The relationship between tumour dosimetry, response, and overall survival in patients with unresectable Neuroendocrine Neoplasms (NEN) treated with 177Lu DOTATATE (LuTate).

Peptide Receptor Radionuclide Therapy (PRRT) delivers targeted radiation to Somatostatin Receptor (SSR) expressing Neuroendocrine Neoplasms (NEN). We sought to assess the predictive and prognostic implications of tumour dosimetry with respect to response by 68 Ga DOTATATE (GaTate) PET/CT molecular imaging tumour volume of SSR (MITVSSR) change and RECIST 1.1, and overall survival (OS). METHODS: Patients with gastro-entero-pancreatic (GEP) NEN who received LuTate followed by quantitative SPECT/CT (Q-SPECT/CT) the next day (Jul 2010 to Jan 2019) were retrospectively reviewed. Single time-point (STP) lesional dosimetry was performed for each cycle using population-based pharmacokinetic modelling. MITVSSR and RECIST 1.1 were measured at 3-months post PRRT. RESULTS: Median of 4 PRRT cycles were administered to 90 patients (range 2-5 cycles; mean 27.4 GBq cumulative activity; mean 7.6 GBq per cycle). 68% received at least one cycle with radiosensitising chemotherapy (RSC). RECIST 1.1 partial response was 24%, with 70% stable and 7% progressive disease. Cycle 1 radiation dose in measurable lesions was associated with local response (odds ratio 1.5 per 50 Gy [95% CI: 1.1-2.0], p = 0.002) when adjusted by tumour grade and RSC. Median change in MITVSSR was -63% (interquartile range -84 to -29), with no correlation with radiation dose to the most avid lesion on univariable or multivariant analyses (5.6 per 10 Gy [95% CI: -1.6, 12.8], p = 0.133). OS at 5-years was 68% (95% CI: 56-78%). Neither baseline MITVSSR (hazard ratio 1.1 [95% CI: 1.0, 1.2], p = 0.128) nor change in baseline MITVSSR (hazard ratio 1.0 [95% CI: 1.0, 1.1], p = 0.223) were associated with OS when adjusted by tumour grade and RSC but RSC was (95% CI: 0.2, 0.8, p = 0.012). CONCLUSION: Radiation dose to tumour during PRRT was predictive of radiologic response but not survival. Survival outcomes may relate to other biological factors. There was no evidence that MITVSSR change was associated with OS, but a larger study is needed.

Investigation of receptor radionuclide therapy with 177Lu-DOTATATE in patients with GEP-NEN and a high Ki-67 proliferation index.

PURPOSE: In the 2010 WHO classification, a Ki-67 proliferation index of 20% is the cut-off between intermediate-grade and high-grade gastroenteropancreatic neuroendocrine neoplasia (GEP-NEN). However, in clinical practice, tumours with a Ki-67 index of >15% are often considered high grade and treated with chemotherapy. In 40-70% of high-grade NENs, somatostatin receptors are overexpressed, enabling peptide receptor radionuclide therapy (PRRT) to be performed. We investigated the role of PRRT with 177Lu-DOTATATE in patients with GEP-NEN and a high Ki-67 proliferation index. METHODS: A total of 33 patients with advanced GEP-NENs, positive somatostatin receptor imaging (SRI+) and a Ki-67 proliferation index ranging from 15% to 70% were treated with Lu-PRRT. A cumulative activity of 18.5 GBq or 27.8 GBq of 177Lu-DOTATATE was administered in four or five cycles. Receiver operating characteristic (ROC) curve analysis was used to determine the best threshold of Ki-67 expression to predict disease progression. RESULTS: All patients completed the intended treatment. The median follow-up was 43 months (range 3-69 months). Two patients (6%) achieved a partial response and 21 (64%) showed stable disease, giving a disease control rate (DCR) of 70%. The median progression-free survival (PFS) was 23 months (95% CI 14.9-31.0 months) and the median overall survival was 52.9 months (95% CI 17.1-68.9 months). ROC curve analysis at 23 months revealed that the best Ki-67 index cut-off was 35%. In 23 patients (70%) the Ki-67 index was ≤35% and in 10 patients (30%) the Ki-67 index was in the range 36-70%. The DCR in the former group was 87% and 30% in the latter. The median PFS was 26.3 months (95% CI 18.4-37.7 months) and 6.8 months (95% CI 2.1-27 months), respectively (p = 0.005). CONCLUSIONS: Lu-PRRT showed antitumour activity in SRI+ GEP-NENs of intermediate and high-grade. DCR and PFS were significantly better in patients with a Ki-67 index of ≤35% than in those with a Ki-67 index of >35%. On the basis of these results, PRRT should be considered as a therapeutic option in patients with high-grade SRI+ GEP-NENs, in particular those with a Ki-67 proliferation index of ≤35%.

Hormone secreting gastro-entero-pancreatic neuroendocrine neoplasias (GEP-NEN): When to consider, how to diagnose?

Neuroendocrine neoplasms of the digestive system (GEP-NEN) represent a heterogeneous group of malignancies with various clinical presentation and prognosis. GEP-NENs can potentially affect all organs of the gastrointestinal tract; characteristically they share the biological property to produce and secrete peptides and neuroamines. About 30% of GEP-NENs are hormonally active and can cause specific clinical syndromes. The clinical presentation mainly depends on the primary site of the tumor and its functionality. Because of the wide spectrum of clinical symptoms and their misperceived rarity, diagnosis of GEP-NENs is often delayed for years and tumors are detected first in an advanced stage. Early identification of a specific hormonal syndrome can significantly impact tumor diagnosis and treatment, moreover the preoperative management of NEN hormonal release avoids potential life threatening hormonal crisis. However, GEP-NEN diagnostic work-up is challenging, it requires a multidisciplinary team and needs particular experience; standardized protocols and clinical experience are essential for a proper endocrine diagnostic work-up. In addition to the biochemical diagnostic, further radiologic and endoscopic imaging modalities are required moreover, somatostatin-receptor based functional imaging, using either Octreotide-scintigraphy or novel PET-based techniques with specific isotopes like Ga68-DOTA-octreotate, plays an important role for the detection of the primary tumor as well as for the evaluation of the tumor extent.

Clinicopathological features and survival analysis of gastroenteropancreatic neuroendocrine neoplasms: a retrospective study in a single center of China.

OBJECTIVE: To investigate the clinicopathological features, survival and prognostic factors for gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) in a Chinese population. METHODS: We investigated 154 consecutive patients (88 males, 66 females; median age 56 years, age range 9-86 years) diagnosed with GEP-NENs between 2001 and 2013 at The Affiliated Hospital of Qingdao University. Demographic, clinical and pathological variables and survival data were retrieved. RESULTS: The pancreas was the most common site of involvement (63/154, 40.9%). Tumor size varied from 0.3 to 16.0 cm (median, 1.2 cm). The patients were followed up for a median period of 22 months (range, 1-157 months). The estimated 3- and 5-year overall survival (OS) rates for all patients were 84.0% and 81.9%, respectively. Multivariate analysis showed that larger tumor size, lymphatic metastases and distant metastases were significant predictors for poor survival outcome. CONCLUSIONS: Our data provide further information on the clinicopathological features of GEP-NENs in China. Additionally, we identified tumor size, lymphatic metastases and distant metastases as independent prognostic factors for long-term survival.

Expression and clinical value of CXCR4 in high grade gastroenteropancreatic neuroendocrine neoplasms.

Background: CXC chemokine receptor 4 (CXCR4) is associated with the progression and metastasis of numerous malignant tumors. However, its relationship with Gastroenteropancreatic Neuroendocrine Neoplasms Grade 3 (GEP-NENs G3) is unclear. The aim of this study was to characterize the expression of CXCR4 in GEP-NENS and to explore the clinical and prognostic value of CXCR4. Methods: This study retrospectively collected clinical and pathological data from patients with GEP-NENs who receiving surgery in Qilu Hospital of Shandong University from January 2013 to April 2021, and obtained the overall survival of the patients based on follow-up. Immunohistochemistry (IHC) was performed on pathological paraffin sections to observe CXCR4 staining. Groups were made according to pathological findings. Kaplan-Meier (K-M) curve was used to evaluate prognosis. SPSS 26.0 was used for statistical analysis. Results: 100 GEP-NENs G3 patients were enrolled in this study. There was a significant difference in primary sites (P=0.002), Ki-67 index (P<0.001), and Carcinoembryonic Antigen (CEA) elevation (P=0.008) between neuroendocrine tumor (NET) G3 and neuroendocrine carcinoma (NEC). CXCR4 was highly expressed only in tumors, low or no expressed in adjacent tissues (P<0.001). The expression level of CXCR4 in NEC was significantly higher than that in NET G3 (P=0.038). The K-M curves showed that there was no significant difference in overall survival between patients with high CXCR4 expression and patients with low CXCR4 expression, either in GEP-NEN G3 or NEC (P=0.920, P=0.842. respectively). Conclusion: Differential expression of CXCR4 was found between tumor and adjacent tissues and between NET G3 and NEC. Our results demonstrated that CXCR4 can be served as a new IHC diagnostic indicator in the diagnosis and differential diagnosis of GEP-NENs G3. Further studies with multi-center, large sample size and longer follow-up are needed to confirm the correlation between CXCR4 expression level and prognosis.

Intratumoral dendritic cells and T cells predict survival in gastroenteropancreatic neuroendocrine neoplasms.

Clinical management of gastroenteropancreatic neuroendocrine neoplasms remains challenging. We recently introduced the FMS-like tyrosine kinase 3 ligand (FLT3LG) as a possible biomarker for a proinflammatory tumor microenvironment. Here, we put a spotlight on the quantitative assessment of classical dendritic cells (cDC) and T cells in the context of FLT3LG mRNA levels in a retrospective study on neuroendocrine tumor (NET) G2/G3 and neuroendocrine carcinoma (NEC) of pancreatic and gastric origin. The abundance of cDC and T cells and their relevant subpopulations were determined by immunofluorescent staining and correlated with FLT3LG mRNA levels as well as clinical outcomes. Immune cell counts attested to highly variable infiltration densities. Samples with the presence of cDC or high numbers of T cells exhibited increased FLT3LG expression. Abundance of cDC, defined as HLA-DR+CD11c+ cells with CLEC9a (cDC1) or CD1c (cDC2), as well as T cells correlated with FLT3LG mRNA levels and predicted disease-specific survival. Combining FLT3LG and T cell counts further improved this prediction. Therefore, tumor-infiltrating cDC and T cells are prognostic markers in NET G2/G3 or NEC and FLT3LG mRNA may serve as a simple-to-use biomarker for a quantitative estimate of their abundance, mandating prospective evaluation in the context of immune-targeted therapies.

Germline pathogenic variants in patients with high-grade gastroenteropancreatic neuroendocrine neoplasms.

High-grade gastroenteropancreatic (HG-GEP) neuroendocrine neoplasms (NENs) are highly aggressive cancers. The molecular etiology of these tumors remains unclear, and the prevalence of pathogenic germline variants in patients with HG-GEP NENs is unknown. We assessed sequencing data of 360 cancer genes in normal tissue from 240 patients with HG-GEP NENs; 198 patients with neuroendocrine carcinomas (NECs) and 42 with grade 3 neuroendocrine tumors (NET G3). Applying strict criteria, we identified pathogenic germline variants and compared the frequency with previously reported data from 33 different cancer types. We found a recurrent MYOC variant in three patients and a recurrent MUTYH variant in two patients, indicating that these genes may be important underlying risk factors for HG-GEP NENs when mutated. Further, germline variants were found in canonical tumor-suppressor genes, such as TP53, RB1, BRIP1 and BAP1. Overall, we found that 4.5% of patients with NEC and 9.5% of patients with NET G3 carry germline pathogenic or highly likely pathogenic variants. Applying identical criteria for variant classification in silico to mined data from 33 other cancer types, the median percentage of patients carrying pathogenic or highly likely pathogenic variants was 3.4% (range: 0-17%). The patients with NEC and pathogenic germline variants had a median overall survival of 9 months, similar to what is generally expected for metastatic GEP NECs. A patient with NET G3 and pathogenic MUTYH variant had much shorter overall survival than expected. The fraction of HG-GEP NENs with germline pathogenic variants is relatively high, but still <10%, meaning that that germline mutations cannot be the major underlying cause of HG-GEP NENs.

Tumor mutation burden in gastro-entero-pancreatic-neuroendocrine neoplasms.

Background: As rare tumors, there are limited treatment options for neuroendocrine neoplasms (NENs). Recently, microsatellite instability (MSI) and tumor mutation burden (TMB) have been emerging as potential biomarkers in various tumors. However, there is a lack of research on the use of these biomarkers in gastro-entero-pancreatic (GEP)-NENs. Methods: We analyzed 31 patients diagnosed with GEP-NEN between 2013 to 2022. The TMB and MSI analyses using next-generation sequencing (NGS) were performed for all patients. The TruSightTM Oncology 500 assay from Illumina was used as the NGS panel. Results: Out of the 31 patients analyzed, the most frequent primary origin was the pancreas (12 patients, 38.7%), followed by the stomach (4 patients, 12.9%), gallbladder (4 patients, 12.9%), rectum (7 patients, 22.6%), small bowel (2 patients, 6.5%), and bile duct (1 patient, 3.2%). Among these patients, 19 (61.3%) were diagnosed with well-differentiated neuroendocrine tumors, with grade 2 being the most common (15 patients, 48.4%), followed by grade 3 (3 patients, 9.7%) and grade 1 (1 patient, 3.2%). Neuroendocrine carcinoma was confirmed in 12 patients (38.7%). The median number of metastases was 2.0 [interquartile range (IQR), 1.0-3.0], and the liver was the most common site of metastasis (23 patients, 74.2%). The median TMB was 4.7 (IQR, 3.1-6.3) mutations/Mb, and all tumors were classified as microsatellite stability (MSS). Only one patient had a high TMB (266.4 mutations/Mb), which was a grade 3 neuroendocrine tumor originating from the pancreas. The TMB value did not vary depending on the primary tumor site or World Health Organization (WHO) grade. Conclusions: This analysis showed that, despite very low incidence, there are GEP-NENs with high TMB. For precision medicine, testing for MSI and TMB is needed for this tumor type.

The Glasgow Prognostic Score Predicts Survival Outcomes in Neuroendocrine Neoplasms of the Gastro-Entero-Pancreatic (GEP-NEN) System.

Background: Across a variety of solid tumors, prognostic implications of nutritional and inflammation-based risk scores have been identified as a complementary resource of risk stratification. Methods: In this retrospective study, we performed a comparative analysis of several established risk scores and ratios, such as the Glasgow Prognostic Score (GPS), in neuroendocrine neoplasms of the gastro−entero−pancreatic (GEP-NEN) system with respect to their prognostic capabilities. Clinicopathological and treatment-related data for 102 GEP-NEN patients administered to the participating institutions between 2011 and 2021 were collected. Scores/ratios significantly associated with overall or progression-free survival (OS, PFS) upon univariate analysis were subsequently included in a Cox-proportional hazard model for the multivariate analysis. Results: The median age was 62 years (range 18−95 years) and the median follow-up period spanned 51 months. Pancreatic or intestinal localization at the initial diagnosis were present in 41 (40.2%) and 44 (43.1%) cases, respectively. In 17 patients (16.7%), the primary manifestation could not be ascertained (NNUP; neuroendocrine neoplasms of unknown primary). Histological grading (HG) revealed 24/102 (23.5%) NET/NEC (poorly differentiated; high grade G3) and 78/102 (76.5%) NET (highly or moderately differentiated; low−high grade G1−G2). In total, 53/102 (51.9%) patients presented with metastatic disease (UICC IV), 11/102 (10.7%) patients presented with multifocal disease, and 56/102 (54.9%) patients underwent a primary surgical or endoscopic approach, whereas 28 (27.5%) patients received systemic cytoreductive treatment. The univariate analysis revealed the GPS and PI (prognostic index), as well as UICC-stage IV, HG, and the Charlson comorbidity index (CCI) to predict both the PFS and OS in GEP-NEN patients. However, the calculation of the survival did not separate GPS subgroups at lower risk (GPS 0 versus GPS 1). Upon the subsequent multivariate analysis, GPS was the only independent predictor of both OS (p < 0.0001; HR = 3.459, 95% CI = 1.263−6.322) and PFS (p < 0.003; HR = 2.119, 95% CI = 0.944−4.265). Conclusion: In line with previous results for other entities, the present study revealed the GPS at baseline to be the only independent predictor of survival across all stages of GEP-NEN, and thus supports its clinical utility for risk stratification in this group of patients.

Nuclear survivin is a prognosticator in gastroenteropancreatic neuroendocrine neoplasms: a meta-analysis.

PURPOSE: Gastroenteropancreatic neuroendocrine neosplasms (GEP-NEN) are biologically heterogenous tumors with an increasing incidence over the past decades. Although efforts have been made in the treatment of these tumors, survival rates in metastasized tumor stages remain frustrating. Thus, there is an urgent need to identify novel targets as alternative treatment options. In this regard, the inhibitor of apoptosis protein (IAP) family member survivin could be such an attractive target. Therefore, aim of our meta-analysis was to assess the role of survivin as a biomarker and predictor in GEP-NEN. METHODS: Medline, Web of Science and Scopus were screened for studies that fulfilled our selection criteria. Quality assessement of the studies was based on design, methodology, generalizability and results analysis. Meta-analyses were conducted using a random-effects model and effect size measures were expressed as pooled Hazard Ratio (HR) or Odds Ratio (OR) with 95% Confidence Interval (CI). RESULTS: Six eligible studies with 649 patients (range 77-132) assessed survivin expression in GEP-NEN by immunohistochemistry. High expression levels of nuclear survivin in GEP-NEN correlated with a shorter overall survival (HR 3.10; 95% CI 2.15-4.47; p < 0.0001). In contrast to cytoplasmic survivin (OR 1.24; CI 0.59-2.57; p = 0.57), nuclear survivin was also associated (OR 15.23; CI 3.61-64.23; p = 0.0002) with G3/poorly differentiated GEP-NEN. CONCLUSION: Nuclear Survivin is highly expressed in more aggressive G3 GEP-NEN and correlates with a poor outcome. Survivin is therefore an interesting molecule for a targeted therapy, especially for patients with highly proliferative G3 GEP-NENs.

The overriding role of surgery and tumor grade for long-term survival in patients with gastroenteropancreatic neuroendocrine neoplasms: A population-based cohort study.

BACKGROUND: Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) comprise a heterogeneous disease group. Factors that affect long-term survival remain uncertain. Complete population-representative cohorts with long-term follow-up are scarce. AIM: To evaluate factors of importance for the long-term survival. METHODS AND RESULTS: An Observational population-based study on consecutive GEP-NEN patients diagnosed from 2003 to 2013, managed according to national guidelines. Univariable and multivariable survival analyses were performed to evaluate overall survival (OS) and to identify independent prognostic factors. One hundred ninety eligible patients (males, 58.9%) (median age, 60.0 years; range, 10.0-94.2 years) were included. The small bowel, appendix, and pancreas were the most common tumor locations. The World Health Organization (WHO) tumor grade 1-3 distributions varied according to the primary location and disease stage. Primary surgery with curative intent was performed in 66% of the patients. The median OS of the study population was 183 months with 5- and 10-year OS rates of 66% and 57%, respectively. Only age, WHO tumor grade, and primary surgical treatment were independent prognostic factors for OS. CONCLUSION: The outcomes of GEP-NEN patients are related to several factors including age and primary surgical treatment. WHO tumor grading, based on the established criteria, should be routine in clinical practice. This may improve clinical decision-making and allow the comparison of outcomes among different centers.

Insulinoma-associated protein 1(INSM1) is a superior marker for the diagnosis of gastroenteropancreatic neuroendoerine neoplasms: a meta-analysis.

PURPOSE: An increasing number of studies have shown that insulinoma-associated protein 1 (INSM1) is a robust marker for the diagnosis of gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN). The overall diagnostic accuracy of INSM1 for GEP-NEN remains unclear. The purpose of this study is to estimate the diagnostic value of INSM1 for GEP-NEN through a meta-analysis. METHODS: We searched relevant studies addressing the accuracy of INSM1 in the diagnosis of GEP-NEN from PubMed, Web of Science, Embase, Cochrane Library and China National Knowledge Infrastructure (CNKI) as well as from reference lists since the establishment of the database to January 12, 2021. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curves were used to comprehensively evaluate the diagnostic value of INSM1 for GEP-NEN. Statistical analysis was performed by Stata 15.0 and RevMan 5.4. RESULTS: Nine studies with a total of 393 patients were included in the meta-analysis. The meta-analysis results showed that the pooled sensitivity and specificity of INSM1 for the diagnosis of GEP-NEN were 0.99 (95% CI: 0.87-1.00) and 0.96 (95% CI: 0.93-0.98), respectively. The PLR and NLR were 23.3 (95% CI: 13.3-40.8) and 0.01 (95% CI: 0.00-0.14), respectively. The DOR was 380.31 (95% CI: 164.14-881.21), and the area under the curve (AUC) of SROC curve was 0.98 (95% CI: 0.96-0.99). CONCLUSIONS: The results show that INSM1 is an effective marker for the diagnosis of GEP-NEN with high sensitivity and specificity. INSM1 is recommended for clinical application to improve the diagnostic accuracy of GEP-NEN. However, more high-quality studies are needed to confirm these findings.

Diagnostic and Predictive Role of DLL3 Expression in Gastroenteropancreatic Neuroendocrine Neoplasms.

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are a rare and heterogeneous subgroup of tumors with a challenging management because of their extremely variable biological and clinical behaviors. Due to their different prognosis, there is an urgent need to identify molecular markers which would enable to discriminate between grade 3 neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs), despite both being diagnosed mainly on the basis of proliferation index and cell differentiation. DLL3, a negative Notch regulator, is a promising molecular target highly expressed in several tumors with neuroendocrine features. We conducted a retrospective analysis of DLL3, RB1, and PD-L1 expression by immunohistochemistry (IHC), in formalin-fixed, paraffin-embedded (FFPE) samples from 47 patients with GEP-NENs. Then, we correlated the results with patients' clinical features and outcome. The absence of DLL3 expression in 5 well-differentiated GEP-NETs with high-grade features (G3 NET), and the presence of DLL3 in 76.9% of poorly-differentiated NECs (G3 NEC), highlights DLL3 expression as a marker of G3 NECs (p = 0.007). DLL3 expression was correlated with RB1-loss (p < 0.001), negative 68 Ga-PET/CT scan (p = 0.001), and an unfavorable clinical outcome, with important implications for treatment response and patient's follow-up. Median progression-free survival (PFS) and overall survival (OS) were 22.7 months (95% CI 6.1-68.8) and 68.8 months (95% CI 26.0-78.1), respectively, in patients with DLL3-negative tumor compared with 5.2 months (95% CI 2.5-18.5) and 9.5 months (95% CI 2.5-25.2), respectively, in patients with DLL3-positive tumor (PFS p = 0.0083, OS p = 0.0071). Therefore, combined with morphological cell analysis, DLL3 could represent a valuable histological marker, for the diagnosis of poorly differentiated NECs. The high percentage of DLL3 expression in NEC patients also highlights a potential opportunity for a DLL3 targeted therapy in this tumor subset.

Pathological Findings of the Host Immune Reaction in the Tumor Microenvironment of Gastroenteropancreatic Neuroendocrine Neoplasms.

Objective Neuroendocrine neoplasms (NENs) are rare and indolent diseases, but the efficacy of treatment without surgical resection is temporary and limited. Targeted immunotherapy is an important treatment strategy in several cancers. However, the tumor and host immune reactions in the NEN microenvironment are poorly understood. Therefore, we investigated the immune checkpoint system and host immune response in pathological NEN specimens. Methods The expression of the mismatch repair proteins MSH2, MSH6, PMS2, and MLH1 was immunohistochemically detected in archival tissue samples obtained from 20 patients with gastroenteropancreatic NENs. We additionally assessed the expression of programmed death (PD)-1, PD-L1, and the tumor-infiltrating lymphocyte (TIL) markers CD8 and family of transcription factor P3 (FOXP3). Results All 20 NENs expressed the mismatch repair proteins MSH2, MSH6, PMS2, and MLH1. The PD-L1 and/or PD-1 expression in the tumor cells and/or TILs was confirmed in 75% of the cases. PD-1-, CD8-, and FOXP3-positive TILs were more frequently associated with PD-L1-positive tumors than with PD-L1 negative tumors (PD-1: 19.5 vs. 7.3, CD8: 18.1 vs. 7.1, FOXP3: 13.2 vs. 3.2, p=0.438, p=0.419, P=0.603, respectively). The number of cells positive for PD-1 tended to gradually increase in increasing grade of NENs but did not reach significance (Grade 1: 5.8, Grade 2: 10.2, NEC: 18.1, p=0.903). Conclusion NENs consistently express mismatch repair proteins but have a high expression of PD-L1 and/or PD-1 in the tumor microenvironment. NEC and PD-L1-positive NENs may be immunologically "hot" tumors, so an immunological approach may be an appropriate treatment strategy for these tumors.

Prognostic features of gastro-entero-pancreatic neuroendocrine neoplasms in primary and metastatic sites: Grade, mesenteric tumour deposits and emerging novelties.

Updates in classification of gastro-entero-pancreatic neuroendocrine neoplasms better reflect the biological characteristics of these tumours. In the present study, we analysed the characteristics of neuroendocrine tumours that could aid in a more precise stratification of risk groups. In addition, we have highlighted the importance of grade (re)assessment based on investigation of secondary tumour lesions. Two hundred and sixty-four cases of neuroendocrine tumours of gastro-entero-pancreatic origin from three centres were included in the study. Tumour morphology, mitotic count and Ki67 labelling index were evaluated in specimens of primary tumours, lymph node metastases and distant metastases. These variables were correlated with overall survival (OS) and relapse-free survival (RFS). Tumour stage, number of affected lymph nodes, presence of tumour deposits and synchronous/metachronous metastases were tested as possible prognostic features. Mitotic count, Ki-67 labelling index, primary tumour site, tumour stage, presence of tumour deposits and two or more affected lymph nodes were significant predictors of OS and RFS. At the same time, mitotic count and Ki-67 labelling index can be addressed as continuous variables determining prognosis. We observed a very high correlation between the measures of proliferative activity in primary and secondary tumour foci. The presence of isolated tumour deposits was identified as an important determinant of both RFS and OS for pancreatic (hazard ratio [HR] = 7.61, 95% confidence interval [CI] = 3.96-14.6, P < 0.0001 for RFS; HR = 3.28, 95% CI = 1.56-6.87, P = 0.0017 for OS) and ileal/jejunal neuroendocrine tumours (HR = 1.98, 95% CI = 1.25-3.13, P = 0.0036 for RFS and HR 2.59, 95% CI = 1.27-5.26, P = 0.009 for OS). The present study identifies the presence of mesenterial tumour deposits as an important prognostic factor for gastro-entero-pancreatic neuroendocrine tumours, provides evidence that proliferative parameters need to be treated as continuous variables and further supports the importance of grade determination in all available tumour foci.

The effect of primary site, functional status and treatment modality on survival in gastroenteropancreatic neuroendocrine neoplasms with synchronous liver metastasis: a US population-based study.

BACKGROUND: The incidence of indolent gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) has increased dramatically. GEP-NENs often present late with concomitant liver metastasis, which is associated with poorer outcomes. METHODS: This is a retrospective cohort study of 3,188 patients with liver metastatic GEP-NENs from the national scale Surveillance, Epidemiology, and End Results (SEER) database in the USA between 2010 and 2016. The population-based sample of GEP-NENs with liver metastasis was stratified by primary site (intestinal, pancreatic or gastric), surgical intervention and functional status. RESULTS: Of the 3,188 patients with liver metastatic GEP-NENs in this study, intestinal NENs (iNENs) were the most common and displayed the best 5-year survival of 42.6% compared to 25.8% in pancreatic NENs (pNENs) and 12.0% in gastric NENs (gNENs). Surgical intervention [hazard ratio (HR): 0.46, 95% CI: (0.40-0.53), P<0.001] and carcinoid subtype showed robust survival advantages across all groups. pNENs with liver metastasis were associated with the greatest benefit of surgery [HR: 0.55, 95% CI: (0.41-0.75), P<0.001] while iNENs were the most commonly treated by surgery. After risk adjustment, primary site was not associated with outcome in the non-surgical group. CONCLUSIONS: Taken collectively, when diagnosed with liver metastasis, iNENs conferred a better overall prognosis than both pNENs and gNENs. Primary surgical resection, especially of carcinoid type tumors, emerged as a robust prognostic indicator of better outcomes irrespective of primary site. This finding was most pronounced in liver metastatic pNENs. When possible, we recommend surgical intervention in GEP-NENs with liver metastasis.

Preclinical assesement of survivin and XIAP as prognostic biomarkers and therapeutic targets in gastroenteropancreatic neuroendocrine neoplasia.

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) represent a rare and heterogenous tumor entity. Importantly, the highly proliferative subgroup of neuroendocrine carcinoma (GEP-NEC) is characterized by high resistance to conventional chemotherapy. Consequently, there is an urgent need to identify novel therapeutic targets, especially for GEP-NEC. Thus, we focused on Inhibitor of apoptosis protein (IAP) family members survivin and XIAP that orchestrate inhibition of apoptosis, induce resistance against chemotherapeutics and facilitate tumor metastasis. Copy number gains (CNGs) could be detected by microarray comparative genomic hybridization for survivin and XIAP in 60 % and 26.7 % of all GEP-NENs, respectively. Immunohistochemical staining of tissue specimens from 77 consecutive patients with GEP-NEN demonstrated increased survivin protein expression levels in tissue specimens of highly proliferative GEP-NEC or GEP-NEN located in the stomach and colon. In contrast, XIAP overexpression was associated with advanced tumor stages. Knockdown of survivin and XIAP markedly reduced cell proliferation and tumor growth. In vitro, YM155 induced apoptotic cell death accompanied by a reduction in cell proliferation and inhibited GEP-NEC xenograft growth. Taken together, our data provide evidence for a biological relevance of these IAPs in GEP-NEN and support a potential role of survivin as therapeutic target especially in the subgroup of aggressive GEP-NEC.

Decoding the Molecular and Mutational Ambiguities of Gastroenteropancreatic Neuroendocrine Neoplasm Pathobiology.

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN), considered a heterogeneous neoplasia, exhibit ill-defined pathobiology and protean symptomatology and are ubiquitous in location. They are difficult to diagnose, challenging to manage, and outcome depends on cell type, secretory product, histopathologic grading, and organ of origin. A morphologic and molecular genomic review of these lesions highlights tumor characteristics that can be used clinically, such as somatostatin-receptor expression, and confirms features that set them outside the standard neoplasia paradigm. Their unique pathobiology is useful for developing diagnostics using somatostatin-receptor targeted imaging or uptake of radiolabeled amino acids specific to secretory products or metabolism. Therapy has evolved via targeting of protein kinase B signaling or somatostatin receptors with drugs or isotopes (peptide-receptor radiotherapy). With DNA sequencing, rarely identified activating mutations confirm that tumor suppressor genes are relevant. Genomic approaches focusing on cancer-associated genes and signaling pathways likely will remain uninformative. Their uniquely dissimilar molecular profiles mean individual tumors are unlikely to be easily or uniformly targeted by therapeutics currently linked to standard cancer genetic paradigms. The prevalence of menin mutations in pancreatic NEN and P27KIP1 mutations in small intestinal NEN represents initial steps to identifying a regulatory commonality in GEP-NEN. Transcriptional profiling and network-based analyses may define the cellular toolkit. Multianalyte diagnostic tools facilitate more accurate molecular pathologic delineations of NEN for assessing prognosis and identifying strategies for individualized patient treatment. GEP-NEN remain unique, poorly understood entities, and insight into their pathobiology and molecular mechanisms of growth and metastasis will help identify the diagnostic and therapeutic weaknesses of this neoplasia.

Expression of O(6)-methylguanine DNA methyltransferase (MGMT) and its clinical significance in gastroenteropancreatic neuroendocrine neoplasm.

O(6)-methylguanine-DNA methyltransferase (MGMT) is a widespread DNA repair enzyme defending against mutation caused by guanine O(6)-alkylating agents. Until now, we know only little about the expression of MGMT in gastroenteropancreatic neuroendocrine neoplasm (GEP-NEN). To study the expression of MGMT and its clinical significance in GEP-NEN, 174 specimens of GEP-NEN were examined, of which 152 specimens came from The First Affiliated Hospital, Sun Yat-sen University during October 1995 to November 2013, 22 specimens came from Peking Union Medical College Hospital during September 2004 to April 2010. MGMT protein was detected with EnVision immunohistochemical staining method. Clinicopathological factors were also collected and analyzed. We observed that the overall expression rate of MGMT was 83.9%. Over expression of MGMT protein was not associated with sex, age, functional status, primary tumor location, grading, classification, TNM stage and metastasis (P > 0.05). Kaplan-Meier analysis revealed that there was no significant difference in survival between MGMT-positive and MGMT-negative tumors of GEP-NEN patients (χ(2) = 0.887, P = 0.346). In multivariate analyses carried out by Cox proportional hazards regression model, MGMT expression was also not an independent predictors of survival. These results demonstrated that MGMT protein was highly expressed in GEP-NEN. MGMT deficiency rate was similar in pancreatic NEN and in gastrointestinal NEN. MGMT expression was not correlated with prognosis of GEP-NEN.