Pilot clinical trial of hedgehog pathway inhibitor GDC-0449 (vismodegib) in combination with gemcitabine in patients with metastatic pancreatic adenocarcinoma

PURPOSE

The hedgehog (HH) signaling pathway is a key regulator in tumorigenesis of pancreatic adenocarcinoma and is upregulated in pancreatic adenocarcinoma cancer stem cells (CSCs). GDC-0449 is an oral small-molecule inhibitor of the HH pathway. This study assessed the effect of GDC-0449-mediated HH inhibition in paired biopsies, followed by combined treatment with gemcitabine, in patients with metastatic pancreatic adenocarcinoma.

EXPERIMENTAL DESIGN

Twenty-five patients were enrolled of which 23 underwent core biopsies at baseline and following 3 weeks of GDC-0449. On day 29, 23 patients started weekly gemcitabine while continuing GDC-0449. We evaluated GLI1 and PTCH1 inhibition, change in CSCs, Ki-67, fibrosis, and assessed tumor response, survival and toxicity.

RESULTS

On pretreatment biopsy, 75% of patients had elevated sonic hedgehog (SHH) expression. On posttreatment biopsy, GLI1 and PTCH1 decreased in 95.6% and 82.6% of 23 patients, fibrosis decreased in 45.4% of 22, and Ki-67 in 52.9% of 17 evaluable patients. No significant changes were detected in CSCs pre- and postbiopsy. The median progression-free and overall survival for all treated patients were 2.8 and 5.3 months. The response and disease control rate was 21.7% and 65.2%. No significant correlation was noted between CSCs, fibrosis, SHH, Ki-67, GLI1, PTCH1 (baseline values or relative change on posttreatment biopsy), and survival. Grade ≥ 3 adverse events were noted in 56% of patients.

CONCLUSION

We show that GDC-0449 for 3 weeks leads to downmodulation of GLI1 and PTCH1, without significant changes in CSCs compared with baseline. GDC-0449 and gemcitabine were not superior to gemcitabine alone in the treatment of metastatic pancreatic cancer.

Trastuzumab emtansine in human epidermal growth factor receptor 2-positive metastatic breast cancer: an integrated safety analysis

PURPOSE

The antibody-drug conjugate trastuzumab emtansine (T-DM1) combines the cytotoxic activity of DM1 with the human epidermal growth factor receptor 2 (HER2) -targeted, antitumor properties of trastuzumab. T-DM1 has shown activity in phase I and II single-arm studies in patients with pretreated HER2-positive metastatic breast cancer (MBC) and has demonstrated superior efficacy and improved tolerability versus standard MBC treatments in randomized phase II and III studies. This analysis, combining available data from all single-agent T-DM1 studies to date, was conducted to better define the T-DM1 safety profile.

PATIENTS AND METHODS

Six studies in patients with HER2-positive MBC who received T-DM1 3.6 mg/kg every 3 weeks and follow-up data from patients in an extension study were analyzed. Analyses included adverse events (AEs) by grade; AEs leading to death, drug discontinuation, or dose reduction; and select AEs.

RESULTS

Among 884 T-DM1-exposed patients, the most commonly reported all-grade AEs were fatigue (46.4%), nausea (43.0%), thrombocytopenia (32.2%), headache (29.4%), and constipation (26.5%). The most common grade 3 to 4 AEs were the laboratory abnormalities of thrombocytopenia (11.9%) and increased AST serum concentration (4.3%). These were manageable and not generally associated with clinical symptoms. There were 12 AE-related deaths. AEs resulted in dose reductions in 17.2% of patients and drug discontinuations in 7.0%.

CONCLUSION

In this analysis of 884 T-DM1-exposed patients, grade 3 or greater AEs were infrequent and typically asymptomatic and manageable. This favorable safety profile makes T-DM1 treatment suitable for exploration in other breast cancer settings.

Lynch syndrome-associated neoplasms: a discussion on histopathology and immunohistochemistry

It was a century ago that Warthin, a pathologist, first described the clinical condition now known as Lynch syndrome. One hundred years later, our understanding of this syndrome has advanced significantly. Much of the progress took place over the last 25 years and was marked by a series of interacting developments from the disciplines of clinical oncology, pathology, and molecular genetics, with each development serving to guide or enhance the next. The advancement of our understanding about the pathology of Lynch syndrome associated tumors exemplifies such intimate interplay among disciplines. Today, accumulative knowledge has enabled surgical pathologists to detect tumors that are likely to be associated with Lynch syndrome, and the pathologist is playing an increasingly more important role in the care of these patients. The pathologist's ability is afforded primarily by information gained from tumor histopathology and by DNA mismatch repair protein immunohistochemistry. It is therefore pertinent both for the pathologists to accurately ascertain this morphologic information, and for all that are involved in the care of these patients to thoroughly understand the implications of such information. This article provides an overview of the development of histopathology and immunohistochemistry in Lynch syndrome-associated tumors, particularly in colorectal and endometrial cancers, and outlines the issues and current status of these specific pathologic aspects in not only the major tumors but also those less commonly seen or only newly reported in Lynch syndrome patients.

A pathologist's survey on the reporting of sessile serrated adenomas/polyps

AIM

The purpose of this survey was to ascertain reporting habits of pathologists towards sessile serrated adenomas/polyps (SSA/P).

METHODS

A questionnaire designed to highlight diagnostic criteria, approach and clinical implications of SSA/P was circulated electronically to 45 pathologists in the UK and North America.

RESULTS

Forty-three of 45 pathologists agreed to participate. The vast majority (88%) had a special interest in gastrointestinal (GI) pathology, had great exposure to GI polyps in general with 40% diagnosing SSA/P at least once a week if not more, abnormal architecture was thought by all participants to be histologically diagnostic, and 11% would make the diagnosis if a single diagnostic histological feature was present in one crypt only, while a further 19% would diagnose SSA/P in one crypt if more than one diagnostic feature was present. The vast majority agreed that deeper sections were useful and 88% did not feel proliferation markers were useful. More than one-third did not know whether, or did not feel that, their clinicians were aware of the implications of SSA/P.

CONCLUSIONS

98% of pathologists surveyed are aware that SSA/P is a precursor lesion to colorectal cancer, the majority agree on diagnostic criteria, and a significant number feel that there needs to be greater communication and awareness among pathologists and gastroenterologists about SSA/P.

Effect of lifetime alcohol consumption on the histological severity of non-alcoholic fatty liver disease

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is defined based on recent alcohol consumption; however, remote or lifetime alcohol consumption is not taken into account. It is not known whether lifetime alcohol consumption contributes to the severity of disease in patients with NAFLD. To determine the effect of lifetime alcohol consumption on the histological severity in patients with NAFLD.

PATIENTS & METHODS

Adults >18 years of age with presumed NAFLD and alcohol consumption <40 g/week were enrolled. Lifetime alcohol consumption was determined using a questionnaire. Patients with a history of long-term alcohol abuse or dependence were excluded. A liver biopsy was reviewed by a single pathologist in a blinded fashion. Demographic, clinical and histological findings were compared in those who had regular alcohol consumption and those who did not.

RESULTS

A total of 77 patients had fatty liver on biopsy. Fifty-two patients had a history of regular alcohol consumption. The median lifetime cumulative alcohol intake was 24 gram-years. On multivariable analysis, increasing age (OR 1.07, 95% CI 1.01-1.14) was associated with severe liver disease, whereas alcohol consumption of ≥24 gram-years was associated with less severe disease (OR 0.26, 95% CI 0.07-0.97, P = 0.04). Patients who continued to consume alcohol or had been abstinent for ≤1 year had less severe disease.

CONCLUSION

Some degree of regular alcohol consumption over the course of a lifetime compared to minimal intake appears to have a protective effect on the histological severity of liver disease among patients with strictly defined NAFLD.

The clinical significance of duodenal lymphocytosis with normal villus architecture

CONTEXT

The finding of increased intraepithelial lymphocytes with normal villous architecture (Marsh I lesion) is seen in up to 3% of duodenal biopsies. The differential diagnosis includes a wide range of possibilities, including celiac disease, bacterial overgrowth, nonsteroidal antiinflammatory drug damage, reaction to Helicobacter pylori infection, tropical sprue, and chronic inflammatory bowel disease.

OBJECTIVES

To highlight the histologic features of the Marsh I lesion, review the diseases and conditions associated with that finding, and to provide pathologists with a rationale and a template for how to identify and report such cases.

DATA SOURCES

A review of the literature regarding the histologic features and clinical associations of Marsh I lesions.

CONCLUSIONS

Marsh I lesions are a nonspecific finding associated with a number of disease conditions. Historically, between 9% and 40% of cases have been shown to represent celiac disease. Current data do not suggest histologic features to differentiate between diseases associated with this histologic change.

Endothelial PAS domain protein 1 activates the inflammatory response in the intestinal epithelium to promote colitis in mice

BACKGROUND & AIMS

Hypoxic inflammation (decreased oxygen tension at sites of inflammation) is a feature of inflammatory bowel disease (IBD). The hypoxia response is mediated by the transcription factors hypoxia-inducible factor (HIF) 1α and endothelial PAS domain protein 1 (EPAS1 or HIF2α), which are induced in intestinal tissues of patients with IBD. HIF1α limits intestinal barrier dysfunction, but the role of EPAS1 has not been assessed under conditions of hypoxic inflammation or in models of IBD.

METHODS

Acute colitis was induced by administration of Citrobacter rodentium or dextran sulfate sodium (DSS) to transgenic hypoxia reporter mice (oxygen-dependent degradation-luciferase), mice with conditional overexpression of Epas1 (Epas1(LSL/LSL)), mice with intestinal epithelium-specific deletion of Epas1 (Epas1(ΔIE) ), or wild-type littermates (controls). Colon tissues from these mice and from patients with ulcerative colitis or Crohn's disease were assessed by histologic and immunoblot analyses, immunohistochemistry, and quantitative polymerase chain reaction.

RESULTS

Levels of hypoxia and EPAS1 were increased in colon tissues of mice after induction of colitis and patients with ulcerative colitis or Crohn's disease compared with controls. Epas1(ΔIE) mice had attenuated colonic inflammation and were protected from DSS-induced colitis. Intestine-specific overexpression of EPAS1, but not HIF-1α, led to spontaneous colitis, increased susceptibility to induction of colitis by C rodentium or DSS, and reduced survival times compared with controls. Disruption of intestinal epithelial EPAS1 attenuated the inflammatory response after administration of DSS or C rodentium, and intestine-specific overexpression of EPAS1 increased this response. We found EPAS1 to be a positive regulator of tumor necrosis factor-α production by the intestinal epithelium. Blocking tumor necrosis factor-α completely reduced hypoxia-induced intestinal inflammation.

CONCLUSIONS

EPAS1 is a transcription factor that activates mediators of inflammation, such as tumor necrosis factor-α, in the intestinal epithelium and promotes development of colitis in mice.

Polyposis Syndromes: Role of the Pathologist

This article reviews the major gastrointestinal polyposis syndromes, with an emphasis on the molecular, clinical, and histopathological features of each. Salient features helpful in making or suggesting the diagnosis of these syndromes are discussed, as is the use of ancillary techniques, such as immunohistochemistry and molecular diagnostic studies in diagnosis confirmation and family screening.

Distinct molecular features of colorectal cancer in Ghana

OBJECTIVES

While colorectal cancer (CRC) is common, its incidence significantly varies around the globe. The incidence of CRC in West Africa is relatively low, but it has a distinctive clinical pattern and its molecular characteristics have not been studied. This study is one of the first attempts to analyze molecular, genetic, and pathological characteristics of colorectal cancer in Ghana.

METHODS

DNA was extracted from microdissected tumor and adjacent normal tissue of 90 paraffin blocks of CRC cases (1997-2007) collected at the University of Ghana. Microsatellite instability (MSI) was determined using fragment analysis of ten microsatellite markers. We analyzed expression of mismatch repair (MMR) proteins by immunohistochemistry and sequenced exons 2 and 3 of KRAS and exon 15 of BRAF.

RESULTS

MSI analysis showed 41% (29/70) MSI-High, 20% (14/70) MSI-Low, and 39% (27/70) microsatellite-stable (MSS) tumors. Sequencing of KRAS exons 2 and 3 identified activating mutations in 32% (24/75) of tumors, and sequencing of BRAF exon 15, the location of the common activating mutation (V600), did not show mutations at codons 599 and 600 in 88 tumors.

CONCLUSIONS

Our study found a high frequency of MSI-High colorectal tumors (41%) in Ghana. While the frequency of KRAS mutations is comparable with other populations, absence of BRAF mutations is intriguing and would require further analysis of the molecular epidemiology of CRC in West Africa.

Debating deposits: an interobserver variability study of lymph nodes and pericolonic tumor deposits in colonic adenocarcinoma

CONTEXT

The American Joint Committee on Cancer's Cancer Staging Manual 7th edition defines pericolonic tumor deposits (TDs) as discrete tumor foci in pericolic fat showing no evidence of residual lymph node (LN). This definition relies on subjective features rather than size (5th edition) or shape (6th edition) and introduced the category N1c. Although typically straightforward, metastases are encountered for which the distinction between LNs and TDs is unclear. For data to be meaningful, agreement on distinguishing features between positive LNs and TDs is needed.

OBJECTIVES

To assess agreement among gastrointestinal pathologists evaluating difficult metastases and to report the distinguishing features they found helpful.

DESIGN

Twenty-five tumor metastases from right-sided colonic adenocarcinomas were selected in which the distinction between positive LNs and TDs was challenging. Virtual slides were reviewed by 7 gastrointestinal pathologists. A list of features potentially helpful in differentiating positive LNs and TDs was ranked for usefulness by each pathologist. Every metastasis was diagnosed as positive LN or TD. For each case diagnosed as positive LN, reviewers were asked to list every feature used in diagnosis.

RESULTS

Complete agreement was found for 11 of 25 metastases, 5 positive LNs and 6 TDs (κ statistic, 0.48; 95% confidence interval, 0.28-0.67). Top-ranked features included round shape, peripheral lymphocyte rim, peripheral lymphoid follicles, possible subcapsular sinus, residual LN in surrounding fibroadipose tissue, and thick capsule. The top used features were similar among reviewers.

CONCLUSIONS

Significant agreement on positive LNs and TDs in difficult colonic adenocarcinoma metastases was found among evaluators, but inconsistency remains. Round shape, peripheral lymphocyte rim, peripheral lymphoid follicles, possible subcapsular sinus, residual LN in surrounding fibroadipose tissue, and thick capsule were most often used to aid in diagnosis.

Adrenocortical carcinoma is a lynch syndrome-associated cancer

PURPOSE

Adrenocortical carcinoma (ACC) is an endocrine malignancy with a poor prognosis. The association of adult-onset ACC with inherited cancer predisposition syndromes is poorly understood. Our study sought to define the prevalence of Lynch syndrome (LS) among patients with ACC.

PATIENTS AND METHODS

One hundred fourteen patients with ACC were evaluated in a specialized endocrine oncology clinic and were prospectively offered genetic counseling and clinical genetics risk assessment (group 1). In addition, families with known mismatch repair (MMR) gene mutations that were recorded in the University of Michigan Cancer Genetics Registry were retrospectively reviewed for the presence of ACC (group 2). ACC tumors from patients with LS were tested for microsatellite instability and immunohistochemistry (IHC) to evaluate for MMR deficiency.

RESULTS

Ninety-four (82.5%) of 114 patients with ACC underwent genetic counseling (group 1). Three individuals (3.2%) had family histories suggestive of LS. All three families were found to have MMR gene mutations. Retrospective review of an additional 135 MMR gene-positive probands identified two with ACC (group 2). Four ACC tumors were available (group 1, 3; group 2, 1). All four tumors were microsatellite stable; three had IHC staining patterns consistent with germline mutation status.

CONCLUSION

The prevalence of LS among patients with ACC is 3.2%, which is comparable to the prevalence of LS in colorectal and endometrial cancer. Patients with ACC and a personal or family history of LS tumors should be strongly considered for genetic risk assessment. IHC screening of all ACC tumors may be an effective strategy for identifying patients with LS.

Sensitization of pancreatic cancer to chemoradiation by the Chk1 inhibitor MK8776

PURPOSE

The combination of radiation with chemotherapy is the most effective therapy for unresectable pancreatic cancer. To improve upon this regimen, we combined the selective Checkpoint kinase 1 (Chk1) inhibitor MK8776 with gemcitabine-based chemoradiation in preclinical pancreatic cancer models.

EXPERIMENTAL DESIGN

We tested the ability of MK8776 to sensitize to gemcitabine-radiation in homologous recombination repair (HRR)-proficient and -deficient pancreatic cancer cells and assessed Rad51 focus formation. In vivo, we investigated the efficacy, tumor cell selectivity, and pharmacodynamic biomarkers of sensitization by MK8776.

RESULTS

We found that MK8776 significantly sensitized HRR-proficient (AsPC-1, MiaPaCa-2, BxPC-3) but not -deficient (Capan-1) pancreatic cancer cells to gemcitabine-radiation and inhibited Rad51 focus formation in HRR-proficient cells. In vivo, MiaPaCa-2 xenografts were significantly sensitized to gemcitabine-radiation by MK8776 without significant weight loss or observable toxicity in the small intestine, the dose-limiting organ for chemoradiation therapy in pancreatic cancer. We also assessed pChk1 (S345), a pharmacodynamic biomarker of DNA damage in response to Chk1 inhibition in both tumor and small intestine and found that MK8776 combined with gemcitabine or gemcitabine-radiation produced a significantly greater increase in pChk1 (S345) in tumor relative to small intestine, suggesting greater DNA damage in tumor than in normal tissue. Furthermore, we demonstrated the utility of an ex vivo platform for assessment of pharmacodynamic biomarkers of Chk1 inhibition in pancreatic cancer.

CONCLUSIONS

Together, our results suggest that MK8776 selectively sensitizes HRR-proficient pancreatic cancer cells and xenografts to gemcitabine-radiation and support the clinical investigation of MK8776 in combination with gemcitabine-radiation in locally advanced pancreatic cancer.

A multi-institutional phase 2 study of neoadjuvant gemcitabine and oxaliplatin with radiation therapy in patients with pancreatic cancer

BACKGROUND

The purpose of this study was to evaluate preoperative treatment with full-dose gemcitabine, oxaliplatin, and radiation therapy (RT) in patients with localized pancreatic cancer.

METHODS

Eligibility included confirmation of adenocarcinoma, resectable or borderline resectable disease, a performance status ≤2, and adequate organ function. Treatment consisted of two 28-day cycles of gemcitabine (1 g/m(2) over 30 minutes on days 1, 8, and 15) and oxaliplatin (85 mg/m(2) on days 1 and 15) with RT during cycle 1 (30 Gray [Gy] in 2-Gy fractions). Patients were evaluated for surgery after cycle 2. Patients who underwent resection received 2 cycles of adjuvant chemotherapy.

RESULTS

Sixty-eight evaluable patients received treatment at 4 centers. By central radiology review, 23 patients had resectable disease, 39 patients had borderline resectable disease, and 6 patients had unresectable disease. Sixty-six patients (97%) completed cycle 1 with RT, and 61 patients (90%) completed cycle 2. Grade ≥3 adverse events during preoperative therapy included neutropenia (32%), thrombocytopenia (25%), and biliary obstruction/cholangitis (14%). Forty-three patients underwent resection (63%), and complete (R0) resection was achieved in 36 of those 43 patients (84%). The median overall survival was 18.2 months (95% confidence interval, 13-26.9 months) for all patients, 27.1 months (95% confidence interval, 21.2-47.1 months) for those who underwent resection, and 10.9 months (95% confidence interval, 6.1-12.6 months) for those who did not undergo resection. A decrease in CA 19-9 level after neoadjuvant therapy was associated with R0 resection (P = .02), which resulted in a median survival of 34.6 months (95% confidence interval, 20.3-47.1 months). Fourteen patients (21%) are alive and disease free at a median follow-up of 31.4 months (range, 24-47.6 months).

CONCLUSIONS

Preoperative therapy with full-dose gemcitabine, oxaliplatin, and RT was feasible and resulted in a high percentage of R0 resections. The current results are particularly encouraging, because the majority of patients had borderline resectable disease.

Inflammatory bowel disease and familial adenomatous polyposis

BACKGROUND

Inflammatory bowel disease (IBD) and familial adenomatous polyposis (FAP) are uncommon diseases and both are associated with marked increased risk of colorectal cancer.

METHODS

We present a patient diagnosed in parallel with ulcerative colitis and FAP. Mutational analysis of the APC germline and somatic DNA was performed by sequencing.

RESULTS

This patient's phenotype consisted of polyps only on the right side of the colon (cecum and ascending colon) whereas the area affected by ulcerative colitis (descending colon and rectum) was free of polyps on endoscopy and microscopic adenomas on histology. This raises the possibility that mosaicism or inflammation in the presence of active ulcerative colitis modified the phenotypic expression of adenomatous polyposis in the left colon. Mosaicism was excluded by DNA analysis.

DISCUSSION

This case of a patient diagnosed with both inflammatory bowel disease and familial adenomatous polyposis offers potential insights into the distinct pathogenesis of cancer susceptibility within these syndromes, and suggests that a collision of phenotypes may influence their mutual presentation. Both of these conditions independently increase the risk of colorectal cancer.

The histone deacetylase SIRT6 is a tumor suppressor that controls cancer metabolism

Reprogramming of cellular metabolism is a key event during tumorigenesis. Despite being known for decades (Warburg effect), the molecular mechanisms regulating this switch remained unexplored. Here, we identify SIRT6 as a tumor suppressor that regulates aerobic glycolysis in cancer cells. Importantly, loss of SIRT6 leads to tumor formation without activation of known oncogenes, whereas transformed SIRT6-deficient cells display increased glycolysis and tumor growth, suggesting that SIRT6 plays a role in both establishment and maintenance of cancer. By using a conditional SIRT6 allele, we show that SIRT6 deletion in vivo increases the number, size, and aggressiveness of tumors. SIRT6 also functions as a regulator of ribosome metabolism by corepressing MYC transcriptional activity. Lastly, Sirt6 is selectively downregulated in several human cancers, and expression levels of SIRT6 predict prognosis and tumor-free survival rates, highlighting SIRT6 as a critical modulator of cancer metabolism. Our studies reveal SIRT6 to be a potent tumor suppressor acting to suppress cancer metabolism.

Life-long learning and self-assessment

New Frontiers in Pathology is a unique educational event intended to meet the ongoing educational needs of practicing pathologists. Continuous medical education (CME) is required for maintenance of licensure by virtually all state licensing bodies. Satisfying CME requirements hinges on earning a minimum number of American Medical Association Physician Recognition Award category 1 credits through various activities, including courses like New Frontiers in Pathology that are accredited by the Accreditation Council for Continuing Medical Education. Self-assessment modules (SAMs) are a key component of the American Board of Pathology expectations for maintenance of board certification. Beginning in 2006, the American Board of Pathology granted only time-limited certificates as part of an American Board of Medical Specialties-wide process for maintenance of board certification. Maintenance of board certification has requirements in 4 categories: professional standing, life-long learning and self-assessment, cognitive expertise, and evaluation of performance in practice. Life-long learning and self-assessment includes not only the traditional elements of CME but also the SAMs that are defined as educational products comprising self-administered examinations with a predetermined minimum performance level and a mechanism for receiving feedback. New Frontiers in Pathology will offer SAMs, in addition to the American Medical Association Physician Recognition Award category 1 credits, which it has been accredited to do since its inception, at its 2012 conference scheduled for August 3 through August 5 at The Homestead Resort, Michigan's largest waterfront resort on beautiful Lake Michigan.

The Differential Diagnosis of Colitis in Endoscopic Biopsy Specimens: A Review Article

Context.—A variety of inflammatory disorders may affect the colon, with widely differing clinical outcomes and management. These conditions encompass a spectrum of acute and chronic conditions.

Objective.—Review the pathology of the major colitides and highlight the most diagnostically useful features.

Data Sources.—Review of recent literature supplemented with personal experience in the field of gastrointestinal pathology.

Conclusions.—The etiologies associated with the various types of colitis are diverse and the range of histologic changes is somewhat limited. Nevertheless, the combination of clinical and endoscopic data coupled with histopathology allows for accurate classification in the majority of cases.

Hypoxia-inducible factor-2α activation promotes colorectal cancer progression by dysregulating iron homeostasis

Hypoxia-inducible factor (HIF), a key modulator of the transcriptional response to hypoxia, is increased in colon cancer. However, the role of HIF in colon carcinogenesis in vivo remains unclear. In this study, we found that intestinal epithelium-specific disruption of the von Hippel-Lindau tumor suppressor protein (VHL) resulted in constitutive HIF signaling, and increased HIF expression augmented colon tumorigenesis in the Apc(min/+) intestinal tumor model. Intestine-specific disruption of Vhl increased colon tumor multiplicity and progression from adenomas to carcinomas. These effects were ameliorated in mice with double disruption of Vhl and HIF-2α. Activation of HIF signaling resulted in increased cell survival in normal colon tissue; however, tumor apoptosis was not affected. Interestingly, a robust activation of cyclin D1 was observed in tumors of Apc(min/+) mice in which HIF-2α was activated in the intestine. Consistent with this result, bromodeoxyuridine incorporation indicated that cellular proliferation was increased in colon tumors following HIF activation. Further analysis showed that dysregulation of the intestinal iron absorption transporter divalent metal transporter-1 (DMT-1) was a critical event in HIF-2α-mediated colon carcinogenesis. These data provide a mechanistic basis for the widely reported link between iron accumulation and colon cancer risk. Together, our findings show that a chronic increase in HIF-2α in the colon initiates protumorigenic signaling, which may have important implications in developing preventive and therapeutic strategies for colon cancer.

Risk of colorectal cancer in self-reported inflammatory bowel disease and modification of risk by statin and NSAID use

BACKGROUND

Statins and nonsteroidal anti-inflammatory drugs (NSAIDs) are associated with reduced risk of colorectal cancer (CRC) in some studies. The objective of this study was to quantify the relative risk of inflammatory bowel disease (IBD) as a risk factor for CRC and to estimate whether this risk may be modified by long-term use of NSAIDs or statins.

METHODS

The Molecular Epidemiology of Colorectal Cancer study is a population-based, case-control study of incident colorectal cancer in northern Israel and controls matched by age, sex, clinic, and ethnicity. Personal histories of IBD and medication use were measured by structured, in-person interview. The relative risk of IBD and effect modification by statins and NSAIDs were quantified by conditional and unconditional logistic regression.

RESULTS

Among 1921 matched pairs of CRC cases and controls, a self-reported history of IBD was associated with a 1.9-fold increased risk of CRC (95% confidence interval [CI], 1.12-3.26). Long-term statin use was associated with a reduced risk of both IBD-associated CRC (odds ratio [OR] = 0.07; 95% CI, 0.01-0.78) and non-IBD CRC (OR = 0.49; 95% CI, 0.39-0.62). Stratified analysis suggested that statins may be more protective among those with IBD (ratio of OR = 0.14; 95% CI, 0.01-1.31; P = .51), although not statistically significant. NSAID use in patients with a history of IBD was suggestive of reduced risk of CRC but did not reach statistical significance (OR = 0.47; 95% CI, 0.12-1.86).

CONCLUSIONS

The risk of CRC was elevated 1.9-fold in patients with IBD. Long-term statin use was associated with reduced risk of CRC in patients with IBD.

Rearrangements of the RAF kinase pathway in prostate cancer, gastric cancer and melanoma

Although recurrent gene fusions involving erythroblastosis virus E26 transformation-specific (ETS) family transcription factors are common in prostate cancer, their products are considered 'undruggable' by conventional approaches. Recently, rare targetable gene fusions involving the anaplastic lymphoma receptor tyrosine kinase (ALK) gene, have been identified in 1-5% of lung cancers, suggesting that similar rare gene fusions may occur in other common epithelial cancers, including prostate cancer. Here we used paired-end transcriptome sequencing to screen ETS rearrangement-negative prostate cancers for targetable gene fusions and identified the SLC45A3-BRAF (solute carrier family 45, member 3-v-raf murine sarcoma viral oncogene homolog B1) and ESRP1-RAF1 (epithelial splicing regulatory protein-1-v-raf-1 murine leukemia viral oncogene homolog-1) gene fusions. Expression of SLC45A3-BRAF or ESRP1-RAF1 in prostate cells induced a neoplastic phenotype that was sensitive to RAF and mitogen-activated protein kinase kinase (MAP2K1) inhibitors. Screening a large cohort of patients, we found that, although rare, recurrent rearrangements in the RAF pathway tend to occur in advanced prostate cancers, gastric cancers and melanoma. Taken together, our results emphasize the key role of RAF family gene rearrangements in cancer, suggest that RAF and MEK inhibitors may be useful in a subset of gene fusion-harboring solid tumors and demonstrate that sequencing of tumor transcriptomes and genomes may lead to the identification of rare targetable fusions across cancer types.

Oncogenic KRAS is not necessary for Wnt signalling activation in APC-associated FAP adenomas

Recent studies have suggested that APC loss alone may be insufficient to promote aberrant Wnt/beta-catenin signalling. Our aim was to comprehensively characterize Wnt signalling components in a set of APC-associated familial adenomatous polyposis (FAP) tumours. Sixty adenomas from six FAP patients with known pathogenic APC mutations were included. Somatic APC and KRAS mutations, beta-catenin immunostaining, and qRT-PCR of APC, MYC, AXIN2 and SFRP1 were analysed. Array-comparative genomic hybridization (aCGH) was also assessed in 26 FAP adenomas and 24 paired adenoma-carcinoma samples. A somatic APC alteration was present in 15 adenomas (LOH in 11 and four point mutations). KRAS mutations were detected in 10% of the cases. APC mRNA was overexpressed in adenomas. MYC and AXIN2 were also overexpressed, with significant intra-case heterogeneity. Increased cytoplasmic and/or nuclear beta-catenin staining was seen in 94% and 80% of the adenomas. beta-Catenin nuclear staining was strongly associated with MYC levels (p value 0.03) but not with KRAS mutations. Copy number aberrations were rare. However, the recurrent chromosome changes observed more frequently contained Wnt pathway genes (p value 0.012). Based on beta-catenin staining and Wnt pathway target genes alterations the Wnt pathway appears to be constitutively activated in all APC-FAP tumours, with alterations occurring both upstream and downstream of APC. Wnt aberrations are present at both the DNA and the RNA level. Somatic profiling of APC-FAP tumours provides new insights into the role of APC in tumourigenesis.

Smoking, gender, and ethnicity predict somatic BRAF mutations in colorectal cancer

Approximately 5% to 15% of all colorectal cancers (CRC) have an activating BRAF somatic mutation, which may be associated with a distinct risk profile compared with tumors without BRAF mutations. Here, we measured the prevalence and epidemiologic correlates of the BRAF V600E somatic mutation in cases collected as a part of a population-based case-control study of CRC in northern Israel. The prevalence of BRAF V600E was 5.0% in this population, and the mutation was more likely to be found in tumors from cases who were of Ashkenazi Jewish descent [odds ratio (OR), 1.87; 95% confidence interval (95% CI), 1.01-3.47], female (OR, 1.97; P = 1.17-3.31), and older (73.8 years versus 70.3 years; P < 0.001). These results were similar when restricting to only tumors with microsatellite instability. Whether smoking was associated with a BRAF somatic mutation depended on gender. Although men were less likely to have a tumor with a BRAF somatic mutation, men who smoked were much more likely to have a tumor with a somatic BRAF mutation (OR(interaction), 4.95; 95% CI, 1.18-20.83) than women who never smoked. We note the strong heterogeneity in the reported prevalence of the BRAF V600E mutation in studies of different ethnicities, with a lower prevalence in Israel than other Western populations but a higher prevalence among Jewish than non-Jewish Israeli cases. Epidemiologic studies of CRC should incorporate somatic characteristics to fully appreciate risk factors for this disease.

Prognostic value of Ishak fibrosis stage: findings from the hepatitis C antiviral long-term treatment against cirrhosis trial

Studies of the prognostic value of Ishak fibrosis stage are lacking. We used multi-year follow-up of the Hepatitis C Antiviral Long-Term Treatment Against Cirrhosis (HALT-C) Trial to determine whether individual Ishak fibrosis stages predicted clinical outcomes in patients with chronic hepatitis C. Baseline liver biopsy specimens from 1050 patients with compensated chronic hepatitis C who had failed combination peginterferon and ribavirin were reviewed by a panel of expert hepatopathologists. Fibrosis was staged with the Ishak scale (ranging from 0 = no fibrosis to 6 = cirrhosis). Biopsy fragmentation and length as well as number of portal tracts were recorded. We compared rates of prespecified clinical outcomes of hepatic decompensation and hepatocellular carcinoma across individual Ishak fibrosis stages. Of 1050 biopsy specimens, 25% were fragmented, 63% longer than 1.5 cm, 69% larger than 10 mm(2), and 75% had 10 or more portal tracts. Baseline laboratory markers of liver disease severity were worse and the frequency of esophageal varices higher with increasing Ishak stage (P < 0.0001). The 6-year cumulative incidence of first clinical outcome was 5.6% for stage 2, 16.1% for stage 3, 19.3% for stage 4, 37.8% for stage 5, and 49.3% for stage 6. Among nonfragmented biopsy specimens, the predictive ability of Ishak staging was enhanced; however, no association was observed between Ishak stage and outcomes for fragmented biopsy specimens because of high rates of outcomes for patients with noncirrhotic stages. Similar results were observed with liver transplantation or liver-related death as the outcome.

CONCLUSION

Ishak fibrosis stage predicts clinical outcomes, need for liver transplantation, and liver-related death in patients with chronic hepatitis C. Patients with fragmented biopsy specimens with low Ishak stage may be understaged histologically.

Human papillomavirus is not associated with colorectal cancer in a large international study

OBJECTIVE OF THE STUDY

Recent publications have reported an association between colon cancer and human papillomaviruses (HPV), suggesting that HPV infection of the colonic mucosa may contribute to the development of colorectal cancer.

METHODS

The GP5+/GP6+ PCR reverse line blot method was used for detection of 37 types of human papillomavirus (HPV) in DNA from paraffin-embedded or frozen tissues from patients with colorectal cancer (n = 279) and normal adjacent tissue (n = 30) in three different study populations, including samples from the United States (n = 73), Israel (n = 106) and Spain (n = 100). Additionally, SPF10 PCR was run on all samples (n = 279) and the Innogenetics INNO-LiPA assay was performed on a subset of samples (n = 15).

RESULTS

All samples were negative for all types of HPV using both the GP5+/GP6+ PCR reverse line blot method and the SPF10 INNO-LiPA method.

CONCLUSIONS

We conclude that HPV types associated with malignant transformation do not meaningfully contribute to adenocarcinoma of the colon.