PREF-NET: a patient preference and experience study of lanreotide autogel administered in the home versus hospital setting among patients with gastroenteropancreatic neuroendocrine tumours in the UK.

PURPOSE: PREF-NET reported patients' experience of Somatuline® (lanreotide) Autogel® (LAN) administration at home and in hospital among patients with gastroenteropancreatic neuroendocrine tumours (GEP-NETs). METHODS: PREF-NET was a multicentre, cross-sectional study of UK adults (aged ≥ 18 years) with GEP-NETs receiving a stable dose of LAN, which comprised of (1) a quantitative online survey, and (2) qualitative semi-structured interviews conducted with a subgroup of survey respondents. The primary objective was the description of overall patient preference for home versus hospital administration of LAN. Secondary objectives included describing patient-reported opinions on the experience and associated preference for each administration setting, and the impact on healthcare utilisation, societal cost, activities of daily living and health-related quality of life (HRQoL). RESULTS: In the primary analysis (80 patients; mean age 63.9 years), 98.7% (95% confidence interval [CI]: 96.1-100.0) of patients preferred to receive LAN at home, compared with 1.3% (95% CI: 0.0-3.9) who preferred the hospital setting. Among participants, over half (60.3%) received their injection from a non-healthcare professional. Most patients (79.5% [95% CI: 70.5-88.4]) reported a positive effect on HRQoL after the switch from hospital to home administration. Qualitative interviews (20 patients; mean age 63.6 years) highlighted that patients preferred home administration because it improved overall convenience; saved time and costs; made them feel more comfortable and relaxed, and less stressed; and increased confidence in their ability to self-manage their treatment. CONCLUSION: Almost all patients preferred to receive LAN treatment at home rather than in hospital with increased convenience and psychological benefits reported as key reasons for this preference.

Management of patients with rare adult solid cancers: objectives and evaluation of European reference networks (ERN) EURACAN.

About 500,000 patients with rare adult solid cancers (RASC) are diagnosed yearly in Europe. Delays and unequal quality of management impact negatively their survival. Since 2017, European reference networks (ERN) aim to improve the quality of care of patients with rare disease. The steering committee of EURACAN, including physicians, researchers and patients review here the previous actions, present objectives of the ERN EURACAN dedicated to RASC. EURACAN promoted management in reference centres, and equal implementation of excellence and innovation in Europe and developed 22 clinical practice guidelines (CPGs). Additionally, fourteen information brochures translated in 24 EU languages were developed in collaboration with patient advocacy groups (ePAGs) and seventeen training session were organized. Nevertheless, connections to national networks in the 26 participating countries (106 centres), simplification of cross-border healthcare, international multidisciplinary tumour boards, registries and monitoring of the quality of care are still required. In this Health Policy, evaluation criteria of the performances of the network and of health care providers are proposed.

[18F]FDG PET/CT-Avid Discordant Volume as a Biomarker in Patients with Gastroenteropancreatic Neuroendocrine Neoplasms: A Multicenter Study.

[18F]FDG PET/CT and [68Ga]Ga-DOTATATE PET/CT are both used to predict tumor biology in neuroendocrine neoplasms. Although the presence of discordant ([18F]FDG-avid/non-[68Ga]Ga-DOTATATE-avid) disease predicts poor prognosis, the significance of the volume of such discordant disease remains undetermined. The aim of this study is to investigate discordant tumor volume as a potential biomarker in patients with advanced gastroenteropancreatic neuroendocrine neoplasms (GEPNENs). Methods: A multicenter retrospective study in patients with advanced GEPNENs and paired [18F]FDG and [68Ga]Ga-DOTATATE PET/CT no more than 85 d apart was conducted. Patients with discordant disease were identified by the NETPET score, and discordant lesions were contoured with a flat [18F]FDG SUV cutoff of 4. The primary variable of interest was the total discordant volume (TDV), which was the sum of the volumes of discordant lesions. Patients were dichotomized into high- and low-TDV cohorts by the median value. The primary endpoint was overall survival. Results: In total, 44 patients were included (50% men; median age, 60 y), with primary cancers in the pancreas (45%), small bowel (23%), colon (20%), and other (12%). Of the patients, 5% had grade 1 disease, 48% had grade 2 disease, and 48% had grade 3 disease (24% well differentiated, 67% poorly differentiated, 10% unknown within the grade 3 cohort). The overall median survival was 14.1 mo. Overall survival was longer in the low-TDV cohort than in the high-TDV cohort (median volume, 43.7 cm3; survival time, 23.8 mo vs. 9.4 mo; hazard ratio, 0.466 [95% CI, 0.229-0.948]; P = 0.0221). Patients with no more than 2 discordant intrahepatic lesions survived longer than those with 2 or more lesions (31.8 mo vs. 10.2 mo, respectively; hazard ratio, 0.389 [95% CI, 0.194-0.779]; P = 0.0049). Conclusion: TDV is a potential prognostic biomarker in GEPNENs and should be investigated in future neuroendocrine neoplasm trials.

Endoscopic Management of Gastro-Entero-Pancreatic Neuroendocrine Tumours: An Overview of Proposed Resection and Ablation Techniques.

A literature search of MEDLINE/PUBMED was conducted with the aim to highlight current endoscopic management of localised gastro-entero-pancreatic NETs. Relevant articles were identified through a manual search, and reference lists were reviewed for additional articles. The results of the research have been displayed in a narrative fashion to illustrate the actual state-of-the-art of endoscopic techniques in the treatment of NETs. Localised NETs of the stomach, duodenum and rectum can benefit from advanced endoscopic resection techniques (e.g., modified endoscopic mucosal resection, endoscopic full thickness resection, endoscopic submucosal dissection) according to centre expertise. Radiofrequency thermal ablation can be proposed as an alternative to surgery in selected patients with localised pancreatic NETs.

Use and perceived utility of [18 F]FDG PET/CT in neuroendocrine neoplasms: A consensus report from the European Neuroendocrine Tumor Society (ENETS) Advisory Board Meeting 2022.

Somatostatin receptor (SST) PET/CT is the gold standard for well-differentiated neuroendocrine tumours (NET) imaging. Higher grades of neuroendocrine neoplasms (NEN) show preferential [18F]FDG (FDG) uptake, and even low-grade NET may de-differentiate over time. FDG PET/CT's prognostic role is widely accepted; however, its impact on clinical decision-making remains controversial and its use varies widely. A questionnaire-based survey on FDG PET/CT use and perceived decision-making utility in NEN was submitted to the ENETS Advisory Board Meeting attendees (November 2022, response rate = 70%). In 3/15 statements, agreement was higher than 75%: (i) FDG was considered useful in NET, irrespective of grade, in case of mis-matched lesions (detectable on diagnostic CT but negative/faintly positive on SST PET/CT), especially if PRRT is contemplated (80%); (ii) in NET G3 if curative surgery is considered (82%); and (iii) in NEC prior to surgery with curative intent (98%). FDG use in NET G3, even in the presence of matched lesions, as a baseline for response assessment was favoured by 74%. Four statements obtained more than 60% consensus: (i) FDG use in NET G3 if locoregional therapy is considered (65%); (ii) in neuroendocrine carcinoma before initiating active therapy as a baseline for response assessment (61%); (iii) biopsy to re-assess tumour grade prior to a change in therapeutic management (68%) upon detection of FDG-positivity on the background of a prior G1-2 NET; (iv) 67% were in favour to reconsider PRRT to treat residual SST-positive lesions after achieving complete remission on FDG of the SST-negative disease component. Multidisciplinary opinion broadly supports the use of FDG PET/CT for characterisation of disease biology and to guide treatment selection across a range of indications, despite the lack of full consensus in many situations. This may reflect existing clinical access due to lack of reimbursement or experience with this investigation, which should be addressed by further research.

Plasma or serum 5-hydroxyindoleacetic acid can be used interchangeably in patients with neuroendocrine tumours.

5-hydroxyindole acetic acid, a metabolite of serotonin, is used in the diagnosis and monitoring of patients with neuroendocrine tumours, in particular patients with small intestinal neuroendocrine tumours associated with the carcinoid syndrome. Analysis of 5-hydroxyindole acetic acid was commonly performed in urine, but blood-based assays are now becoming available. The objective of this study was to assess how 5-hydroxyindole acetic acid compares in plasma and serum as a biochemical marker of neuroendocrine tumours. Twenty-four-hour urine, plasma and serum samples were obtained from 80 patients with neuroendocrine tumours and 30 healthy volunteers. We developed a liquid chromatography tandem mass spectrometry assay for plasma and serum 5-hydroxyindole acetic acid. Comparison was made between them, and their cut-off was determined using a receiver-operating characteristic curve. A close correlation was shown between plasma and serum 5-hydroxyindole acetic acid. At a cut-off of 135 nmol/l, a sensitivity of 91.2% with a specificity of 61.9% was obtained for both compared to the urinary assay. A statistically significant agreement was shown when plasma and serum 5-hydroxyindole acetic acid were compared with the currently used urine assay in patients with neuroendocrine tumours; κ = 0.675 (95% CI 0.49 to 0.86), p < 0.001 and healthy volunteers; 0.967 (95% CI 0.828 to 0.999), p = <0.001. In conclusion, 5-hydroxyindole acetic acid in plasma and serum were comparable, hence either sample type can be used interchangeably.

Management Strategies and Outcomes for Small Intestinal Neuroendocrine Tumours with Involvement of the Superior Mesenteric Vessels: A Systematic Review.

Small intestinal neuroendocrine tumours (SI-NETs) are the most common small intestinal tumours. A particularly challenging subset of these tumours is those that involve the superior mesenteric artery or vein for which the role and feasibility of surgery are often questioned. This systematic review aimed to identify and evaluate the management strategies used for these complex SI-NETs. The identified studies showed positive outcomes with surgery and multimodality therapy.

Safety and Efficacy of 177 Lu-DOTATATE in Neuroendocrine Tumor Patients With Extensive Bone Disease.

AIM: The aim of this study was to assess the efficacy and safety of 177 Lu-DOTATATE in patients with neuroendocrine tumors (NETs) and extensive bone metastases, that is, more than 50% of the skeleton involved. METHOD: A single-center retrospective analysis was performed in 30 patients (13 women and 17 men, mean age, 60 years; range, 35-77 years) undergoing 177 Lu-DOTATATE therapy. Patients had progressive metastatic NETs with extensive skeletal metastases (>50% skeletal involvement seen on baseline 68 Ga-DOTATATE PET/CT). The average administered activity was 7.308 (SD, 0.02) GBq per cycle with average treatment interval of 15 weeks. Survival analyses (progression-free survival [PFS], overall survival), radiological response assessment, toxicity assessment, and health-related quality of life (QoL) was performed. RESULTS: Overall, 26 patients completed 4 cycles, and 4 patients had less than 4 cycles of 177 Lu-DOTATATE. One patient (3%) did not complete treatment because of hematological toxicity. The estimated median PFS and median overall survival were calculated at 27 and 35 months, respectively. End-of-treatment radiological assessment showed partial response in 5 patients (17%), stable disease in 20 patients (66%), and radiological progressive disease in 3 patients (10%). Clinical progression was seen in a further 2 patients (7%).The incidence of grade 3/4 bone marrow toxicity was 10%. No patient had grade 3/4 peptide receptor radionuclide therapy-related nephrotoxicity. There was overall improvement in global QoL score (European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Gastrointestinal NET-21) ( P = 0.019). CONCLUSION: 177 Lu-DOTATATE seems to have satisfactory therapeutic outcome in patients with advanced metastatic NET with extensive bone disease, with reasonable PFS and significant improvement in the global health-related QoL. The bone marrow toxicity was within the accepted range. Increasing the interval between cycles does not seem to reduce efficacy and may reduce toxicity, ensuring the bone marrow has sufficient time to recover between cycles.

Where Are We Now with Liver Transplantation in Neuroendocrine Neoplasms? The Place of Liver Transplantation for Grades 1 and 2 Well-Differentiated Unresectable Liver Metastatic Neuroendocrine Tumours.

PURPOSE OF REVIEW: This review outlines the role of liver transplantation in selected patients with unresectable neuroendocrine tumour liver metastases. It discusses the international consensus on eligibility criteria and outlines the efforts taking place in the UK and Ireland to develop effective national liver transplant programmes for neuroendocrine tumour patients. RECENT FINDINGS: In the early history of liver transplantation, indications included cancer metastases to the liver as well as primaries of liver origin. Often, liver transplantation was a salvage procedure. The early results were disappointing, including in patients with neuroendocrine tumours. These data discouraged the widespread adoption of liver transplantation for neuroendocrine tumour liver metastases (NET LM). A few centres persisted in performing liver transplantation for patients with NET LM and in determining parameters predictive of good outcomes. Their work has provided evidence for benefit of liver transplantation in a selected group of patients with NET LM. Liver transplantation for NET LM is now accepted as a valid indication by many professional bodies, including the European Neuroendocrine Tumour Society (ENETS) and the United Network for Organ Sharing (UNOS). It is nevertheless rarely utilised. The UK and the Republic of Ireland are commencing a pilot programme of liver transplantation in selected patients. This programme will help develop the expertise and infrastructure to make liver transplantation for NET LM a routine procedure.

Dual [68Ga]DOTATATE and [18F]FDG PET/CT in patients with metastatic gastroenteropancreatic neuroendocrine neoplasms: a multicentre validation of the NETPET score.

BACKGROUND: Gastroenteropancreatic neuroendocrine neoplasms (GEPNENs) are heterogeneous in clinical course, biology, and outcomes. The NETPET score predicts survival by scoring uptake on dual [68Ga]DOTATATE and [18F]FDG PET/CT scans. We aimed to validate previous single-centre findings in a multicentre, international study. METHODS: Dual scans were assigned a NETPET score of P1 (DOTATATE positive/FDG negative), P2-4 (DOTATATE positive/FDG positive), or P5 (DOTATATE negative/FDG positive). NETPET score, histological grade, age at diagnosis, and presence/absence of extrahepatic disease were compared to overall survival/time to progression on univariate and multivariate analysis. RESULTS: 319 metastatic/unresectable GEPNEN patients were included. The NETPET score was significantly associated with overall survival and time to progression on univariate and multivariate analysis (all p < 0.01). Median overall survival/time to progression was 101.8/25.5 months for P1, 46.5/16.7 months for P2-4, and 11.5/6.6 months for P5. Histological grade correlated with overall survival and time to progression on univariate and multivariate analysis (all p < 0.01), while presence/absence of extrahepatic disease did not. Age at diagnosis correlated with overall survival on univariate and multivariate analysis (p < 0.01). The NETPET score also correlated with histological grade (p < 0.001). CONCLUSION: This study validates the NETPET score as a prognostic biomarker in metastatic GEPNENs, capturing the complexity of dual PET imaging.

Single centre retrospective review of outcome of 177 Lu-DOTATATE peptide receptor radionuclide therapy in the treatment of progressive metastatic neuroendocrine tumours: Survival, toxicity, and prognostic factors.

The aim of this study was to evaluate the efficacy and safety of 177 Lu-DOTATATE therapy in advanced metastatic disease. A retrospective analysis of 395 patients (180 female, 215 males, mean age 62) with progressive metastatic neuroendocrine tumours (NETs) who were treated with 177 Lu-DOTATATE was performed. Overall, 115 patients had less than four cycles and 280 completed four cycles of treatment. Progression-free survival (PFS) and overall survival (OS) was performed using Kaplan-Meier analysis. Analysis of survival predictors was performed using Cox regression model. Toxicity was defined using the Common Terminology Criteria for Adverse Events version 5 (CTCAE 5.0). The percentage of patients with liver and skeletal metastases were 91 and 57%, respectively. Median PFS and OS were calculated at 33 months (95% CI: 29-37 months) and 46 months (95% CI: 48-56 months), respectively. End of treatment response assessment was performed using cross sectional imaging demonstrated partial response in 22%, stable disease in 64% and progressive disease in 14% of patients. Overall, grade 3 and 4 bone marrow toxicity was seen in 8%. One patient (0.3%) developed irreversible grade 4 nephrotoxicity. Myelodysplastic disease was recorded in one patient (0.3%). Univariate analysis of PFS predictors showed that body mass index (BMI), baseline chromogranin A (CgA) >400 ng/l, baseline alkaline phosphatase (ALP) >130 mg/dl, liver tumour volume and overall tumour burden were significant. On multivariate analysis only Ki67, high CgA and low BMI retained significance. 177 Lu-DOTATATE is an effective treatment in advanced NETs with generally high-volume metastases. It is well-tolerated. Ki-67, CgA and BMI appear to be predictors for PFS.

Diagnostic features and management options for duodenal neuroendocrine neoplasms: a retrospective, multi-centre study.

Duodenal neuroendocrine neoplasms (dNENs) are rare neoplasms but their incidence is on the rise. They are classified into 5 sub-types but there remains much heterogeneity in behaviour in particular of non-functioning dNENs. To retrospectively analyse outcomes for all types of dNENs, and highlight prognostic factors associated with worse outcome. 102 (57 m/45f.) patients were identified with mean age at diagnosis 62 (range 32-87) years. The majority were non-functioning tumours 87/102 and median size was 10 mm (range 0.9-130 mm). 83 patients had Stage I or II disease, of which 17 underwent endoscopic resection with R1 rate of 45% and complication rate 12%. 36 patients were kept under endoscopic surveillance. There were 11 deaths of which 4 were disease related. Age and Ki67 > 20% were associated with worse OS in all dNENs. In non-functioning dNENs Ki67 > 3% was a predictor of lymph nodes metastases with OR 18.2 (2.54-13) (p < 0.005) in univariate analyses and liver metastases with OR 6.79 (1.56-29.5) (p < 0.05) in the multivariate analysis. Lesions 11-20 mm in size had OR 11.1 (1.16-106) compared to lesions < 11 mm for the prediction of lymph node metastases in the multivariate analysis (p < 0.05). ROC analysis of size of non-functioning dNENs to predict LN metastases found < 15 mm had an AUROC of 0.9 (0.81-0.99) with a sensitivity of 85% and specificity of 88%. dNENs are increasing in incidence, however low grade and smaller lesions have an indolent course and the role of endoscopic resection and active surveillance needs to be reviewed.

Insulinoma: a quarter century of dietary control.

Summary: Insulinomas are rare pancreatic neuroendocrine neoplasms (NENs) that are typically sporadic and solitary, with the majority being <2 cm in diameter at diagnosis. The median duration of symptoms before diagnosis is variable; however, this is usually in the region of 12-18 months. We report on an insulinoma diagnosed some 25 years following initial symptoms, having by that stage attained a diameter of 4 cm. We present a 50-year-old man who was reported with hypoglycaemic symptoms on his wedding 25 years prior to eventual confirmation of an insulinoma. He had since learned to live with the symptoms by eating frequently to manage his hypoglycaemia. However, over recent months, he reported a substantial deterioration in his symptoms, and indeed, had collapsed on two occasions. He had a fasting glucose of 2.9 mmol/L with grossly inappropriate elevated insulin and C-peptide levels. MRI demonstrated a 4.1 cm lesion at the body of pancreas and an indeterminate 9-mm liver lesion with a negative 68Gallium-DOTATATE PET scan. Accordingly, he was initiated on diazoxide and referred to the surgical team for distal pancreatectomy: histology confirmed a 4.4-cm well-differentiated pancreatic NEN of intermediate grade (NEN G2, Grade 2, 2017 World Health Organization (WHO) pancreatic-NEN classification), with positive immunohistochemistry for insulin. His hypoglycaemia episodes have ceased, and he remains under active surveillance. Our case demonstrates the possibility of dietary control of insulinoma-induced hypoglycaemia, and the likelihood that such a prolonged delay in diagnosis has led to the uncommonly large size of the apparently benign tumour which is usually 'small and indolent'. Learning points: Most patients with insulinomas have lesions that are 1-2 cm in size, with 96% being less than 3 cm. The mean tumour size of insulinomas found in 3 of the largest reported series was 1.5 cm, with a range of 0.1-7.0 cm. It is not uncommon for patients to have symptoms for several months to years before diagnosis; however, no reported cases had the symptoms such long for 25 years, and the large size of the tumour in this case may reflect the very long history.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH): Prevalence, clinicopathological characteristics and survival outcome in a cohort of 311 patients with well-differentiated lung neuroendocrine tumours.

INTRODUCTION: Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is considered to be a rare condition associated with lung neuroendocrine tumours (NET), and its natural history is poorly described. We aimed to assess the prevalence and clinicopathologic characteristics of DIPNECH in the lung NET population, and to investigate predictors of time-to-progression (TTP) and overall survival (OS). METHODS: We retrospectively identified patients diagnosed with DIPNECH between April 2005 and December 2020. Clinical data were collected from medical records. The relationship between baseline characteristics and TTP and OS was analysed using the Kaplan-Meier method. Univariate analysis was performed using the Cox proportional hazards model. RESULTS: Of 311 patients with well-differentiated lung NETs, 61 (20%) had DIPNECH and were included in the study. Baseline demographics described 95% female, 59% never smokers and mean body mass index 34.4 kg m-2 ; 77% were typical carcinoids (TC), 13% atypical carcinoids (AC), and 10% both TC and AC (multicentric). At presentation, 54% of patients were asymptomatic. Multicentric NETs were demonstrated in 16 (26%) on histopathology, and a further 32 (52%) had synchronous NETs suggested on imaging (multiple nodules ≥ 5 mm). Seven (11%) patients developed metastases and the median OS from time of first metastasis was 37 months. AC histopathology and NET TNM stage ≥ IIA were associated with poorer TTP and OS. Of the DIPNECH cohort, the 15-year survival rate was 86%. CONCLUSIONS: DIPNECH may be more prevalent in the lung NET population than previously appreciated, especially in women. Although our results confirm that DIPNECH is predominantly an indolent disease associated with TC, 23% developed AC and these patients may warrant closer observation.

The impact of COVID-19 on the management of neuroendocrine tumors (NETS): An international NET CONNECT survey of NET patients and healthcare professionals treating net patients.

The COVID-19 outbreak has added complexity in the management of patients with neuroendocrine tumors (NETs). Little information is currently available regarding the real impact of the pandemic in current practice. The present study aimed to capture patients' and healthcare professionals' experiences on how the NET management has changed during the pandemic and how it should be modified in a foreseeable post-pandemic environment. Physicians and nurses working in ENETS Centers of Excellence or other hospitals with high volume of NET patients (n = 48), as well as NET patients residing worldwide (n = 353), were asked to respond to two online anonymous surveys addressing different aspects of NET care. Deferred diagnoses, delayed surveillance procedures and postponed elective surgeries were among the main negative consequences of the COVID-19 outbreak according to 40%, 54% and 46% of healthcare professionals (HPs) respectively. Somatostatin analogs were increasingly used as bridging strategy for delaying surgery based on the views of 31% of HPs and were self-injected or delivered by home care services more frequently than before the initiation of the pandemic (53% of patients during the pandemic vs. 44% before the pandemic). Multidisciplinary tumor boards kept their usual schedule according to 58% of HPs, but were held virtually in the 77% of cases. The contact with healthcare professionals was maintained by remote methods more often than in the past (69% of patients), but only 34% of patients (59% among subjects < 41 years) would prefer telemedicine to face-to-face consultations in the future. New health policy measures should guarantee the highest standard of treatment to NET patients, regardless of the trajectory followed by the COVID-19 pandemic in the next months. Pros and cons of telemedicine should be carefully weighted before systematic implementation.

The Role of Diet and Supplements in the Prevention and Progression of COVID-19: Current Knowledge and Open Issues.

A healthy diet and dietary supplements have gained attention as potential co-adjuvants in managing and preventing coronavirus disease 2019 (COVID-19). This paper critically reviews the current evidence regarding the impact of diet and supplements on the prevention and progression of COVID-19. According to available data, a healthy diet and normal weight are considered protective factors. Regarding dietary supplementation, the most robust results from human studies are for vitamin C, which appears to decrease inflammatory markers and suppress cytokine storm. A small, randomized trial showed that a high dose of vitamin D significantly reduced the need for intensive care unit treatment of patients requiring hospitalization for COVID-19. According to retrospective human studies, there is limited evidence for vitamin E and selenium supplements. Animal studies have investigated the effects of green tea and curcumin. Xanthohumol and probiotics, interesting for their antiviral, anti-inflammatory, and immunoregulatory properties, need formal clinical study. In summary, there is promising evidence supporting the role of diet and supplements as co-adjuvants in the treatment of COVID-19. Further studies and properly designed clinical trials are necessary to draw more robust conclusions; however, it is not unreasonable to take a pragmatic approach and promote the use of appropriate diet and supplements to counter the effects of COVID-19, ideally with a mechanism to assess outcomes.

What Causes Desmoplastic Reaction in Small Intestinal Neuroendocrine Neoplasms?

PURPOSE OF REVIEW: Mesenteric desmoplasia in small intestinal neuroendocrine neoplasms (SINENs) is associated with increased morbidity and mortality. In this paper, we discuss the development of desmoplasia in SINENs. RECENT FINDINGS: The fibrotic reactions associated with these tumours could be limited to the loco-regional environment of the tumour and/or at distant sites. Mesenteric fibrotic mass forms around a local lymph node. Formation of desmoplasia is mediated by interactions between the neoplastic cells and its microenvironment via number of profibrotic mediators and signalling pathways. Profibrotic molecules that are mainly involved in the desmoplastic reaction include serotonin, TGFß (transforming growth factor ß) and CTGF (connective tissue growth factor), although there is some evidence to suggest that there are a number of other molecules involved in this process. Desmoplasia is a result of autocrine and paracrine effects of multiple molecules and signalling pathways. However, more research is needed to understand these mechanisms and to develop targeted therapy to minimise desmoplasia.

Systematic Evaluation of the Immune Environment of Small Intestinal Neuroendocrine Tumors.

PURPOSE: The immune tumor microenvironment and the potential therapeutic opportunities for immunotherapy in small intestinal neuroendocrine tumors (siNET) have not been fully defined. EXPERIMENTAL DESIGN: Herein, we studied 40 patients with primary and synchronous metastatic siNETs, and matched blood and normal tissue obtained during surgery. We interrogated the immune checkpoint landscape using multi-parametric flow cytometry. In addition, matched FFPE tissue was obtained for multi-parametric IHC to determine the relative abundance and distribution of T-cell infiltrate. Tumor mutational burden (TMB) was also assessed and correlated with immune infiltration. RESULTS: Effector tumor-infiltrating lymphocytes (TIL) had a higher expression of PD-1 in the tumor microenvironment compared with the periphery. In addition, CD8+ TILs had a significantly higher co-expression of PD-1/ICOS and PD-1/CTLA-4 (cytotoxic T lymphocyte antigen-4) and higher levels of PD-1 expression compared with normal tissue. IHC revealed that the majority of cases have ≤10% intra-tumoral T cells but a higher number of peri-tumoral T cells, demonstrating an "exclusion" phenotype. Finally, we confirmed that siNETs have a low TMB compared with other tumor types in the TCGA database but did not find a correlation between TMB and CD8/Treg ratio. CONCLUSIONS: Taken together, these results suggest that a combination therapy approach will be required to enhance the immune response, using PD-1 as a checkpoint immunomodulator backbone in combination with other checkpoint targeting molecules (CTLA-4 or ICOS), or with drugs targeting other pathways to recruit "excluded" T cells into the tumor microenvironment to treat patients with siNETs.