Whole-exome sequencing of calcitonin-producing pancreatic neuroendocrine neoplasms indicates a unique molecular signature.

Introduction: Calcitonin-producing pancreatic neuroendocrine neoplasms (CT-pNENs) are an extremely rare clinical entity, with approximately 60 cases reported worldwide. While CT-pNENs can mimic the clinical and diagnostic features of medullary thyroid carcinoma, their molecular profile is poorly understood. Methods: Whole-exome sequencing (WES) was performed on tumor and corresponding serum samples of five patients with increased calcitonin serum levels and histologically validated calcitonin-positive CT-pNENs. cBioPortal analysis and DAVID gene enrichment analysis were performed to identify dysregulated candidate genes compared to control databases. Immunohistochemistry was used to detect the protein expression of MUC4 and MUC16 in CT-pNEN specimens. Results: Mutated genes known in the literature in pNENs like MEN1 (35% of cases), ATRX (18-20% of cases) and PIK3CA (1.4% of cases) were identified in cases of CT-pNENs. New somatic SNVs in ATP4A, HES4, and CAV3 have not been described in CT- pNENs, yet. Pathogenic germline mutations in FGFR4 and DPYD were found in three of five cases. Mutations of CALCA (calcitonin) and the corresponding receptor CALCAR were found in all five tumor samples, but none of them resulted in protein sequelae or clinical relevance. All five tumor cases showed single nucleotide variations (SNVs) in MUC4, and four cases showed SNVs in MUC16, both of which were membrane-bound mucins. Immunohistochemistry showed protein expression of MUC4 in two cases and MUC16 in one case, and the liver metastasis of a third case was double positive for MUC4 and MUC16. The homologous recombination deficiency (HRD) score of all tumors was low. Discussion: CT-pNENs have a unique molecular signature compared to other pNEN subtypes, specifically involving the FGFR4, DPYD, MUC4, MUC16 and the KRT family genes. However, a major limitation of our study was the relative small number of only five cases. Therefore, our WES data should be interpreted with caution and the mutation landscape in CT-pNENs needs to be verified by a larger number of patients. Further research is needed to explain differences in pathogenesis compared with other pNENs. In particular, multi-omics data such as RNASeq, methylation and whole genome sequencing could be informative.

Gastric enterochromaffin-like cell changes in multiple endocrine neoplasia type 1.

BACKGROUND: Gastric enterochromaffin-like cell (ECL) tumours can occur in patients with multiple endocrine neoplasia type 1 (MEN1), especially in those affected by Zollinger Ellison syndrome (ZES). Since the prevalence of ECL lesions is not well defined yet, the present study evaluated the presence and extent of ECL lesions in MEN1 patients with and without ZES. METHODS: Multiple endocrine neoplasia type 1 patients being part of a regular screening program (2014-2018) underwent gastroduodenoscopies with biopsies of the stomach and determination of serum gastrin and chromogranin A levels. Haematoxylin- and immunostaining with chromogranin A, gastrin and VMAT I and II (vesicular monoamine transporter I and II) of the biopsies were performed. RESULTS: Thirty-eight MEN1 patients, of whom 16 (42%) were diagnosed and treated earlier for ZES, were analysed. In ten of 16 (62.5%) ZES patients, a locally scattered, mixed image of diffuse, linear and micronodular mild hyperplasia was present. In addition, two of these patients (13%) showed small (max 1.5 mm in size) intramucosal ECL tumours. Neither ECL changes, nor tumours were found in MEN1 patients without ZES (n = 22). In MEN1/ZES patients, the median serum gastrin level was significantly elevated compared to MEN1 patients without ZES (206 pg/ml vs. 30.5 pg/ml, p < .001). A subgroup analysis of the serum gastrin and chromogranin A levels of MEN1/ZES patients with or without ECL hyperplasia did not show significant differences (gastrin level: p = .302, chromogranin A: p = .464). CONCLUSION: Enterochromaffin-like cell hyperplasia and gastric carcinoids occur only in MEN1 patients with ZES, but less frequently than reported.

Gender Differences in Multiple Endocrine Neoplasia Type 1: Implications for Screening?

BACKGROUND: Some gender-related differences have been reported in multiple endocrine neoplasia type 1 (MEN1), although not all reports are conclusive. This systematic review with analysis of the own MEN1 cohort evaluates gender differences and potential consequences for screening. METHODS: A systematic review of the literature between 1990 and 2019 with the search terms "MEN1" or "multiple endocrine neoplasia type 1" and "gender" or "sex" was performed. In addition, the prospectively collected data of a genetically confirmed MEN1 cohort of the Philipps University Marburg were retrospectively analyzed. RESULTS: Review of the literature identified five retrospective case series with original data of 1,057 MEN1 patients. One series suggested a higher frequency of pancreatic neuroendocrine neoplasms (NEN), especially gastrinomas, in men (61 vs. 54%) and a higher frequency of pituitary tumors in women (47 vs. 30%), but others did not. Only thymic NEN occurred predominantly in men throughout all studies. Women with MEN1 were found to have an increased risk of breast cancer. In the own series consisting of 116 MEN1 patients (male = 58, female = 58), thymic lesions were also more frequently detected in male patients (male = 5, female = 1). No gender difference was found with regard to the other manifestations. CONCLUSION: Regarding the typical MEN1 tumor manifestations, gender-adapted diagnostic and therapeutic approaches cannot be recommended. Female MEN1 patients should be encouraged to participate in breast cancer screening programs.

Single gland excision for MEN1-associated primary hyperparathyroidism.

IMPORTANCE: Guidelines advocate subtotal parathyroidectomy (SPTX) or total parathyroidectomy with autotransplantation (TPTX) with bilateral cervical thymectomy for primary hyperparathyroidism (pHPT) associated with multiple endocrine neoplasia type 1 (MEN1). However, both procedures are associated with a significant risk of permanent hypoparathyroidism. OBJECTIVE: The aim of the current study was to compare long-term results of either single gland excision (SGE, 1-2 glands), SPTX and TPTX for the treatment of MEN1-associated pHPT. DESIGN AND SETTING: Data of genetically confirmed MEN1 patients who underwent surgery for pHPT between 1987 and 2017 were retrieved from a prospective database and were retrospectively analysed. RESULTS: Eighty-nine MEN1 patients underwent either TPTX (n = 38, 42.7%), SPTX (n = 23, 25.8%) or SGE (n = 28, 31.5%). The rate of disease persistence after initial surgery was 2.6%, 0% and 14.2% in the TPTX, SPTX and SGE groups, respectively. After median follow-up of 112 (range 7-411) months, the rate of recurrent pHPT was significantly higher in the SGE group (n = 19, 21.3%) compared with the TPTX (n = 4, 4.4%, P = .001) and the SPTX (n = 9, 10.1%, P = .03) groups. Analysis of the recurrence-free time among the surgical groups revealed a significant difference (P = .036). The median time to recurrence was significantly shorter after SGE (101, range 3-301 months) than after SPTX (139, range 28-278 months, P = .018) and TPTX (204, range 75-396 months, P = .049). Twelve (32%) patients who underwent TPTX developed permanent hypoparathyroidism compared with only 4 (17%, P = .06) in the SPTX and 0 in the SGE group (P = .001). CONCLUSION: Given the high rate of postoperative permanent hypoparathyroidism after TPTX and SPTX, SGE is a valid option for the treatment of MEN1-associated pHPT.

Chemoprevention with Somatuline© Delays the Progression of Pancreatic Neuroendocrine Neoplasms in a Mouse Model of Multiple Endocrine Neoplasia Type 1 (MEN1).

OBJECTIVE: Long-acting synthetic somatostatin analogues (SSA) are an essential part of the treatment of neuroendocrine neoplasms. We evaluated the chemopreventive effects of a long-acting somatostatin analogue on the development of pancreatic neuroendocrine neoplasms (pNENs) in a genetically engineered MEN1 knockout mouse model. MATERIALS AND METHODS: Heterozygote MEN1 knockout mice were injected every 28 days subcutaneously with the somatostatin analogue lanreotide (Somatuline Autogel©; Ipsen Pharma) or a placebo starting at day 35 after birth. Mice were euthanized after 6, 9, 12, 15 and 18 months, and the size and number of pNENs were measured due histological analysis and compared to the placebo group. RESULTS: The median tumor size of pNENs was statistically significantly smaller after 9 (control group vs. SSA group; 706.476 µm2 vs. 195.271 µm2; p = 0.0012), 12 (placebo group vs. SSA group 822.022 vs. 255.482; p ≤ 0.001), 15 (placebo group vs. SSA group 1192.568 vs. 273.533; p ≤ 0.001) and after 18 months (placebo group vs. SSA group 1328.299 vs. 864.587; p ≤ 0.001) in the SSA group. Comparing the amount of tumors in both groups, a significant reduction was achieved in treated Men1(+/-) mice (41%, p = 0.002). Immunostaining showed, however, no significant difference in the expression of the apoptosis marker caspase-3, but a significant difference in Ki67 index as a marker for tumor cell proliferation (p ≤ 0.005). CONCLUSION: Long-acting somatostatin analogues may be an effective chemopreventive approach to delay the progression of MEN1-associated pNENs. After our preclinical results, we would recommend to evaluate the effects of long-acting SSA in a prospective clinical trial.

Results of Duodenopancreatic Reoperations in Multiple Endocrine Neoplasia Type 1.

BACKGROUND: To evaluate the outcome of duodenopancreatic reoperations in patients with multiple endocrine neoplasia type 1 (MEN1). METHODS: MEN1 patients who underwent reoperations for duodenopancreatic neuroendocrine neoplasms (dpNENs) were retrieved from a prospective database and retrospectively analyzed. RESULTS: Twelve of 101 MEN1 patients underwent up to three reoperations, resulting in a total of 18 reoperations for dpNEN recurrence. Patients initially underwent either formal pancreatic resections (n = 7), enucleations (n = 3), or duodenotomy with lymphadenectomy for either NF-pNEN (seven patients), Zollinger-Ellison syndrome (ZES, three patients), organic hyperinsulinism (one patient) or VIPoma (one patient). Six patients had malignant dpNENs with lymph node (n = 5) and/or liver metastases (n = 2). The indication of reoperations was NF-pNEN (five patients), ZES (five patients), organic hyperinsulinism (one patient), and recurrent VIPoma (one patient). Median time to first reoperation was 67.5 (range 6-251) months. Five patients required a second duodenopancreatic reoperation for 60-384 months after initial surgery, and one patient underwent a third reoperation after 249 months. The rate of complications (Clavien-Dindo ≥3) was 28%. Four patients required completion pancreatectomy. Six patients developed pancreoprivic diabetes. After a median follow-up of 18 (6-34) years after initial surgery, ten of 12 patients are alive, one died of metastatic pancreatic VIPoma, and one died of metastatic thymic NEN. CONCLUSION: Reoperations are frequently necessary for dpNEN in MEN1 patients, but are not associated with an increased perioperative morbidity in specialized centers. Organ-sparing resections should be preferred as initial duodenopancreatic procedures to maintain pancreatic function and avoid completion pancreatectomy.

Chemoprevention with Enalapril and Aspirin in Men1(+/T) Knockout Mouse Model.

Pancreatic neuroendocrine neoplasias (pNEN) are the most common cause of death in adult patients with multiple endocrine neoplasia type 1 (MEN1). So far, only few chemopreventive strategies (e.g., with somatostatin analogues) have been evaluated for MEN1 associated pNENs. In this experimental study on 75 Men1(+/T) knockout mice, the effect of aspirin (n = 25) and an inhibitor of angiotensin-I converting enzyme (enalapril, n = 25) compared to controls (n = 25) were evaluated as single chemopreventive strategies for pNENs after 6, 9, 12, 15, and 18 months. After each study period, mice were sacrificed and the resected pancreata were evaluated by histopathological analysis, immunostaining, and real-time PCR. PNEN size and number was measured. Aspirin and enalapril lead to a pNEN size reduction of 80% (167,518 vs. 838,876 µm2, p < 0.001) and 79% (174,758 vs. 838,876 µm2, p < 0.001) compared to controls. Furthermore, aspirin and enalapril treatment resulted in a significant reduction of the number of pNENs by 33%, (p = 0.04) and 41% (p = 0.002) respectively. The apoptosis marker caspase 3 revealed a higher positive expression in pNEN of treated Men1(+/T) mice. Immunostaining of VEGF in pNEN detected a downregulation of its expression in treated Men1(+/T) mice compared to the control group. REL A transcript was significantly downregulated in 18-months treated enalapril Men1(+/T) mice, but not in aspirin-treated Men1(+/T) mice. There was no significant difference in the Ki-67 index. Using a transgenic mouse model that imitates human MEN1, this study provides first evidence that aspirin and enalapril are effective chemopreventive agents that aid in the progression of pNENs.

Is Routine Screening of Young Asymptomatic MEN1 Patients Necessary?

BACKGROUND: Recent clinical practice guidelines recommend that routine screening of MEN1 mutation carriers should start at the age of 5 years. The occurrence of clinically relevant MEN1 organ manifestations in children (≤18 years) was evaluated. METHODS: Two prospective collected databases of MEN1 patients (n = 166) who underwent annual screening were retrospectively analyzed for organ manifestations in MEN1 patients ≤18 years. The follow-up was based on the most recent screening examination until December 2015. RESULTS: Twenty [11 females, 9 males, (12%)] of 166 MEN1 patients were diagnosed with at least one organ manifestation at age ≤18 years. The most frequent manifestation was mild asymptomatic pHPT (n = 9, 45%, age range 8-18 years). Eight (40%) young patients had pNENs (three non-functioning pNENs, five insulinomas, age range 9-18 years). All five insulinomas were diagnosed based on hypoglycemic symptoms. The other organ manifestations were asymptomatic pituitary adenomas in six patients (30%, age range 15-18 years) and a bronchial carcinoid in one 15-year-old patient. Only six (30%) patients ≤18 years had clinically relevant organ manifestations. CONCLUSION: Symptomatic or severe manifestations in MEN1 patients rarely occur below the age of 16 years. With regard to psychological burden and cost-effectiveness, routine screening of asymptomatic MEN1 patients should be postponed at least until the age of 16 years.

Limited Value of Ga-68-DOTATOC-PET-CT in Routine Screening of Patients with Multiple Endocrine Neoplasia Type 1.

BACKGROUND: Routine screening is recommended for patients with multiple endocrine neoplasia type 1 (MEN1) to enable early detection and treatment of associated neuroendocrine neoplasms (NEN). Gallium68-DOTATOC-Positron emission tomography combined with computed tomography (Ga-68-DOTATOC-PET-CT) is a very sensitive and specific imaging technique for the detection of sporadic neuroendocrine tumors. The present study evaluated the value of Ga-68-DOTATOC-PET-CT in routine screening of patients with MEN1. METHODS: Between January 2014 and March 2016, all MEN1 patients underwent Ga-68-DOTATOC-PET-CT in addition to conventional imaging (computed tomography of the thorax, magnetic resonance imaging of the abdomen and pituitary, endoscopic ultrasonography). The diagnostic yield of conventional imaging and Ga-68-DOTATOC-PET-CT was prospectively documented and compared, and treatment changes caused by the addition of Ga-68-DOTATOC-PET-CT were recorded. RESULTS: Conventional imaging detected 145 NENs, mainly pancreaticoduodenal NENs (n = 117, 81%), in 31 of 33 MEN1 patients. Ga-68-DOTATOC-PET-CT detected 55 NENs in 23 of the 33 patients (p = 0.0001). Ninety (62%) NENs detected by conventional imaging were missed by DOTATOC-PET-CT. The majority of missed lesions were pNEN (n = 68; 74%). The sensitivity of Ga-68-DOTATOC-PET-CT for NENs <5, 5-9, 10-19 and ≥20 mm was 0, 29, 81 and 100%, respectively. However, Ga-68-DOTATOC-PET-CT detected more liver and lymph node metastases in patients with known metastatic disease, which did not lead to a change of patients' management. In one patient (3%), Ga-68-DOTATOC-PET-CT was the only imaging modality that detected a small intestine NEN and led to potentially curative surgery. CONCLUSION: Ga-68-DOTATOC-PET-CT cannot be recommended for routine screening of MEN1 patients. It might provide important additional information in patients with suspected or known metastatic disease.

Minimally Invasive Versus Open Pancreatic Surgery in Patients with Multiple Endocrine Neoplasia Type 1.

OBJECTIVE: The role of minimally invasive pancreatic surgery for pancreatic neuroendocrine neoplasms (pNENs) in patients with multiple endocrine neoplasia type 1 (MEN1) is not well defined. The aim of this study was to compare the outcome of minimally invasive versus open pancreatic resections in patients with MEN1. MATERIALS AND METHODS: Prospectively collected data of MEN1 patients who underwent a primary distal pancreatic resection and/or enucleation for non-functioning pNENs or insulinoma were retrospectively analyzed regarding the outcome of minimally invasive or open pancreatic resections. RESULTS: Thirty-three patients underwent primary pancreatic resection for either organic hyperinsulinism (n = 9, 27 %) or non-functioning pNENs >1 cm in size (n = 24, 73 %) between 1987 and 2015. 21 (64 %) patients underwent an open surgical (group 1) and 12 patients (36 %) a minimally invasive approach, either laparoscopic (n = 8) or robotic assisted (n = 4) (group 2). Both groups were comparable regarding age, gender, number, and size of pancreatic tumors. In both groups, the hyperinsulinism of all patients (9/9,100 %) could be cured and all NF-pNENs >1 cm could be resected. Group 2 had a significant shorter operative time (200 vs. 260 min; p = 0.036), less intraoperative blood loss (120 vs. 280 ml; p < 0.001), and a shorter hospital stay (11 vs. 15.5 days; p = 0.034). The rate of patients with postoperative complications, especially postoperative pancreatic fistulas, was not different between groups (62 % group 1 vs. 67 % group 2, p = 0.74). CONCLUSION: Minimally invasive distal pancreatic resections and enucleations are feasible and safe in MEN1 patients with insulinoma or non-functioning pNENs.

Endoplasmic Reticulum Stress in Pancreatic Neuroendocrine Tumors is Linked to Clinicopathological Parameters and Possible Epigenetic Regulations.

BACKGROUND: Endoplasmic reticulum (ER) stress is a highly-conserved cellular defense mechanism in response to perturbations of ER function. The role of ER stress in pancreatic neuroendocrine tumors (pNET) still remains unclear. MATERIALS AND METHODS: We analyzed the protein expression pattern of the four key players of ER stress, (chaperone binding imunoglobluin protein (BiP), C/EBP homologous protein (CHOP), activating transcription factor 4 (ATF4) and caspase 4) as well as histone deacetylases (HDACs) by a tissue microarray (TMA) of 49 human pNET resected between 1997 and 2013 following, extensive clinicopathological characterization. RESULTS: Immunohistochemical profiling revealed a significant up-regulation of BiP, ATF4, CHOP and caspase 4 in pNET cases compared to normal controls. Correlated to clinicopathological parameters especially BiP expression could be linked to higher grading and proliferation as well as to lower survival probability. Finally, expression of ER stress markers correlated with HDAC expression in situ and pharmalogical inhibition by panobinostat significantly reduced cell viability in vitro. CONCLUSION: Up-regulation of ER stress in pNET indicates the presence and engagement of ER stress signaling in this tumor entity demonstrating another possible anticancer therapy option in pNET.