Impact of age, comorbidities and relevant changes on surveillance strategy of intraductal papillary mucinous neoplasms: a competing risk analysis

OBJECTIVE

Cost-effectiveness of surveillance for branch-duct intraductal papillary mucinous neoplasms (BD-IPMNs) is debated. We combined different categories of risks of IPMN progression and of IPMN-unrelated mortality to improve surveillance strategies.

DESIGN

Retrospective analysis of 926 presumed BD-IPMNs lacking worrisome features (WFs)/high-risk stigmata (HRS) under surveillance. Charlson Comorbidity Index (CACI) defined the severity of comorbidities. IPMN relevant changes included development of WF/HRS, pancreatectomy or death for IPMN or pancreatic cancer. Pancreatic malignancy-unrelated death was recorded. Cumulative incidence of IPMN relevant changes were estimated using the competing risk approach.

RESULTS

5-year cumulative incidence of relevant changes was 17.83% and 1.6% developed pancreatic malignancy. 5-year cumulative incidences for IPMN relevant changes were 13.73%, 19.93% and 25.04% in low-risk, intermediate-risk and high-risk groups, respectively. Age ≥75 (HR: 4.15) and CACI >3 (HR: 3.61) were independent predictors of pancreatic malignancy-unrelated death. 5-year cumulative incidence for death for other causes was 15.93% for age ≥75+CACI >3 group and 1.49% for age <75+CACI ≤3. 5-year cumulative incidence of IPMN relevant changes were 13.94% in patients with age <75+CACI ≤3 compared with 29.60% in those with age ≥75+CACI >3. In this group 5-year rate of malignancy-free patients was 95.56% with a 5-year survival of 79.51%.

CONCLUSION

Although it is not uncommon the occurrence of changes considered by current guidelines as relevant during surveillance of low risk BD-IPMNs, malignancy rate is low and survival is significantly affected by competing patients' age and comorbidities. IPMN surveillance strategy should be tailored based on these features and modulated over time.

Optimal age to discontinue long-term surveillance of intraductal papillary mucinous neoplasms: comparative cost-effectiveness of surveillance by age

OBJECTIVE

Current guidelines recommend long-term image-based surveillance for patients with low-risk intraductal papillary mucinous neoplasms (IPMNs). This simulation study aimed to examine the comparative cost-effectiveness of continued versus discontinued surveillance at different ages and define the optimal age to stop surveillance.

DESIGN

We constructed a Markov model with a lifetime horizon to simulate the clinical course of patients with IPMNs receiving imaging-based surveillance. We calculated incremental cost-effectiveness ratios (ICERs) for continued versus discontinued surveillance at different ages to stop surveillance, stratified by sex and IPMN types (branch-duct vs mixed-type). We determined the optimal age to stop surveillance as the lowest age at which the ICER exceeded the willingness-to-pay threshold of US$100 000 per quality-adjusted life year. To estimate model parameters, we used a clinical cohort of 3000 patients with IPMNs and a national database including 40 166 patients with pancreatic cancer receiving pancreatectomy as well as published data.

RESULTS

In male patients, the optimal age to stop surveillance was 76-78 years irrespective of the IPMN types, compared with 70, 73, 81, and 84 years for female patients with branch-duct IPMNs <20 mm, =20-29 mm, ≥30 mm and mixed-type IPMNs, respectively. The suggested ages became younger according to an increasing level of comorbidities. In cases with high comorbidity burden, the ICERs were above the willingness-to-pay threshold irrespective of sex and the size of branch-duct IPMNs.

CONCLUSIONS

The cost-effectiveness of long-term IPMN surveillance depended on sex, IPMN types, and comorbidity levels, suggesting the potential to personalise patient management from the health economic perspective.

Prediction of disease recurrence in patients after complete pancreatic NET (PanNET) G2 resection

INTRODUCTION

The number of detected pancreatic neuroendocrine tumours (PanNETs) has been increasing over the last decades. Surgical resection remains the only potentially curative treatment, but the management is still controversial. This study aimed to compare patients after radical PanNET G2 resection to determine the most important predictive factors for relapse.

MATERIAL AND METHODS

All patients with histologically confirmed PanNET G2 who underwent successful surgery between 2006 and 2020 with the intention of radical treatment were enrolled.

RESULTS

In total, 44 patients were eligible for the analysis. The average follow-up was 8.39 ± 4.5 years. Disease recurrence was observed in 16 (36.36%) patients. The dominant location of the primary tumour was the tail of the pancreas (43.18%), especially in the subgroup with disease recurrence (56.25%). The smallest tumour diameter associated with the PanNET G2 recurrence was 22 mm. The relationship between the largest dimension of the tumour with a division of < 4 cm vs. > 4 cm and the relapse was close to statistical significance. Recurrence was associated with a larger tumour size (p = 0.018). There was a statistically significant relationship and a weak correlation between Ki-67 (p = 0.036, V Cramer = 0.371) and disease relapse.

CONCLUSION

For the group of PanNET G2 patients after radical surgery, the overall risk of recurrence was 36.36%, with the highest rate in the first 5 years after surgery, but in individual cases it occurred significantly later, even 10 years after surgery. The most important predictive factors of the PanNET G2 recurrence was Ki-67 over 5.75% and size of tumour > 4 cm.

Differences in clinical characteristics, treatment, and outcomes of sporadic and MEN-1-related insulinomas

INTRODUCTION

Although in most cases insulinomas are small, benign, sporadic tumours, they can also be associated with hereditary syndromes, most commonly multiple endocrine neoplasia type 1 (MEN-1). Such a diagnosis significantly affects patient management. The objective was to elucidate the clinical differences between sporadic and MEN-1-linked insulinoma.

MATERIAL AND METHODS

Comparison of clinical and histopathological characteristics, types of surgery, and outcomes of patients with sporadic and MEN-1-related insulinoma diagnosed between 2015 and 2022.

RESULTS

There were 17 cases of insulinomas that underwent MEN-1 genetic testing (10 women and 7 men). In 7 cases, the mutation in the menin gene was confirmed. The median age at the time of diagnosis of sporadic insulinoma related to MEN-1 was 69 years (range 29-87) and 31.5 years (16-47), respectively. Primary hyperparathyroidism (PHP) was found in 6 of 7 patients with MEN-1-related insulinoma, while in none of the patients without MEN-1 mutations. Multifocal pancreatic NETs were found in 3 patients with MEN-1 syndrome, while in all sporadic cases there was a single pancreatic tumour. Two patients with insulinoma related to MEN-1 had a positive familial history of MEN-1-related diseases, while none with sporadic form. Dissemination at diagnosis was found in 4 cases, including 3 patients with insulinoma related to MEN-1-related insulinoma. Patients with sporadic and MEN-1-related insulinoma did not differ in tumour size, Ki-67 proliferation index, and outcome.

CONCLUSIONS

Of all the features evaluated, only the multifocal nature of pancreatic neuroendocrine tumour (PanNET) lesions and a positive family history differentiated between patients with sporadic and MEN-1-related insulinomas. An age of insulinoma diagnosis of less than 30 years may be a strong indicator of an increased risk of MEN-1 syndrome.

Molecular heterogeneity and commonalities in pancreatic cancer precursors with gastric and intestinal phenotype

OBJECTIVE

Due to the limited number of modifiable risk factors, secondary prevention strategies based on early diagnosis represent the preferred route to improve the prognosis of pancreatic ductal adenocarcinoma (PDAC). Here, we provide a comparative morphogenetic analysis of PDAC precursors aiming at dissecting the process of carcinogenesis and tackling the heterogeneity of preinvasive lesions.

DESIGN

Targeted and whole-genome low-coverage sequencing, genome-wide methylation and transcriptome analyses were applied on a final collective of 122 morphologically well-characterised low-grade and high-grade PDAC precursors, including intestinal and gastric intraductal papillary mucinous neoplasms (IPMN) and pancreatic intraepithelial neoplasias (PanIN).

RESULTS

Epigenetic regulation of mucin genes determines the phenotype of PDAC precursors. PanIN and gastric IPMN display a ductal molecular profile and numerous similarly regulated pathways, including the Notch pathway, but can be distinguished by recurrent deletions and differential methylation and, in part, by the expression of mucin-like 3. Intestinal IPMN are clearly distinct lesions at the molecular level with a more instable genotype and are possibly related to a different ductal cell compartment.

CONCLUSIONS

PDAC precursors with gastric and intestinal phenotype are heterogeneous in terms of morphology, genetic and epigenetic profile. This heterogeneity is related to a different cell identity and, possibly, to a different aetiology.

Pathological and immunohistochemical characterization of pancreatic carcinoma in cats

The aim of this study was to characterize the pathological and immunohistochemical aspects of pancreatic carcinoma in cats, through a retrospective study. From January 2010 to December 2021, 1,908 cat necropsies were performed, in which 20 cases of exocrine pancreatic neoplasia were diagnosed (1.04%). Affected cats were mature adults and seniors, except for one 1-year-old cat. In 11 cases the neoplasm was a soft, focal nodule on the left (8/11) or right (3/11) lobe. In nine cases there were multifocal nodules throughout the pancreatic parenchyma. The size of the single masses ranged from 2 to 12 cm, and the multifocal masses from 0.5 to 2 cm. The most frequent tumour type was acinar carcinoma (11/20), followed by ductal carcinoma (8/20), undifferentiated carcinoma (1/20) and carcinosarcoma (1/20). On immunohistochemical evaluation, all the neoplasms were remarkably reactive to pancytokeratin antibody. The ductal carcinomas were strongly reactive for cytokeratins 7 and 20, which proved to be a good marker for pancreatic ductal carcinoma in cats. The main form of metastasis was abdominal carcinomatosis, with a marked invasion of blood and lymphatic vessels by neoplastic cells. Our findings reinforce the fact that pancreatic carcinoma should be rated highly in the differential diagnosis in mature adult and senior cats with abdominal masses, ascites and/or jaundice.

A rare case of concomittant pancreatic adenosquamous and neuroendocrine tumours

Only two cases of concomitantly occurring adenosquamous and neuroendocrine tumours (NET) have been reported in the literature. We report a case where both NET and adenosquamous are simultaneously occurring. A 42-year-old lady was hospitalized following painless jaundice and loss of weight. Computer tomography scan showed 3.0 x 2.9 cm hypo enhancing and hypovascular mass in the uncinate/head process. Another hypervascular mass was seen in the body of the pancreas. Pathological examination showed that the lesion in the uncinate process/neck of pancreas was an adenosquamous in the main pancreatic duct intraductal papillary mucinous neoplasm. The second tumour was a NET measuring 36 mm with no metastatic involvement. These findings suggested concurrently occurring but separated adenocarcinoma and NET tumours. This is the third case in the literature where both NET and adenosquamous are happening concomitantly, and the previous two other cases are also reviewed in the article.

A faecal microbiota signature with high specificity for pancreatic cancer

BACKGROUND

Recent evidence suggests a role for the microbiome in pancreatic ductal adenocarcinoma (PDAC) aetiology and progression.

OBJECTIVE

To explore the faecal and salivary microbiota as potential diagnostic biomarkers.

METHODS

We applied shotgun metagenomic and 16S rRNA amplicon sequencing to samples from a Spanish case-control study (n=136), including 57 cases, 50 controls, and 29 patients with chronic pancreatitis in the discovery phase, and from a German case-control study (n=76), in the validation phase.

RESULTS

Faecal metagenomic classifiers performed much better than saliva-based classifiers and identified patients with PDAC with an accuracy of up to 0.84 area under the receiver operating characteristic curve (AUROC) based on a set of 27 microbial species, with consistent accuracy across early and late disease stages. Performance further improved to up to 0.94 AUROC when we combined our microbiome-based predictions with serum levels of carbohydrate antigen (CA) 19-9, the only current non-invasive, Food and Drug Administration approved, low specificity PDAC diagnostic biomarker. Furthermore, a microbiota-based classification model confined to PDAC-enriched species was highly disease-specific when validated against 25 publicly available metagenomic study populations for various health conditions (n=5792). Both microbiome-based models had a high prediction accuracy on a German validation population (n=76). Several faecal PDAC marker species were detectable in pancreatic tumour and non-tumour tissue using 16S rRNA sequencing and fluorescence in situ hybridisation.

CONCLUSION

Taken together, our results indicate that non-invasive, robust and specific faecal microbiota-based screening for the early detection of PDAC is feasible.

Next-generation sequencing of bile cell-free DNA for the early detection of patients with malignant biliary strictures

OBJECTIVE

Despite significant progresses in imaging and pathological evaluation, early differentiation between benign and malignant biliary strictures remains challenging. Endoscopic retrograde cholangiopancreatography (ERCP) is used to investigate biliary strictures, enabling the collection of bile. We tested the diagnostic potential of next-generation sequencing (NGS) mutational analysis of bile cell-free DNA (cfDNA).

DESIGN

A prospective cohort of patients with suspicious biliary strictures (n=68) was studied. The performance of initial pathological diagnosis was compared with that of the mutational analysis of bile cfDNA collected at the time of first ERCP using an NGS panel open to clinical laboratory implementation, the Oncomine Pan-Cancer Cell-Free assay.

RESULTS

An initial pathological diagnosis classified these strictures as of benign (n=26), indeterminate (n=9) or malignant (n=33) origin. Sensitivity and specificity of this diagnosis were 60% and 100%, respectively, as on follow-up 14 of the 26 and eight of the nine initially benign or indeterminate strictures resulted malignant. Sensitivity and specificity for malignancy of our NGS assay, herein named Bilemut, were 96.4% and 69.2%, respectively. Importantly, one of the four Bilemut false positives developed pancreatic cancer after extended follow-up. Remarkably, the sensitivity for malignancy of Bilemut was 100% in patients with an initial diagnosis of benign or indeterminate strictures. Analysis of 30 paired bile and tissue samples also demonstrated the superior performance of Bilemut.

CONCLUSION

Implementation of Bilemut at the initial diagnostic stage for biliary strictures can significantly improve detection of malignancy, reduce delays in the clinical management of patients and assist in selecting patients for targeted therapies.

Senolytic elimination of Cox2-expressing senescent cells inhibits the growth of premalignant pancreatic lesions

OBJECTIVE

Cellular senescence limits tumourigenesis by blocking the proliferation of premalignant cells. Additionally, however, senescent cells can exert paracrine effects influencing tumour growth. Senescent cells are present in premalignant pancreatic intraepithelial neoplasia (PanIN) lesions, yet their effects on the disease are poorly characterised. It is currently unknown whether senolytic drugs, aimed at eliminating senescent cells from lesions, could be beneficial in blocking tumour development.

DESIGN

To uncover the functions of senescent cells and their potential contribution to early pancreatic tumourigenesis, we isolated and characterised senescent cells from PanINs formed in a Kras-driven mouse model, and tested the consequences of their targeted elimination through senolytic treatment.

RESULTS

We found that senescent PanIN cells exert a tumour-promoting effect through expression of a proinflammatory signature that includes high Cox2 levels. Senolytic treatment with the Bcl2-family inhibitor ABT-737 eliminated Cox2-expressing senescent cells, and an intermittent short-duration treatment course dramatically reduced PanIN development and progression to pancreatic ductal adenocarcinoma.

CONCLUSIONS

These findings reveal that senescent PanIN cells support tumour growth and progression, and provide a first indication that elimination of senescent cells may be effective as preventive therapy for the progression of precancerous lesions.

Multiregion whole-exome sequencing of intraductal papillary mucinous neoplasms reveals frequent somatic KLF4 mutations predominantly in low-grade regions

OBJECTIVE

Intraductal papillary mucinous neoplasms (IPMNs) are non-invasive precursor lesions that can progress to invasive pancreatic cancer and are classified as low-grade or high-grade based on the morphology of the neoplastic epithelium. We aimed to compare genetic alterations in low-grade and high-grade regions of the same IPMN in order to identify molecular alterations underlying neoplastic progression.

DESIGN

We performed multiregion whole exome sequencing on tissue samples from 17 IPMNs with both low-grade and high-grade dysplasia (76 IPMN regions, including 49 from low-grade dysplasia and 27 from high-grade dysplasia). We reconstructed the phylogeny for each case, and we assessed mutations in a novel driver gene in an independent cohort of 63 IPMN cyst fluid samples.

RESULTS

Our multiregion whole exome sequencing identified KLF4, a previously unreported genetic driver of IPMN tumorigenesis, with hotspot mutations in one of two codons identified in >50% of the analyzed IPMNs. Mutations in KLF4 were significantly more prevalent in low-grade regions in our sequenced cases. Phylogenetic analyses of whole exome sequencing data demonstrated diverse patterns of IPMN initiation and progression. Hotspot mutations in KLF4 were also identified in an independent cohort of IPMN cyst fluid samples, again with a significantly higher prevalence in low-grade IPMNs.

CONCLUSION

Hotspot mutations in KLF4 occur at high prevalence in IPMNs. Unique among pancreatic driver genes, KLF4 mutations are enriched in low-grade IPMNs. These data highlight distinct molecular features of low-grade and high-grade dysplasia and suggest diverse pathways to high-grade dysplasia via the IPMN pathway.

Synergistic targeting and resistance to PARP inhibition in DNA damage repair-deficient pancreatic cancer

OBJECTIVE

ATM serine/threonine kinase (ATM) is the most frequently mutated DNA damage response gene, involved in homologous recombination (HR), in pancreatic ductal adenocarcinoma (PDAC).

DESIGN

Combinational synergy screening was performed to endeavour a genotype-tailored targeted therapy.

RESULTS

Synergy was found on inhibition of PARP, ATR and DNA-PKcs (PAD) leading to synthetic lethality in ATM-deficient murine and human PDAC. Mechanistically, PAD-induced PARP trapping, replication fork stalling and mitosis defects leading to P53-mediated apoptosis. Most importantly, chemical inhibition of ATM sensitises human PDAC cells toward PAD with long-term tumour control in vivo. Finally, we anticipated and elucidated PARP inhibitor resistance within the ATM-null background via whole exome sequencing. Arising cells were aneuploid, underwent epithelial-mesenchymal-transition and acquired multidrug resistance (MDR) due to upregulation of drug transporters and a bypass within the DNA repair machinery. These functional observations were mirrored in copy number variations affecting a region on chromosome 5 comprising several of the upregulated MDR genes. Using these findings, we ultimately propose alternative strategies to overcome the resistance.

CONCLUSION

Analysis of the molecular susceptibilities triggered by ATM deficiency in PDAC allow elaboration of an efficient mutation-specific combinational therapeutic approach that can be also implemented in a genotype-independent manner by ATM inhibition.

N6-methyladenosine mRNA methylation of PIK3CB regulates AKT signalling to promote PTEN-deficient pancreatic cancer progression

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers worldwide. Thus far, most drugs have failed to significantly improve patient survival. N⁶-methyladenosine (m⁶A) plays an important role in the progression of PDAC, but its aberrant regulation driven by germline variants in human diseases remains unclear.

DESIGN

We first performed an exome-wide association analysis in 518 PDAC patients with overall survival and replicated in an independent population containing 552 PDAC patients. Then, a series of biochemical experiments in vitro and in vivo were conducted to investigate potential mechanisms of the candidate variant and its target gene PIK3CB underlying the PDAC progression. Moreover, the PIK3CB-selective inhibitor KIN-193 was used to block PDAC tumour growth.

RESULTS

We identified a missense variant rs142933486 in PIK3CB that is significantly associated with the overall survival of PDAC by reducing the PIK3CB m⁶A level, which facilitated its mRNA and protein expression levels mediated by the m⁶A 'writer' complex (METTL13/METTL14/WTAP) and the m⁶A 'reader' YTHDF2. The upregulation of PIK3CB is widely found in PDAC tumour tissues and significantly correlated with the poor prognosis of PDAC, especially in PTEN-deficient patients. We further demonstrated that PIK3CB overexpression substantially enhanced the proliferation and migration abilities of PTEN-deficient PDAC cells and activated AKT signalling pathway. Remarkably, KIN-193, a PIK3CB-selective inhibitor, is shown to serve as an effective anticancer agent for blocking PTEN-deficient PDAC.

CONCLUSIONS

These findings demonstrate aberrant m⁶A homoeostasis as an oncogenic mechanism in PDAC and highlight the potential of PIK3CB as a therapeutic target for this disease.

Enrichment of oral microbiota in early cystic precursors to invasive pancreatic cancer

OBJECTIVES

Intraductal papillary mucinous neoplasms (IPMNs) are pancreatic cysts that can progress to invasive pancreatic cancer. Associations between oncogenesis and oral microbiome alterations have been reported. This study aims to investigate a potential intracystic pancreatic microbiome in a pancreatic cystic neoplasm (PCN) surgery patient cohort.

DESIGN

Paired cyst fluid and plasma were collected at pancreatic surgery from patients with suspected PCN (n=105). Quantitative and qualitative assessment of bacterial DNA by qPCR, PacBio sequencing (n=35), and interleukin (IL)-1β quantification was performed. The data were correlated to diagnosis, lesion severity and clinical and laboratory profile, including proton-pump inhibitor (PPI) usage and history of invasive endoscopy procedures.

RESULTS

Intracystic bacterial 16S DNA copy number and IL-1β protein quantity were significantly higher in IPMN with high-grade dysplasia and IPMN with cancer compared with non-IPMN PCNs. Despite high interpersonal variation of intracystic microbiota composition, bacterial network and linear discriminant analysis effect size analyses demonstrated co-occurrence and enrichment of oral bacterial taxa including Fusobacterium nucleatum and Granulicatella adiacens in cyst fluid from IPMN with high-grade dysplasia. The elevated intracystic bacterial DNA is associated with, but not limited to, prior exposure to invasive endoscopic procedures, and is independent from use of PPI and antibiotics.

CONCLUSIONS

Collectively, these findings warrant further investigation into the role of oral bacteria in cystic precursors to pancreatic cancer and have added values on the aetiopathology as well as the management of pancreatic cysts.

Impact of peroral cholangioscopy on the management of indeterminate biliary conditions: a multicentre prospective trial

BACKGROUND AND AIMS

Single-operator cholangioscopy (SOC) can help diagnose biliopancreatic conditions. The impact of SOC on patient outcome has never been specifically addressed.

PATIENTS AND METHODS

Consecutive patients bearing indeterminate biliary strictures (IDBS), or primary sclerosing cholangitis (PSC) with suspected cholangiocarcinoma, were included. Patients with IDBS had at least one previous inconclusive endoscopic retrograde cholangio pancreatography (ERCP) + cytology. Primary endpoint was the difference in adequacy of management planned before and after SOC with regard to final diagnosis obtained after surgery or 24 months follow-up.

DESIGN

Prospective open-label multicentre trial.

RESULTS

61 patients were included (IDBS: 48; PSC: 13); 70.5% had a benign lesion (IDBS 66.7%, PSC 84.6%). The management adequacy rate was significantly higher after SOC than before SOC overall (p<10^-5), in IDBS (p<0.001) and PSC (p<0.05) patients. SOC induced changes in the management of the majority of patients in all groups (60.3%). The overall sensitivity of combined visual impression and biopsy ranged from 52% to 63.6% depending on investigator or independent expert rating (κ 0.92-0.96), whereas specificity, positive and negative predictive values of SOC were, respectively, 100%, 100% and 83.6%. Patient management observed at the end of follow-up was consistent with that anticipated after SOC in 88.5% overall.

CONCLUSION

Despite a moderate sensitivity for the diagnosis of malignancy, SOC has a dramatic impact on the management of patients with IDBS and PSC with suspected carcinoma. Cholangioscopy might be implemented in the workup of selected patients with challenging diagnosis, when a significant impact on outcome (essentially resection vs conservative management) is to be expected.

Recent advances in the diagnosis and management of pancreatic neuroendocrine tumours

The incidence of pancreatic neuroendocrine tumours (PNET) is rising mainly due to the increased use of cross-sectional imaging. Although many PNETs are asymptomatic and non-functioning, the overall 5-year survival is still less than 50%. In this article, we review the advances in diagnosis, classification and staging of PNET that have evolved with the development of new cross-sectional imaging methods and biopsy techniques. With accurate classification, evidence-based, individualised prognostic outcomes and treatments are able to be given which are also discussed.

Diagnosis and management of pancreatic cystic neoplasms

This review outlines the current classification of pancreatic cystic lesions, with a particular emphasis on pancreatic cystic neoplasms (PCNs). It will describe the diagnostic approach to PCNs, with reference to clinicopathological features, cross-sectional radiology and endoscopic ultrasound. This review will conclude with an evidence-based discussion of the management of PCNs focused on recent clinical guidelines.

SWI/SNF component ARID1A restrains pancreatic neoplasia formation

OBJECTIVE

ARID1A is commonly mutated in pancreatic ductal adenocarcinoma (PDAC), but the functional effects of ARID1A mutations in the pancreas are unclear. Understanding the molecular mechanisms that drive PDAC formation may lead to novel therapies.

DESIGN

Concurrent conditional Arid1a deletion and Kras activation mutations were modelled in mice. Small-interfering RNA (siRNA) and CRISPR/Cas9 were used to abrogate ARID1A in human pancreatic ductal epithelial cells.

RESULTS

We found that pancreas-specific Arid1a loss in mice was sufficient to induce inflammation, pancreatic intraepithelial neoplasia (PanIN) and mucinous cysts. Concurrent Kras activation accelerated the development of cysts that resembled intraductal papillary mucinous neoplasm. Lineage-specific Arid1a deletion confirmed compartment-specific tumour-suppressive effects. Duct-specific Arid1a loss promoted dilated ducts with occasional cyst and PDAC formation. Heterozygous acinar-specific Arid1a loss resulted in accelerated PanIN and PDAC formation with worse survival. RNA-seq showed that Arid1a loss induced gene networks associated with Myc activity and protein translation. ARID1A knockdown in human pancreatic ductal epithelial cells induced increased MYC expression and protein synthesis that was abrogated with MYC knockdown. ChIP-seq against H3K27ac demonstrated an increase in activated enhancers/promoters.

CONCLUSIONS

Arid1a suppresses pancreatic neoplasia in a compartment-specific manner. In duct cells, this process appears to be associated with MYC-facilitated protein synthesis.

Pancreatic cystic lesions: risk stratification and management based on recent guidelines

Pancreatic cystic lesions (PCLs) can present complex diagnostic and management challenges with uncertainty as to the most appropriate investigations, interventions and surveillance. Guidelines have been developed to aid decision making, including the European Study Group, American College of Gastroenterology and International Study Group guidelines. This paper presents issues relating to risk stratification and the appropriate management of patients with PCLs, reviewing these recently published guidelines. While there are similarities across these expert guidelines, there are notable differences in terms of features associated with increased risk of malignant transformation, the most appropriate imaging modality and timing of interval imaging. Where variations exist, this reflects differing interpretations of a limited evidence base, and decision making will likely evolve further as experience with these guidelines develops.

Targeted next-generation sequencing of cancer genes dissects the molecular profiles of intraductal papillary neoplasms of the pancreas

Intraductal neoplasms are important precursors to invasive pancreatic cancer and provide an opportunity to detect and treat pancreatic neoplasia before an invasive carcinoma develops. The diagnostic evaluation of these lesions is challenging, as diagnostic imaging and cytological sampling do not provide accurate information on lesion classification, the grade of dysplasia or the presence of invasion. Moreover, the molecular driver gene mutations of these precursor lesions have yet to be fully characterized. Fifty-two intraductal papillary neoplasms, including 48 intraductal papillary mucinous neoplasms (IPMNs) and four intraductal tubulopapillary neoplasms (ITPNs), were subjected to the mutation assessment in 51 cancer-associated genes, using ion torrent semiconductor-based next-generation sequencing. P16 and Smad4 immunohistochemistry was performed on 34 IPMNs and 17 IPMN-associated carcinomas. At least one somatic mutation was observed in 46/48 (96%) IPMNs; 29 (60%) had multiple gene alterations. GNAS and/or KRAS mutations were found in 44/48 (92%) of IPMNs. GNAS was mutated in 38/48 (79%) IPMNs, KRAS in 24/48 (50%) and these mutations coexisted in 18/48 (37.5%) of IPMNs. RNF43 was the third most commonly mutated gene and was always associated with GNAS and/or KRAS mutations, as were virtually all the low-frequency mutations found in other genes. Mutations in TP53 and BRAF genes (10% and 6%) were only observed in high-grade IPMNs. P16 was lost in 7/34 IPMNs and 9/17 IPMN-associated carcinomas; Smad4 was lost in 1/34 IPMNs and 5/17 IPMN-associated carcinomas. In contrast to IPMNs, only one of four ITPNs had detectable driver gene (GNAS and NRAS) mutations. Deep sequencing DNA from seven cyst fluid aspirates identified 10 of the 13 mutations detected in their associated IPMN. Using next-generation sequencing to detect cyst fluid mutations has the potential to improve the diagnostic and prognostic stratification of pancreatic cystic neoplasms.

Functions of TAp63 and p53 in restraining the development of metastatic cancer

Many tumours harbour mutations in the p53 tumour-suppressor gene that result in the expression of a mutant p53 protein. This mutant p53 protein has, in most cases, lost wild-type transcriptional activity and can also acquire novel functions in promoting invasion and metastasis. One of the mechanisms underlying these novel functions involves the ability of the mutant p53 to interfere with other transcription factors, including the p53 family protein TAp63. To investigate whether simultaneous depletion of both p53 and TAp63 can recapitulate the effect of mutant p53 expression in vivo, we used a mouse model of pancreatic cancer in which the expression of mutant p53 resulted in the rapid appearance of primary tumours and metastases. As shown previously, loss of one allele of wild-type (WT) p53 accelerated tumour development. A change of one WT p53 allele into mutant p53 did not further accelerate tumour development, but did promote the formation of metastasis. By contrast, loss of TAp63 did not significantly accelerate tumour development or metastasis. However, simultaneous depletion of p53 and TAp63 led to both rapid tumour development and metastatic potential, although the incidence of metastases remained lower than that seen in mutant p53-expressing tumours. TAp63/p53-null cells derived from these mice also showed an enhanced ability to scatter and invade in tissue culture as was observed in mutant p53 cells. These data suggest that depletion of TAp63 in a p53-null tumour can promote metastasis and recapitulate-to some extent-the consequences of mutant p53 expression.

Mutant GNAS detected in duodenal collections of secretin-stimulated pancreatic juice indicates the presence or emergence of pancreatic cysts

OBJECTIVE

Pancreatic cysts are commonly detected in patients undergoing pancreatic imaging. Better approaches are needed to characterise these lesions. In this study we evaluated the utility of detecting mutant DNA in secretin-stimulated pancreatic juice.

DESIGN

Secretin-stimulated pancreatic juice was collected from the duodenum of 291 subjects enrolled in Cancer of the Pancreas Screening trials at five US academic medical centres. The study population included subjects with a familial predisposition to pancreatic cancer who underwent pancreatic screening, and disease controls with normal pancreata, chronic pancreatitis, sporadic intraductal papillary mucinous neoplasm (IPMN) or other neoplasms. Somatic GNAS mutations (reported prevalence ≈ 66% of IPMNs) were measured using digital high-resolution melt-curve analysis and pyrosequencing.

RESULTS

GNAS mutations were detected in secretin-stimulated pancreatic juice samples of 50 of 78 familial and sporadic cases of IPMN(s) (64.1%), 15 of 33 (45.5%) with only diminutive cysts (<5 mm), but none of 57 disease controls. GNAS mutations were also detected in five of 123 screened subjects without a pancreatic cyst. Among 97 subjects who had serial pancreatic evaluations, GNAS mutations detected in baseline juice samples predicted subsequent emergence or increasing size of pancreatic cysts.

CONCLUSION

Duodenal collections of secretin-stimulated pancreatic juice from patients with IPMNs have a similar prevalence of mutant GNAS to primary IPMNs, indicating that these samples are an excellent source of mutant DNA from the pancreas. The detection of GNAS mutations before an IPMN is visible suggests that analysis of pancreatic juice has the potential to help in the risk stratification and surveillance of patients undergoing pancreatic screening.

Claudin-4-targeted optical imaging detects pancreatic cancer and its precursor lesions

OBJECTIVES

Novel imaging methods based on specific molecular targets to detect both established neoplasms and their precursor lesions are highly desirable in cancer medicine. Previously, we identified claudin-4, an integral constituent of tight junctions, as highly expressed in various gastrointestinal tumours including pancreatic cancer. Here, we investigate the potential of targeting claudin-4 with a naturally occurring ligand to visualise pancreatic cancer and its precursor lesions in vitro and in vivo by near-infrared imaging approaches.

DESIGN

A non-toxic C-terminal fragment of the claudin-4 ligand Clostridium perfringens enterotoxin (C-CPE) was labelled with a cyanine dye (Cy5.5). Binding of the optical tracer was analysed on claudin-4 positive and negative cells in vitro, and tumour xenografts in vivo. In addition, two genetically engineered mouse models for pancreatic intraepithelial neoplasia (PanIN) and pancreatic cancer were used for in vivo validation. Optical imaging studies were conducted using 2D planar fluorescence reflectance imaging (FRI) technology and 3D fluorescence-mediated tomography (FMT).

RESULTS

In vitro, the peptide-dye conjugate showed high binding affinity to claudin-4 positive CAPAN1 cells, while claudin-4 negative HT1080 cells revealed little or no fluorescence. In vivo, claudin-4 positive tumour xenografts, endogenous pancreatic tumours, hepatic metastases, as well as preinvasive PanIN lesions, were visualised by FRI and FMT up to 48 h after injection showing a significantly higher average of fluorochrome concentration as compared with claudin-4 negative xenografts and normal pancreatic tissue.

CONCLUSIONS

C-CPE-Cy5.5 combined with novel optical imaging methods enables non-invasive visualisation of claudin-4 positive murine pancreatic tumours and their precursor lesions, representing a promising modality for early diagnostic imaging.

Hyaluronan impairs vascular function and drug delivery in a mouse model of pancreatic cancer

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDA) is characterised by stromal desmoplasia and vascular dysfunction, which critically impair drug delivery. This study examines the role of an abundant extracellular matrix component, the megadalton glycosaminoglycan hyaluronan (HA), as a novel therapeutic target in PDA.

METHODS

Using a genetically engineered mouse model of PDA, the authors enzymatically depleted HA by a clinically formulated PEGylated human recombinant PH20 hyaluronidase (PEGPH20) and examined tumour perfusion, vascular permeability and drug delivery. The preclinical utility of PEGPH20 in combination with gemcitabine was assessed by short-term and survival studies.

RESULTS

PEGPH20 rapidly and sustainably depleted HA, inducing the re-expansion of PDA blood vessels and increasing the intratumoral delivery of two chemotherapeutic agents, doxorubicin and gemcitabine. Moreover, PEGPH20 triggered fenestrations and interendothelial junctional gaps in PDA tumour endothelia and promoted a tumour-specific increase in macromolecular permeability. Finally, combination therapy with PEGPH20 and gemcitabine led to inhibition of PDA tumour growth and prolonged survival over gemcitabine monotherapy, suggesting immediate clinical utility.

CONCLUSIONS

The authors demonstrate that HA impedes the intratumoral vasculature in PDA and propose that its enzymatic depletion be explored as a means to improve drug delivery and response in patients with pancreatic cancer.

Chemokine-driven lymphocyte infiltration: an early intratumoural event determining long-term survival in resectable hepatocellular carcinoma

OBJECTIVE

Hepatocellular carcinoma (HCC) is a heterogeneous disease with poor prognosis and limited methods for predicting patient survival. The nature of the immune cells that infiltrate tumours is known to impact clinical outcome. However, the molecular events that regulate this infiltration require further understanding. Here the ability of immune genes expressed in the tumour microenvironment to predict disease progression was investigated.

METHODS

Using quantitative PCR, the expression of 14 immune genes in resected tumour tissues from 57 Singaporean patients was analysed. The nearest-template prediction method was used to derive and test a prognostic signature from this training cohort. The signature was then validated in an independent cohort of 98 patients from Hong Kong and Zurich. Intratumoural components expressing these critical immune genes were identified by in situ labelling. Regulation of these genes was analysed in vitro using the HCC cell line SNU-182.

RESULTS

The identified 14 immune-gene signature predicts patient survival in both the training cohort (p=0.0004 and HR=5.2) and the validation cohort (p=0.0051 and HR=2.5) irrespective of patient ethnicity and disease aetiology. Importantly, it predicts the survival of patients with early disease (stages I and II), for whom classical clinical parameters provide limited information. The lack of predictive power in late disease stages III and IV emphasises that a protective immune microenvironment has to be established early in order to impact disease progression significantly. This signature includes the chemokine genes CXCL10, CCL5 and CCL2, whose expression correlates with markers of T helper 1 (Th1), CD8(+) T and natural killer (NK) cells. Inflammatory cytokines (tumour necrosis factor α, interferon γ) and Toll-like receptor 3 ligands stimulate intratumoural production of these chemokines which drive tumour infiltration by T and NK cells, leading to enhanced cancer cell death.

CONCLUSION

A 14 immune-gene signature, which identifies molecular cues driving tumour infiltration by lymphocytes, accurately predicts survival of patients with HCC especially in early disease.

Guidelines for the management of gastroenteropancreatic neuroendocrine (including carcinoid) tumours (NETs)

These guidelines update previous guidance published in 2005. They have been revised by a group who are members of the UK and Ireland Neuroendocrine Tumour Society with endorsement from the clinical committees of the British Society of Gastroenterology, the Society for Endocrinology, the Association of Surgeons of Great Britain and Ireland (and its Surgical Specialty Associations), the British Society of Gastrointestinal and Abdominal Radiology and others. The authorship represents leaders of the various groups in the UK and Ireland Neuroendocrine Tumour Society, but a large amount of work has been carried out by other specialists, many of whom attended a guidelines conference in May 2009. We have attempted to represent this work in the acknowledgements section. Over the past few years, there have been advances in the management of neuroendocrine tumours, which have included clearer characterisation, more specific and therapeutically relevant diagnosis, and improved treatments. However, there remain few randomised trials in the field and the disease is uncommon, hence all evidence must be considered weak in comparison with other more common cancers.