Multicenter validation of cancer gene panel-based next-generation sequencing for translational research and molecular diagnostics.

The simultaneous detection of multiple somatic mutations in the context of molecular diagnostics of cancer is frequently performed by means of amplicon-based targeted next-generation sequencing (NGS). However, only few studies are available comparing multicenter testing of different NGS platforms and gene panels. Therefore, seven partner sites of the German Cancer Consortium (DKTK) performed a multicenter interlaboratory trial for targeted NGS using the same formalin-fixed, paraffin-embedded (FFPE) specimen of molecularly pre-characterized tumors (n = 15; each n = 5 cases of Breast, Lung, and Colon carcinoma) and a colorectal cancer cell line DNA dilution series. Detailed information regarding pre-characterized mutations was not disclosed to the partners. Commercially available and custom-designed cancer gene panels were used for library preparation and subsequent sequencing on several devices of two NGS different platforms. For every case, centrally extracted DNA and FFPE tissue sections for local processing were delivered to each partner site to be sequenced with the commercial gene panel and local bioinformatics. For cancer-specific panel-based sequencing, only centrally extracted DNA was analyzed at seven sequencing sites. Subsequently, local data were compiled and bioinformatics was performed centrally. We were able to demonstrate that all pre-characterized mutations were re-identified correctly, irrespective of NGS platform or gene panel used. However, locally processed FFPE tissue sections disclosed that the DNA extraction method can affect the detection of mutations with a trend in favor of magnetic bead-based DNA extraction methods. In conclusion, targeted NGS is a very robust method for simultaneous detection of various mutations in FFPE tissue specimens if certain pre-analytical conditions are carefully considered.

Management of patients with pancreatic cystic lesions: A case-based survey.

BACKGROUND: Pancreatic cystic lesions (PCL), including intraductal papillary mucinous neoplasia (IPMN), harbor different malignant potential and the optimal management is often challenging. The present study aims to depict the compliance of experts with current consensus guidelines and the accuracy of treatment recommendations stratified by the medical specialty and hospital volume. METHODS: An international survey was conducted using a set of 10 selected cases of PCL that were presented to a cohort of international experts on pancreatology. All presented cases were surgically resected between 2004 and 2015 and histopathological examination was available. Accuracy of the treatment recommendations was based on the European and international consensus guideline algorithms, and the histopathological result. RESULTS: The response rate of the survey was 26% (46 of 177 contacted experts), consisting of 70% surgeons and 30% gastroenterologists/oncologists (GI/Onc). In the case of main-duct IPMN (MD-IPMN), surgeons preferred more often the surgical approach in comparison with the GI/Onc (55 versus 44%). The mean accuracy rate based on the European and international consensus guidelines, and the histopathological result, were 71/76/38% (surgeons), and 70/73/34% (GI/Onc), respectively. High-volume centers achieved insignificantly higher accuracy scores with regard to the histopathology. Small branch-duct IPMN with cysts <2 cm and malignant potential were not identified by the guideline algorithms. CONCLUSION: The survey underlines the complexity of treatment decisions for patients with PCL; less than 40% of the recommendations were in line with the final histopathology in this selected case panel. Experts and consensus guidelines may fail to predict malignant potential in small PCL.

[Current biomarkers for gastric cancer]. / Aktuelle Biomarker beim Magenkarzinom.

Gastric cancer is still a relevant malignant disease with high morbidity and mortality. Current molecular genetic data show that gastric cancer, as other solid tumors as well, is not a single entity but consists of several molecular subtypes of gastric cancer with diverse biology. The increasing understanding of molecular pathways is the basis for innovative therapies. These either directly target altered signaling pathways or genes in tumor cells or as in immune checkpoint inhibitors, indirectly target tumor cells by blocking tumor-induced immune inhibition leading to improvement in the prognosis. The selection of eligible patients is a prerequisite for the successful clinical application of these targeted drugs. Pathologists play an important role in integrating tissue-based biomarkers and established pathological parameters (typing, grading and staging) into one comprehensive morphomolecular report.

[Histological diagnosis and complications of celiac disease. Update according to the new S2k guidelines]. / Histologische Diagnostik und Komplikationen der Zöliakie. Aktualisierung entsprechend der neuen S2k-Leitlinie.

Celiac disease is a relatively common immunological systemic disease triggered by the protein gluten in genetically predisposed individuals. Classical symptoms like chronic diarrhea, steatorrhea, weight loss and growth retardation are nowadays relatively uncommon. Diagnostic workup includes serological tests for IgA antibodies against tissue transglutaminase 2 (anti-TG2-IgA) and total IgA and histology of duodenal biopsies. Histomorphological classification should be done according to the modified Marsh-Oberhuber classification. Diagnosis of celiac disease should be based on serological, clinical, and histological findings. The only treatment is a life-long gluten-free diet. Unchanged or recurrent symptoms under gluten-free diet may indicate refractory celiac disease. Enteropathy-associated T-cell lymphoma and adenocarcinomas of the small intestine are known complications of celiac disease.

[Histopathology of microscopic colitis]. / Histopathologie der mikroskopischen Kolitis.

Microscopic colitis (MC) is recognized to be a common cause of chronic, non-bloody diarrhea with rising incidence in the last decade. The diagnosis can only be made by histology and the specific histological findings define two subtypes of MC: lymphocytic (LC) or collagenous colitis (CC). The key histological feature of LC is an increased number of surface intraepithelial lymphocytes (IEL). In the literature, >20 IELs/100 epithelial cells are required to warrant the diagnosis of LC. IELs are mostly cytotoxic CD8+ T-lymphocytes. The key histological criterion for CC is a continuous subepithelial fibrous band underneath the surface epithelium (>10 µm). Other hallmarks of CC are chronic mucosal inflammation, and the collagen band can contain entrapped capillaries, red blood cells, and inflammatory cells. Damaged epithelial cells appear flattened, mucin depleted, and irregularly oriented. Focally, small strips of surface epithelium may lift off from their basement membrane. In both subtypes of MC, the lamina propria shows increased numbers of plasma cells and lymphocytes with loss of the normal gradient, even eosinophilic and neutrophilic granulocytes may be present. But these histological features alone do not warrant the diagnosis of MC even though they may be responsible for the clinical symptoms. The term MCi (MC incomplete) is suggested for the subgroup of patients with diarrhea and an increase in cellular infiltrate in the colonic lamina propria and either an abnormal collagenous layer and/or intraepithelial lymphocytes coming but not fulfilling the criteria for CC or LC.

What can molecular pathology offer for optimal decision making?

In recent years, colorectal cancer (CRC), once a uniform disease with well-understood carcinogenesis, has been divided into at least five different subgroups with distinct precursor lesions, pathways of carcinogenesis, morphological, and molecular characteristics. Moreover, new therapeutic concepts with 'targeted' substances have added to the complexity of the management of CRC patients. The clinical value of biomarkers in advanced CRC is indisputable ever since activating mutations of the KRAS oncogene have been shown to predict resistance to anti-epidermal growth factor receptor antibodies. Prognostic biomarkers predicting patient outcomes and predictive biomarkers forecasting response to a certain therapy may help us to improve therapeutic agent selection and patient management with the ultimate goal of maximizing the benefit of treatment and minimizing toxicity. Biomarkers with known implications in advanced CRC will be discussed in this paper.

[Barrett's esophagus. An update]. / Barrett-Ösophagus. Aktueller Stand.

Barrett's esophagus (BE), a well-known complication of gastroesophageal reflux disease (GERD), constitutes a precancerous condition for adenocarcinoma of the distal esophagus. The so-called Barrett's carcinoma shows increasing incidences in countries of the western hemisphere; new data, however, indicate that the rise in incidence is not quite as dramatic as previously assumed. The definition of BE is currently changing: despite good reasons for a purely endoscopic definition of BE, goblet cells are still mandatory for this diagnosis in Germany and the USA. Dysplastic changes in the epithelium are the most important risk factor for the development of Barrett's adenocarcinoma and recently dysplasia was subclassified into a more frequent adenomatous (intestinal) and a non-adenomatous (gastric-foveolar) types. The gold standard for diagnosing dysplasia is still H&E staining. The histological diagnosis of dysplasia is still encumbered by a significant interobserver variability, especially regarding the differentiation between low grade dysplasia and inflammatory/reactive changes and the discrimination between high grade dysplasia and adenocarcinoma. Current data, however, show much higher interobserver agreement in endoscopic resection specimens than in biopsies. Nevertheless, the histological diagnosis of dysplasia should be corroborated by an external second opinion because of its clinical consequences. In endoscopic resections of early Barrett's adenocarcinoma, the pathological report has to include a risk stratification for the likelihood of lymphogenic metastases.

[Bacterial colitis]. / Bakterielle Kolitiden.

The question of whether there are inflammatory changes in colorectal biopsy specimens is frequently asked, especially when the patient reports diarrhea or when the mucosa is reddened on endoscopy. The pathologist first has to find out whether there is, in fact, an increase in the inflammatory infiltrate of the colorectal mucosa which warrants the diagnosis of inflammation. If so, the second challenge is to ascertain the etiology of these inflammatory changes, in particular to differentiate between infectious and non-infectious causes. In principle, we can distinguish forms of colitis with distinct morphological hallmarks confirming the diagnosis (e.g. microscopic detection of the causative organism, as well as lymphocytic or collagenous colitis) from other forms of colitis which have a characteristic pattern of findings not necessarily allowing to deduce the etiology (e.g. infectious colitis without microscopic evidence of the germ vs. inflammatory bowel disease). The present article discusses the pathomorphology and differential diagnosis of the most important forms of bacterial colitis.

[Nonbacterial colitides]. / Nichtbakterielle Kolitiden.

Aside from bacterial infections, viral, fungal, and parasitic infections are important differential diagnoses in inflammatory disorders of the colorectum. In contrast to bacterial infections, in which the causative organism can hardly ever be detected histologically, in non bacterial infections the germs can often be verified by either histology, immunohistochemistry, or at least by molecular pathology. This manuscript will give an overview of the spectrum of pathogenic germs, the clinical symptoms, and pathological findings of the most important infections.

[WHO classification 2010 for the lower gastrointestinal tract: what is new?]. / WHO-Klassifikation 2010 für den unteren Gastrointestinaltrakt: Was ist neu?

The new WHO classification of tumors of the digestive system not only redefines common diagnostic terms, such as intraepithelial neoplasia and dysplasia but also introduces changes in the nomenclature and diagnostics of colorectal tumors which will be important in daily practice. Changes in nomenclature and classification include the introduction of serrated adenocarcinoma, cribriform comedo type adenocarcinoma and micropapillary adenocarcinoma as new distinct histological subtypes of colorectal cancer. The grading of mucinous and signet ring carcinomas, which were previously invariably graded as G3/high grade, is now dependent on the microsatellite instability (MSI) status as a high MSI (MSI-H) indicates a better and low or no MSI (MSI-L/MSS) a worse prognosis. Thus, analysis of microsatellite instability via immunohistochemistry or fragment length analysis must be included in the pathological report of these tumors. Serrated polyps/adenomas and their potential of progression into colorectal cancer via the alternative pathway of colorectal carcinogenesis will be discussed as well as new insights into prognostic and predictive markers of colorectal cancer. This manuscript will give an overview of the most important changes within the new WHO classification of colorectal tumors.

[Serrated precursor lesions]. / Serratierte Vorläuferläsionen.

The so-called serrated pathway has in recent years been well established as a second route of colorectal carcinogenesis. Sessile serrated polyps, especially sessile serrated adenomas (SSA) and traditional serrated adenomas (TSA) were identified as precursor lesions of this pathway. Activating mutations in either the BRAF (in SSAs) or the KRAS oncogene (in TSAs) have been determined as the initiating molecular alterations, followed by epigenetic methylation of CpG islands in promoter regions of genes which are implicated in cell cycle control or DNA repair. These findings have led to a paradigm shift in gastrointestinal pathology as lesions without cytological dysplasia, such as SSAs and certain forms of hyperplastic polyps, are now accepted to be precancerous lesions. In addition, carcinomas that have developed through the serrated pathway of colorectal carcinogenesis show varying biological behavior relevant for the clinical management of these tumors depending on the molecular aberrations.

[Polyps of the colorectum: non-neoplastic and non-hamartomatous]. / Polypen im Kolorektum: Nichtneoplastisch und nichthamartomatös.

Non-neoplastic and non-hamartomatous colorectal polyps or tumor-like lesions comprise a very heterogeneous group of changes in the colorectal mucosa or the colon wall. Mucosal prolapse-associated lesions and inflammatory polyps, which are predominantly associated with chronic inflammatory bowel disease, are the most prominent examples for polypoid lesions difficult to distinguish from neoplastic lesions such as adenomas, hyperplastic/serrated polyps/adenomas and invasive carcinomas. The considerably less frequent tumor-like lesions like heterotopias, endometriosis, amyloid tumors and pseudolipomatous changes are histologically often well defined and should be considered in the differential diagnosis of colorectal lesions. The etiology, endoscopic and histological appearance of these entities and their most important differential diagnoses are discussed.

[Histopathological diagnosis and differential diagnosis of colorectal serrated polys: findings of a consensus conference of the working group "gastroenterological pathology of the German Society of Pathology"]. / Histopathologische Diagnostik und Differenzialdiagnostik serratierter Polypen im Kolorektum : Ergebnisse einer Konsensuskonferenz der AG "Gastroenterologische Pathologie der DGP"

Until recently, two major types of colorectal epithelial polyps were distinguished: the adenoma and the hyperplastic polyp. While adenomas - because of their cytological atypia - were recognized as precursor lesions for colorectal carcinoma, hyperplastic polyps were perceived as harmless lesions without any potential for malignant progression, mainly because hyperplastic polyps lack cytological atypia. Meanwhile, it is evident that the lesions formerly classified as hyperplastic represent a heterogeneous group of polyps, some of which exhibit a significant risk of neoplastic progression. These lesions show characteristic epigenetic alterations not commonly seen in colorectal adenomas and progress to colorectal carcinoma via the so-called serrated pathway (CIMP pathway). This group of polyps is comprised not only of hyperplastic polyps, but also of sessile serrated adenomas (SSA), traditional serrated adenomas (TSA) and mixed polyps, showing serrated and "classical" adenomatous features. In a consensus conference of the working group of gastroenterological pathology of the German Society of Pathology, standardization of nomenclature and diagnostic criteria as well as recommendations for clinical management of these serrated polyps were formulated and are presented herein.

[Intraepithelial neoplasia/dysplasia - histopathology in ulcerative colitis]. / Intraepitheliale Neoplasie/Dysplasie - Diagnose bei Colitis ulcerosa.

About 1-2% of all colorectal carcinomas (CRCs) arise from a background of chronic inflammatory bowel diseases (IBDs) such as ulcerative colitis (UC) or Crohn's disease, and around 15% of patients with IBD die from colorectal cancer. Intraepithelial neoplasia/dysplasia in the setting of IBD is considered a precancerous lesion by definition. Intraepithelial neoplasia may present itself either as a flat or polypoid mucosal lesion and is referred to as a dysplasia-associated lesion or mass (DALM) in the latter case. The therapeutic consequence of high-grade intraepithelial neoplasia/dysplasia and/or DALM is proctocolectomy in most centers because of the high risk of synchronous or metachronous CRC. The diagnosis of ulcerative colitis-related intraepithelial neoplasia and its distinction from regenerative changes and sporadic adenomas (ALMs) occurring in UC is still one of the greatest challenges in gastrointestinal pathology. Intra- and interobserver variability for the distinction between low-grade intraepithelial neoplasia and regenerative lesions tends to be quite high. This is partly due to the difficult histomorphology and partly due to the relative rareness of this diagnosis (approximately 10% of patients with IBD).

[Intraepithelial neoplasia in ulcerative colitis: on the way to more diagnostic confidence]. / Intraepitheliale Neoplasie bei Colitis ulcerosa: Wege zu mehr Diagnosesicherheit.

Ulcerative colitis (UC)-related intraepithelial neoplasia and its distinction from regenerative changes and sporadic adenomas occurring in UC is one of the greatest challenges in gastrointestinal pathology. Recently, the molecular changes in UC-related neoplastic progression have been determined and compared with the molecular changes in sporadic carcinogenesis. Diagnostically promising differences between sporadic and UC-related carcinogenesis are the advent of genetic changes in non-neoplastic UC-related mucosa and the early loss of 18q (harbouring SMAD2, SMAD4, and DCC) and 17p (site of p53) in UC-related tumorigenesis. These studies have given rise to a number of adjunct methods in the determination of UC-related neoplasia. Never the less, conventional histopathology still remains the gold standard in the diagnosis of UC-related neoplasia. Training of histopathologists therefore is one of the most important issues in conquering the diagnostic challenges of UC-related neoplasia. The working group "Gastrointestinal Pathology" of the German Society for Pathology set up a diagnostic multicenter trial which was open to everyone interested. The interobserver variability regarding ulcerative colitis-related neoplasia was quite promising (kappa = 0.63). A consensus diagnosis was reached for all the specimens and diagnostic criteria for UC-related neoplasia were discussed, reevaluated, and agreed on. Adjunct methods and emerging markers for the diagnosis of ulcerative colitis-related neoplasia (p53, Ki67, AMACR) and its distinction from regenerative changes and sporadic adenomas occurring in UC (ALM) will be presented and discussed.

[GIPC: a new target for therapy in pancreatic adenocarcinoma?]. / Ist GIPC ein neuer Kandidat für die Therapie des Pankreaskarzinoms?

GIPC is highly expressed in human pancreatic adenocarcinoma and is a central protein for the stability of IGF-1R in pancreatic adenocarcinoma cell lines (15). The goal of this study was to prove the importance of GIPC in vivo and to evaluate possible therapeutic strategies that target this protein and its PDZ domain. In vivo effects of GIPC knockout were studied after lentiviral transduction of luciferase-expressing MiaPaCa2 pancreatic cancer cells with shRNA against GIPC; growth characteristics were monitored with bioluminiscence. Knockdown of GIPC led to a significant inhibition of pancreatic tumor cell growth in vivo in different mouse models. To test a possible therapeutic approach, the PDZ domain of GIPC was targeted by a short peptide composed of the amino acid sequence PSQSSSEA. This octapeptide was designed based on the C-terminal binding motif of GAIP. Targeting GIPC with this peptide inhibited the association between IGF-1R and GIPC. The subsequent downregulation of IGF-1R decreased proliferation in vitro and in vivo. In conclusion, our findings suggest that targeting GIPC and its PDZ domain-mediated interaction with the tyrosine kinase receptor IGF-1R could be a promising new treatment option for pancreatic cancer.

Characterization of macrophage subpopulations in colon cancer using tissue microarrays.

AIMS: To determine the pattern of macrophage infiltration in colon cancers and its correlation with clinicopathological characteristics. METHODS AND RESULTS: Colon cancers from 100 patients were arrayed into a tissue microarray (TMA). Four cores per tumour were taken: three from the invasion front (IF) and one from the tumour surface (TS). Macrophages were quantified by immunohistochemistry with antibodies to the PG-M1, KP-1, MRP8, MRP14 and MRP8/14 antigens. The number of macrophages was significantly higher in the TS cores than in the IF cores and both tumour sites showed a higher number of macrophages than the normal mucosa. The number of macrophages decreased in higher stage tumours. The different tumour-associated macrophage (TAM) subpopulations were positively correlated with each other. CONCLUSIONS: The increased number of macrophages in cancers compared with normal colon mucosa indicates that macrophages are attracted to the tumour site. However, decreasing macrophages in higher stage colon cancers suggest that this attraction decreases with tumour progression.

Prognostic relevance of 20q13 gains in sporadic colorectal cancers: a FISH analysis.

BACKGROUND: Amplification of 20q13 is a frequent chromosomal alteration in solid tumors and harbors a number of putative oncogenes (CAS/CSE1-L, NABC1, or Aurora2). Amplifications on 20q13 have been identified as an independent prognostic marker indicating worse survival in breast and ovarian cancer. However, little is known about the prognostic significance of 20q13 gains in sporadic colorectal cancers. The aim of this study was to correlate 20q13 gains in sporadic colorectal cancers with other known prognostic factors, tumor progression, and overall survival. METHODS: Nuclei were extracted from 146 paraffin-embedded colorectal cancers of different UICC stages and used for fluorescence in situ hybridization (FISH) with a directly labeled probe for 20q13.2 (VYSIS). Signals were counted in 120 nuclei per sample. 20q13 was considered gained when > or =40% of the nuclei showed 3 or more FISH signals. Statistical correlations were tested with log-rank tests and Kaplan-Meier survival curves. RESULTS: Signal numbers for 20q13.2 were gained in 78 cases (53%). Cases with gains on 20q13.2 showed worse outcome than cases without: the gain of 20q13.2 was an independent prognostic marker for overall survival (P=0.006) as well as tumor progression (P=0.012) in univariate and multivariate analyses. Gains on 20q13.2 did not correlate with tumor stage. However, there was a significant association between 20q13.2 gains and tumor location in the left-sided colon and an inverse correlation between histologic grade and 20q13.2 gains. CONCLUSION: These data indicate that gains on 20q13.2 correlate with faster tumor progression and worse patient survival independent from tumor size and lymph node involvement. Therefore, alterations on 20q13 are an important biological event in colorectal tumor progression with independent prognostic relevance.

[Molecular pathology in hereditary colorectal cancer. Recommendations of the Collaborative German Study Group on hereditary colorectal cancer funded by the German Cancer Aid (Deutsche Krebshilfe)]. / Molekularpathologische Diagnostik beim erblichen Dickdarmkarzinom. Empfehlungen und Resultate aus dem Verbundprojekt der Deutschen Krebshilfe "Krebsvorsorge und Krebsfrüherkennung bei Familiärem Darmkrebs".

Although twin studies indicate that inherited genetic factors contribute to about 35% of colorectal cancers (CRC), the exact genetic background has currently been elucidated in only 5-10% of cases. These comprise several hereditary cancer predisposition syndromes that present with a high number of syn- or metachronous neoplasms within an affected person and/or family. Many of these tumors exhibit typical histopathological changes. In general, one should discriminate between cancer syndromes associated with adenomatous and non-adenomatous (i.e., hamartomatous) polyps, the latter being quite rare. The patient's age often serves as a substantial hint to hereditary cancer. The next step of diagnostic work-up includes analysis of microsatellite instability (MSI) together with immunohistochemical detection of a loss of expression in one of the most frequently affected mismatch repair genes (MSH2, MSH6; MLH1, PMS2). Finally, the molecular demonstration of a gene mutation in the blood or germline is the most expensive and tedious procedure. This requires a signed informed consent from the patient after appropriate genetic counseling.