GNAS mutation is a frequent event in pancreatic intraductal papillary mucinous neoplasms and associated adenocarcinomas

Neoplastic Progression in Macroscopic Precursor Lesions of the Pancreas

CONTEXT.—

Macroscopic precursor lesions of the pancreas represent a complex clinical management problem. Molecular characterization of pancreatic cysts has helped to confirm and refine clinical and pathologic classifications of these lesions, inform our understanding of tumorigenesis in the pancreas, and provide opportunities for preoperative diagnosis.

OBJECTIVE.—

To review the pathologic classification of macroscopic cystic lesions of the pancreas: intraductal papillary mucinous neoplasms (IPMNs), mucinous cystic neoplasms (MCNs), intraductal oncocytic papillary neoplasms (IOPNs), and intraductal tubulopapillary neoplasms (ITPNs), and to describe our current state of understanding of their molecular underpinnings, relationship to invasive carcinomas, and implications for diagnosis and prognostication.

DATA SOURCES.—

We assessed the current primary literature and current World Health Organization Classification of Digestive System Tumours.

CONCLUSIONS.—

Macroscopic cystic lesions of the pancreas are morphologically and molecularly diverse. IPMNs and MCNs share mucinous cytoplasm with papillae. MCNs are defined by ovarian-type stroma. IOPNs have granular eosinophilic cytoplasm, prominent nucleoli, and complex, arborizing papillae. ITPNs demonstrate complex, back-to-back tubules and anastomosing papillae and lack prominent intracellular mucin. IPMNs and MCNs are characterized by driver mutations in KRAS/GNAS (IPMNs) and KRAS (MCNs), with later driver events in RNF43, CDKN2A, SMAD4, and TP53. In contrast, IOPNs and ITPNs have recurrent rearrangements in PRKACA/PRKACB and MAPK-associated genes, respectively. The recurrent alterations described in cysts provide an opportunity for diagnosis using aspirated cyst fluid. Molecular characterization of IPMNs shows a striking spatial and mutational heterogeneity, challenging traditional models of neoplastic development and creating challenges to interpretation of cyst fluid sequencing results.

KRAS and GNAS mutations in cell-free DNA and in circulating epithelial cells in patients with intraductal papillary mucinous neoplasms-an observational pilot study

Intraductal papillary mucinous neoplasms (IPMNs) are potential precursor lesions of pancreatic cancer. We assessed the efficacy of screening for KRAS proto-oncogene, GTPase (KRAS), and GNAS complex locus (GNAS) mutations in cell-free DNA (cfDNA)-using digital droplet polymerase chain reaction (ddPCR) and circulating epithelial cell (CEC) detection-as biomarkers for risk stratification in IPMN patients. We prospectively collected plasma samples from 25 resected patients at risk of malignant progression, and 23 under clinical surveillance. Our findings revealed KRAS mutations in 10.4% and GNAS mutations in 18.8% of the overall cohort. Among resected IPMN patients, KRAS and GNAS mutation detection rates were 16.0% and 32.0%, respectively, whereas both rates were 4.0% in conservatively managed IPMN. GNAS mutations in cfDNA were significantly more prevalent in resected IPMN (P = 0.024) compared with IPMN under surveillance. No CECs were detected. The absence of KRAS and GNAS mutations could be a reliable marker for branch duct IPMN without worrisome features. The emergence of GNAS mutations could prompt enhanced imaging surveillance. Neither the presence of established worrisome features nor GNAS or KRAS mutations appear effective in identifying high-grade dysplasia among IPMN patients.

Association of elevated autoantibody to high expression of GNAS in hepatocellular carcinoma

Purpose

This study was based on hepatocellular carcinoma (HCC) patients of early-stage to explore the diagnostic capability and possible production causes of anti-GNAS autoantibody.

Methods

We evaluated the frequency of anti-GNAS autoantibody in sera from patients with early-stage HCC by enzyme-linked immunosorbent assay (ELISA) and the expression of GNAS protein in early-stage HCC tissues by immunohistochemistry. Western blotting (WB) and real-time polymerase chain reaction (RT-PCR) were utilized to examine the expressions of GNAS protein and mRNA in cell lines. GEO and International Cancer Genome Consortium (ICGC) databases were inquired to explore mRNA expression and mutation of GNAS in HCC tissues.

Results

The positive rates of anti-GNAS autoantibody in HCC patients at clinical stage I (78.1 %) and clinical stage II (57.1 %) were all significantly higher than that in healthy control (20 %). There was also a significant difference in GNAS protein expression between HCC and its adjacent normal liver tissues. The results from WB and RT-PCR showed a significant difference at the mRNA level but no statistical difference at the protein level between HCC and normal liver cell lines. The difference in mRNA level between HCC and adjacent normal liver tissues was verified to be significant. Furthermore, the ICGC database demonstrated a 10.6 % mutation frequency for GNAS in HCC patients.

Conclusion

The coordination of elevated anti-GNAS autoantibody, high expression of GNAS in the mRNA and protein levels in HCC, and high frequency of GNAS mutation indicates that anti-GNAS autoantibody may be used as an early indicator of HCC.

Co-occurring IPMN and pancreatic cancer: the same or different? An overview from histology to molecular pathology

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is one of the most well-established precursors of pancreatic cancer. Its progression to acquire invasiveness is a complex process, based on the accumulation of morphological and genetic alterations. Recent advances in DNA sequencing also showed that co-occurring IPMNs and pancreatic cancers could be totally independent, further complicating our understanding of this complex scenario. The distinction between IPMN and related pancreatic cancer vs IPMN and co-occurring-but not related-pancreatic cancer is a challenging task in routine diagnostic activity, but may have important implications for precision oncology. Of note, recent multiregional sequencing-based studies focused not only on IPMN multi-step tumourigenesis, but also on the divergent intratumoural heterogeneity of this neoplasm. Globally considered, there are three different situations in which co-occurring IPMNs and invasive carcinomas can be found in the same pancreata, indicated with different terminologies: (1) IPMN-associated carcinoma: this definition indicates a carcinoma arising from an IPMN and can be also defined as IPMN-derived carcinoma, sequential or likely related; (2) independent IPMN and invasive carcinoma: the two lesions are not related, and this situation is defined as concomitant, de novo or likely independent; (3) branch-off pathway, where an invasive carcinoma and an adjacent IPMN develop divergently in a forked fashion from a common ancestral clone. In this review, we aim at clarifying the most important nomenclature/definitions of these different situations, also providing an overview of the molecular state-of-the-art and of the clinical implications of this complex landscape.

Systematic review of challenging issues in pathology of intraductal papillary mucinous neoplasms

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMNs) are a cystic precursor to pancreatic cancer. IPMNs deemed clinically to be at high-risk for malignant progression are frequently treated with surgical resection, and pathological examination of the pancreatectomy specimen is a key component of the clinical care of IPMN patients.

METHODS

Systematic literature reviews were conducted around eight topics of clinical relevance in the examination of pathological specimens in patients undergoing resection of IPMN.

RESULTS

This review provides updated perspectives on morphological subtyping of IPMNs, classification of intraductal oncocytic papillary neoplasms, nomenclature for high-grade dysplasia, assessment of T stage, distinction of carcinoma associated or concomitant with IPMN, role of molecular assessment of IPMN tissue, role of intraoperative assessment by frozen section, and preoperative evaluation of cyst fluid cytology.

CONCLUSIONS

This analysis provides the foundation for data-driven approaches to several challenging issues in the pathology of IPMNs.

First-in-Class NADH/Ubiquinone Oxidoreductase Core Subunit S7 (NDUFS7) Antagonist for the Treatment of Pancreatic Cancer

Pancreatic cancer cells adapt to nutrient-scarce metabolic conditions by increasing their oxidative phosphorylation reserve to survive. Here, we present a first-in-class small-molecule NDUFS7 antagonist that inhibits oxidative phosphorylation (OXPHOS) for the treatment of pancreatic cancer. The lead compound, DX2-201, suppresses the proliferation of a panel of cell lines, and a metabolically stable analogue, DX3-213B, shows significant efficacy in a syngeneic model of pancreatic cancer. Exome sequencing of six out of six clones resistant to DX2-201 revealed a pV91M mutation in NDUFS7, providing direct evidence of its drug-binding site. In combination studies, DX2-201 showed synergy with multiple metabolic modulators, select OXPHOS inhibitors, and PARP inhibitors. Importantly, a combination with 2-deoxyglucose overcomes drug resistance in vivo. This study demonstrates that an efficacious treatment for pancreatic cancer can be achieved through inhibition of OXPHOS and direct binding to NDUFS7, providing a novel therapeutic strategy for this hard-to-treat cancer.

Clinical and Molecular Attributes and Evaluation of Pancreatic Cystic Neoplasm

Intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs) are all considered "Pancreatic cystic neoplasms (PCNs)" and show a varying risk of developing into pancreatic ductal adenocarcinoma (PDAC). These lesions display different molecular characteristics, mutations, and clinical manifestations. A lack of detailed understanding of PCN subtype characteristics and their molecular mechanisms limits the development of efficient diagnostic tools and therapeutic strategies for these lesions. Proper in vivo mouse models that mimic human PCNs are also needed to study the molecular mechanisms and for therapeutic testing. A comprehensive understanding of the current status of PCN biology, mechanisms, current diagnostic methods, and therapies will help in the early detection and proper management of patients with these lesions and PDAC. This review aims to describe all these aspects of PCNs, specifically IPMNs, by describing the future perspectives.

Pancreatic Cystic Lesions: A Focused Review on Cyst Clinicopathological Features and Advanced Diagnostics

Macroscopic, endomicroscopic, and histologic findings and correlation are an integral part of the diagnostic evaluation of pancreatic cystic lesions (PCLs), as complementing morphologic features seen by different specialties are combined to contribute to a final diagnosis. However, malignancy risk stratification of PCLs with worrisome features can still be challenging even after endoscopic ultrasound guided-fine needle aspiration (EUS-FNA) with cytological evaluation. This review aims to summarize cyst clinicopathological features from the pathologists' perspective, coupled with knowledge from advanced diagnostics-confocal laser endomicroscopy and cyst fluid molecular analysis, to demonstrate the state-of-art risk stratification of PCLs. This review includes illustrative photos of surgical specimens, endomicroscopic and histologic images, and a summary of cyst fluid molecular markers.

Integrative characterization of intraductal tubulopapillary neoplasm (ITPN) of the pancreas and associated invasive adenocarcinoma

Pancreatic intraductal tubulopapillary neoplasm (ITPN) is a recently recognized intraductal neoplasm. This study aimed to clarify the clinicopathologic and molecular features of this entity, based on a multi-institutional cohort of 16 pancreatic ITPNs and associated adenocarcinomas. The genomic profiles were analyzed using histology-driven multi-regional sequencing to provide insight on tumor heterogeneity and evolution. Furthermore, an exploratory transcriptomic characterization was performed on eight invasive adenocarcinomas. The clinicopathologic parameters and molecular alterations were further analyzed based on survival indices. The main findings were as follows: 1) the concomitant adenocarcinomas, present in 75% of cases, were always molecularly associated with the intraductal components. These data definitively establish ITPN as origin of invasive pancreatic adenocarcinoma; 2) alterations restricted to infiltrative components included mutations in chromatin remodeling genes ARID2, ASXL1, and PBRM1, and ERBB2-P3H4 fusion; 3) pancreatic ITPN can arise in the context of genetic syndromes, such as BRCA-germline and Peutz-Jeghers syndrome; 4) mutational profile: mutations in the classical PDAC drivers are present, but less frequently, in pancreatic ITPN; 5) novel genomic alterations were observed, including amplification of the Cyclin and NOTCH family genes and ERBB2, fusions involving RET and ERBB2, and RB1 disruptive variation; 6) chromosomal alterations: the most common was 1q gain (75% of cases); 7) by transcriptome analysis, ITPN-associated adenocarcinomas clustered into three subtypes that correlate with the activation of signaling mechanism pathways and tumor microenvironment, displaying squamous features in their majority; and 8) TP53 mutational status is a marker for adverse prognosis. ITPNs are precursor lesions of pancreatic cancer with a high malignant transformation risk. A personalized approach for patients with ITPN should recognize that such neoplasms could arise in the context of genetic syndromes. BRCA alterations, ERBB2 and RET fusions, and ERBB2 amplification are novel targets in precision oncology. The TP53 mutation status can be used as a prognostic biomarker.

A pilot study to evaluate tissue- and plasma-based DNA driver mutations in a cohort of patients with pancreatic intraductal papillary mucinous neoplasms

Intraductal papillary mucinous neoplasms (IPMNs) are precursor lesions to pancreatic ductal adenocarcinoma that are challenging to manage due to limited imaging, cytologic, and molecular markers that accurately classify lesions, grade of dysplasia, or focus of invasion preoperatively. The objective of this pilot study was to determine the frequency and type of DNA mutations in a cohort of surgically resected, pathologically confirmed IPMN, and to determine if concordant mutations are detectable in paired pretreatment plasma samples. Formalin-fixed paraffin-embedded (FFPE) tissue from 46 surgically resected IPMNs (31 low-grade, 15 high-grade) and paired plasma from a subset of 15 IPMN cases (10 low-grade, 5 high-grade) were subjected to targeted mutation analysis using a QIAseq Targeted DNA Custom Panel. Common driver mutations were detected in FFPE from 44 of 46 (95.6%) IPMN cases spanning all grades; the most common DNA mutations included: KRAS (80%), RNF43 (24%), and GNAS (43%). Of note, we observed a significant increase in the frequency of RNF43 mutations from low-grade to high-grade IPMNs associated or concomitant with invasive carcinoma (trend test, P = 0.01). Among the subset of cases with paired plasma, driver mutations identified in the IPMNs were not detected in circulation. Overall, our results indicate that mutational burden for IPMNs is a common occurrence, even in low-grade IPMNs. Furthermore, although blood-based biopsies are an attractive, noninvasive method for detecting somatic DNA mutations, the QIAseq panel was not sensitive enough to detect driver mutations that existed in IPMN tissue using paired plasma in the volume we were able to retrieve for this retrospective study.

The molecular, immune features, and risk score construction of intraductal papillary mucinous neoplasm patients

Intraductal papillary mucinous neoplasm (IPMN) is a common pancreatic precancerous lesion, with increasing incidence in recent years. However, the mechanisms of IPMN progression into invasive cancer remain unclear. The mRNA expression data of IPMN/PAAD patients were extracted from the TCGA and GEO databases. First, based on GSE19650, we analyzed the molecular alterations, tumor stemness, immune landscape, and transcriptional regulation of IPMN progression. The results indicated that gene expression changed dramatically, specifically at the intraductal papillary-mucinous adenoma (IPMA) stage. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Kyoto Encyclopedia of Genes and Genomes (GSEA) pathway analyses showed that glycoprotein-related, cell cycle, and P53 pathways displayed the most significant changes during progression. With IPMN progression, tumor stemness increased continuously, and KRAS, ERBB3, RUNX1, and ELF3 are essential driver genes affecting tumor stemness. Motif analysis suggested that KLF4 may be a specific transcription factor that regulates gene expression in the IPMA stage, while MYB and MYBL1 control gene expression in the IPMC and invasive stages, respectively. Then, GSE19650 and GSE71729 transcriptome data were combined to perform the least absolute shrinkage and selection operator (LASSO) method and Cox regression analysis to develop an 11-gene prediction model (KCNK1, FHL2, LAMC2, CDCA7, GPX3, C7, VIP, HBA1, BTG2, MT1E, and LYVE1) to predict the prognosis of pancreatic cancer patients. The reliability of the model was validated in the GSE71729 and TCGA databases. Finally, 11 additional IPMN patients treated in our hospital were included, and the immune microenvironment changes during IPMN progression were analyzed by immunohistochemistry (IHC). IHC results suggest that Myeloid-derived suppressor cells (MDSCs) and macrophages may be key in the formation of immunosuppressive microenvironment of IPMN progression. Our study deepens our understanding of IPMN progression, especially the changes in the immune microenvironment. The findings of this work may contribute to the development of new therapeutic strategies for IPMN.

Oncogene addiction to GNAS in GNASR201 mutant tumors

The GNAS^R201 gain-of-function mutation is the single most frequent cancer-causing mutation across all heterotrimeric G proteins, driving oncogenesis in various low-grade/benign gastrointestinal and pancreatic tumors. In this study, we investigated the role of GNAS and its product Gαs in tumor progression using peritoneal models of colorectal cancer (CRC). GNAS was knocked out in multiple CRC cell lines harboring GNAS^R201C/H mutations (KM12, SNU175, SKCO1), leading to decreased cell-growth in 2D and 3D organoid models. Nude mice were peritoneally injected with GNAS-knockout KM12 cells, leading to a decrease in tumor growth and drastically improved survival at 7 weeks. Supporting these findings, GNAS overexpression in LS174T cells led to increased cell-growth in 2D and 3D organoid models, and increased tumor growth in PDX mouse models. GNAS knockout decreased levels of cyclic AMP in KM12 cells, and molecular profiling identified phosphorylation of β-catenin and activation of its targets as critical downstream effects of mutant GNAS signaling. Supporting these findings, chemical inhibition of both PKA and β-catenin reduced growth of GNAS mutant organoids. Our findings demonstrate oncogene addiction to GNAS in peritoneal models of GNAS^R201C/H tumors, which signal through the cAMP/PKA and Wnt/β-catenin pathways. Thus, GNAS and its downstream mediators are promising therapeutic targets for GNAS mutant tumors.

Telomere Attrition in Intraductal Papillary Mucinous Neoplasms of the Pancreas Associated With Carcinogenesis and Aging

OBJECTIVES

It is challenging to preoperatively distinguish malignant and benign forms of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. The aims of this study were to investigate whether telomere length is associated with pathological grade of IPMNs and age and to clarify the utility of telomere length as a marker to identify malignant IPMNs.

METHODS

Pancreas tissue was obtained from 28 patients after resection. We measured the telomere lengths of tumor cells in IPMNs and normal duct cells by quantitative fluorescence in situ hybridization. The association of normalized telomere-centromere ratio (NTCR) to pathological grade of IPMNs and age were determined.

RESULTS

The NTCR showed a gradual decrease with increasing pathological grade of IPMNs. The NTCR in intermediate- and high-grade dysplasia and adenocarcinoma lesions was significantly shorter than in normal pancreatic ducts (P < 0.05). In multivariate analysis, telomere length was most associated with carcinogenesis. When the cutoff value of NTCR was set to 0.74, the sensitivity for detection of high-grade dysplasia and adenocarcinoma was 82.8%, with a specificity of 87.5%.

CONCLUSIONS

Telomere shortening occurs with carcinogenesis and aging. A significant reduction of telomere length in IPMNs may be useful for surgical decision making.

Is Biannual Surveillance for Pancreatic Cancer Sufficient in Individuals With Genetic Syndromes or Familial Pancreatic Cancer?

BACKGROUND

Individuals with a family history of pancreatic adenocarcinoma (PC) or with a germline mutation in a PC susceptibility gene are at increased risk of developing PC. These high-risk individuals (HRIs) may benefit from PC surveillance.

METHODS

A PC surveillance program was developed to evaluate the detection of premalignant lesions and early-stage PCs using biannual imaging and to determine whether locally advanced or metastatic PCs develop despite biannual surveillance. From January 2013 to April 2020, asymptomatic HRIs were enrolled and followed with alternating MRI and endoscopic ultrasound every 6 months.

RESULTS

Of 75 HRIs, 43 (57.3%) had a germline mutation in a PC susceptibility gene and 32 (42.7%) had a familial pancreatic cancer (FPC) pedigree. Branch-duct intraductal papillary mucinous neoplasms (BD-IPMNs) were identified in 26 individuals (34.7%), but only 2 developed progressive lesions. One patient with Peutz-Jeghers syndrome (PJS) developed locally advanced PC arising from a BD-IPMN. Whole-genome sequencing of this patient's PC and of a second patient with PJS-associated PC from the same kindred revealed biallelic inactivation of STK11 in a KRAS-independent manner. A review of 3,853 patients from 2 PC registries identified an additional patient with PJS-associated PC. All 3 patients with PJS developed advanced PC consistent with the malignant transformation of an underlying BD-IPMN in <6 months. The other surveillance patient with a progressive lesion had FPC and underwent resection of a mixed-type IPMN that harbored polyclonal KRAS mutations.

CONCLUSIONS

PC surveillance identifies a high prevalence of BD-IPMNs in HRIs. Patients with PJS with BD-IPMNs may be at risk for accelerated malignant transformation.

Current Pathology Model of Pancreatic Cancer

Pancreatic cancer (PC) is one of the most aggressive and lethal malignant neoplasms, ranking in seventh place in the world in terms of the incidence of death, with overall 5-year survival rates still below 10%. The knowledge about PC pathomechanisms is rapidly expanding. Daily reports reveal new aspects of tumor biology, including its molecular and morphological heterogeneity, explain complicated "cross-talk" that happens between the cancer cells and tumor stroma, or the nature of the PC-associated neural remodeling (PANR). Staying up-to-date is hard and crucial at the same time. In this review, we are focusing on a comprehensive summary of PC aspects that are important in pathologic reporting, impact patients' outcomes, and bring meaningful information for clinicians. Finally, we show promising new trends in diagnostic technologies that might bring a difference in PC early diagnosis.

Relevance of gene mutations and methylation to the growth of pancreatic intraductal papillary mucinous neoplasms based on pyrosequencing

We aimed to assess some of the potential genetic pathways for cancer development from non-malignant intraductal papillary mucinous neoplasm (IPMN) by evaluating genetic mutations and methylation. In total, 46 dissected regions in 33 IPMN cases were analyzed and compared between malignant-potential and benign cases, or between malignant-potential and benign tissue dissected regions including low-grade IPMN dissected regions accompanied by malignant-potential regions. Several gene mutations, gene methylations, and proteins were assessed by pyrosequencing and immunohistochemical analysis. RASSF1A methylation was more frequent in malignant-potential dissected regions (p = 0.0329). LINE-1 methylation was inversely correlated with GNAS mutation (r =  - 0.3739, p = 0.0105). In cases with malignant-potential dissected regions, GNAS mutation was associated with less frequent perivascular invasion (p = 0.0128), perineural invasion (p = 0.0377), and lymph node metastasis (p = 0.0377) but significantly longer overall survival, compared to malignant-potential cases without GNAS mutation (p = 0.0419). The presence of concordant KRAS and GNAS mutations in the malignant-potential and benign dissected regions were more frequent among branch-duct IPMN cases than among the other types (p = 0.0319). Methylation of RASSF1A, CDKN2A, and LINE-1 and GNAS mutation may be relevant to cancer development, IPMN subtypes, and cancer prognosis.

Cell Lineage Infidelity in PDAC Progression and Therapy Resistance

Infidelity to cell fate occurs when differentiated cells lose their original identity and either revert to a more multipotent state or transdifferentiate into a different cell type, either within the same embryonic lineage or in an entirely different one. Whilst in certain circumstances, such as in wound repair, this process is beneficial, it can be hijacked by cancer cells to drive disease initiation and progression. Cell phenotype switching has been shown to also serve as a mechanism of drug resistance in some epithelial cancers. In pancreatic ductal adenocarcinoma (PDAC), the role of lineage infidelity and phenotype switching is still unclear. Two consensus molecular subtypes of PDAC have been proposed that mainly reflect the existence of cell lineages with different degrees of fidelity to pancreatic endodermal precursors. Indeed, the classical subtype of PDAC is characterised by the expression of endodermal lineage specifying transcription factors, while the more aggressive basal-like/squamous subtype is defined by epigenetic downregulation of endodermal genes and alterations in chromatin modifiers. Here, we summarise the current knowledge of mechanisms (genetic and epigenetic) of cell fate switching in PDAC and discuss how pancreatic organoids might help increase our understanding of both cell-intrinsic and cell-extrinsic factors governing lineage infidelity during the distinct phases of PDAC evolution.

Intraductal Papillary Mucinous Neoplasms of the Pancreas: A Review of Their Genetic Characteristics and Mouse Models

Simple Summary

Pancreatic cancer is one of the deadliest cancers with the lowest survival rate. Little progress has been achieved in prolonging the survival for patients with pancreatic adenocarcinoma. Hence, special attention should be paid to pre-cancerous lesions, for instance, an intraductal papillary mucinous neoplasm (IPMN). Here, we reviewed its genetic characteristics and the mouse models involving mutations in specific pathways, and updated our current perception of how this lesion develops into a precursor of invasive cancer.

Abstract

The intraductal papillary mucinous neoplasm (IPMN) is attracting research attention because of its increasing incidence and proven potential to progress into invasive pancreatic ductal adenocarcinoma (PDAC). In this review, we summarized the key signaling pathways or protein complexes (GPCR, TGF, SWI/SNF, WNT, and PI3K) that appear to be involved in IPMN pathogenesis. In addition, we collected information regarding all the genetic mouse models that mimic the human IPMN phenotype with specific immunohistochemistry techniques. The mouse models enable us to gain insight into the complex mechanism of the origin of IPMN, revealing that it can be developed from both acinar cells and duct cells according to different models. Furthermore, recent genomic studies describe the potential mechanism by which heterogeneous IPMN gives rise to malignant carcinoma through sequential, branch-off, or de novo approaches. The most intractable problem is that the risk of malignancy persists to some extent even if the primary IPMN is excised with a perfect margin, calling for the re-evaluation and improvement of diagnostic, pre-emptive, and therapeutic measures.

Uncertain Beginnings: Acinar and Ductal Cell Plasticity in the Development of Pancreatic Cancer

The pancreas consists of several specialized cell types that display a remarkable ability to alter cellular identity in injury, regeneration, and repair. The abundant cellular plasticity within the pancreas appears to be exploited in tumorigenesis, with metaplastic, dedifferentiation, and transdifferentiation processes central to the development of pancreatic intraepithelial neoplasia and intraductal papillary neoplasms, precursor lesions to pancreatic ductal adenocarcinoma. In the face of shifting cellular identity, the cell of origin of pancreatic cancer has been difficult to elucidate. However, with the extensive utilization of in vivo lineage-traced mouse models coupled with insights from human samples, it has emerged that the acinar cell is most efficiently able to give rise to both intraductal papillary neoplasms and pancreatic intraepithelial neoplasia but that acinar and ductal cells can undergo malignant transformation to pancreatic ductal adenocarcinoma. In this review, we discuss the cellular reprogramming that takes place in both the normal and malignant pancreas and evaluate the current state of evidence that implicate both the acinar and ductal cell as context-dependent origins of this deadly disease.

Intraductal Papillary Mucinous Carcinoma Versus Conventional Pancreatic Ductal Adenocarcinoma: A Comprehensive Review of Clinical-Pathological Features, Outcomes, and Molecular Insights

Intraductal papillary mucinous neoplasms (IPMN) are common and one of the main precursor lesions of pancreatic ductal adenocarcinoma (PDAC). PDAC derived from an IPMN is called intraductal papillary mucinous carcinoma (IPMC) and defines a subgroup of patients with ill-defined specificities. As compared to conventional PDAC, IPMCs have been associated to clinical particularities and favorable pathological features, as well as debated outcomes. However, IPMNs and IPMCs include distinct subtypes of precursor (gastric, pancreato-biliary, intestinal) and invasive (tubular, colloid) lesions, also associated to specific characteristics. Notably, consistent data have shown intestinal IPMNs and associated colloid carcinomas, defining the “intestinal pathway”, to be associated with less aggressive features. Genomic specificities have also been uncovered, such as mutations of the GNAS gene, and recent data provide more insights into the mechanisms involved in IPMCs carcinogenesis. This review synthetizes available data on clinical-pathological features and outcomes associated with IPMCs and their subtypes. We also describe known genomic hallmarks of these lesions and summarize the latest data about molecular processes involved in IPMNs initiation and progression to IPMCs. Finally, potential implications for clinical practice and future research strategies are discussed.

Curing pancreatic cancer

The distinct biology of pancreatic cancer with aggressive and early invasive tumor cells, a tumor promoting microenvironment, late diagnosis, and high therapy resistance poses major challenges on clinicians, researchers, and patients. In current clinical practice, a curative approach for pancreatic cancer can only be offered to a minority of patients and even for those patients, the long-term outcome is grim. This bitter combination will eventually let pancreatic cancer rise to the second leading cause of cancer-related mortalities. With surgery being the only curative option, complete tumor resection still remains the center of pancreatic cancer treatment. In recent years, new developments in neoadjuvant and adjuvant treatment have emerged. Together with improved perioperative care including complication management, an increasing number of patients have become eligible for tumor resection. Basic research aims to further increase these numbers by new methods of early detection, better tumor modelling and personalized treatment options. This review aims to summarize the current knowledge on clinical and biologic features, surgical and non-surgical treatment options, and the improved collaboration of clinicians and basic researchers in pancreatic cancer that will hopefully result in more successful ways of curing pancreatic cancer.

A case of undifferentiated carcinoma with osteoclast-like giant cells of the pancreas derived from an intraductal papillary mucinous neoplasm

Pancreatic undifferentiated carcinoma with osteoclast-like giant cells (UC-OGC) is an extremely rare and aggressive malignancy. We report the case of a 71-year-old male who presented with a solid-and-cystic mass in the pancreatic head. The cut section of the pancreaticoduodenectomy specimen showed hemorrhagic polypoid lesions localized to the cyst spaces. Histological examination revealed a cystic background as an intraductal papillary mucinous neoplasm (IPMN) with low-grade dysplasia, while the intra-cystic polypoid mass was morphologically identical to giant cell tumors (GCT) of bone and soft tissue, consisting of a mixture of mononuclear histiocyte-like cells and multinucleated osteoclast-like giant cells. Nuclei of the mononuclear cells were similar to those of the multinucleated giant cells, showing no obvious atypia. The mononuclear cells were diffusely immunoreactive for CD163 and completely negative for all examined epithelial markers. Genetic analysis showed both the IPMN and the GCT-like components harbored identical double mutations of KRAS (G12V) and GNAS (R201C), and confirmed a diagnosis of UC-OGC originating from IPMN. This case emphasized that pancreatic UC-OGC can provide bland morphology, which is morphologically and immunohistochemically undistinguishable from GCT of the bone and soft tissue. Our study also highlights the importance of genetic analyses in properly diagnosing and managing such patients.

Multi-Omic Biomarkers as Potential Tools for the Characterisation of Pancreatic Cystic Lesions and Cancer: Innovative Patient Data Integration

Pancreatic cancer (PC) is regarded as one of the most lethal malignant diseases in the world, with GLOBOCAN 2020 estimates indicating that PC was responsible for almost half a million deaths worldwide in 2020. Pancreatic cystic lesions (PCLs) are fluid-filled structures found within or on the surface of the pancreas, which can either be pre-malignant or have no malignant potential. While some PCLs are found in symptomatic patients, nowadays many PCLs are found incidentally in patients undergoing cross-sectional imaging for other reasons-so called 'incidentalomas'. Current methods of characterising PCLs are imperfect and vary hugely between institutions and countries. As such, there is a profound need for improved diagnostic algorithms. This could facilitate more accurate risk stratification of those PCLs that have malignant potential and reduce unnecessary surveillance. As PC continues to have such a poor prognosis, earlier recognition and risk stratification of PCLs may lead to better treatment protocols. This review will focus on the importance of biomarkers in the context of PCLs and PCand outline how current 'omics'-related work could contribute to the identification of a novel integrated biomarker profile for the risk stratification of patients with PCLs and PC.

Activation of the RAS pathway through uncommon BRAF mutations in mucinous pancreatic cysts without KRAS mutation

Diagnostic testing of pancreatic cyst fluid obtained by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) has traditionally utilized elevated carcinoembryonic antigen (CEA) (≥192 ng/ml) and cytomorphologic examination to differentiate premalignant mucinous from benign pancreatic cystic lesions (PCLs). Molecular testing for KRAS/GNAS mutations has been shown to improve accuracy of detecting mucinous PCLs. Using a targeted next-generation sequencing (NGS) panel, we assess the status of PCL-associated mutations to improve understanding of the key diagnostic variables. Molecular analysis of cyst fluid was performed on 108 PCLs that had concurrent CEA and/or cytological analysis. A 48-gene NGS assay was utilized, which included genes commonly mutated in mucinous PCLs such as GNAS, KRAS, CDKN2A, and TP53. KRAS and/or GNAS mutations were seen in 59 of 68 (86.8%) cases with multimodality diagnosis of a mucinous PCL. Among 31 patients where surgical histopathology was available, the sensitivity, specificity, and diagnostic accuracy of NGS for the diagnosis of mucinous PCL was 88.5%, 100%, and 90.3%, respectively. Cytology with mucinous/atypical findings were found in only 29 of 62 cases (46.8%), with fluid CEA elevated in 33 of 58 cases (56.9%). Multiple KRAS mutations at different variant allele frequencies were seen in seven cases favoring multiclonal patterns, with six of them showing at least two separate PCLs by imaging. Among the 6 of 10 cases with GNAS + /KRAS- results, uncommon, non-V600E exon 11/15 hotspot BRAF mutations were identified. The expected high degree of accuracy of NGS detection of KRAS and/or GNAS mutations for mucinous-PCLs, as compared with CEA and cytological examination, was demonstrated. Multiple KRAS mutations correlated with multifocal cysts demonstrated by radiology. In IPMNs that lacked KRAS mutations, the concurring BRAF mutations with GNAS mutations supports an alternate mechanism of activation in the Ras pathway.

Molecular drivers and cells of origin in pancreatic ductal adenocarcinoma and pancreatic neuroendocrine carcinoma

Pancreatic cancer is one of the most common causes of cancer-related deaths worldwide. The two major histological subtypes of pancreatic cancer are pancreatic ductal adenocarcinoma (PDAC), accounting for 90% of all cases, and pancreatic neuroendocrine neoplasm (PanNEN), which makes up 3-5% of all cases. PanNEN is classified into well-differentiated pancreatic neuroendocrine tumor and poorly-differentiated pancreatic neuroendocrine carcinoma (PanNEC). Although PDAC and PanNEN are commonly thought to be different diseases with distinct biology, cell of origin, and genomic abnormalities, the idea that PDAC and PanNEC share common cells of origin has been gaining support. This is substantiated by evidence that the molecular profiling of PanNEC is genetically and phenotypically related to PDAC. In the current review, we summarize published studies pointing to common potential cells of origin and speculate about how the distinct paths of differentiation are determined by the genomic patterns of each disease. We also discuss the overlap between PDAC and PanNEC, which has been noted in clinical observations.

GNAS mutation detection in circulating cell-free DNA is a specific predictor for intraductal papillary mucinous neoplasms of the pancreas, especially for intestinal subtype

Pancreatic cystic neoplasms (PCNs) are a heterogeneous group with varying risks of malignancy. To explore the clinical utility of liquid biopsy in cyst type classification, we analyzed the GNAS/KRAS mutations in circulating cell-free DNA (cfDNA) obtained from 57 patients with histologically diagnosed PCNs, including 34 with intraductal papillary mucinous neoplasms (IPMNs) and compared the mutant allele prevalence and variant patterns with the paired resected specimens using next-generation sequencing. The positive prevalence of GNAS mutations in cfDNA of patients with IPMN (n = 11, 32%) was significantly higher than that in those with other PCNs (0%, P = 0.002). Conversely, KRAS mutations were detected in cfDNA of only 2 (6%) IPMN patients. The paired-sample comparison revealed highly concordance between the GNAS mutation status of cfDNA and resected IPMN specimens. Similar distributions of GNAS mutation positivity in cfDNA were observed across the different histological grades, whereas IPMNs with intestinal subtype showed a significantly higher prevalence of GNAS mutations than other subtypes (P = 0.030). GNAS mutation positivity in cfDNA was significantly associated with the acellular mucin pool of histological findings in primary IPMN lesions (P = 0.017). Detection of GNAS mutation in cfDNA can serve as a novel biomarker for cyst type classification and differentiation of intestinal subtype IPMN from the other PCNs.

Pancreatic Ductal Adenocarcinoma (PDAC) Organoids: The Shining Light at the End of the Tunnel for Drug Response Prediction and Personalized Medicine

Pancreatic ductal adenocarcinoma (PDAC) represents 90% of pancreatic malignancies. In contrast to many other tumor entities, the prognosis of PDAC has not significantly improved during the past thirty years. Patients are often diagnosed too late, leading to an overall five-year survival rate below 10%. More dramatically, PDAC cases are on the rise and it is expected to become the second leading cause of death by cancer in western countries by 2030. Currently, the use of gemcitabine/nab-paclitaxel or FOLFIRINOX remains the standard chemotherapy treatment but still with limited efficiency. There is an urgent need for the development of early diagnostic and therapeutic tools. To this point, in the past 5 years, organoid technology has emerged as a revolution in the field of PDAC personalized medicine. Here, we are reviewing and discussing the current technical and scientific knowledge on PDAC organoids, their future perspectives, and how they can represent a game change in the fight against PDAC by improving both diagnosis and treatment options.

RNF43 Mutations in IPMN Cases: A Potential Prognostic Factor

An intraductal papillary mucinous neoplasm (IPMN) is a common pancreatic precursor lesion, and it often harbors mutations in KRAS, GNAS, and RNF43. To clarify the molecular profiles of IPMNs, we conducted mutation analysis of KRAS, GNAS, and RNF43 in 61 IPMN formalin-fixed, paraffin-embedded (FFPE) specimens. The mutation rates of codons 12, 13, and 61 in KRAS and codon 201 in GNAS were detected by Sanger sequencing. Next-generation sequencing was performed on RNF43, and the results were further verified by Sanger sequencing. We identified KRAS and GNAS mutations in 35 (57%) and 40 (66%) IPMN cases, respectively. GNAS mutations were significantly correlated with the morphologic subtype (P < 0.001) and were more prevalent in the intestinal subtype (93%) than in the gastric (55%) and pancreatobiliary subtypes (44%) but were absent in the oncocytic subtype. RNF43 mutations were found in 5 cases (8%), all of which occurred in high-grade dysplasia and invasive lesions (2/5 and 3/5). All 5 cases harboring RNF43 mutations also exhibited GNAS mutations. RNF43 mutations were associated with a worse prognosis in invasive IPMN patients (P = 0.002), while KRAS and GNAS mutations did not affect the prognosis of patients.

Activating genomic alterations in the Gs alpha gene (GNAS) in 274 694 tumors

Activating point mutations in two codons (R201 and Q227) in the alpha subunit of the stimulatory GTP binding protein (GNAS) gene-coined gsp mutations-were originally reported in growth hormone secreting pituitary adenomas. In these tumor types, gsp activating mutations were associated with uncontrolled intracellular cAMP accumulation leading to cellular proliferation and tumor formation. Since the original description of gsp mutations in pituitary and later thyroid neoplasia, many more tumors were genotyped for these specific activating mutations. In this paradigm, GNAS is an oncogene that can be activated by other molecular mechanisms, such as DNA amplification and translocation. Herein, we describe the largest account to date of tumor types that harbor pathogenic GNAS genomic alterations (GAs) including the "classical" gsp activating point mutations, delineate some common features of these tumors, and speculate as to the possible mechanisms whereby GNAS activating GAs are associated with the various stages of tumorigenesis.

From Genetic Alterations to Tumor Microenvironment: The Ariadne's String in Pancreatic Cancer

The threatening notoriety of pancreatic cancer mainly arises from its negligible early diagnosis, highly aggressive progression, failure of conventional therapeutic options and consequent very poor prognosis. The most important driver genes of pancreatic cancer are the oncogene KRAS and the tumor suppressors TP53, CDKN2A, and SMAD4. Although the presence of few drivers, several signaling pathways are involved in the oncogenesis of this cancer type, some of them with promising targets for precision oncology. Pancreatic cancer is recognized as one of immunosuppressive phenotype cancer: it is characterized by a fibrotic-desmoplastic stroma, in which there is an intensive cross-talk between several cellular (e.g., fibroblasts, myeloid cells, lymphocytes, endothelial, and myeloid cells) and acellular (collagen, fibronectin, and soluble factors) components. In this review; we aim to describe the current knowledge of the genetic/biological landscape of pancreatic cancer and the composition of its tumor microenvironment; in order to better direct in the intrinsic labyrinth of this complex tumor type. Indeed; disentangling the genetic and molecular characteristics of cancer cells and the environment in which they evolve may represent the crucial step towards more effective therapeutic strategies

From somatic mutation to early detection: insights from molecular characterization of pancreatic cancer precursor lesions

Pancreatic cancer arises from noninvasive precursor lesions, including pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and mucinous cystic neoplasm (MCN), which are curable if detected early enough. Recently, these types of precursor lesions have been extensively characterized at the molecular level, defining the timing of critical genetic alterations in tumorigenesis pathways. The results of these studies deepen our understanding of tumorigenesis in the pancreas, providing novel insights into tumor initiation and progression. Perhaps more importantly, they also provide a rational foundation for early detection approaches that could allow clinical intervention prior to malignant transformation. In this review, we summarize the results of comprehensive molecular characterization of PanINs, IPMNs, and MCNs and discuss the implications for cancer biology as well as early detection. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Case of Invasive Carcinoma Derived from Intraductal Papillary Mucinous Neoplasm Negative for GNAS Mutation

A 70-year-old woman with loss of appetite was referred to our hospital for further examinations. Computed tomography revealed a low density tumor in the body of the pancreas measuring 4 cm in diameter. The main pancreatic duct was dilated on both the head and caudal side of the tumor. Magnetic resonance imaging showed the mass as a low intensity area in T1-weighted and high intensity area in T2-weighted images. Endoscopic retrograde cholangiopancreatography findings indicated that the main pancreatic duct was continuous with the lumen of the tumor. A cytological examination of pancreatic juice showed a class IV tumor. A distal pancreatectomy was performed as a curative resection procedure. The findings of hematoxylin eosin staining and mucus trait led to a diagnosis of invasive cancer derived from an intraductal papillary mucinous neoplasm (IPMN). We also performed sequencing analysis to investigate GNAS and K-RAS mutations in the tumor, though neither the GNAS mutation c602G>A nor K-RAS mutation c35G>A were observed. Cases negative for a GNAS mutation can be considered to have an increased risk of invasive cancer derived from an IPMN.

Cytologic Analysis of Pancreatic Juice Increases Specificity of Detection of Malignant IPMN-A Systematic Review

BACKGROUND & AIMS

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas can progress to cancer. Biomarkers have been identified that were reported to increase the accuracy of identification of malignant lesions; we performed a systematic review of the accuracy of these markers.

METHODS

We performed a systematic review of published studies on biomarkers of malignant IPMNs by searching MEDLINE and Web of Science databases from January 2005 through December 2017. Our methods were developed based on the Meta-analysis Of Observational Studies in Epidemiology guidelines. Pooled sensitivity, specificity, receiver operating characteristic curves, and their respective areas under the curve (AUC) were calculated from groups of markers (cell-, protein-, or DNA-based) measured in samples collected before and after surgery. A hypothetical test model was developed to determine how to meaningfully amend the revised Fukuoka guidelines, focusing on increasing test specificity for patients with IPMNs that have worrisome features.

RESULTS

We collected data from 193 published studies, comprising 12,297 patients, that analyzed 7 preoperative and 21 postoperative markers of IPMNs. The 3 biomarkers that identified malignant IPMNs with the largest AUC values were pancreatic juice cytology (AUC, 0.84; sensitivity, 0.54; specificity, 0.91), serum protein carbohydrate antigen 19-9 (AUC, 0.81; sensitivity, 0.45; specificity, 0.90), and cyst fluid cytology (AUC, 0.82; sensitivity, 0.57; specificity, 0.84). A combination of cytologic and immunohistochemical analysis of MUC1 and MUC2 in pancreatic juice samples identified malignant IPMNs with the largest AUC and sensitivity values (AUC, 0.85; sensitivity, 0.85; specificity, 0.65). In a test model, inclusion of cytologic analysis of pancreatic juice in the guideline algorithm significantly increased the specificity of detection of malignant IPMNs.

CONCLUSIONS

In a systematic review, we found cytologic analysis of pancreatic juice to have the greatest effect in increasing the specificity of detection of malignant IPMNs. We propose addition of this test to the Fukuoka guidelines for assessment of patients with IPMNs with worrisome features.

Next-Generation Sequencing in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is lethal, and the majority of patients present with locally advanced or metastatic disease that is not amenable to cure. Thus, with surgical resection being the only curative modality, it is critical that disease is identified at an earlier stage to allow the appropriate therapy to be applied. Unfortunately, a specific biomarker for early diagnosis has not yet been identified; hence, no screening process exists. Recently, high-throughput screening and next-generation sequencing (NGS) have led to the identification of novel biomarkers for many disease processes, and work has commenced in PDAC. Genomic data generated by NGS not only have the potential to assist clinicians in early diagnosis and screening, especially in high-risk populations, but also may eventually allow the development of personalized treatment programs with targeted therapies, given the large number of gene mutations seen in PDAC. This review introduces the basic concepts of NGS and provides a comprehensive review of the current understanding of genetics in PDAC as related to discoveries made using NGS.

Best practice management guidelines for fibrous dysplasia/McCune-Albright syndrome: a consensus statement from the FD/MAS international consortium

Fibrous Dysplasia / McCune Albright syndrome (FD/MAS) represents a wide spectrum of diseases due to somatic gain-of-function mutations of the GNAS gene. The mutation leads to overactivity in the target tissues and to a wide phenotype of clinical features that vary in severity and age of onset. The rarity of the disease and its variable presentation to multiple specialities often leads to misdiagnosis and inappropriate variability in investigations and treatments. To address this, our international consortium of clinicians, researchers, and patients’ advocates has developed pragmatic clinical guidelines for best clinical practice for the definition, diagnosis, staging, treatment and monitoring for FD/MAS to empower patients and support clinical teams in both general and specialised healthcare settings. With the lack of strong evidence to inform care, the guidelines were developed based on review of published literature, long-standing extensive experience of authors, input from other healthcare professionals involved in the care of FD/MAS patients and feedback from patients and patient groups across the globe. This has led to the formulation of a set of statements to inform healthcare professionals, patients, their families, carers and patient groups of the best practice of care. It is anticipated the implementation of these recommendations will lead to improvement in the care of patients with FD/MAS internationally.

Molecular Profiling of Appendiceal Adenocarcinoma and Comparison with Right-sided and Left-sided Colorectal Cancer

PURPOSE

The natural history and prognosis of appendiceal adenocarcinomas differ from those of adenocarcinomas arising in other large bowel sites. We aimed to compare the molecular profiles exhibited by appendiceal adenocarcinomas and colorectal cancers, or between the histopathologic subtypes of appendiceal adenocarcinoma.

EXPERIMENTAL DESIGN

A total of 183 samples from appendiceal adenocarcinoma [46 adenocarcinoma, not otherwise specified (NOS), 66 pseudomyxoma peritonei (PMP), 44 mucinous adenocarcinoma (MU), and 27 signet ring cell carcinoma (SR)], 994 from right-sided colorectal cancer (R-CRC), and 1,080 from left-sided CRC (L-CRC) were analyzed by next-generation sequencing (NGS) and IHC markers. Microsatellite instability (MSI) and tumor mutational burden (TMB) were tested by NGS, and programmed death ligand 1 (PD-L1) by IHC.

RESULTS

We observed high mutation rates in appendiceal adenocarcinoma samples for KRAS (55%), TP53 (40%), GNAS (31%), SMAD4 (16%), and APC (10%). Appendiceal adenocarcinoma exhibited higher mutation rates in KRAS and GNAS, and lower mutation rates in TP53, APC, and PIK3CA (6%) than colorectal cancers. PMP exhibited much higher mutation rates in KRAS (74%) and GNAS (63%), and much lower mutation rates in TP53 (23%), APC (2%), and PIK3CA (2%) than NOS. Alterations associated with immune checkpoint inhibitor response (MSI-high, TMB-high, PD-L1 expression) showed similar frequency in appendiceal adenocarcinoma compared with L-CRC, but not R-CRC, and those of NOS were higher than other subtypes of appendiceal adenocarcinoma and L-CRC.

CONCLUSIONS

Molecular profiling of appendiceal adenocarcinoma revealed different molecular characteristics than noted in R-CRC and L-CRC, and molecular heterogeneity among the histopathologic subtypes of appendiceal adenocarcinoma. Our findings may be critical to developing an individualized approach to appendiceal adenocarcinoma treatment.

Targeted next generation sequencing of pancreatic solid pseudopapillary neoplasms show mutations in Wnt signaling pathway genes

Solid pseudopapillary neoplasms of the pancreas are rare neoplasms that have been shown to harbor recurrent somatic pathogenic variants in the beta-catenin gene, CTNNB1. Here, we used targeted next generation sequencing to analyze these tumors for other associated mutations. Six cases of solid pseudopapillary neoplasms were studied. DNA extracted from formalin-fixed paraffin embedded tissue blocks was analyzed using the Ion Torrent platform, with the 50-gene Ampliseq Cancer Hotspot Panel v2 (CHPv2), with further variant validation performed by Sanger sequencing. Four tumors (67%) were confirmed to harbor mutations within CTNNB1, two with c.109T > G p.(Ser37Ala) and two with c.94G > A p.(Asp32Asn). One case showed a frameshift deletion in the Adenomatous Polyposis Coli gene, APC c.3964delG p.(Glu1322Lysfs*93) with a variant allele frequency of 42.6%. Sanger sequencing on non-tumoral tissue confirmed the variant was somatic. The patient with the APC mutation developed metastasis and died. In addition to the four cases harboring CTNNB1 variants, we found a case characterized by poor outcome, showing a rare frameshift deletion in the APC gene. Since the APC product interacts with beta-catenin, APC variants may, in addition to CTNNB1, contribute to the pathogenesis of solid pseudopapillary neoplasms via the Wnt signaling pathway.

Preoperative risk prediction for intraductal papillary mucinous neoplasms by quantitative CT image analysis

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMNs) are radiographically identifiable potential precursor lesions of pancreatic adenocarcinoma. While resection is recommended when main duct dilation is present, management of branch duct IPMN (BD-IPMN) remains controversial. This study sought to evaluate whether preoperative quantitative imaging features of BD-IPMNs could distinguish low-risk disease (low- and intermediate-grade dysplasia) from high-risk disease (high-grade dysplasia and invasive carcinoma).

METHODS

Patients who underwent resection between 2005 and 2015 with pathologically proven BD-IPMN and a preoperative CT scan were included in the study. Quantitative image features were extracted using texture analysis and a novel quantitative mural nodularity feature developed for the study. Significant features on univariate analysis were combined with clinical variables to build a multivariate prediction model.

RESULTS

Within the study group of 103 patients, 76 (74%) had low-risk disease and 27 (26%) had high-risk disease. Quantitative imaging features were prognostic of low-vs. high-risk disease. The model based only on clinical variables achieved an AUC of 0.67 and 0.79 with the addition of quantitative imaging features.

CONCLUSION

Quantitative image analysis of BD-IPMNs is a novel method that may enable risk stratification. External validation may provide a reliable non-invasive prognostic tool for clinicians.

Clinical and Radiographic Gastrointestinal Abnormalities in McCune-Albright Syndrome

Context

McCune-Albright syndrome (MAS) is a rare disorder characterized by fibrous dysplasia of bone, café-au-lait macules, and hyperfunctioning endocrinopathies. It arises from somatic gain-of-function mutations in GNAS, which encodes the cAMP-regulating protein Gαs. Somatic GNAS mutations have been reported in intraductal papillary mucinous neoplasms (IPMNs) and various gastrointestinal (GI) tumors. The clinical spectrum and prevalence of MAS-associated GI disease is not well established.

Objective

Define the spectrum and prevalence of MAS-associated GI pathology in a large cohort of patients with MAS.

Design

Cross-sectional study.

Setting

National Institutes of Health Clinical Center and The Johns Hopkins Hospital.

Methods

Fifty-four consecutive subjects with MAS (28 males; age range, 7 to 67 years) were screened with magnetic resonance cholangiopancreatography (MRCP).

Results

Thirty of 54 subjects (56%) had radiographic GI abnormalities. Twenty-five (46%) of the screened subjects had IPMNs (mean age of 35.1 years). Fourteen of the 25 had IPMNs alone, and 11 had IPMNs and abnormal hepatobiliary imaging. The 30 patients with MAS-associated GI pathology had a higher prevalence of acute pancreatitis, diabetes mellitus, and skeletal disease burden of fibrous dysplasia than patients without GI disease.

Conclusions

A broad spectrum of GI pathology is associated with MAS. IPMNs are common and occur at a younger age than in the general population. Patients with MAS should be considered for screening with a focused GI history and baseline MRCP. Further determination of the natural history and malignant potential of IPMNs in MAS is needed.

Histo-molecular oncogenesis of pancreatic cancer: From precancerous lesions to invasive ductal adenocarcinoma

Pancreatic cancer is a lethal malignancy, whose precursor lesions are pancreatic intraepithelial neoplasm, intraductal papillary mucinous neoplasm, intraductal tubulopapillary neoplasm, and mucinous cystic neoplasm. To better understand the biology of pancreatic cancer, it is fundamental to know its precursors and to study the mechanisms of carcinogenesis. Each of these precursors displays peculiar histological features, as well as specific molecular alterations. Starting from such pre-invasive lesions, this review aims at summarizing the most important aspects of carcinogenesis of pancreatic cancer, with a specific focus on the recent advances and the future perspectives of the research on this lethal tumor type.

The Use of Biomarkers in the Risk Stratification of Cystic Neoplasms

Cyst fluid biomarkers may be used to identify pancreatic cyst subtypes. Biomarkers are selected based on their ability to accurately distinguish mucinous from nonmucinous cysts and to risk stratify cysts based on malignant potential. Biomarkers of interest include but are not limited to amylase, oncogenes, DNA analysis, and epigenetic markers. The introduction of next-generation sequencing and molecular panels has aided in improved diagnostic accuracy and risk stratification. This review presents the diagnostic performance of currently available biomarkers and proposes an algorithm to incorporate their use in the diagnosis of pancreatic cysts.

PRDM14 is overexpressed in chronic pancreatitis prior to pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and lethal cancer that is typically diagnosed at a later stage with metastases and is difficult to treat. Therefore, investigating the mechanism of PDAC initiation is important to aid early‐stage cancer detection. PRDM14 is a transcription factor that maintains pluripotency in embryonic stem cells and is overexpressed in several cancers. We previously reported that PRDM14 is overexpressed and regulates cancer stem‐like phenotypes in PDAC, and herein, we assess whether PRDM14 expression increases prior to tumorigenesis. Through immunohistochemistry analyses of clinical tissues, we detected PRDM14‐positive cells in precursor pancreatic intraepithelial neoplasia and chronic pancreatitis, which is a risk factor for PDAC, lesions. PRDM14 staining in chronic pancreatitis was as high as that in PDAC and cancer adjacent tissues. We induced pancreatitis in mouse models by cerulein injection, and observed that PRDM14 expression increased in chronic pancreatitis models but not in control or acute pancreatitis mice. Moreover, cerulein treatment increased PRDM14 expression in PK‐1 and AsPC‐1 pancreatic cancer cell lines. Our results suggest that inflammation increases the expression of PRDM14, which regulates cancer stem‐like phenotypes, and this occurs prior to PDAC initiation and progression.

Management of Intraductal Papillary Mucinous Neoplasms: Controversies in Guidelines and Future Perspectives

Purpose of review

Management of intraductal papillary mucinous neoplasm (IPMN) is currently based on consensus, in the absence of evidence-based guidelines. In recent years, several consensus guidelines have been published, with distinct management strategies. In this review, we will discuss these discrepancies, in order to guide treating physicians in clinical management.

Recent findings

The detection rate of pancreatic cysts has increased substantially with the expanded use of high-quality imaging techniques to up to 45%. Of these cysts, 24–82% are IPMNs, which harbour a malignant potential. Timely detection of high-risk lesions is therefore of great importance. Surgical management is based on the presence of clinical and morphological high-risk features, yet the majority of resected specimens appear to be low risk.

Summary

International collaboration and incentive large-scale prospective registries of individuals undergoing cyst surveillance are needed to accumulate unbiased data and develop evidence-based guidelines. Additionally, development of non-invasive, accurate diagnostic tools (e.g. biomarkers) is needed to differentiate between neoplastic and non-neoplastic pancreatic cysts and detect malignant transformation at an early stage (i.e. high-grade dysplasia).

Liver and Pancreas: Do Similar Embryonic Development and Tissue Organization Lead to Similar Mechanisms of Tumorigenesis?

The liver and pancreas are closely associated organs that share a common embryological origin. They display amphicrine properties and have similar exocrine organization with parenchymal cells, namely, hepatocytes and acinar cells, secreting bile and pancreatic juice into the duodenum via a converging network of bile ducts and pancreatic ducts. Here we compare and highlight the similarities of molecular mechanisms leading to liver and pancreatic cancer development. We suggest that unraveling tumor development in an organ may provide insight into our understanding of carcinogenesis in the other organ.

Pancreatic neuroendocrine carcinomas reveal a closer relationship to ductal adenocarcinomas than to neuroendocrine tumors G3

Pancreatic neuroendocrine carcinoma is a rare aggressive tumor commonly harboring TP53 and RB1 alterations and lacking neuroendocrine-related genetic changes such as mutations in MEN1 and ATRX/DAXX. Little is known about its genetic profile with regard to that of pancreatic ductal adenocarcinoma. We therefore conducted a detailed genetic study in 12 pancreatic neuroendocrine carcinomas of large cell (n = 9) and small cell type (n = 3) using massive parallel sequencing applying a 409-gene panel on an Ion Torrent system. The genetic data were compared with known data of pancreatic ductal adenocarcinoma and correlated with exocrine lineage marker expression. A similar analysis was performed in 11 pancreatic neuroendocrine tumors G3. Neuroendocrine carcinomas harbored 63 somatic mutations in 45 different genes, affecting most commonly TP53 (8/12 cases), KRAS (5/12 cases), and RB1 (loss of expression with or without deletion in 4/12 cases). Five carcinomas had both TP53 and KRAS mutations. Neuroendocrine tumors G3 only shared singular mutations in 5 different genes with neuroendocrine carcinomas, including TP53, CDKN2A, ARID1A, LRP1B, and APC, affecting 5 different cases. Most KRAS-positive neuroendocrine carcinomas also expressed MUC1 (4/5) and carcinoembryonic antigen (3/5) as markers of ductal differentiation. Our data indicate that almost half of the pancreatic neuroendocrine carcinomas are genetically and phenotypically related to pancreatic ductal adenocarcinoma, and might therefore respond to chemotherapies targeting the latter carcinomas.

Analysis of Mutation and Loss of Heterozygosity by Whole-Exome Sequencing Yields Insights into Pseudomyxoma Peritonei

Pseudomyxoma peritonei (PMP) is a clinical syndrome characterized by gross mucinous ascites originating from a disseminated intraperitoneal neoplasm. Although typically confined to the abdomen, mortality is high if untreated. Biomarkers, including genetic mutation profiles, may aid treatment selection and decision making. We applied whole-exome sequencing to five patients diagnosed with low-grade appendiceal mucinous neoplasms, using paired tumor and germline samples identify biomarkers. Multiple bioinformatic approaches were applied to these data to assess both somatic mutation profiles and loss of heterozygosity events. Mutation profiles of the tumors were consistent with deamination of methylcytosine being the prevailing mechanism. Pathogenic mutations were identified in both KRAS and GNAS in all samples, and further mutations in genes implicated in PMP, namely FGFR2, APC, SMAD2, and FAT4. No TP53 somatic mutations were identified, matching expectations for low-grade tumors. Four of five samples exhibited clonal loss of heterozygosity; these regions were further examined and found to contain genes harboring pathogenic somatic mutations in some samples. RNF43 was hereby implicated in the pathogenesis of PMP of appendiceal origin, having previously been found to increase sensitivity to Wnt signaling and to have involvement in similar mucinous tumors. In conclusion, we have investigated the mutation profile of PMP of appendiceal origin and provided the first report of RNF43 involvement in its progression.

The curious case of Gαs gain-of-function in neoplasia

BACKGROUND

Mutations activating the α subunit of heterotrimeric Gs protein are associated with a number of highly specific pathological molecular phenotypes. One of the best characterized is the McCune Albright syndrome. The disease presents with an increased incidence of neoplasias in specific tissues.

MAIN BODY

A similar repertoire of neoplasms can develop whether mutations occur spontaneously in somatic tissues during fetal development or after birth. Glands are the most "permissive" tissues, recently found to include the entire gastrointestinal tract. High frequency of activating Gαs mutations is associated with precise diagnoses (e.g., IPMN, Pyloric gland adenoma, pituitary toxic adenoma). Typically, most neoplastic lesions, from thyroid to pancreas, remain well differentiated but may be a precursor to aggressive cancer.

CONCLUSIONS

Here we propose the possibility that gain-of-function mutations of Gαs interfere with signals in the microenvironment of permissive tissues and lead to a transversal neoplastic phenotype.