Primary Pancreatic Tumors Research Articles

Abstract PO-062: EMT-induced gemcitabine resistance in pancreatic cancer involves the functional loss of equilibrative nucleoside transporter 1

Abstract Epithelial-mesenchymal transition (EMT) in cancer cells drives cancer chemoresistance, yet the molecular events of EMT that underpin the acquisition of chemoresistance are poorly understood. Here, we demonstrate a significant loss of gemcitabine chemosensitivity facilitated by human equilibrative nucleoside transporter 1 (ENT1) during EMT in pancreatic cancer and identify that cadherin switching from the epithelial (E) to neuronal (N) type, a hallmark of EMT, contributes to this loss. Our findings demonstrate that N-cadherin decreases ENT1 expression, basolateral membrane localization and gemcitabine transport, while E-cadherin augments each of these. Besides E- and N-cadherin, another epithelial cell adhesion molecule, EpCAM, played a more prominent role in determining ENT1 membrane localization. Forced expression of EpCAM opposed cadherin switching with restored ENT1 expression, basolateral localization and gemcitabine transport in EMT-committed pancreatic cancer cells. In gemcitabine-treated mice, EpCAM positive tumors had high ENT1 expression and reduced metastasis, whereas tumors with N-cadherin expression resisted gemcitabine treatment and formed extensive secondary metastatic nodules. Tissue microarray profiling and multiplexed immunohistochemical analysis of pancreatic cancer patient-derived primary tumors revealed EpCAM and ENT1 cell surface co-expression is favored, and ENT1 plasma membrane expression positively predicted median overall survival times in patients treated with adjuvant gemcitabine. Together, our findings identify ENT1 as an inadvertent target of EMT signaling mediated by cadherin switching and provide a mechanism by which mesenchymal pancreatic cancer cells evade gemcitabine therapy during EMT. Citation Format: Brenna Weadick, Debasis Nayak, Avinash K. Persaud, Sau Wai Hung, Radhika Raj, Wei Chen, Junan Li, Terence M. Williams, Rajgopal Govindarajan. EMT-induced gemcitabine resistance in pancreatic cancer involves the functional loss of equilibrative nucleoside transporter 1 [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-062.

Abstract PO-008: Multi-omic Profiling of primary pancreatic adenocarcinomas obtained from the APACT adjuvant trial of nab-paclitaxel + gemcitabine vs gemcitabine

Abstract Pancreatic ductal adenocarcinoma (PDAC) remains a difficult disease to treat, with few therapies available that target specific patient subgroups. Translational studies in pancreatic cancer can be technically challenging due to biopsy specimen characteristics including low tumor cellularity and dense fibrotic stroma. Resected primary pancreatic tumors obtained during the phase 3 APACT clinical trial (NCT01964430 adjuvant nab-paclitaxel + gemcitabine versus gemcitabine monotherapy n = 866) are a unique resource for characterizing molecular and immune subtypes among PDAC tumors and their association with treatment outcomes in the adjuvant chemotherapy setting. Tumor-infiltrating immune cells were assessed in serial sections of 453 tumors by dual-chromogen immuno-histochemical (IHC) staining (CD4 CD8 CD20 CD163 CMAF CD56 FoxP3 PD-1 PD-L1). Image alignment, segmentation, and spatial localization of stained cells relative to a pan-cytokeratin staining-based tumor epithelial mask was performed using a commercial analysis platform. Expression profiles were obtained for 515 macrodissected tumor biopsy regions by RNA-seq. Transcriptional subtypes were assigned based on schema previously reported by Moffit and Bailey, and molecular pathway correlates were characterized using gene set enrichment analysis. Based on immunochemical staining, higher intratumoral CD8+ or lower CD163+ cell densities were associated with modestly longer disease-free or overall survival in patients treated with nab-paclitaxel plus gemcitabine. The combination of both high CD8+ and low CD163+ cell density was notably associated with longer overall survival compared to other subjects treated with the combination regimen (mOS>55months versus 36 months HR=0.46 p=<0.01) Transcriptional subtyping of tumors, based on schema such as those previously reported by Moffit et al or Bailey et al, identified groups defined by anticipated signatures. Classical/progenitor subtypes differentially expressed genes involved in oxidative respiration and endodermal cell fate, while basal/squamous subtypes showed high expression of signatures for hypoxia, mesenchymal transformation, and TGFb signaling. Longer overall survival in subjects treated with nab-paclitaxel plus gemcitabine as compared to gemcitabine monotherapy was seen principally in subjects with tumors of Moffit classical (HR=0.59 P=0.01) and Bailey progenitor (HR=0.42 P<0.01) subtypes. The observations highlighted provide insight into primary PDAC tumor characteristics that are associated with treatment-specific outcomes to nab-paclitaxel based adjuvant chemotherapy. Future work will combine data described here with mutational and genetic studies in progress as well as with other public, proprietary, or commercial data sources. In combination, we anticipate that these data may be useful in identifying patient subsets and molecular mechanisms that might be targeted by novel combination therapies for improved treatment of pancreatic cancer. Citation Format: Thomas Lila, Andrew Biankin, Andrew Browne, David J. Reiss, Brian Lu, Daniel Pierce, Alexander Ratushny, Kao-tai Tsai, Sneh Lata, Sitharthan Kamalakaran, Tomas Babak, Brian Fox, Sam Danziger, Konstantinos Mavrommatis, Matthew W. B. Trotter, David Chang, Fadi Towfic. Multi-omic Profiling of primary pancreatic adenocarcinomas obtained from the APACT adjuvant trial of nab-paclitaxel + gemcitabine vs gemcitabine [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-008.

Validation of Prognostic Radiomic Features From Resectable Pancreatic Ductal Adenocarcinoma in Patients With Advanced Disease Undergoing Chemotherapy.

Radiomic features in pancreatic ductal adenocarcinoma (PDAC) often lack validation in independent test sets or are limited to early or late stage disease. Given the lethal nature of PDAC it is possible that there are similarities in radiomic features of both early and advanced disease reflective of aggressive biology. To assess the performance of prognostic radiomic features previously published in patients with resectable PDAC in a test set of patients with unresectable PDAC undergoing chemotherapy. The pre-treatment CT of 108 patients enrolled in a prospective chemotherapy trial were used as a test cohort for 2 previously published prognostic radiomic features in resectable PDAC (Sum Entropy and Cluster Tendency with square-root filter[Sqrt]). We assessed the performance of these 2 radiomic features for the prediction of overall survival (OS) and time to progression (TTP) using Cox proportional-hazard models. Sqrt Cluster Tendency was significantly associated with outcome with a hazard ratio (HR) of 1.27(for primary pancreatic tumor plus local nodes), (Confidence Interval(CI):1.01 -1.6, P-value = 0.039) for OS and a HR of 1.25(CI:1.00 -1.55, P-value = 0.047) for TTP. Sum entropy was not associated with outcomes. Sqrt Cluster Tendency remained significant in multivariate analysis. The CT radiomic feature Sqrt Cluster Tendency, previously demonstrated to be prognostic in resectable PDAC, remained a significant prognostic factor for OS and TTP in a test set of unresectable PDAC patients. This radiomic feature warrants further investigation to understand its biologic correlates and CT applicability in PDAC patients.

Primary pancreatic glomus tumor invading into the superior mesenteric vein: a case report.

BackgroundGlomus tumors are subcutaneous tumors arising from glomus bodies, thermoregulatory components of the skin. These tumors could occur in visceral organs where glomus bodies are not normally present. Herein, we report a case of primary pancreatic glomus tumor with aggressive direct invasion into the superior mesenteric vein (SMV). To the best of our knowledge, this is the second case report of a glomus tumor arising in the pancreas.Case presentationA 46-year-old woman was referred to our hospital due to vomiting with epigastric and back pain. Dynamic-CT revealed a well-circumscribed hypervascular mass, measuring 37 mm in its maximal diameter involving the pancreatic head. Both CT and endoscopic ultrasonography (EUS) revealed direct invasion into the SMV and radiologically suspected tumor thrombus. Biopsy sample obtained by EUS-guided fine needle aspiration revealed proliferation of small cells, round-to-oval tumor cells with round nuclei and scant cytoplasm. A histological diagnosis of pancreatic neuroendocrine tumor, G1 was initially considered. Therefore, subtotal stomach-preserving pancreatoduodenectomy using Child-II reconstruction was subsequently performed. Her SMV was resected and reconstructed due to extensive tumor involvement. Subsequent histopathological analysis revealed solid tumor cells proliferation that comprised oval-shaped nuclei and scant cytoplasm around disorganized or slit-shaped vessels in hematoxylin–eosin-stained slides. Immunohistochemical analysis then demonstrated positive immunoreactivity for smooth muscle actin, vimentin, and CD34, but negative for chromogranin A, synaptophysin, CD56, and signal transducer and activator of transcription 6. Based on these histological findings of resected specimens, the lesion was subsequently diagnosed as a primary pancreatic glomus tumor harboring direct invasion into the SMV. Her postoperative course was uneventful and annual surveys for the following 4 years post-op detected no clinical signs of recurrence.ConclusionsWe report a very rare case of glomus tumor of the pancreas accompanied by venous invasion. Curative surgical resection is the best treatment option for pancreatic glomus tumors. Although pancreatic glomus tumor is rare, it should be taken into consideration in the differential diagnosis of a pancreatic solid tumor with hypervascularity.

Clinical Efficacy of High-dose Hypofractionated Radiotherapy for Oligometastases From Pancreatic Cancer after Radiochemotherapy

The aim of the study reported here was to assess the clinical efficacy of high-dose hypofractionated radiotherapy (HDHR) for oligometastases from pancreatic cancer after radiochemotherapy. Patients with newly diagnosed oligometastases from pancreatic cancer were included in this study if (1) the pancreatic primary tumor was controlled after radiochemotherapy; (2) patients were ineligible for or refused surgery; (3) patients had 5 or fewer metastatic lesions in no more than 3 organs. All metastatic lesions were treated with HDHR. The metastases were treated with a dose of 70-50Gy in 15 or 20 fractions. According to the curative effect of previous chemotherapy, individual concurrent and sequential chemotherapy schemes were chosen. Treatment toxicity was scored according to the NCI Common Terminology Criteria for Adverse Events (CTCAE) v4.02. Local control rate (LCR), progression free survival (PFS) and overall survival (OS) were calculated, and various potentially prognostic factors were evaluated. 41 patients with 108 metastatic tumors were analyzed. LCR was 85.2%. Median PFS and median OS were 4.2 months and 8.3 months, respectively. The 1-year PFS and 1-year OS rate were 19.5% and 37.7%, respectively. Three grade 3 and no grade 4 toxicity were reported. The BED10 and KPS score were independent prognostic factors for overall survival (p = 0.042 and p = 0.020, respectively). Radiotherapy is still of great clinical value when new oligometastases appear after radiochemotherapy. The higher the dose of radiotherapy, the longer the survival time.

7-T MRI of explanted liver and ex-vivo pancreatic specimens: prospective study protocol of radiological-pathological correlation feasibility (the EXLIPSE project)

The study focuses on radiological-pathological correlation between imaging of ex vivo samples obtained by a 7-T scanner and histological examination. The specimens will be derived from native explanted cirrhotic livers, liver grafts excluded from donation because of severe steatosis, and primary pancreatic tumours. Magnetic resonance imaging (MRI) examinations will be performed within 24 h from liver or pancreatic lesion surgical removal. The MRI protocol will include morphological sequences, quantitative T1, T2, and fat-, water-fraction maps with Cartesian k-space acquisition, and multiparametric methods based on a transient-state “MRI fingerprinting”. Finally, the specimen will be fixed by formalin. Qualitative imaging analysis will be performed by two independent blinded radiologists to assess image consistency score. Quantitative analysis will be performed by drawing regions of interest on different tissue zones to measure T1 and T2 relaxation times as well as fat- and water-fraction. The same tissue areas will be analysed by the pathologists. This study will provide the possibility to improve our knowledge about qualitative and quantitative abdominal imaging assessment at 7 T, by correlating imaging characteristics and the corresponding histological composition of ex vivo specimens, in order to identify imaging biomarkers. Trial registration: ClinicalTrials.gov: 13646. Registered 9 July 2019—retrospectively registered

S1440 A Case Series of Five Solid Pseudopapillary Neoplasm of Pancreas: Comparison of Four Putative Immunohistochemical Stains With Four Conventional Immunohistochemical Stains

INTRODUCTION: Solid pseudopapillary neoplasm (SPN), a rare exocrine tumor, accounts for 0.2-2.7% of primary pancreatic tumors occurs mostly in young females. The histologic origin is debatable and thus, it is important to identify the most sensitive and specific biomarkers. Through this case series, we are addressing the comparative analysis of four commonly used immunostains with 4 new putative immunohistochemical markers. CASE DESCRIPTION/METHODS: We performed an electronic search of pathology records for a 25 years-period (1994-2019) for SPN. Formalin-fixed, paraffin-embedded tissue blocks were retrieved and used for staining for four commonly used (CD-10, Beta- Catenin, Progesterone receptor, Alpha-1 antitrypsin) and four new (LEF-1, TFE-3, SOX-11 and AMACR) immunohistochemical markers.: In our case-series, female-to-male ratio is 4:1, with a mean age of 37.6 years. The tumor size ranged from 2.3 to 14 cm. Only one case showed aggressive features of necrosis, perineural invasion and lymphovascular invasion. None of the cases showed lymph node or distant metastasis. The results from the immunohistochemical staining are noted in Table 1. DISCUSSION: In our case series, lymphoid enhancer factor-1 (LEF-1) emerged out as the most sensitive new putative marker with 100% diffuse nuclear positivity among the other new markers. To the best of our knowledge, these novel results are noted for the first time in our case series. This significant finding is in congruence with the emerging molecular diagnostic finding that the long isoform of LEF-1 expresses b-catenin binding domain and functions as a transcriptional enhancer factor. It also emphasizes the involvement of Wnt/β-catenin signaling pathway in the histologic origin of this tumor. Further studies are needed to evaluate its specificity especially against SPN mimickers such as Acinar-cell carcinoma and pancreatic neuroendocrine tumors.Figure 1.: Figure 1: A. Solid pseudopapillary neoplasm H&E section at 200x. B. SPN TFE-3 stain at 200x C. SPN Alpha 1 antitrypsin 200x D. SPN AMACR stain at 400x E. SPN Beta Catenin at 400x F. SPN CD10 at 400x G. SPN LEF-1 stain at 400x H. SPN SOX-11 stain at 400x.Table 1.: Staining pattern and comparison of four conventional stains with 4 putative stains in 5 cases of Solid Pseudopapillary neoplasm of pancreas.

Proteomic Analysis of Cell Lines and Primary Tumors in Pancreatic Cancer Identifies Proteins Expressed Only In Vitro and Only In Vivo.

A limited repertoire of good pancreatic ductal adenocarcinoma (PDAC) models is one of the main barriers in developing effective new PDAC treatments. We aimed to characterize 6 commonly used PDAC cell lines and compare them with PDAC patient tumor samples using proteomics. Proteomic methods were used to generate an extensive catalog of proteins from 10 PDAC surgical specimens, 9 biopsies of adjacent normal tissue, and 6 PDAC cell lines. Protein lists were interrogated to determine what extent the proteome of the cell lines reflects the proteome of primary pancreatic tumors. We identified 7973 proteins from the cell lines, 5680 proteins from the tumor tissues, and 4943 proteins from the adjacent normal tissues. We identified 324 proteins unique to the cell lines, some of which may play a role in survival of cells in culture. Conversely, a list of 63 proteins expressed only in the patient samples, whose expression is lost in culture, may place limitations on the degree to which these model systems reflect tumor biology in vivo. Our work offers a catalog of proteins detected in each of the PDAC cell lines, providing a useful guide for researchers seeking model systems for PDAC functional studies.

Abstract 6651: Combination of hetIL-15 with chemotherapy in triple negative breast and pancreatic cancer mouse models increases tumor necrosis and alleviates metastatic disease

Abstract Introduction: We evaluated the potential therapeutic benefit of conventional chemotherapy combined with hetIL-15 immunotherapy in two mouse models of pancreatic and breast cancer. IL-15 is an important cytokine that stimulates the proliferation and cytotoxic functions of CD8+ T cells and NK cells. We have produced the native heterodimeric form of IL-15 (hetIL-15), which has advanced in clinical trials due to its anticancer activities. Study design and methods: We assessed the efficacy of hetIL-15 immunotherapy in combination with the chemotherapeutic agents gemcitabine or doxorubicin on the growth of primary pancreatic and breast tumors, and on the metastatic disease. We used the genetically engineered mouse model (GEMM) KPC of pancreatic cancer (LSL-KrasG12D/+;LSL-Trp53R172H/+;Pdx-1-Cre) and the orthotopic 4T1 triple negative breast cancer (TNBC) model. We analyzed the tumor infiltrating lymphocytes (TILs) by flow cytometry and immunohistochemistry (IHC) and evaluated the extent of necrosis on the primary tumors by H&E and cytokeratin staining. We also evaluated the lung metastatic burden by histology. Results: The combination of hetIL-15 and doxorubicin significantly delayed 4T1 tumor growth. In addition, histological analysis showed an increase in the percentage of the necrotic areas of the primary tumors in the combination group. hetIL-15 treated groups also showed increased necrotic areas of the primary pancreatic tumors, although tumor growth showed no significant change compared to the control group. Flow analysis of TILs showed increased CD8+/CD4+ T cell ratios in tumors of hetIL-15 treated groups in both cancer models, which was confirmed by IHC. Importantly, the evaluation of the metastatic disease showed that hetIL-15 treated animals in both cancer models had reduced metastatic foci and in some cases were completely disease free. Chemotherapy did not significantly reduce the numbers of the total metastatic lesions but reduced their size. Conclusions: Chemotherapy can be combined with hetIL-15 treatment in both breast and pancreatic mouse models. Despite small beneficial results in the size of primary tumor, histological evaluation revealed increased tumor necrosis and potential synergy of chemotherapy and immunotherapy. The observed decreased metastatic burden in the lungs in both cancer models indicates that hetIL-15 strongly reduces metastases in several cancer types and suggests that hetIL-15 is a promising therapeutic agent against metastatic disease. Citation Format: Dimitris Stellas, Vasiliki Stravokefalou, Sevasti Karaliota, Bethany Nagy, Serguei Koslov, Konstantinos Dimas, Barbara K. Felber, George N. Pavlakis. Combination of hetIL-15 with chemotherapy in triple negative breast and pancreatic cancer mouse models increases tumor necrosis and alleviates metastatic disease [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6651.

Comparing prognostic factors of Glut-1 expression and maximum standardized uptake value by FDG-PET in patients with resectable pancreatic cancer

BackgroundThis study aimed to assess the prognostic values of preoperative maximum standardized uptake value (SUVmax) of primary pancreatic tumors and Glut-1 expression in patients with resectable pancreatic ductal adenocarcinoma (R-PDAC), and to investigate whether Glut-1 expression is more effective than SUVmax in predicting survival in patients with R-PDAC. MethodsWe investigated 101 R-PDAC patients who underwent pancreatectomy for pancreatic cancer treatment. SUVmax analyzed through 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT), and Glut-1 expression, were assessed for predicting the prognosis of patients with R-PDAC. ResultsIn patients with R-PDAC, the high SUVmax group (≥4.25) had significantly shorter overall survival (OS) and disease-free survival (DFS) than the low SUVmax group (＜4.25). Surprisingly, Glut-1 expression was not significantly correlated with SUVmax. Moreover, the high Glut-1 expression group, which was related to higher levels of CA 19–9, had significantly shorter OS and DFS than the low Glut-1 expression group. Furthermore, among the high SUVmax group, OS and DFS were significantly shorter in the high Glut-1 expression group. Multivariate analyses revealed that Glut-1 overexpression was an independent prognostic factor in patients with R-PDAC. Glut-1 knockdown also induced cell cycle arrest in PDAC cells in vitro. ConclusionsThe study determined that Glut-1 overexpression is a more powerful prognostic factor than SUVmax for predicting OS and higher risk of recurrence in R-PDAC patients. Glut-1 overexpression is also more likely to be associated with malignant activity in PDAC patients.

Primary Pancreatic Diffuse Large B-Cell Lymphoma Involving the Stomach

Primary pancreatic lymphoma (PPL) is extremely rare, comprising fewer than 1% of non-Hodgkin lymphomas. The most common histological subtype of PPL is diffuse large Bcell lymphoma (DLBCL). A 46-year-old man presented with indigestion, epigastric pain, and weight loss for 2 months. Abdominal computed tomography showed a well-defined hypodense mass located at the pancreas head involving the stomach, as well as enlargement of several mesenteric and perigastric lymph nodes. Histological examination was performed by upper gastrointestinal endoscopy of the stomach and endoscopic ultrasound-guided fine-needle aspiration and biopsy of the pancreatic mass. Histology of the pancreatic mass and the stomach revealed pancreatic DLBCL, involving the stomach. The patient received chemotherapy and is currently in complete remission. We report a rare presentation of DLBCL, appearing as a primary pancreatic tumor involving the stomach, which we presume is the first such report in South Korea.

Pancreatic Adenocarcinoma with Primary Tumor Calcification and Calcified Liver Metastasis: Report of a Rare Case and Review of Literature

AbstractCalcification is a feature of benign pancreatic diseases such as chronic calcific pancreatitis (CCP) or benign pancreatic tumors such as solid and papillary epithelial neoplasm of the pancreas and serous cystadenoma. The presence of calcification in a primary malignant pancreatic tumor is uncommon except for neuroendocrine tumors of the pancreas. Calcification in adenocarcinoma of the pancreas involving the primary tumor as well as the metastasis resulting thereof is extremely rare in the absence of CCP. To our knowledge, this is the first report of a case of primary adenocarcinoma of the pancreas that presented with calcification of the primary tumor as well as the metastatic liver nodules, accompanied by hypercalcemia.

P-155 Efficacy of somatostatin analogues in the treatment of metastatic and unresectable pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumours represent 1.3% of primary pancreatic tumours. Evidence for the use of somatostatin analogues for pNET is solid in favour of lanreotide, while the potential benefit of octreotide remains unclear beyond symptom control.

Development of a non-functional pancreatic neuroendocrine tumor and a duodenal ulceration after cholecystoduodenostomy in a cat

A six-year-old Ragdoll with previous extrahepatic biliary tract obstruction due to cholangiohepatitis, treated with cholecystoduodenostomy, was presented for acute vomiting, hyporexia, and weight loss. Abdominal ultrasound examination revealed randomly distributed hepatic nodules and dilated biliary ducts. Gastroduodenoscopy showed a patent cholecystoduodenostoma but disclosed a perforated duodenal ulceration. Conversion to celiotomy revealed extensive liver pathology, a discrete pancreatic nodule, and a duodenal ulcer opposite to the cholecystoduodenostoma. The cat was euthanized intra-operatively and necropsy was performed. The intrahepatic biliary tract of the right liver lobes was obstructed and severely dilated, whereas bile from the left lobes drained through the cholecystoduodenostoma. Histopathologic diagnoses were a primary pancreatic tumor, positive for glucagon on immunohistochemistry, with liver metastases, chronic purulent cholecystitis, and duodenal ulceration. To the authors’ knowledge, this is the first report in which the development of pancreatic neoplasia is described in a cat with a history of biliary tract disease.

Metastatic pancreatic neuroendocrine tumors have decreased somatostatin expression and increased Akt signaling

BackgroundPatients with pancreatic neuroendocrine tumors often present with metastases, which reduce survival. Molecular features associated with pancreatic neuroendocrine tumor tumorigenesis have been reported, but mechanisms of metastasis remain incompletely understood. MethodsRNA sequencing was performed on primary and metastatic pancreatic neuroendocrine tumors from 43 patients. Differentially expressed genes were identified, and quantitative polymerase chain reaction used to confirm expression differences. BON cells were transfected with short interfering RNAs and short hairpin RNAs to create knockdowns. Expression changes were confirmed by quantitative polymerase chain reaction, cell viability assessed, and protein levels evaluated by Western blot and immunofluorescence. ResultsNodal and hepatic metastases had decreased expression of somatostatin compared with primary tumors (P = .003). Quantitative polymerase chain reaction in a validation cohort confirmed 5.3-fold lower somatostatin expression in hepatic metastases (P = .043) with no difference in somatostatin receptor, synaptophysin, or chromogranin A expression. Somatostatin knockdown in BON cells increased cell metabolic activity, viability, and growth. Somatostatin-knockdown cells had significantly higher levels of phosphorylated Akt protein and higher mTOR compared with controls. ConclusionPancreatic neuroendocrine tumor metastases have lower expression of somatostatin than primary tumors, and somatostatin knockdown increased growth in pancreatic neuroendocrine tumor cell lines. This was associated with increased activation of Akt, identifying this pathway as a potential mechanism by which loss of somatostatin expression promotes the metastatic phenotype.

The impact of immunotherapy on the survival of pancreatic adenocarcinoma patients who do not receive definitive surgery of the tumor

Background and PurposeImmunotherapy has shown great efficacy in many cancers, but its role in pancreatic ductal adenocarcinoma (PDAC) remains unclear. The objective of this study was to investigate the impact of immunotherapy on the overall survival of PDAC patients who did not receive definitive surgery of the pancreatic primary tumor site using the National Cancer Database (NCDB). Materials and MethodsPatients with pancreatic adenocarcinoma who did not receive surgery were identified from NCDB. Cox proportional hazard models were employed to assess the impact of immunotherapy on survival after adjusting for age at diagnosis, race, sex, place of living, income, education, treatment facility type, insurance status, year of diagnosis, and treatment types such as chemotherapy and radiation therapy. ResultsOf 263,886 patients who were analyzed, 911 (0.35%) received immunotherapy. Among patients who received chemotherapy (101,546), and chemoradiation (30,226) therapy, 555/101,546 (0.55%) received chemotherapy plus immunotherapy, and 299/3,022 (9.9%) received chemoradiation plus immunotherapy. In a multivariable analysis adjusted for the factors mentioned above, immunotherapy was associated with significantly improved OS (HR: 0.866 (0.800–0.937); P < 0.001) compared to no immunotherapy. Chemotherapy plus immunotherapy was significantly associated with improved OS (HR: 0.848 (0.766–0.938); P < 0.001) compared to chemotherapy without immunotherapy. Further, chemoradiation plus immunotherapy was associated with significantly improved OS (HR: 0.813 (0.707–0.936); P < 0.001) compared to chemoradiation alone. ConclusionIn this study, the addition of immunotherapy to chemotherapy and chemoradiation therapy was associated with significantly improved OS in PDAC patients without definitive surgery. The study warrants future clinical trials of immunotherapy in PDAC.

Development and Validation of a Modified Eighth AJCC Staging System for Primary Pancreatic Neuroendocrine Tumors.

To improve the prognostic accuracy of the eighth edition of AJCC staging system for pNETs with establishment and validation of a new staging system. Validation of the updated eighth AJCC staging system for pNETs has been limited and controversial. Data from the SEER registry (1975-2016) (n = 3303) and a multi-institutional database (2000-2016) (n = 825) was used as development and validation cohorts, respectively. A mTNM was proposed by maintaining the eighth AJCC T and M definitions, and the recently proposed N status as N0 (no LNM), N1 (1-3 LNM), and N2 (≥4 LNM), but adopting a new stage classification. The eighth TNM staging system failed to stratify patients with stage I versus IIA, stage IIB versus IIIA, and overall stage I versus II relative to long-term OS in both database. There was a monotonic decrement in survival based on the proposed mTNM staging classification among patients derived from both the SEER (5-year OS, stage I 87.0% vs stage II 80.3% vs stage III 72.9% vs stage IV 57.2%, all P < 0.001), and multi-institutional (5-year OS, stage I 97.6% vs stage II 82.7% vs stage III 78.4% vs stage IV 50.0%, all P < 0.05) datasets. On multivariable analysis, mTNM staging remained strongly associated with prognosis, as the hazard of death incrementally increased with each stage among patients in the 2 cohorts. A mTNM pNETs clinical staging system using N0, N1, N2 nodal categories was better at stratifying patients relative to long-term OS than the eighth AJCC staging.

Surgical management of primary pancreatic neuroendocrine tumors.

Pancreatic neuroendocrine tumors (PanNETs) are the second most common malignancy of the pancreas, and their incidence is increasing. PanNETs are a diverse group of diseases which range from benign to malignant, can be sporadic or associated with genetic mutations, and be functional or nonfunctional. In as much, the treatment and management of PanNETs can vary from a "Wait and See" approach to orthotopic liver transplantation (OLT). Despite this, surgical resection is still the primary treatment modality to achieve cure. This review focuses on the surgical management of PanNETs.

CD200 promotes immunosuppression in the pancreatic tumor microenvironment.

BackgroundA significant challenge to overcome in pancreatic ductal adenocarcinoma (PDAC) is the profound systemic immunosuppression that renders this disease non-responsive to immunotherapy. Our supporting data provide evidence that CD200, a regulator of myeloid cell activity, is expressed in the PDAC microenvironment. Additionally, myeloid-derived suppressor cells (MDSC) isolated from patients with PDAC express elevated levels of the CD200 receptor (CD200R). Thus, we hypothesize that CD200 expression in the PDAC microenvironment limits responses to immunotherapy by promoting expansion and activity of MDSC.MethodsImmunofluorescent staining was used to determine expression of CD200 in murine and human PDAC tissue. Flow cytometry was utilized to test for CD200R expression by immune populations in patient blood samples. In vivo antibody blocking of CD200 was conducted in subcutaneous MT-5 tumor-bearing mice and in a genetically engineered PDAC model (KPC-Brca2 mice). Peripheral blood mononuclear cells (PBMC) from patients with PDAC were analyzed by single-cell RNA sequencing. MDSC expansion assays were completed using healthy donor PBMC stimulated with IL-6/GM-CSF in the presence of recombinant CD200 protein.ResultsWe found expression of CD200 by human pancreatic cell lines (BxPC3, MiaPaca2, and PANC-1) as well as on primary epithelial pancreatic tumor cells and smooth muscle actin+ stromal cells. CD200R expression was found to be elevated on CD11b+CD33+HLA-DRlo/− MDSC immune populations from patients with PDAC (p=0.0106). Higher expression levels of CD200R were observed in CD15+ MDSC compared with CD14+ MDSC (p<0.001). In vivo studies demonstrated that CD200 antibody blockade limited tumor progression in MT-5 subcutaneous tumor-bearing and in KPC-Brca2 mice (p<0.05). The percentage of intratumoral MDSC was significantly reduced in anti-CD200 treated mice compared with controls. Additionally, in vivo blockade of CD200 can also significantly enhance the efficacy of PD-1 checkpoint antibodies compared with single antibody therapies (p<0.05). Single-cell RNA sequencing of PBMC from patients revealed that CD200R+ MDSC expressed genes involved in cytokine signaling and MDSC expansion. Further, in vitro cytokine-driven expansion and the suppressive activity of human MDSC was enhanced when cocultured with recombinant CD200 protein.ConclusionsThese results indicate that CD200 expression in the PDAC microenvironment may regulate MDSC expansion and that targeting CD200 may enhance activity of checkpoint immunotherapy.

Patient Derived Xenografts Expand Human Primary Pancreatic Tumor Tissue Availability for ex vivo Irreversible Electroporation Testing

New methods of tumor ablation have shown exciting efficacy in pre-clinical models but often demonstrate limited success in the clinic. Due to a lack of quality or quantity in primary malignant tissue specimens, therapeutic development and optimization studies are typically conducted on healthy tissue or cell-line derived rodent tumors that don't allow for high resolution modeling of mechanical, chemical, and biological properties. These surrogates do not accurately recapitulate many critical components of the tumor microenvironment that can impact in situ treatment success. Here, we propose utilizing patient-derived xenograft (PDX) models to propagate clinically relevant tumor specimens for the optimization and development of novel tumor ablation modalities. Specimens from three individual pancreatic ductal adenocarcinoma (PDAC) patients were utilized to generate PDX models. This process generated 15–18 tumors that were allowed to expand to 1.5 cm in diameter over the course of 50–70 days. The PDX tumors were morphologically and pathologically identical to primary tumor tissue. Likewise, the PDX tumors were also found to be physiologically superior to other in vitro and ex vivo models based on immortalized cell lines. We utilized the PDX tumors to refine and optimize irreversible electroporation (IRE) treatment parameters. IRE, a novel, non-thermal tumor ablation modality, is being evaluated in a diverse range of cancer clinical trials including pancreatic cancer. The PDX tumors were compared against either Pan02 mouse derived tumors or resected tissue from human PDAC patients. The PDX tumors demonstrated similar changes in electrical conductivity and Joule heating following IRE treatment. Computational modeling revealed a high similarity in the predicted ablation size of the PDX tumors that closely correlate with the data generated with the primary human pancreatic tumor tissue. Gene expression analysis revealed that IRE treatment resulted in an increase in biological pathway signaling associated with interferon gamma signaling, necrosis and mitochondria dysfunction, suggesting potential co-therapy targets. Together, these findings highlight the utility of the PDX system in tumor ablation modeling for IRE and increasing clinical application efficacy. It is also feasible that the use of PDX models will significantly benefit other ablation modality testing beyond IRE.