECs) and neuroendocrine tumors (NETs), which have been increasing in incidence in recent years. Few cell lines and pre-clinical models exist for studying GEP NECs and NETs, limiting the ability to discover novel imaging and treatment modalities. To address this gap, we isolated tumor cells from cryopreserved patient GEP NECs and NETs and injected them into the flanks of immunocompromised mice to establish patient-derived xenograft (PDX) models. Two of six mice developed tumors (NEC913 and NEC1452). Over 80% of NEC913 and NEC1452 tumor cells stained positive for Ki67. NEC913 PDX tumors expressed neuroendocrine markers such as chromogranin A (CgA), synaptophysin (SYP), and somatostatin receptor-2 (SSTR2), whereas NEC1452 PDX tumors did not express SSTR2. Exome sequencing revealed loss of TP53 and RB1 in both NEC tumors. To demonstrate an application of these novel NEC PDX models for SSTR2-targeted peptide imaging, the NEC913 and NEC1452 cells were bilaterally injected into mice. Near infrared-labelled octreotide was administered and the fluorescent signal was specifically observed for the NEC913 SSTR2 positive tumors. These 2 GEP NEC PDX models serve as a valuable resource for GEP NEN therapy testing.

Training on Reporting and Data System (RADS) for Somatostatin-Receptor Targeted Molecular Imaging Can Reduce the Test Anxiety of Inexperienced Readers

Purpose

For somatostatin receptor (SSTR)-positron emission tomography/computed tomography (PET/CT), a standardized framework termed SSTR-reporting and data system (RADS) has been proposed. We aimed to elucidate the impact of a RADS-focused training on reader’s anxiety to report on SSTR-PET/CT, the motivational beliefs in learning such a system, whether it increases reader’s confidence, and its implementation in clinical routine.

Procedures

A 3-day training course focusing on SSTR-RADS was conducted. Self-report questionnaires were handed out prior to the course (Pre) and thereafter (Post). The impact of the training on the following categories was evaluated: (1) test anxiety to report on SSTR-PET/CT, (2) motivational beliefs, (3) increase in reader’s confidence, and (4) clinical implementation. To assess the effect size of the course, Cohen’s d was calculated (small, d = 0.20; large effect, d = 0.80).

Results

Of 22 participants, Pre and Post were returned by 21/22 (95.5%). In total, 14/21 (66.7%) were considered inexperienced (IR, < 1 year experience in reading SSTR-PET/CTs) and 7/21 (33.3%) as experienced readers (ER, > 1 year). Applying SSTR-RADS, a large decrease in anxiety to report on SSTR-PET/CT was noted for IR (d =  − 0.74, P = 0.02), but not for ER (d = 0.11, P = 0.78). For the other three categories motivational beliefs, reader’s confidence, and clinical implementation, agreement rates were already high prior to the training and persisted throughout the course (P ≥ 0.21).

Conclusions

A framework-focused reader training can reduce anxiety to report on SSTR-PET/CTs, in particular for inexperienced readers. This may allow for a more widespread adoption of this system, e.g., in multicenter trials for better intra- and interindividual comparison of scan results.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11307-022-01712-6.

Diagnosis and Surgical Treatment of Gastroenteropancreatic Neuroendocrine Neoplasms: A Literature Review

This review aimed to highlight the characteristics and surgical treatments of tumours, and answer questions regarding the assessment of gastrointestinal neuroendocrine neoplasms (NENs) and optimal therapy. NENs comprise tumours that can produce hormones and cause a secretory syndrome. The diagnostic method and accuracy differ depending on the site of occurrence; hence, the relevant scientific society has created NEN treatment guidelines for each organ. Gastroenteric pancreatic (GEP) NENs have been unified and classified together according to the 2019 World Health Organization classification. Treatment is based on complete tumour resection, and when metastatic or primary lesions cannot be completely resected, lesions and symptoms are treated. Except for surgery for NENs, chemotherapy, molecularly targeted drugs, transarterial chemoembolization, etc., have also been confirmed as treatments. GEP NEN treatment methods will continue to advance and change because of surgery and other advances in treatment and diagnostic methods.

Complete Resolution of Disease After Peptide Receptor Radionuclide Therapy in a Patient of Metastatic Insulinoma

ABSTRACT

A 48-year-old man, a case of metastatic insulinoma, who failed transarterial chemoembolization of liver metastases underwent multiple cycles of peptide receptor radionuclide therapy with 177Lu-DOTATATE, following which a complete morphologic and metabolic response was demonstrated on 68Ga-DOTATATE PET/CT. Patient had a remarkable improvement in his quality of life as intractable hypoglycemic episodes resolved after treatment. Peptide receptor radionuclide therapy is a promising targeted radionuclide therapy in patients of metastatic insulinomas that can result in reduced tumor burden and improved quality of life, particularly those who fail the conventional treatment modalities as seen in the present case.

Diagnostic performance of noninvasive imaging modalities for localization of insulinoma: A meta-analysis

BACKGROUND

Insulinoma is the most common functional neuroendocrine tumor found only in the pancreas. The early detection of insulinoma is of importance. Studies comparing the performance of noninvasive modalities were limited by sample size and heterogeneity between studies. The aim of this meta-analysis was to evaluate the diagnostic performance of PET/CT, SPECT/CT, CT and MRI for the localization of insulinoma, and to provide evidence for clinical practice.

METHODS

PubMed, Embase, Cochrane Library, Wanfang Data and China National Knowledge Infrastructure were searched from inception to May 31, 2021. Pooled sensitivity, specificity, positive Likelihood Ratio (+LR) and negative Likelihood Ratio (-LR), diagnostic odds ratio (DOR), and concordance rate were calculated.

RESULTS

A total of 19 studies including 708 patients of insulinoma reached the inclusion criteria. PET/CT imaging demonstrated a pooled sensitivity of 0.79 (95% CI: 0.54-0.92) and a pooled specificity of 0.84 (95% CI: 0.20-0.99). The pooled sensitivity and specificity of SPECT/CT were 0.77 (95% CI: 0.46-0.93) and 0.45 (95% CI: 0.22-0.70). CT showed an overall sensitivity of 0.54 (95% CI: 0.35-0.72) and specificity of 0.75 (95% CI: 0.54-0.88). The pooled sensitivity and specificity for MRI were 0.54 (95% CI: 0.31-0.75) and 0.65 (95% CI: 0.39-0.84), respectively. The concordance rates of PET, SPECT, CT, and MRI were 78% (95% CI: 66-90%), 74% (95% CI: 52-97%), 56% (95% CI: 41-72%), and 53% (95% CI: 33-73%), respectively.

CONCLUSION

Results of this study indicate that PET/CT demonstrated superior performance than SPECT/CT, CT and MRI for the localization of insulinoma. GLP-1R based PET/CT manifested better diagnostic performance in comparison with SSTR based PET/CT imaging modality.

Long-term outcome of "Sandwich" chemo-PRRT: a novel treatment strategy for metastatic neuroendocrine tumors with both FDG- and SSTR-avid aggressive disease

OBJECTIVE

The primary aims of this study were to evaluate the long-term outcome of a "sandwich chemo-PRRT (SCPRRT)" regimen with regard to therapeutic response rate, progression-free survival (PFS), and overall survival (OS) rates in metastatic neuroendocrine tumors (NETs) with both somatostatin receptor (SSTR)- and fluorodeoxyglucose (FDG)-avid aggressive disease. Additionally, health-related quality of life (HRQoL) scales, clinical toxicity, and association of PFS and disease control rate (DCR) with various variables were also evaluated.

MATERIALS AND METHODS

A total of 38 patients of the aforementioned cohort, who received SCPRRT (at least 2 cycles of each PRRT and chemotherapy) at our institute between January 2012 and December 2018, were included and analyzed in this retrospective study. Between two cycles of 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT), two cycles of oral capecitabine and temozolomide (CAPTEM) were sandwiched. Therapeutic responses following SCPRRT were assessed by using pre-defined criteria. PFS and OS after first SCPRRT were determined. Eastern Cooperative Oncology Group (ECOG) and Karnofsky score were used for evaluation of HRQoL before and after SCPPRT in all 38 patients. Any adverse events were graded according to the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v5.0) of the National Cancer Institute. Associations of PFS and DCR with various variables were evaluated.

RESULTS

Response (complete response and partial response) to SCPRRT was seen in 28 patients (73%), 15 patients (39%), and 16 patients (42%) on symptomatic, biochemical, and molecular imaging response evaluation criteria respectively. A total of 17 patients (45%) had anatomical imaging response with DCR of 84% based upon the RECIST 1.1 criteria. Pre-therapy mean ECOG and KPS was 2.0 and 68, which changed to 1.0 and 75 respectively following SCPRRT. Long-term follow-up data was available and ranged from 12 to 65 months after the first SCPRRT. Median PFS and OS were not reached at a median follow-up of 36 months. An estimated PFS rate of 72.5% and OS rate of 80.4% was found at 36 months. Longer PFS was dependent upon high SSTR uptake and number of CAPTEM cycle (≥ 7 cycles), absence of skeletal metastasis, and no previous external beam radiotherapy (EBRT) exposure with significant P value. Higher DCR was dependent upon absence of skeletal metastasis with significant P value. SCPRRT was tolerated well with none developing grade 4 hematotoxicity and nephrotoxicity of any grade. Anemia (grade 3), thrombocytopenia (grade 3), and leukopenia (grade 3) were noticed in 1 patient (2.5%), 2 patients (5%), and 1 patient (2.5%) respectively in this study.

CONCLUSION

Thus, favorable response rates with effective control of symptoms and longer PFS and OS without high-grade or life-threatening toxicities were important observations in the present study following SCPRRT in NET patients with aggressive, both FDG- and SSTR-avid, metastatic progressive disease. The study results indicate the potential role of "sandwich chemo-PRRT" in future therapeutic algorithms of aggressive, both SSTR- and FDG-positive subset of neuroendocrine tumors.

Treatment personalization in gastrointestinal neuroendocrine tumors

The clinical scenario of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) is continuously changing due to significant improvements in the definition of their molecular landscapes and the introduction of innovative therapeutic approaches. Many efforts are currently employed in the integration of the genetics/epigenetics and clinical information. This is leading to an improvement of tumor classification, prognostic stratification and ameliorating the management of patients based on a personalized approach.

Predicting the Survival Probability of Neuroendocrine Tumor Populations: Developing and Evaluating a New Predictive Nomogram

Purpose

The purpose of this study was to develop and initially validate a nomogram model in order to predict the 3-year and 5-year survival rates of neuroendocrine tumor patients.

Methods

Accordingly, 348 neuroendocrine tumor patients were enrolled as study objects, of which 244 (70%) patients were included in the training set to establish the nomogram model, while 104 (30%) patients were included in the validation set to verify the robustness of the model. First, the variables related to the survival rate were determined by univariable analysis. In addition, variables that were sufficiently significant were selected for constructing the nomogram model. Furthermore, the concordance index (C-index), receiver operating characteristic (ROC), and calibration curve analysis were used to evaluate the performance of the proposed nomogram model. The survival analysis was then used to evaluate the return to survival probability as well as the indicators of constructing the nomogram model.

Results

According to the multivariable analysis, lymphatic metastasis, international normalized ratio (INR), prothrombin time (PT), tumor differentiation, and the number of tumor metastases were found to be independent predictors of survival rate. Moreover, the C-index results demonstrated that the model was robust in both the training set (0.891) and validation set (0.804). In addition, the ROC results further verified the robustness of the model either in the training set (AUC = 0.823) or training set (AUC = 0.768). Furthermore, the calibration curve results showed that the model can be used to predict the 3-year and 5-year survival probability of neuroendocrine tumor patients. Meaningfully, five variables were found: lymphatic metastasis (p = 0.0095), international standardized ratio (p = 0.024), prothrombin time (p = 0.0036), tumor differentiation (p = 0.0026), and the number of tumor metastases (p = 0.00096), which were all significantly related to the 3-year and 5-year survival probability of neuroendocrine tumor patients.

Conclusion

In summary, a nomogram model was constructed in this study based on five variables (lymphatic metastasis, international normalized ratio (INR), prothrombin time (PT), tumor differentiation, and number of tumor metastases), which was shown to predict the survival probability of patients with neuroendocrine tumors. Additionally, the proposed nomogram exhibited good ability in predicting survival probability, which may be easily adopted for clinical use.

Currently available treatment options for neuroendocrine liver metastases

Neuroendocrine neoplasms (NEN) are frequently characterized by a high propensity for metastasis to the liver, which appears to be a dominant site of distant-stage disease, affecting quality of life and overall survival. Liver surgery with the intention to cure is the treatment of choice for resectable neuroendocrine liver metastases (NELM), aiming to potentially prolong survival and ameliorate hormonal symptoms refractory to medical control. Surgical resection is indicated for patients with NELM from well-differentiated NEN, while its feasibility and complexity are largely dictated by the degree of liver involvement. As a result of advances in surgical techniques over the past decades, complex 1- and 2-stage, or repeat liver resections are performed safely and effectively by experienced surgeons. Furthermore, liver transplantation for the treatment of NELM should be anchored in a multimodal and multidisciplinary therapeutic strategy and restricted only to highly selected individual cases. A broad spectrum of interventional radiology treatments for NELM have recently been available, with expanding indications that are more applicable, as they are less limited by patient- and tumor-related parameters, being therefore important adjuncts or alternatives to surgery. Overall, liver-targeted treatment modalities may precede the administration of systemic molecular targeted agents and chemotherapy for patients with liver-dominant metastatic disease; these appear to be a crucial component of multimodal management of patients with NEN. In the present review, we discuss surgical and non-surgical liver-targeted treatment approaches for NELM, each complementing the other, with a view to assisting physicians in optimizing multimodal NEN patient care.

A literature-based treatment algorithm for low-grade neuroendocrine liver metastases

BACKGROUND

The optimal timing of treatment of liver metastases from low-grade neuroendocrine tumors (LG-NELM) varies significantly due to numerous treatment modalities and the literature supporting various treatment(s). This study sought to create and validate a literature-based treatment algorithm for LG-NELM.

METHODS

A treatment algorithm to maximize overall survival (OS) was designed using peer-reviewed articles evaluating treatment of LG-NELM. This algorithm was retrospectively applied to patients treated for LG-NELM at our institution. Deviation was determined based on whether or not a patient received treatment consistent with that recommended by the algorithm. Patients who did and did not deviate from the algorithm were compared with respect to OS and number of treatments.

RESULTS

Applying our algorithm to a 149-patient cohort, 57 (38%) deviated from recommended treatment. Deviation occurred in the form of alternative (28, 49%) versus additional procedures (29, 51%). Algorithm deviators underwent significantly more procedures than non-deviators (median 1 vs. 2, p < 0.001). Cox model indicated no difference in OS associated with algorithm deviation (HR 1.19, p = 0.58) when controlling for age and tumor characteristics.

CONCLUSION

This literature-based algorithm helps standardize treatment protocols in patients with LG-NELM and can reduce cost and risk by minimizing unnecessary procedures. Prospective implementation and validation is required.

Neoadjuvant Therapy for Neuroendocrine Neoplasms: Recent Progresses and Future Approaches

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors, their treatment being challenging and requiring a multidisciplinary approach. Though the only curative treatment is surgery, up to 50% of patients are diagnosed with metastatic disease. In the last years, neoadjuvant chemo(radio)therapy has become part of the standard of care in the treatment of different cancer types. However, evidence of its efficacy and safety in NEN patients has not yet been confirmed in the literature. The aim of the present review is to perform an extensive review of the scientific evidence for neoadjuvant therapy in patients with gastroenteropancreatic and thoracic NENs.

Inflammation-related cytokines and their roles in gastroenteropancreatic neuroendocrine neoplasms

Proinflammatory counterworks are important at different stages of tumor development, particularly during invasion and metastasis. Immune cells and their signal molecules can influence all stages of tumor progression, as well as therapeutic intervention. Proinflammatory cytokines are known triggers of growth in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). In this study, we explored the immunohistochemical expression of tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), IL-2, and IL-6 in tissues from 43 GEP-NEN patients with tumors of gastric, duodenal, ileal, appendiceal, and colonic origin. The immunohistochemical expression of TNF-α was increased in tumor groups with high proliferation rates (Ki-67; p = 0.034), as well as in those with higher tumor grades (p = 0.05). Moreover, the immunohistochemical expression of TNF-α positively correlated with death outcomes (p = 0.016). Expression of IL-6, IL-1β, and IL-2 displayed similar immunohistochemical expression patterns regardless of Ki-67, although the expression between the ILs differed. Most GEP-NENs had high levels of IL-6 and lower levels of IL-1β and IL-2. Although further comprehensive studies are required for a complete understanding of activated mechanisms in proinflammatory protumoral microenvironment of GEP-NENs, TNF-α is a potential marker in the prognosis of those tumors.

Cytoreduction and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) Versus Surgery Without HIPEC for Goblet-Cell Carcinoids and Mixed Adenoneuroendocrine Carcinomas: Propensity Score-Matched Analysis of Centers in the Netherlands and Belgium

BACKGROUND

The value of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for patients with peritoneally metastasized goblet-cell carcinoids (GCCs) and mixed adenoneuroendocrine carcinomas (MANECs) is currently unclear. We compared outcomes of CRS-HIPEC to surgery alone for peritoneally metastasized GCCs and MANECs.

PATIENTS AND METHODS

Two cohorts were obtained from the Netherlands Cancer Registry (n = 569): patients with peritoneally metastasized GCCs and MANECs treated with CRS-HIPEC in Dutch and Belgian centers (n = 45), and patients treated with surgery alone. Primary outcome was overall survival (OS). Secondary outcomes were morbidity and hospital mortality. After propensity score matching, OS was compared in univariate and multivariate analyses. A systematic literature review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines from database inception to June 25, 2018.

RESULTS

After matching for sex, tumor stage, lymph node stage, and liver metastases, CRS-HIPEC was associated with improved median OS in the combined GCC and MANEC group and the separate GCC subgroup in univariate (GCC + MANEC: 39 vs. 12 months, P < .001; GCC: 39 vs. 12 months, P = .017) and multivariate analysis (GCC + MANEC: hazard ratio 4.27, 95% confidence interval 1.88-9.66, P = .001; GCC: hazard ratio 2.77, 95% confidence interval 1.06-7.26, P = .038). Acceptable grade III-IV morbidity (17.5%) and mortality (0) were seen after CRS-HIPEC. The literature review supported these findings.

CONCLUSION

CRS-HIPEC is associated with substantial survival benefit in patients with peritoneally metastasized GCCs and MANECs compared to surgery alone and is a safe treatment option. These data support centralized care of GCC and MANEC patients with peritoneal spread in expert centers offering CRS-HIPEC.

Sequence of therapy and survival in patients with advanced pancreatic neuroendocrine tumours

Background

Pancreatic neuroendocrine tumours (pnets) often present as advanced disease. The optimal sequence of therapy is unknown.

Methods

Sequential patients with advanced pnets referred to BC Cancer between 2000 and 2013 who received 1 or more treatment modalities were reviewed, and treatment patterns, progression-free survival (pfs), and overall survival (os) were characterized. Systemic treatments included chemotherapy, small-molecule therapy, and peptide receptor radionuclide therapy.

Results

In 66 cases of advanced pnets, median patient age was 61.2 years (25%-75% interquartile range: 50.8-66.2 years), and men constituted 47% of the group. First-line therapies were surgery (36%), chemotherapy (33%), and somatostatin analogues (32%). Compared with first-line systemic therapy, surgery in the first line was associated with increased pfs and os (20.6 months vs. 6.3 months and 100.3 months vs. 30.5 months respectively, p < 0.05). In 42 patients (64%) who received more than 1 line of therapy, no difference in os or pfs between second-line therapies was observed.

Conclusions

Our results confirm the primary role of surgery for advanced pnets. New systemic treatments will further increase options.

Previously undiagnosed neuroendocrine tumour mimicking breast cancer metastasis to the orbit

Metastatic neuroendocrine neoplasms to the breast are rare and histopathologic overlap with mammary carcinomas has led to misdiagnosis. We present a case of a middle-aged woman with diplopia and a right medial rectus mass. Metastatic breast cancer was initially suspected based on a history of invasive ductal carcinoma. Detailed immunohistochemistry of the orbital biopsy, gallium-68 dotatate positron emission tomography-CT, and reevaluation of her prior breast specimen, demonstrated that her initial breast carcinoma diagnosis was in error and she was ultimately diagnosed with a previously unknown gastrointestinal neuroendocrine tumour metastatic to both the orbit and breast. This case highlights the challenges of differentiating between metastatic neuroendocrine tumours and invasive mammary carcinomas with neuroendocrine differentiation both in the breast and in the orbit. It is important to recognise the overlap so that a primary neuroendocrine neoplasm is not missed, or treatment significantly delayed.

Blood-based next-generation sequencing analysis of neuroendocrine neoplasms

Background: Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplasms that span from well-differentiated neuroendocrine tumors (NETs) to highly aggressive neoplasms classified as neuroendocrine carcinomas (NECs). The genomic landscape of NENs has not been well studied. The aim of this study is to confirm the feasibility of next generation sequencing (NGS) testing circulating tumor DNA (ctDNA) in patients with NENs and characterize common alterations in the genomic landscape.

Results: Of the 320 NEN patients, 182 (57%) were male with a median age of 63 years (range: 8-93) years. Tumor type included pancreatic NET (N = 165, 52%), gastrointestinal NEC (N = 52, 16%), large cell lung NEC (N = 21, 7%), nasopharyngeal NEC (N = 16, 5%) and NEC/NET not otherwise specified (N = 64, 20%). ctDNA NGS testing was performed on 338 plasma samples; 14 patients had testing performed twice and 2 patients had testing performed three times. Genomic alterations were defined in 280 (87.5%) samples with a total of 1,012 alterations identified after excluding variants of uncertain significance (VUSs) and synonymous mutations. Of the 280 samples with alterations, TP53 associated genes were most commonly altered (N = 145, 52%), followed by KRAS (N = 61, 22%), EGFR (N = 33, 12%), PIK3CA (N = 30, 11%), BRAF (N = 28, 10%), MYC (N = 28, 10%), CCNE1 (N = 28, 10%), CDK6 (N = 22, 8%), RB1 (N = 19, 7%), NF1 (N = 19, 7%), MET (N = 19, 7%), FGFR1 (N = 19, 7%), APC (N = 19, 7%), ERBB2 (N = 16, 6%) and PTEN (N = 14, 5%).

Conclusions: Evaluation of ctDNA was feasible among individuals with NEN. Liquid biopsies are non-invasive methods that can provide personalized options for targeted therapies in NEN patients.

Patients and Methods: Molecular alterations in 338 plasma samples from 320 patients with NEN were evaluated using clinical-grade NGS of ctDNA (Guardant360^®) across multiple institutions. The test detects single nucleotide variants in 54-73 genes, copy number amplifications, fusions, and indels in selected genes.

Repeat hepatectomy for patients with recurrent neuroendocrine liver metastasis: Comparison with first hepatectomy

BACKGROUND

The value of repeat hepatectomy for intrahepatic recurrence after curative resection of neuroendocrine liver metastasis (NELM) remains unclear. The aim of this retrospective cohort study was to determine the significance of repeat hepatectomy for recurrent NELM.

METHODS

Patients who underwent hepatectomy for NELM between 1994 and 2016 were identified. The indications for a first hepatectomy were adequate liver remnant volume and no extrahepatic metastasis. The diagnosis of recurrent NELM was based on radiographic examinations. The indications for a repeat hepatectomy were the same as those for the first hepatectomy. Clinicopathologic factors, short-term survival, and long-term survival were investigated using clinical records.

RESULTS

Forty-four patients enrolled in this study. Thirty-three patients among them underwent a curative hepatectomy, and 28 of them developed recurrence. Of them, 16 patients underwent a repeat hepatectomy. The overall survival of the repeat hepatectomy cohort (n = 16) was significantly better than that of the no repeat hepatectomy cohort (n = 12) (P < .001). The progression free survival after the first hepatectomy (n = 44) and that after repeat hepatectomy (n = 16) were similar (P = .546). No significant difference was seen between the frequency of major complications (Clavien-Dindo score ≥ 3a) after the first and repeat hepatectomy (P = .279). No repeat hepatectomy (hazard ratio [HR] 5.0, P = .036) was identified as an independent predictive factor of a poor outcome among the recurrent cohort, along with the presence of multiple nodules (HR 26.2, P = .008) and a CA19-9 level ≥40 U/mL (HR 11.2, P = .012).

CONCLUSIONS

A repeat hepatectomy is feasible in selected patients with recurrent NELM.

New and emerging systemic therapy options for well-differentiated gastroenteropancreatic neuroendocrine tumors

Introduction: Well-differentiated gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) are a heterogeneous group of neoplasms with a wide range of clinical behavior. Multiple treatment modalities exist, including novel and emerging systemic options, and an understanding of the advantages and disadvantages of each is imperative for optimizing the outcomes of patients with GEP-NETs.Areas covered: While surgical resection remains the preferred treatment for localized well-differentiated GEP-NETs, treatment of unresectable disease depends on its extent, location, and distribution as well as underlying aspects of tumor biology. Isolated hepatic metastases can be successfully treated with liver-directed therapies such as hepatic arterial based therapies or ablation. Diffuse metastatic disease often requires systemic treatments such as molecular-targeted therapeutics, peptide receptor radionuclide therapy (PRRT), or traditional chemotherapy. Somatostatin analogs are often the primary treatment option capable of simultaneously inhibiting hormone production and slowing tumor growth.Expert opinion: Recent advances in systemic treatment options for advanced well-differentiated GEP-NETs have emerged due to an improved understanding of the molecular mechanisms responsible for tumor development and progression. Future research is needed to determine the optimal indications for and sequencing of these novel therapies.

Therapeutic sequences in patients with grade 1-2 neuroendocrine tumors (NET): an observational multicenter study from the ELIOS group

PURPOSE

Many different treatments are suggested by guidelines to treat grade 1-2 (G1-G2) neuroendocrine tumors (NET). However, a precise therapeutic algorithm has not yet been established. This study aims at identifying and comparing the main therapeutic sequences in G1-G2 NET.

METHODS

A retrospective observational Italian multicenter study was designed to collect data on therapeutic sequences in NET. Median progression-free survival (PFS) was compared between therapeutic sequences, as well as the number and grade of side effects and the rate of dose reduction/treatment discontinuation.

RESULTS

Among 1182 patients with neuroendocrine neoplasia included in the ELIOS database, 131 G1-G2 gastroenteropancreatic, lung and unknown primary NET, unresectable or persistent/relapsing after surgery, treated with ≥2 systemic treatments, were included. Four main therapeutic sequences were identified in 99 patients: (A) somatostatin analogs (SSA) standard dose to SSA high dose (n = 36), (B) SSA to everolimus (n = 31), (C) SSA to chemotherapy (n = 17), (D) SSA to peptide receptor radionuclide therapy (PRRT) (n = 15). Median PFS of the second-line treatment was not reached in sequence A, 33 months in sequence B, 20 months in sequence C, 30 months in sequence D (p = 0.16). Both total number and severity of side effects were significantly higher in sequences B and C than A and D (p = 0.04), as well as the rate of dose reduction/discontinuation (p = 0.03).

CONCLUSIONS

SSA followed by SSA high dose, everolimus, chemotherapy or PRRT represent the main therapeutic sequences in G1-G2 NET. Median PFS was not significantly different between sequences. However, the sequences with SSA high dose or PRRT seem to be better tolerated than sequences with everolimus or chemotherapy.

Selective internal radiation therapy: an effective treatment for hormonal syndromes in pancreatic neuroendocrine tumors

The hormone secretion in pancreatic neuroendocrine tumors (pNET) causes an important interference in patients' quality of life. We present two cases of pNET metastatic to the liver (a pancreatic endocrine carcinoma with a severe hormonal syndrome and an insulinoma with severe crisis of hypoglycemia and coma) refractory to conventional treatments, which were finally solved with selective internal radiation therapy (SIRT), a nonstandard level 1 therapy. We show two examples of an excellent control of symptoms together with a long survival after treatment with SIRT. The evidence supporting the use of this therapy is level 2. Our case reports strongly support the use of SIRT for the severe clinical syndrome in pNET metastatic to the liver and refractory to somatostatin analogs.

Telotristat Ethyl: A Review in Carcinoid Syndrome Diarrhoea

Telotristat ethyl (Xermelo^®), a first-in-class peripheral tryptophan hydroxylase (TPH) inhibitor, is approved to treat carcinoid syndrome diarrhoea in combination with somatostatin analogue (SSA) therapy in adults inadequately controlled by SSA therapy alone. Some neuroendocrine tumours secrete serotonin (5-HT) into the blood, resulting in frequent bowel movements (BMs) and other symptoms. Telotristat ethyl inhibits TPH, thereby reducing the production of 5-HT and improving carcinoid syndrome diarrhoea. In the 12-week placebo-controlled phase of randomized trials in patients with carcinoid syndrome diarrhoea (most of whom were receiving SSA therapy), the addition of oral telotristat ethyl 250 three times daily provided significant reductions in the frequency of BMs and levels of urinary 5-hydroxyindolacetic acid (u5-HIAA; a metabolite of 5-HT) relative to placebo. Telotristat ethyl 250 mg three times daily was well tolerated, with the proportion of patients reporting at least one treatment-emergent adverse event being similar to that with placebo. With regard to adverse events of special interest, relative to placebo, telotristat ethyl had a comparable incidence of depression-related symptoms, a somewhat higher incidence of gastrointestinal (GI) disorders and a higher incidence of elevated hepatic enzyme levels.

Peptide receptor radionuclide therapy with 177Lu-DOTA-TATE as a promising treatment of malignant insulinoma: a series of case reports and literature review

INTRODUCTION

Insulinomas are a rare type of pancreatic neuroendocrine tumours characterized by insulin hypersecretion. They are considered malignant when metastases are present. Traditional therapies often promote only temporarily symptomatic relief and may be associated with severe adverse effects. There is scarce experience in treating malignant insulinomas with peptide receptors radionuclide therapy (PRRNT).

PATIENTS AND METHODS

We describe PRRNT results in four patients with inoperable malignant insulinomas with poorly controllable hypoglycaemia. All patients received therapy with ¹⁷⁷Lu-DOTA-TATE after conventional therapies failed in controlling disease progression and symptoms. The activity administered per cycle was 4.8-7.4 GBq. The interval between cycles was 10-16 weeks. Haematology, liver and kidney function tests were performed before treatment initiation and 5 and 10 weeks after each cycle.

RESULTS

Patient 1 presented significant clinical benefit for 13 months after PRRNT, with imaging improvement. Patient 2 obtained reduction of the number and severity of hypoglycaemic episodes during 15 months after therapy. Patient 3 is asymptomatic since PRRNT first cycle performed 23 months ago and revealed significant imaging improvement. Patient 4 had resolution of hypoglycaemia only 3 days after PRRNT first cycle and today, 16 months after therapy, the disease seems to be in remission and the patient maintains euglycaemic state. PRRNT was well tolerated, with only hematologic grade 2 toxicity in patient 1 and mild kidney toxicity in patient 3.

CONCLUSIONS

After the start of ¹⁷⁷Lu-DOTA-TATE all patients achieved hypoglycaemia symptomatic control and had evident improvement of their quality of life. Three patients showed imagiological improvement suggesting reduced tumour load.

Gastrinomas: Medical or Surgical Treatment

This article reviews the role of surgical and medical management in patients with Zollinger-Ellison syndrome (ZES) due to a gastrin-secreting neuroendocrine tumor (gastrinoma). It concentrates on the status at present but also briefly reviews the changes over time in treatment approaches. Generally, surgical and medical therapy are complementary today; however, in some cases, such as patients with ZES and multiple endocrine neoplasia type 1, the treatment approach remains controversial.

New Treatments for the Carcinoid Syndrome

Neuroendocrine tumors, including carcinoids, are rare and insidiously growing tumors. Related to their site of origin, tumors can be functional, causing various forms of the carcinoid syndrome, owing to the overproduction of serotonin, histamine, or other bioactive substances. They often invade adjacent structures or metastasize to the liver and elsewhere. Treatment includes multimodal approaches, including cytoreductive surgery, locoregional embolization, cytotoxic therapy, peptide receptor radionuclide therapy, and various targeted therapies with goals of symptom relief and control of tumor growth. This article summarizes current and emerging approaches to management and reviews several promising future therapies.

Emerging multitarget tyrosine kinase inhibitors in the treatment of neuroendocrine neoplasms

In the last few years, the therapeutic approach for neuroendocrine neoplasms (NENs) has changed dramatically following the approval of several novel targeted treatments. The multitarget tyrosine kinase inhibitor (MTKI), sunitinib malate, has been approved by Regulatory Agencies in pancreatic NENs. The MTKI class, however, includes several other molecules (approved for other conditions), which are currently being studied in NENs. An in-depth review on the studies published on the MTKIs in neuroendocrine tumors such as axitinib, cabozantinib, famitinib, lenvatinib, nintedanib, pazopanib, sorafenib and sulfatinib was performed. Furthermore, we extensively searched on the Clinical Trial Registries databases worldwide, in order to collect information on the ongoing clinical trials related to this topic. Our systematic analysis on emerging MTKIs in the treatment of gastroenteropancreatic and lung NENs identifies in vitro and in vivo studies, which demonstrate anti-tumor activity of diverse MTKIs on neuroendocrine cells and tumors. Moreover, for the first time in the literature, we report an updated view concerning the upcoming clinical trials in this field: presently, phase I, II and III clinical trials are ongoing and will include, overall, a staggering 1667 patients. This fervid activity underlines the increasing interest of the scientific community in the use of emerging MTKIs in NEN treatment.

Liquid Biopsies for Neuroendocrine Tumors: Circulating Tumor Cells, DNA, and MicroRNAs

Effective management of neuroendocrine tumors depends on early diagnosis, personalized risk stratification, and monitoring response to therapy. During cancer progression, tumors shed circulating tumor cells, circulating tumor DNA, and microRNAs into the bloodstream. Analysis of these biomarkers offers the prospect of a liquid biopsy to predict/monitor therapeutic responses, assess drug resistance, and quantify residual disease. Compared with single-site biopsies, these entities have the potential to inform intratumor heterogeneity and tumor evolution in a reproducible and less invasive way. This article summarizes the state-of-the-art on the potential role of these markers as prognostic and predictive factors in neuroendocrine tumors.

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.

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.

Aggressive neuroendocrine tumor of the ovary with multiple metastases treated with everolimus: A case report

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Neuroendocrine tumors (NETs) frequently occur in the lungs or the gastrointestinal tract; they are uncommon in the ovary.

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The mammalian target of rapamycin (mTOR) pathway has been reported as a treatment for advanced NETs.

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We describe a patient with an aggressive primary ovarian NET, successfully treated with everolimus (an mTOR inhibitor).

Extremely Long Survival under Combined Immunotherapy in a Metastatic Functional Neuroendocrine Neoplasia Patient

Treatment and prognosis of neuroendocrine neoplasia depends on tumor size, stage, grade, resectability, and extent of distant metastasis. In most cases a multimodality approach including surgical, locally invasive procedures, peptide-guided radioreceptor therapy (PRRT), and medical therapies represent the mainstay of treatment in advanced disease. In the reported case, a 68-year-old man was diagnosed in 2010 with an initially functional (histamine) neuroendocrine tumor of gastric type III, G2, stage IVB, cT4cN1cM1 (hepatic, peritoneal, nodal, osseous), including a hepatic tumor load of 25%. Intensive multimodality approaches including combined immunotherapy (vaccination and PD-1/CTLA-4 blockade) led to a survival of 8 years until now with a high quality of life and minimal residual disease (only a single, small paragastric recurrence) despite the dedifferentiation of the tumor into a neuroendocrine carcinoma G3 (Ki-67 of 80%) including a nonfunctional stage.

Pathophysiology of Gastric NETs: Role of Gastrin and Menin

PURPOSE OF REVIEW

Neuroendocrine tumors (NETs) were initially identified as a separate entity in the early 1900s as a unique malignancy that secretes bioactive amines. GI-NETs are the most frequent type and represent a unique subset of NETs, because at least 75% of these tumors represent gastrin stimulation of the enterochromaffin-like cell located in the body of the stomach. The purpose of this review is to understand the specific role of gastrin in the generation of Gastric NETs (G-NETs).

RECENT FINDINGS

We review here the origin of enterochromaffin cells gut and the role of hypergastrinemia in gastric enteroendocrine tumorigenesis. We describe generation of the first genetically engineered mouse model of gastrin-driven G-NETs that mimics the human phenotype. The common mechanism observed in both the hypergastrinemic mouse model and human carcinoids is translocation of the cyclin-dependent inhibitor p27^kip to the cytoplasm and its subsequent degradation by the proteasome. Therapies that block degradation of p27^kip, the CCKBR2 gastrin receptor, or gastrin peptide are likely to facilitate treatment.

Histone deacetylase inhibitor thailandepsin-A activates Notch signaling and suppresses neuroendocrine cancer cell growth in vivo

Novel therapies for neuroendocrine (NE) cancers are desperately needed as they frequently present as metastatic disease and cause debilitating symptoms by secreting excessive hormones. Induction of Notch isoforms has a tumor suppressive effect in NE cancer cell lines, and we have observed that histone deacetylase inhibitors (HDACi) potently activate Notch. In this study, we describe the potential for Burkholderia thailandensis-derived class I HDACi thailandepsin A (TDP-A) as a Notch activator and therapeutic agent against NE cancer. IC₅₀ for TDP-A was determined to be 4-6 nM in NE cancer cell lines (BON, MZ-CRC-1, and TT) without cytotoxicity to lung fibroblasts. The binding characteristics of TDP-A to its target HDAC1 was examined using bioluminescence resonance energy transfer (BRET). Western blot and flow cytometry analysis showed that TDP-A induces cell cycle arrest and apoptosis in a dose-dependent manner. TDP-A dose-dependently activated the Notch pathway as measured by increasing functional CBF1-luciferase reporter signal and mRNA and protein expressions of Notch isoforms, which were attenuated by pretreatment with γ-secretase inhibitor DAPT. Furthermore, TDP-A lead to changes in expression level of downstream targets of Notch pathway and reduced expression of NE cancer markers. An in vivo study demonstrated that TDP-A suppressed NE cancer progression. These results show that TDP-A, as a Notch activator, is a promising agent against NE cancers.

Acyclonucleosides bearing coplanar arylethynyltriazole nucleobases: synthesis, structural analysis, and biological evaluation

The efficient synthesis of acyclonucleosides bearing coplanar 3-arylethynyltriazole motifs was established and several compounds displayed antiproliferative activity against cancer cells.