Well-differentiated Pancreatic Neuroendocrine Tumors Research Articles

An Uncommon Culprit: Pancreatic Neuroendocrine Tumor in a Patient with Uncontrolled Diabetes

Pancreatic Neuro Endocrine Tumors (NETs) are rare neoplasms that originate from the endocrine tissues of the pancreas, accounting for only 1-2% of pancreatic tumors. Despite their low incidence, these tumors present with a wide range of symptoms and have the ability to secrete hormones, posing significant challenges for their diagnosis and treatment. There are two distinct types of pancreatic NETs: functioning and nonfunctioning. Functioning tumors are characterized by hormone-related clinical syndromes, while nonfunctioning tumors are often found incidentally. The pathogenesis of pancreatic NETs involves both sporadic and hereditary factors, including syndromes such as MEN1, VHL, and NF1. Typically, these tumors are diagnosed in individuals between the ages of 40 and 60, and their effective management requires a multidisciplinary approach. Diagnostic imaging techniques, such as CT and EUS, play a crucial role in accurate diagnosis, while PET scans aid in staging and treatment planning. Histological analysis is essential for determining the tumor grade and predicting prognosis. Treatment strategies are tailored to the tumor's characteristics and the patient's overall health. These may include the use of somatostatin analogs, such as Lanreotide and Octreotide, to control hormone secretion and inhibit tumor growth, as well as systemic therapies like everolimus, sunitinib, and PRRT for metastatic disease. This case report describes the clinical course of a 66-year-old male with a well-differentiated pancreatic NET who initially presented with persistent hyperglycemia. Further investigations revealed a sizable pancreatic mass and liver metastases. Diagnostic evaluation confirmed a grade 1 Neuro Endocrine Tumor, and the patient was started on treatment with Lanreotide. However, his management was complicated by the development of hepatic encephalopathy, which necessitated treatment with lactulose and rifaximin. This case highlights the importance of considering pancreatic NETs in cases of atypical diabetes presentations and emphasizes the need for a multidisciplinary team to provide optimal care. Given the complex nature of pancreatic NETs, a comprehensive diagnostic workup and personalized treatment approach are essential for improving patient outcomes.

Oncogenic pathway signatures predict the risk of progression and recurrence in well-differentiated pancreatic neuroendocrine tumors.

Pancreatic neuroendocrine tumors (pNETs) are genomically diverse tumors. The management of newly diagnosed well-differentiated pNETs is limited by a lack of sensitivity of existing biomarkers for prognostication. Our goal was to investigate the potential utility of genetic markers as a predictor of progression-free survival (PFS) and recurrence-free survival (RFS). Whole-exome sequencing of resected well-differentiated, low and intermediate-grade (G1 and G2) pNETs and normal adjacent tissue from patients who underwent resection from 2005 to 2015 was performed. Genetic alterations were classified using pan-genomic and oncogenic pathway classifications. Additional samples with genetic and clinicopathologic data available were obtained from the publicly available International Cancer Genome Consortium (ICGC) database and included in the analysis. The prognostic relevance of these genomic signatures on PFS and RFS was analyzed. Thirty-one patients who underwent resection for pNET were identified. Genomic analysis of mutational, copy number, cytogenetic, and complex phenomena revealed similar patterns to prior studies of pNETs with relatively few somatic gene mutations but numerous instances of copy number changes. Analysis of genomic and clinicopathologic outcomes using the combined data from our study as well as the ICGC pNET cohort (n = 124 patients) revealed that the recurrent pattern of whole chromosome loss (RPCL) and metastatic disease were independently associated with disease progression. When evaluating patients with local disease at the time of resection, RPCL and alterations in the TGFβ oncogenic pathway were independently associated with the risk of recurrence. Well-differentiated pNETs are genomically diverse tumors. Pathway signatures may be prognostic for predicting disease progression and recurrence.

Childhood pancreatic neuroendocrine neoplasms: A national experience.

National multicenter retrospective study of all patients, aged from 0 to 17 years at diagnosis, treated from 2011 to 2020 for a pNEN and registered in the French National Registry of Childhood Cancers or FRACTURE database. Fifteen patients, 13 well-differentiated pancreatic neuroendocrine tumors (pNETs) and two neuroendocrine carcinomas (pNECs), were selected. Median age at diagnosis was 14 years (range, 7-17). Eight patients, all with localized disease, had a cancer predisposition syndrome (CPS), including five cases diagnosed during systematic screening. Five (31%) had metastatic disease at diagnosis: three grade 2 pNETs and two pNECs. First line therapy included exclusive pancreatectomy (seven cases, all M0), active surveillance (three cases, all M0), medical therapies (somatostatin analogues, chemotherapy; four cases, all M1), and surgery with medical therapy (one M1 case). Three-year progression-free survival was 57% (confidence interval [CI] 95%: 27-78) and was significantly better for patients with low-grade well differentiated (73vs. 0%; p<10-4) and localized (76vs. 20%; p=.02) tumors. The two patients with pNECs died. Three-year overall survival was 92% (CI95%: 59-99) and was significantly better in patients with low-grade tumor (100vs. 50%; p=10-4). Childhood pNENs occur more frequently in adolescents with CPS. Localized low-grade pNETs in children have a very good prognosis, whereas the treatment of high-grade and metastatic pNETs/pNECs should be better defined.

Well-differentiated G1 and G2 pancreatic neuroendocrine tumors: a meta-analysis of published expanded DNA sequencing data.

Well-differentiated pancreatic neuroendocrine tumors (PNETs) can be non-functional or functional, e.g. insulinoma and glucagonoma. The majority of PNETs are sporadic, but PNETs also occur in hereditary syndromes, primarily multiple endocrine neoplasia type 1 (MEN1). The Knudson hypothesis stated a second, somatic hit in MEN1 as the cause of PNETs of MEN1 syndrome. In the recent years, reports on genetic somatic events in both sporadic and hereditary PNETs have emerged, providing a basis for a more detailed molecular understanding of the pathophysiology. In this systematic review and meta-analysis, we made a collation and statistical analysis of aggregated frequent genetic alterations and potential driver events in human grade G1/G2 PNETs. A systematic search was performed in concordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) reporting guidelines of 2020.A search in Pubmed for published studies using whole exome, whole genome, or targeted gene panel (+400 genes) sequencing of human G1/G2 PNETs was conducted at the 25th of September 2023. Fourteen datasets from published studies were included with data on 221 patients and 225 G1/G2 PNETs, which were divided into sporadic tumors, and hereditary tumors with pre-disposing germline variants, and tumors with unknown germline status. Further, non-functioning and functioning PNETs were distinguished into two groups for pathway evaluation. The collated genetical analyses were conducted using the 'maftools' R-package. Sporadic PNETs accounted 72.0% (162/225), hereditary PNETs 13.3% (30/225), unknown germline status 14.7% (33/225). The most frequently altered gene was MEN1, with somatic variants and copy number variations in overall 42% (95/225); hereditary PNETs (germline variations in MEN1, VHL, CHEK2, BRCA2, PTEN, CDKN1B, and/or MUTYH) 57% (16/30); sporadic PNETs 36% (58/162); unknown germline status 64% (21/33). The MEN1 point mutations/indels were distributed throughout MEN1. Overall, DAXX (16%, 37/225) and ATRX-variants (12%, 27/225) were also abundant with missense mutations clustered in mutational hotspots associated with histone binding, and translocase activity, respectively. DAXX mutations occurred more frequently in PNETs with MEN1 mutations, p<0.05. While functioning PNETs shared few variated genes, non-functioning PNETs had more recurrent variations in genes associated with the Phosphoinositide 3-kinase, Wnt, NOTCH, and Receptor Tyrosine Kinase-Ras signaling onco-pathways. The somatic genetic alterations in G1/G2 PNETs are diverse, but with distinct differences between sporadic vs. hereditary, and functional vs. non-functional PNETs. Increased understanding of the genetic alterations may lead to identification of more drivers and driver hotspots in the tumorigenesis in well-differentiated PNETs, potentially giving a basis for the identification of new drug targets. (Funded by Novo Nordisk Foundation, grant number NNF19OC0057915).

Malignant tumors in tuberous sclerosis complex: a case report and review of the literature

BackgroundTuberous sclerosis complex (TSC) is a rare, autosomal dominant genetic disease that arises from TSC1 or TSC2 genetic mutations. These genetic mutations can induce the development of benign tumors in any organ system with significant clinical implications in morbidity and mortality. In rare instances, patients with TSC can have malignant tumors, including renal cell carcinoma (RCC) and pancreatic neuroendocrine tumor (PNET). It is considered a hereditary renal cancer syndrome despite the low incidence of RCC in TSC patients. TSC is typically diagnosed in prenatal and pediatric patients and frequently associated with neurocognitive disorders and seizures, which are often experienced early in life. However, penetrance and expressivity of TSC mutations are highly variable. Herein, we present a case report, with associated literature, to highlight that there exist undiagnosed adult patients with less penetrant features, whose clinical presentation may contain non-classical signs and symptoms, who have pathogenic TSC mutations.Case presentationA 31-year-old female with past medical history of leiomyomas status post myomectomy presented to the emergency department for a hemorrhagic adnexal cyst. Imaging incidentally identified a renal mass suspicious for RCC. Out of concern for hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome, the mass was surgically removed and confirmed as RCC. Discussion with medical genetics ascertained a family history of kidney cancer and nephrectomy procedures and a patient history of ungual fibromas on the toes. Genetic testing for hereditary kidney cancer revealed a 5’UTR deletion in the TSC1 gene, leading to a diagnosis of TSC. Following the diagnosis, dermatology found benign skin findings consistent with TSC. About six months after the incidental finding of RCC, a PNET in the pancreatic body/tail was incidentally found on chest CT imaging, which was removed and determined to be a well-differentiated PNET. Later, a brain MRI revealed two small cortical tubers, one in each frontal lobe, that were asymptomatic; the patient’s history and family history did not contain seizures or learning delays. The patient presently shows no evidence of recurrence or metastatic disease, and no additional malignant tumors have been identified.ConclusionsTo our knowledge, this is the first report in the literature of a TSC patient without a history of neurocognitive disorders with RCC and PNET, both independently rare occurrences in TSC. The patient had a strong family history of renal disease, including RCC, and had several other clinical manifestations of TSC, including skin and brain findings. The incidental finding and surgical removal of RCC prompted the genetic evaluation and diagnosis of TSC, leading to a comparably late diagnosis for this patient. Reporting the broad spectrum of disease for TSC, including more malignant phenotypes such as the one seen in our patient, can help healthcare providers better identify patients who need genetic evaluation and additional medical care.

Preoperative assessment of lymph nodal metastases with [68Ga]Ga-DOTATOC PET radiomics for improved surgical planning in well-differentiated pancreatic neuroendocrine tumours.

Accurate identification of lymph node (LN) metastases is pivotal for surgical planning of pancreatic neuroendocrine tumours (PanNETs); however, current imaging techniques have sub-optimal diagnostic sensitivity. Aim of this study is to investigate whether [68Ga]Ga-DOTATOC PET radiomics might improve the identification of LN metastases in patients with non-functioning PanNET (NF-PanNET) referred to surgical intervention. Seventy-two patients who performed preoperative [68Ga]Ga-DOTATOC PET between December 2017 and March 2022 for NF-PanNET. [68Ga]Ga-DOTATOC PET qualitative assessment of LN metastases was measured using diagnostic balanced accuracy (bACC), sensitivity (SN), specificity (SP), positive and negative predictive values (PPV, NPV). SUVmax, SUVmean, Somatostatin receptor density (SRD), total lesion SRD (TLSRD) and IBSI-compliant radiomic features (RFs) were obtained from the primary tumours. To predict LN involvement, these parameters were engineered, selected and used to train different machine learning models. Models were validated using tenfold repeated cross-validation and control models were developed. Models' bACC, SN, SP, PPV and NPV were collected and compared (Kruskal-Wallis, Mann-Whitney). LN metastases were detected in 29/72 patients at histology. [68Ga]Ga-DOTATOC PET qualitative examination of LN involvement provided bACC = 60%, SN = 24%, SP = 95%, PPV = 78% and NPV = 65%. The best-performing radiomic model provided a bACC = 70%, SN = 77%, SP = 61%, PPV = 60% and NPV = 83% (outperforming the control model, p < 0.05*). In this study, [68Ga]Ga-DOTATOC PET radiomics allowed to increase diagnostic sensitivity in detecting LN metastases from 24 to 77% in NF-PanNET patients candidate to surgery. Especially in case of micrometastatic involvement, this approach might assist clinicians in a better patients' stratification.

Consensus on the clinical diagnosis and treatment of grade 3 pancreatic neuroendocrine tumors

The World Health Organization (WHO) 2017 classifications for neuroendocrine neoplasms (NENs) subdivided grade 3 pancreatic neuroendocrine neoplasms (pNENs) into G3 well-differentiated pancreatic neuroendocrine tumors (G3 pNETs) and poorly differentiated pancreatic neuroendocrine carcinomas (pNECs), according to the mitotic count, Ki-67 index, and cell differentiation. As a new category, G3 pNETs remain a challenging group of tumors to manage by lacking large randomized trials and consensus to support its clinical practice. Therefore, the Chinese Pancreatic Surgery Association, Chinese Society of Surgery, Chinese Medical Association gathered experts in this field to formulate this consensus for the diagnosis and treatment of G3 pNETs.

INSM1 is a useful neuroendocrine marker to differentiate pancreatic serous cystadenoma from pancreatic well-differentiated neuroendocrine tumors in cytology and surgical specimens

IntroductionDifferentiating pancreatic serous cystadenoma (SCA) from well-differentiated neuroendocrine tumors (WDNETs) based on histomorphology is critical yet challenging, particularly in small biopsy samples. Our study aimed to examine the expression profile of INSM1 in cytologic and surgical resection specimens from pancreatic SCA to evaluate its potential as a discriminative marker against pancreatic WDNET. MethodsWe characterized INSM1 immunohistochemistry in 34 patients with pancreatic SCA, comprising 23 surgical resections and 11 cytology specimens. As a control, we used 28 cytology specimens from pancreatic WDNET. Clinical information was retrieved through a review of electronic medical records. ResultsAll 11 pancreatic SCA cytology specimens and 15 of 23 pancreatic SCA surgical resections exhibited absent INSM1 immunostaining. Each of the remaining eight surgical resection specimens demonstrated 1 % immunoreactivity. In contrast, 27 out of 28 (96 %) pancreatic WDNET cytology specimens were positive for INSM1 immunostaining, with a median immunoreactivity of 90 % and a range of 30–90 %. Overall, INSM1 immunostains perform similarly to chromogranin and synaptophysin in pancreatic SCA. ConclusionsThe results indicate that INSM1 immunohistochemistry staining may serve as a useful neuroendocrine marker to differentiate pancreatic SCA from pancreatic WDNET in clinical practice. To our knowledge, this represents the first large-scale study to evaluate INSM1 immunostaining in surgical and cytology specimens from pancreatic SCA.

Sequencing Treatments in Patients with Advanced Well-Differentiated Pancreatic Neuroendocrine Tumor (pNET): Results from a Large Multicenter Italian Cohort.

Background: The optimal treatment sequencing for advanced, well-differentiated pancreatic neuroendocrine tumors (pNETs) is unknown. We performed a multicenter, retrospective study to evaluate the best treatment sequence in terms of progression-free survival to first-line (PFS1) and to second-line (PFS2), and overall survival among patients with advanced, well-differentiated pNETs. Methods: This multicenter study retrospectively analyzed the prospectively collected data of patients with sporadic well-differentiated pNETs who received at least two consecutive therapeutic lines, with evidence of radiological disease progression before change of treatment lines. Results: Among 201 patients, 40 (19.9%) had a grade 1 and 149 (74.1%) a grade 2 pNET. Primary tumor resection was performed in 98 patients (48.8%). First-line therapy was performed in 128 patients with somatostatin analogs (SSA), 35 received SSA + radioligand therapy (RLT), 21 temozolomide-based chemotherapy, and 17 SSA + targeted therapy. PFS was significantly longer in patients with grade 1 pNETs compared to those with grade 2, in patients who received primary tumor surgery, and in patients treated with RLT compared to other treatments. At multivariate analysis, the use of upfront RLT was independently associated with improved PFS compared to SSA. Second-line therapy was performed in 94 patients with SSA + targeted therapy, 35 received chemotherapy, 45 SSA + RLT, and 27 nonconventional-dose SSA or SSA switch. PFS was significantly longer in patients treated with RLT compared to other treatments. At multivariate analysis, the type of second-line therapy was independently associated with the risk for progression. OS was significantly longer in patients who received primary tumor surgery, with Ki67 < 10%, without extrahepatic disease, and in patients who received SSA-RLT sequence compared to other sequences. Conclusions: In this large, multicenter study, RLT was associated with better PFS compared to other treatments, and the SSA-RLT sequence was associated with the best survival outcomes in patients with pNETs with Ki67 < 10%. Primary tumor surgery was also associated with improved survival.

Treatment strategies for borderline resectable pancreatic neuroendocrine tumors: a narrative review.

Well-differentiated pancreatic neuroendocrine tumors (pNETs) are a group of rare, heterogeneous tumors that originate in the endocrine tissue of the pancreas and account for 1-2% of all pancreatic neoplasms. The majority of pNETs are non-functional and typically follow a more indolent course. Especially at early stages, the primary management of pNETs is surgical resection which is associated with relatively low rates of recurrence and excellent long-term prognosis. On the other hand, some patients will present with locally advanced primary tumors or low volume metastatic disease in which complete surgical resection may be more difficult to achieve and recurrence rates are significant. Unlike treatment of borderline resectable (BR) pancreatic adenocarcinoma, in which neoadjuvant treatment strategies are becoming standardized, borderline resectability is not a currently established terminology for pNETs and the optimal multidisciplinary treatment approach is poorly understood. We performed a literature search on PubMed, Google Scholar, and ClinicalTrials.gov using keywords, including 'pancreatic neuroendocrine tumor' and 'borderline resectable'. All studies and review articles in English with full text were considered. Each publication was independently reviewed. We introduce the concept of BR-pNETs, focusing on important criteria that should be included in their definition by balancing the feasibility of resection and the clinical utility of surgery. We suggest that extended resection, involving vascular reconstruction, adjacent organ resection, and/or liver metastasis, should be considered at experienced, high volume centers. Furthermore, we outline multidisciplinary treatment strategies, including systemic and locoregional treatment options, for optimizing outcomes for this growing patient population. Formalizing the definition of resectability in pNETs through multidisciplinary collaborative research will be important for standardizing the indications for multimodality treatment and aggressive surgical approaches for patients.

Abstract 6825: Epigenetic dysregulation in well-differentiated pancreatic neuroendocrine tumor (PNET): An immunohistochemistry (IHC) analysis

Abstract Epigenetic dysregulation through DNA Methyltransferase 1 (DNMT1) is integral to pancreatic neuroendocrine tumorigenesis. We aim to investigate the interplay between epigenetic modifiers and pathogenetic markers in the PNET microenvironment. 12 paraffin-embedded PNET specimens and 12 benign adjacent tissue specimens, used as controls, were obtained from Cooper University Hospital Pathology Department (IRB 23-130). IHC was performed using epigenetic markers, including DNMT1, DNMT3A, DNMT3B, and 5-Hydroxymethylcytosine (5-HMC), and pathogenic markers, including Multiple Endocrine Neoplasia 1 (MEN1), Protein-Tyrosine Phosphatase (PTEN), and Ras Association Domain Family 1 (RASSF1). Image J software was utilized for IHC scoring under the guidance of a board-certified pathologist. DNMT1 was upregulated in PNET tumor specimens with a mean density score of 72.02 +/- 31 versus 16.02 +/- 17 in adjacent benign tissue (p&amp;lt;.001). Grade 2 tumors displayed increased DNMT1 expression compared to Grade 1 tumors with a mean score of 37 +/-21 versus 71 +/- 23 (p&amp;lt;.05). Decreased expression of 5-HMC was noted in tumor specimens in comparison to benign tissue with a mean score of 3.92 +/- 5.05 versus 19.37 +/- 5.05 (p&amp;lt;.05). Loss of 5-HMC was observed in higher tumor grades with a mean score of .79 +/- 2 versus 8.2+/-2 (p&amp;lt;.01). DNMT3B was upregulated in PNET tumor specimens with a mean score of 13.16 +/- 3.94 versus 7.02+/- 2.553 (p&amp;lt;.01) in adjacent benign tissue and was positively correlated to DNMT1 expression. DNMT3A was not found to have a difference in expression between tumor and benign tissue. MEN1 was downregulated in PNET, with 45% of tumor specimens displaying loss of MEN1 expression. Mean MEN1 density in tumor tissue was 4.47 +/- 5.95 versus 11.41 +/- 3.53 in adjacent benign (p&amp;lt;.01). Increased expression of DNMT1 found to negatively correlate with MEN1 expression (R2=.23). Loss of RASSF1 expression was present in 70% of tumor specimens with a mean score of 1.32 +/- 1.99 versus 9.50+/- 6.89 (p&amp;lt;.001) in adjacent benign tissue. RASSF1 expression correlated negatively with DNMT1 (R2=.21). PTEN expression showed intratumoral homogeneity to benign tissue, and its expression was not correlated with any epigenetic markers. Our work provides a framework of epigenetic regulators involved in the pathobiology of PNET, and can refine prognostic evaluation while providing therapeutic benefits for patients with PNET. Citation Format: Zena Saleh, Yazid Ghanem, Hansa Joshi, Mathew C. Moccia, Helen Toma, Yahui Li, Upsana Joneja, Tao Gao, Young Hong. Epigenetic dysregulation in well-differentiated pancreatic neuroendocrine tumor (PNET): An immunohistochemistry (IHC) analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6825.

Tyrosine kinase inhibitors in patients with neuroendocrine neoplasms: a systematic literature review.

Several tyrosine kinase receptors inhibitors (TKIs) have demonstrated antiproliferative effects in well-differentiated neuroendocrine tumors (NETs). We aimed to summarize and appraise the current evidence of the efficacy of TKIs in patients with different types of NETs. We performed a systematic review of clinical trials of TKIs in patients with advanced gastroenteropancreatic or lung NETs (PROSPERO registration number: CRD42024507379). Population characteristics, efficacy, and safety results were summarized by type of NET. Twenty-eight studies were eligible, totaling 2284 patients. While sunitinib remains the only Food and Drug Administration-approved TKI in patients with NETs (for patients with pancreatic well-differentiated NETs), recent placebo-controlled randomized trials have demonstrated improved response rates and progression-free survival for patients with progressive and pre-treated well-differentiated pancreatic (cabozantinib or surufatinib) or gastrointestinal (GI) NETs (pazopanib, cabozantinib, or surufatinib). There is limited evidence to support the use of a TKI in patients with lung or grade 3 NETs. The toxicity associated with TKIs follows a class effect, with a significant proportion of patients experiencing fatigue, hypertension, and hand-foot skin reactions. TKIs are effective therapies in patients with pancreatic or GI well-differentiated NETs and should be part of the therapeutical sequencing of these patients.

SAT171 An Unusual Presentation Of Insulinoma With Postprandial Hypoglycemia

Abstract Disclosure: J.G. Melendez-Rivera: None. F.H. Morgan: None. A. Aneja: None. Background: Insulinomas are rare neuroendocrine tumors of the pancreas with an incidence of four cases per million individuals per year. The most common presentation of insulinoma is fasting hypoglycemia with associated neuroglycopenic symptoms. Postprandial hypoglycemia has been previously reported, usually in combination with fasting hypoglycemia. Exclusive postprandial hypoglycemia is estimated to occur in 6% of insulinomas. Clinical Case: A 61-year-old woman presented with episodes of postprandial blurry vision, diaphoresis, nausea, and dizziness occurring for the last 18 months that have become more frequent. The patient reported blood glucose measurements in the 35 - 40 mg/dL range at the time of symptoms. Fasting blood glucose levels remained consistently in the 70 - 90 mg/dL range. These symptoms were originally sporadic but progressively became more common to the point that they were occurring daily after meals, and she gained 20 pounds due to increased food intake. BMI was 36.28. Her physical exam was unremarkable. Fasting labs revealed a glucose of 82mg/dl and C-peptide of 2.8ng/ml with normal cortisol. After a short trial of a reactive hypoglycemia diet, the patient had no improvement in symptoms, and was admitted for a 72-hour fast. She developed hypoglycemia with a glucose of 42mg/dl within four hours of starting her inpatient fast. At the time of hypoglycemia, insulin and C-peptide were inappropriately normal (insulin 15.9 mIU/mL and C-peptide 2.57 ng/mL) with an elevated proinsulin (42.3 pmol/L). An MRI abdomen with and without IV contrast showed a 16 mm hypervascular mass in the head of the pancreas. She subsequently underwent endoscopic ultrasonography with fine needle aspiration showing findings consistent with a well-differentiated pancreatic neuroendocrine tumor. Ga-68 DOTATATE PET CT revealed increased DOTATATE avidity in the pancreatic head mass compatible with neuroendocrine tumor but no evidence of metastatic disease. She underwent surgical resection of the tumor with resolution of symptoms. Conclusion: The absence of fasting hypoglycemia does not rule out pancreatic neuroendocrine tumors. While rare, exclusive postprandial hypoglycemia can be seen in these types of tumors, especially proinsulin-secreting tumors. This case illustrates the importance of considering insulinoma during the evaluation of postprandial hypoglycemia in the absence of fasting hypoglycemia and persistent hypoglycemia despite dietary modifications. Presentation: Saturday, June 17, 2023

FRI603 Treatment Of Severe Refractory Hypoglycemia Due To Malignant Insulinoma With A Novel Anti-insulin Receptor Antibody

Abstract Disclosure: S. Osataphan: None. M. Vamvini: None. E.D. Rosen: Consulting Fee; Self; Novartis Pharmaceuticals. L. Pei: None. N. Erlikh: None. G. Singh: None. P. Dhorajiya: None. J. Parker: None. J.M. Dreyfuss: None. A. Rattani: Stock Owner; Self; Vertex Pharmaceuticals, Provention Bio, Bluebird Bio, Agenus, MacroGenics, Immunity Bio, Mirati Therapeutics, Actinium Pharmaceuticals, Bausch Health Companies, Compass Therapeutics, Magenta Therapeutics. M. Patti: Advisory Board Member; Self; Fractyl Laboratories. Consulting Fee; Self; AstraZeneca, Hanmi Pharmaceuticals, MBX. Grant Recipient; Self; Dexcom. Severe hypoglycemia caused by malignant insulinoma is often resistant to medical therapy targeting both tumor burden and insulin secretion. We report a patient who developed severe, treatment-resistant hypoglycemia after receiving 177lutetium-DOTATATE (Lu-177). Hypoglycemia was completely ameliorated after treatment with RZ358, a human monoclonal antibody that functions as a negative allosteric modulator of the insulin receptor, reducing insulin signaling. This 55 year old man presented with abdominal pain, fatigue, and weight loss; imaging showed a 1.8 cm pancreatic tail mass and numerous hepatic lesions. Liver biopsy demonstrated well-differentiated pancreatic neuroendocrine tumor, WHO Grade 2, and pathogenic MEN1 mutation. Following one year of octreotide therapy, both pancreatic and hepatic tumors increased in size, prompting Lu-177 therapy. Two days after the first dose, the patient became unresponsive, with capillary glucose 20 mg/dL. He developed recurrent neuroglycopenia on day 8, with venous glucose 41 mg/dL, insulin 45 µIU/mL, C-peptide 6.5 ng/mL and proinsulin 453 pmol/L, requiring intensive care unit admission for for intravenous glucose. High-dose diazoxide, everolimus, dexamethasone, glucagon, pasireotide, or enteral feeding did not produce a response. Despite multiple therapies, neuroglycopenia required frequent dextrose boluses and continuous intravenous glucose (up to 30 g/hr of 50% dextrose); up to 58% of sensor glucose was below 70 mg/dL and 19% below 54 mg/dL over 24 hours. CT imaging 1 month after Lu-177 showed significant reduction in liver metastases size. Given the severity of hypoglycemia despite tumor regression, we considered treatment with RZ358, a human monoclonal antibody that acts as a negative allosteric modulator of the insulin receptor, inducing insulin resistance. We obtained emergency use authorization from the FDA, approval from the local Institutional Review Board, and written informed consent. Following a 6 mg/kg dose of RZ358, there was transient worsening of hypoglycemia accompanied by an 8-fold increase in insulin, potentially due to reduced insulin clearance. After dose increase to 9 mg/kg weekly, glucose infusion was weaned. Metabolic stability was achieved after 6 doses, allowing a second dose of Lu-177 and eventual discharge. Diazoxide was discontinued, steroid doses were reduced, and RZ358 dosing was reduced to every 3-4 weeks. A third dose of Lu-177 was administered without complications. Despite elevated insulin (537 uIU/mL), C-peptide (10.1 ng/mL), and proinsulin (634.0 pmol/L), he remains free of level 3 hypoglycemia. No adverse effects have been observed. In summary, the anti-insulin receptor monoclonal antibody RZ358 effectively controlled hypoglycemia refractory to multiple other therapies, allowing restoration of normoglycemia and enabling additional successful cancer therapy. Presentation: Friday, June 16, 2023

ASO Visual Abstract: Detecting Somatic Mutations for Well-Differentiated Pancreatic Neuroendocrine Tumors in EndoscopicUltrasound-GuidedFine Needle Aspirationwith Next-Generation Sequencing.

ASO Visual Abstract: Detecting Somatic Mutations for Well-Differentiated Pancreatic Neuroendocrine Tumors in EndoscopicUltrasound-GuidedFine Needle Aspirationwith Next-Generation Sequencing.

Tuberous sclerosis complex mutations in patients with pancreatic neuroendocrine tumors. Observations on phenotypic and treatment-related associations.

Pancreatic neuroendocrine tumors (PanNETs) in familial tuberous sclerosis (TSC1 and TSC2 mutations) have been known and studied. However, little is known about PanNET patients harboring the very rare (less than 2%) sporadic TSC mutations. Some renal tumors have been shown to harbor sporadic TSC mutations, with a distinctive morphological correlate. We hereby describe this rather unusual molecular alteration in well-differentiated pancreatic neuroendocrine tumors (WD PanNETs) with a focus on their morphology and treatment outcomes. Six cases of WD PanNETs harboring sporadic TSC mutations were identified retrospectively. H&E slides and corresponding immunostains were reviewed for all cases. Clinical, molecular, and radiological information was obtained using the electronic medical records. Cohort consisted of 4 males and 2 females. Median age at diagnosis was 50years (range 33-74years). Origin of neoplasm was the pancreas and, in all but one, patient had liver metastasis by the time of presentation. Six out of six cases demonstrated a unique tumor morphology, with ample eosinophilic cytoplasm. Tumors were arranged in sheets and nests; prominent cystic change was noted in one case. Two cases were additionally biopsied post-treatment with capecitabine and temozolomide, and showed even more abundant oncocytic cytoplasm, eccentric nuclei, and a prominent cherry red nucleolus, and were arranged in a cluster of 3-4 cells, separated by stromal cells. Every patient had a different TSC2 variant with no cases of TSC1 mutations. Other common variants included MEN1 (4/6), DAXX (2/6), and TP53 (2/6). Per the WH0 2019 classification, tumors were graded as NET-G3 (n = 3) and NET-G2 (n = 3). Ki-67s ranged from 7.2 to 60. All cases had retained MMR protein expression. The majority of patients (4/6) have expired. Although they received multiple treatments, a consistent pattern observed in patients was marked radiologic response to chemotherapy with capecitabine and temozolomide (offered in 5/6 patients) with duration of responses reaching 11months in the majority of cases, with one patient showing near complete pathologic response of localized disease. TSC2 mutations may confer distinctive appearance in WD PanNETs, reminiscent of their effects in renal tumors. Although not entirely specific, this distinct morphological pattern with abundant eosinophilic cytoplasm in WD PanNETs could be reflective of an associated TSC mutation, with suggestions of significant therapeutic response to a specific cytotoxic chemotherapy.

Targeted deep sequencing reveals the genetic heterogeneity in well-differentiated pancreatic neuroendocrine tumors with liver metastasis.

Pancreatic neuroendocrine tumor is a rare and heterogeneous entity, and approximately half of the patients harbored liver metastasis when initially diagnosed, whose prognosis is dismal. High-throughput sequencing has largely uncovered the genomic features of pancreatic neuroendocrine tumor, but the genetic alterations in the metastatic cases remain relatively unclear, which we aimed to study. Pathologically confirmed well-differentiated pancreatic neuroendocrine tumor samples resected in our hospital from 2000 to 2019 were collected. We performed deep sequencing on the exome of 341 tumor-related genes, and compared the differences of genetic alterations between the metastatic and the non-metastatic cases, as well as between the primary and the paired liver metastatic tumors. Sequencing data of 79 samples from 29 pancreatic neuroendocrine tumor patients were included into analysis. A total of 2,471 somatic variants were identified, 75.5% of which were considered as low-abundance. NOTCH1 was the most frequently mutated gene, altered in 26 (53.1%) pancreatic neuroendocrine tumor samples from 18 (62.1%) patients. Compared with the non-metastatic pancreatic neuroendocrine tumors, the metastatic cases were discovered with more single nucleotide variants and copy number variations, indicating the increased genomic instability. In addition, among the paired metastatic cases, the primary and the metastatic lesions shared limited mutated genes. Through the targeted deep sequencing, we identified the intratumor, intraindividual, and interindividual heterogeneity in the pancreatic neuroendocrine tumor patients, particularly in the metastatic cases, bringing potential challenges for the current biopsy strategies in guiding clinical treatments.

Cytomorphologic observations on the sclerosing variant of well-differentiated pancreatic neuroendocrine tumors: Towards making specific diagnoses early.

The recently described sclerosing variant of pancreatic neuroendocrine tumor (spNET) shows prominent stromal fibrosis and decreased tumor cellularity in surgical pathology specimens. Although prognostic data are currently ambivalent, some studies have reported metastatic disease in small primary tumors, highlighting the need for early diagnosis. The aim of our study is to evaluate cytology specimens of spNET to determine its characteristic cytomorphologic features to expedite an early diagnosis. Twenty-five cytology cases of spNET from 23 patients and 29 cytology cases of typical pancreatic neuroendocrine tumor (tpNET) from 29 patients diagnosed as such by surgical pathology evaluation were reviewed by two pathologists to assess adequacy of diagnostic material, cellularity and fibrosis. Radiographic findings and outcome data were collected. With only 13 of 25 specimens deemed as diagnostic, spNET specimens were more often non-diagnostic (p < .01) and less often hypercellular (p = .03) compared to tpNET counterparts. While at least focal fibrosis was observed in both groups, a subset of spNET cases showed small tumor cell groups entrapped in large fibrotic fragments. Importantly, spNETs tended to be metastatic at diagnosis (both regionally and distant), with a smaller average tumor size. The hypocellular nature of spNET cytology samples makes this variant difficult to diagnose. However, when adequate sample is available, a subset of spNET show characteristic cytomorphology that enables us to consider this specific diagnosis at first diagnostic sampling. It is crucial to diagnose this variant early given the propensity of small tumors with regional lymph node involvement and liver metastases.

Surufatinib-induced renal thrombotic microangiopathy: first case report and review of literature

Angiogenesis inhibitors such as tyrosine kinase inhibitors (TKIs) are common therapeutics currently used to treat oncologic disease. Surufatinib is a novel, small-molecule multiple receptor TKI approved by the National Medical Products Administration (NMPA) for the treatment of progressive, advanced, and well-differentiated pancreatic and extrapancreatic neuroendocrine tumours (NETs). Thrombotic microangiopathy (TMA) is a well-documented complication of TKIs targeting the VEGF-A/VEGFR2 signalling pathway. Here, we describe a 43-year-old female patient with biopsy-proven TMA and nephrotic syndrome due to surufatinib treatment for adenoid cystic carcinoma. Histological lesions included glomerular endothelial swelling, widening of subendothelial spaces, mesangiolysis, and double contour, which caused nephrotic proteinuria. Effective management was achieved by drug withdrawal and oral anti-hypertensive regents. The management of surufatinib-related nephrotoxicity without compromising its anticancer effects is challenging. Hypertension and proteinuria must be closely monitored during drug use to reduce or stop the dose in a timely manner before severe nephrotoxicity occurs.

Somatostatin receptor activity assessed by 68Ga-DOTATOC PET can preoperatively predict DAXX/ATRX loss of expression in well-differentiated pancreatic neuroendocrine tumors.

To evaluate the role of 68Ga-DOTATOC PET parameters in predicting DAXX/ATRX loss of expression in patients with Pancreatic neuroendocrine tumors (PanNET) candidate to surgery. This retrospective study included 72 consecutive patients with PanNET (January 2018-March 2022) who underwent to 68Ga-DOTATOC PET for preoperative staging. Image analysis: qualitative assessment and extraction of SUVmax, SUV mean, somatostatin receptor density (SRD), and total lesion somatostatin receptor density (TLSRD) from primary PanNET. Radiological diameter and biopsy information (grade, Ki67) were collected. Loss of expression (LoE) of DAXX/ATRX was assessed by immunohistochemistry on surgical specimen. Student t-test, univariate and multivariate logistic regression and ROC curves have been used to investigate the predictive value of PET parameters on DAXX/ATRX LoE. Forty-two/72 patients had a G1, 28/72 a G2, and 2/72 a G3 PanNET. Seven/72 patients had DAXX LoE, 10/72 ATRX LoE, and 2/72 DAXX/ATRX LoE. SRD and TLSRD could predict DAXX LoE (p = 0.002, p = 0.018, respectively). By evaluating SRD in combination with radiological diameter, only SRD maintained statistical significance (multivariate logistic regression: p = 0.020, OR = 1.05), providing the best prediction (AUC-ROC = 79.01%; cut-off = 46.96; sensitivity = 77.78%; specificity = 88.89%). In the sub-analysis performed on 55 patients with biopsy availability, SRD demonstrated its role in providing useful and additional information (multivariate logistic regression: SRD p = 0.007; grade p = 0.040). SRD has a predictive role on DAXX LoE in PanNETs, with higher probability of LoE at increasing SRD values. SRD provides complementary/additional information to grade assessed on biopsy material, and the combined use of these approaches might support patients' management by preoperatively identifying subjects with more aggressive diseases.