Mutational analysis of BRAF in gallbladder carcinomas in association with K-ras and p53 mutations and microsatellite instability

Identification of genes associated with gall bladder cell carcinogenesis: Implications in targeted therapy of gall bladder cancer

Gall bladder cancer (GBC) is becoming a very devastating form of hepatobiliary cancer in India. Every year new cases of GBC are quite high in India. Despite recent advanced multimodality treatment options, the survival of GBC patients is very low. If the disease is diagnosed at the advanced stage (with local nodal metastasis or distant metastasis) or surgical resection is inoperable, the prognosis of those patients is very poor. So, perspectives of targeted therapy are being taken. Targeted therapy includes hormone therapy, proteasome inhibitors, signal transduction and apoptosis inhibitors, angiogenesis inhibitors, and immunotherapeutic agents. One such signal transduction inhibitor is the specific short interfering RNA (siRNA) or short hairpin RNA (shRNA). For developing siRNA-mediated therapy shRNA, although several preclinical studies to evaluate the efficacy of these key molecules have been performed using gall bladder cells, many more clinical trials are required. To date, many such genes have been identified. This review will discuss the recently identified genes associated with GBC and those that have implications in its treatment by siRNA or shRNA.

The pleiotropic roles of circular and long noncoding RNAs in cutaneous melanoma

Cutaneous melanoma (CM) is a very aggressive disease, often characterized by unresponsiveness to conventional therapies and high mortality rates worldwide. The identification of the activating BRAFV600 mutations in approximately 50% of CM patients has recently fueled the development of novel small-molecule inhibitors that specifically target BRAFV600 -mutant CM. In addition, a major progress in CM treatment has been made by monoclonal antibodies that regulate the immune checkpoint inhibitors. However, although target-based therapies and immunotherapeutic strategies have yielded promising results, CM treatment remains a major challenge. In the last decade, accumulating evidence points to the aberrant expression of different types of noncoding RNAs (ncRNAs) in CM. While studies on microRNAs have grown exponentially leading to significant insights on CM biology, the role of circular RNAs (circRNAs) and long noncoding RNAs (lncRNAs) in this tumor is less understood, and much remains to be discovered. Here, we summarize and critically review the available evidence on the molecular functions of circRNAs and lncRNAs in BRAFV600 -mutant CM and CM immunogenicity, providing recent updates on their functional role in targeted therapy and immunotherapy resistance. In addition, we also include an evaluation of several algorithms and databases for prediction and validation of circRNA and lncRNA functional interactions.

Gallbladder Cancer: Current Insights in Genetic Alterations and Their Possible Therapeutic Implications

Simple Summary

Knowledge of genetic alterations in gallbladder cancer (GBC) continues to increase. This systematic review provides an overview of frequently occurring genetic alterations in GBC and describes their possible therapeutic implications. We detected three frequently (>5%) altered genes (ATM, ERBB2 and PIK3CA) for which targeted therapies are available in other cancer types. For solid cancers with microsatellite instability or a high tumor mutational burden pembrolizumab is FDA-approved. Altogether, these five biomarkers might be used in future molecular panels to enable precision medicine for patients with GBC. We found only nine clinical trials evaluating targeted therapies in GBC directed at frequently altered genes (ERBB2, ARID1A, ATM and KRAS). This underlines the challenges to perform such clinical trials in this rare, heterogeneous cancer type and emphasizes the need for multicenter clinical trials.

Abstract

Due to the fast progression in molecular technologies such as next-generation sequencing, knowledge of genetic alterations in gallbladder cancer (GBC) increases. This systematic review provides an overview of frequently occurring genetic alterations occurring in GBC and their possible therapeutic implications. A literature search was performed utilizing PubMed, EMBASE, Cochrane Library, and Web of Science. Only studies reporting genetic alterations in human GBC were included. In total, data were extracted from 62 articles, describing a total of 3893 GBC samples. Frequently detected genetic alterations (>5% in >5 samples across all studies) in GBC for which targeted therapies are available in other cancer types included mutations in ATM, ERBB2, and PIK3CA, and ERBB2 amplifications. High tumor mutational burden (TMB-H) and microsatellite instability (MSI-H) were infrequently observed in GBC (1.7% and 3.5%, respectively). For solid cancers with TMB-H or MSI-H pembrolizumab is FDA-approved and shows an objective response rates of 50% for TMB-H GBC and 41% for MSI-H biliary tract cancer. Only nine clinical trials evaluated targeted therapies in GBC directed at frequently altered genes (ERBB2, ARID1A, ATM, and KRAS). This underlines the challenges to perform such clinical trials in this rare, heterogeneous cancer type and emphasizes the need for multicenter clinical trials.

Targeted therapies for gallbladder cancer: an overview of agents in preclinical and clinical development

Introduction: Gallbladder cancer (GC) is a rare malignancy with a dismal prognosis. When diagnosed early enough, it can be cured by surgical removal. Unfortunately, only few GC patients can be amenable to surgery, though, with a high relapse rate. Conventional chemotherapy remains the golden standard for unresectable or metastatic GC, both in the first and second-line settings, even if leading to a fair outcome improvement.Areas covered: In recent years, according to the concept of 'precision medicine', new potential molecular targets have been examined. We provided a general outline of the current first- and second-line chemotherapies. New therapeutic possibilities are also reviewed, particularly HER2, EGFR, VEGF, TKI, MEK and BRAF inhibitors, and immunotherapy. Furthermore, published clinical trials are utilized to analyze the principal drug effectiveness in GC.Expert opinion: GC is characterized by vast cancer heterogeneity and individual's efficacy to different drugs. The ongoing trials have the potentiality of reshaping the landscape of systemic treatments for GC in the very next years. Nowadays, amongst therapeutic combinations, the addition of ICIs to chemotherapy has yielded encouraging results needing confirmation. In the next future, systematic implementation of gene profiling and further explorations of combination therapies will likely change the treatment scenario.

Rare DNA Mismatch Repair-Related Protein Loss in Patients with Intrahepatic Cholangiocarcinoma and Combined Hepatocellular-Cholangiocarcinoma and Their Response to Immunotherapy

Purpose

The patients with advanced mismatch repair deficiency (dMMR) cancers can benefit from programmed cell death 1 (PD-1) pathway blockade, regardless of the tumor type. Little is known about the prevalence of dMMR in intrahepatic cholangiocarcinoma (ICC) and combined hepatocellular-cholangiocarcinoma (cHCC-CC). This study aimed to assess the mismatch repair (MMR)-related protein expression in patients with ICC and cHCC-CC.

Patients and Methods

Formalin-fixed, paraffin-embedded tumor specimens were obtained from patients undergoing surgery at the West china Hospital between 2009 and 2017. The immunoreactions for MLH1, MSH2, MSH6, and PMS2 were investigated to determine the MMR status.

Results

A total of 97 patients were evaluated, including 73 ICC patients and 24 cHCC-CC patients. The prevalence of dMMR was only found in two cases of 97 patients (2.06%). Both patients are ICC. In 24 cHCC-CC patients, no dMMR was observed. They did not receive an adjuvant chemotherapy after surgery. At the end of the follow-up, one patient was in a tumor-free state, and the other patient had local recurrence and metastasis. After receiving sintilimumab (an immune checkpoint inhibitor [ICI] for PD- 1), the patient had a partial response.

Conclusion

DMMR was detected in few patients with ICC and cHCC-CC. Thus, it is not recommended to routinely evaluate the MMR status of patients with ICC or cHCC-CC after surgery, but that of patients with advanced ICC or cHCC-CC should be assessed.

Choledochal Cysts Resected during Childhood Show No Mutations of KRAS and BRAF as Early Markers of Malignancy in Cholangiocytes

INTRODUCTION

 In patients with choledochal cysts (CDC), a hyperplasia-dysplasia-carcinoma sequence can lead to biliary tract malignancy. The limited data available suggest that the risk decreases considerably after excision in childhood. We analyzed samples of resected CDC from pediatric patients histologically and performed mutational analysis of the proto-oncogenes KRAS and BRAF as early markers of malignant alteration in cholangiocytes.

MATERIALS AND METHODS

 After institutional review board approval, patients undergoing resection for CDC in our center from 2011 to 2019 were retrospectively identified. Histopathological reports were searched for inflammation and endothelial alteration. Cases with sufficient tissue specimen were tested for KRAS codon 12/13 and BRAF codon 600 mutations by pyrosequencing.

RESULTS

 In total, 42 patients underwent resection for choledochal cyst in the study period. Median age at surgery was 2.4 years (range = 18 days-18 years). Histopathological analysis showed no malignancy, but various degrees of inflammation or fibrosis in approximately 50% of the patients and in all age groups. Sufficient tissue for mutation analysis was available for 22 cases, all of which tested negative for KRAS or BRAF mutation.

CONCLUSION

 In our series, chronic inflammatory changes were frequently present in CDC of infants and children. However, the lack of KRAS and BRAF mutations suggests that no malignant changes have been initiated in this group of European patients undergoing early resection.

Neuroendocrine Carcinomas of the Gallbladder: A Clinicopathologic and Immunohistochemical Analysis of 34 Resected Cases

Neuroendocrine carcinoma (NEC) is an aggressive malignant tumor that rarely arises from the gallbladder. Here, we investigated the clinicopathologic and immunohistochemical characteristics of 34 NECs of the gallbladder. The patients were predominantly women (68%) with a median age of 63 years (range, 37 to 82 y). NECs frequently occurred in the fundus (44%) as mass-forming lesions (66%). Histologically, 17 tumors were of small cell type, and another 17 were of large cell type. Twenty-three cases (68%) were associated with biliary intraepithelial neoplasia (38%) and intracholecystic papillary neoplasm (29%). The majority of tumors exhibited a diffuse growth pattern (74%), followed by organoid (24%) or scirrhous (2%) growth patterns. Histologic features related to neuroendocrine differentiation, such as nuclear molding (56%), perilobular pseudopalisading (18%), and rosette formation (15%), were identified. Immunohistochemically, cytokeratin 7 and 20 were expressed in 19 (56%) and 8 (24%) cases, respectively. Loss of Rb1 expression and concomitant overexpression of p16 were observed in 25 (74%) cases. No BRAF mutations were identified in any of the 34 NECs. For survival analysis, the 1-, 3-, and 5-year overall survival rates were 64%, 35%, and 19%, respectively. In a multivariate analysis, the receipt of adjuvant chemoradiation therapy was identified as the only independent prognostic factor associated with the overall survival rate. The 1- and 3-year overall survival rates of patients with NECs were poorer for patients with poorly differentiated adenocarcinoma of the gallbladder (P<0.001). The complete resection and application of postoperative adjuvant therapy may influence a better clinical outcome in patients with NEC of the gallbladder.

Overview of current targeted therapy in gallbladder cancer

Gallbladder cancer (GBC) is rare, but is the most malignant type of biliary tract tumor. Unfortunately, only a small population of cancer patients is acceptable for the surgical resection, the current effective regimen; thus, the high mortality rate has been static for decades. To substantially circumvent the stagnant scenario, a number of therapeutic approaches owing to the creation of advanced technologic measures (e.g., next-generation sequencing, transcriptomics, proteomics) have been intensively innovated, which include targeted therapy, immunotherapy, and nanoparticle-based delivery systems. In the current review, we primarily focus on the targeted therapy capable of specifically inhibiting individual key molecules that govern aberrant signaling cascades in GBC. Global clinical trials of targeted therapy in GBC are updated and may offer great value for novel pathologic and therapeutic insights of this deadly disease, ultimately improving the efficacy of treatment.

[Biliary tract cancers : Molecular characterization and identification of novel prognostic markers]

BACKGROUND

Bile duct cancers (BTCs) are highly aggressive tumors with a dismal prognosis and an increasing incidence. BTC is a tumorbiologically and clinically heterogeneous tumor group and can be subdivided according to anatomical aspects into intrahepatic cholangiocarcinomas (iCCA), extrahepatic cholangiocarcinomas (eCCA) and gallbladder carcinomas (GBC).

NEW THERAPY OPTIONS

Chronic inflammatory processes of the biliary system seem to play a role in the development of these tumors. Insights into molecular cholangiocarcinogenesis could make an important contribution to novel and more precise classification attempts and to the development of new, targeted therapies for BTC.

EPIGENETIC AND GENETIC ALTERATIONS IN CHOLANGIOCARCINOMAS

The first description of genome-wide DNA methylation patterns in CCA showed drastic global methylation differences between CCA and corresponding non-neoplastic tissue (matched-pair analyses). Moreover, significant methylation differences between the CCA subtypes (eCCA and iCCA) could be found. Using immunohistochemistry and Sanger sequencing, it was shown that the actual BRAF V600E mutation rate seems to be significantly lower (1.3%) than previously described in the literature.

IMMUNEPHENOTYPING IN BILIARY TRACT CANCERS

A comprehensive, subtype-specific characterization of tumor-infiltrating immune cells as well as an expression analysis of Major Histocompatibility Complex I was performed in a large and well-characterized BTC cohort. For further studies on the efficacy of immunomodulatory therapy approaches for BTC, the presented results provide a solid basis.

Progress in molecular targeted therapy of intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma is an uncommon malignant tumor with a poor prognosis due to an incomplete understanding of its molecular pathogenesis and a lack of effective treatment. Precision medical planning and cancer genomics can help to understand the molecular pathogenesis of cancer and identify potential therapeutic targets. With the deepening of basic and clinical research, accurate targeted therapy will be able to improve the prognosis and overall survival of patients with intrahepatic cholangiocarcinoma.

Gallbladder cancer: review of a rare orphan gastrointestinal cancer with a focus on populations of New Mexico

Gallbladder cancer is a rare malignancy of the biliary tract with a poor prognosis, frequently presenting at an advanced stage. While rare in the United States overall, gallbladder cancer has an elevated incidence in geographically distinct locations of the globe including Chile, North India, Korea, Japan and the state of New Mexico in the United States. People with Native American ancestry have a much elevated incidence of gallbladder cancer compared to Hispanic and non-Hispanic white populations of New Mexico. Gallbladder cancer is also one of the few bi-gendered cancers with an elevated female incidence compared to men. Similar to other gastrointestinal cancers, gallbladder cancer etiology is likely multi-factorial involving a combination of genomic, immunological, and environmental factors. Understanding the interplay of these unique epidemiological factors is crucial in improving the prevention, early detection, and treatment of this lethal disease. Previous studies have failed to identify a distinct genomic mutational profile in gallbladder cancers, however, work to identify promising clinically actionable targets is this form of cancer is ongoing. Examples include, interest in the HER2/Neu signaling pathway and the recognition that chronic inflammation plays a crucial role in gallbladder cancer pathogenesis. In this review, we provide a comprehensive overview of gallbladder cancer epidemiology, risk factors, pathogenesis, and treatment with a specific focus on the rural and Native American populations of New Mexico. We conclude this review by discussing future research directions with the goal of improving clinical outcomes for patients of this lethal malignancy.

Identification of MAP kinase pathways as therapeutic targets in gallbladder carcinoma using targeted parallel sequencing

The aim of this study was to profile somatic mutation spectrum in gallbladder cancers (GBCs), and determine the role of MAP kinase pathway in GBC by a series of in vitro and in vivo studies. We performed targeted massively parallel sequencing of DNA isolated from GBCs and matched blood from 14 GBC patients to search for mutations in 504 genes commonly altered in human cancers. We identified recurrent mutations enriched in several major signaling pathways including MAP kinase, Wnt/β-catenin and NF-κB pathways. Immunohistochemistry analysis further validated overactivation of MAP kinase and Wnt pathways in a panel of GBC samples. By treating GBC cells with MEK inhibitor trametinib, we found that trametinib not only dramatically inhibited the activity of MAPK/ERK pathway, but also blocked the Wnt/β-catenin signaling through decreasing β-catenin expression or suppressing nucleus translocation of β-catenin. Moreover, trametinib inhibited the proliferation of GBC cell in a dose- and time-dependent manner, induced GBC cell apoptosis, and inhibited GBC cell migration and invasion. Growth of xenograft tumors derived from GBC cell line NOZ in nude mice was also significantly inhibited by trametinib. Our data highlight the critical role of MAP kinase pathways in GBC pathogenesis, and may represent therapeutic targets for this cancer.

Efficacy and safety of trametinib in Japanese patients with advanced biliary tract cancers refractory to gemcitabine

Gemcitabine‐based therapy remains the mainstay of treatment for patients with biliary tract cancers (BTCs) with no second‐line treatment(s) established yet. Aberrant activation of the MAPK pathway in patients with BTC indicates its importance in BTC. Trametinib is a potent, highly selective, allosteric non‐competitive inhibitor of MEK1/MEK2. In this phase IIa open‐label, single‐arm study, we investigated the efficacy and safety of trametinib in Japanese patients with advanced BTC refractory to gemcitabine‐based therapy. All patients received oral trametinib 2 mg once daily until progressive disease (PD), death, or unacceptable toxicity. The primary objective was to determine the 12‐week non‐PD rate. Secondary assessments included safety, progression‐free survival (PFS), overall survival, and overall response rate. Targeted exome sequencing was used to identify biomarkers for sensitivity or resistance to trametinib monotherapy. Twenty patients (median age, 61.5 years) with carcinoma of gall bladder (40%), intrahepatic (25%) or extrahepatic (30%) bile duct, and ampulla of Vater (5%) were enrolled. The non‐PD rate at week 12 was 10% (95% confidence interval, 1.2‐31.7); it did not reach the threshold rate of 25%. Median PFS was 10.6 weeks (95% confidence interval, 4.6‐12.1) and 1‐year overall survival was 20.0%. Stable disease and PD were observed in 13 (65%) and seven (35%) patients, respectively. No new safety signals were reported. Although the primary end‐point was not met, prolonged PFS was observed in one patient having six somatic variants including synonymous NF1 exon 12 splice variant and a loss‐of‐function variant in ARID1A. Efforts to understand responsive mutations and sensitivity to targeted therapies are warranted. This trial was registered with ClinicalTrials.gov: NCT01943864.

Successful immune checkpoint blockade in a patient with advanced stage microsatellite-unstable biliary tract cancer

Cancers acquire multiple somatic mutations that can lead to the generation of immunogenic mutation-induced neoantigens. These neoantigens can be recognized by the host's immune system. However, continuous stimulation of immune cells against tumor antigens can lead to immune cell exhaustion, which allows uncontrolled outgrowth of tumor cells. Recently, immune checkpoint inhibitors have emerged as a novel approach to overcome immune cell exhaustion and reactivate antitumor immune responses. In particular, antibodies blocking the exhaustion-mediating programmed death receptor (PD-1)/programmed death receptor ligand (PD-L1) pathway have shown clinical efficacy. The effects were particularly pronounced in tumors with DNA mismatch repair (MMR) deficiency and a high mutational load, which typically occur in the colon and endometrium. Here, we report on a 24-yr-old woman diagnosed with extrahepatic cholangiocarcinoma who showed strong and durable response to the immune checkpoint inhibitor pembrolizumab, although treatment was initiated at an advanced stage of disease. The patient's tumor displayed DNA MMR deficiency and microsatellite instability (MSI) but lacked other features commonly discussed as predictors of response toward checkpoint blockade, such as PD-L1 expression or dense infiltration with cytotoxic T cells. Notably, high levels of HLA class I and II antigen expression were detected in the tumor, suggesting a potential causal relation between functionality of the tumor's antigen presentation machinery and the success of immune checkpoint blockade. We suggest determining MSI status in combination with HLA class I and II antigen expression in tumors potentially eligible for immune checkpoint blockade even in the absence of conventional markers predictive for anti-PD-1/PD-L1 therapy and in entities not commonly linked to the MSI phenotype. Further studies are required to determine the value of these markers for predicting the success of immune checkpoint blockade.

New Horizons for Precision Medicine in Biliary Tract Cancers

Biliary tract cancers (BTC), including cholangiocarcinoma and gallbladder cancer, are poor-prognosis and low-incidence cancers, although the incidence of intrahepatic cholangiocarcinoma is rising. A minority of patients present with resectable disease but relapse rates are high; benefit from adjuvant capecitabine chemotherapy has been demonstrated. Cisplatin/gemcitabine combination chemotherapy has emerged as the reference first-line treatment regimen; there is no standard second-line therapy. Selected patients may be suitable for liver-directed therapy (e.g., radioembolization or external beam radiation), pending confirmation of benefit in randomized studies. Initial trials targeting the epithelial growth factor receptor and angiogenesis pathways have failed to deliver new treatments. Emerging data from next-generation sequencing analyses have identified actionable mutations (e.g., FGFR fusion rearrangements and IDH1 and IDH2 mutations), with several targeted drugs entering clinical development with encouraging results. The role of systemic therapies, including targeted therapies and immunotherapy for BTC, is rapidly evolving and is the subject of this review.Significance: The authors address genetic drivers and molecular biology from a translational perspective, in an intent to offer a clear view of the recent past, present, and future of BTC. The review describes a state-of-the-art update of the current status and future directions of research and therapy in advanced BTC. Cancer Discov; 7(9); 943-62. ©2017 AACR.

New Horizons for Precision Medicine in Biliary Tract Cancers

Biliary tract cancers (BTC), including cholangiocarcinoma and gallbladder cancer, are poor-prognosis and low-incidence cancers, although the incidence of intrahepatic cholangiocarcinoma is rising. A minority of patients present with resectable disease but relapse rates are high; benefit from adjuvant capecitabine chemotherapy has been demonstrated. Cisplatin/gemcitabine combination chemotherapy has emerged as the reference first-line treatment regimen; there is no standard second-line therapy. Selected patients may be suitable for liver-directed therapy (e.g., radioembolization or external beam radiation), pending confirmation of benefit in randomized studies. Initial trials targeting the epithelial growth factor receptor and angiogenesis pathways have failed to deliver new treatments. Emerging data from next-generation sequencing analyses have identified actionable mutations (e.g., FGFR fusion rearrangements and IDH1 and IDH2 mutations), with several targeted drugs entering clinical development with encouraging results. The role of systemic therapies, including targeted therapies and immunotherapy for BTC, is rapidly evolving and is the subject of this review.Significance: The authors address genetic drivers and molecular biology from a translational perspective, in an intent to offer a clear view of the recent past, present, and future of BTC. The review describes a state-of-the-art update of the current status and future directions of research and therapy in advanced BTC. Cancer Discov; 7(9); 943-62. ©2017 AACR.

Second-Line Palliative Chemotherapy in Advanced Gall Bladder Cancer, CAP-IRI: Safe and Effective Option

INTRODUCTION

Gall bladder cancer (GBC) has high prevalence in the Indo-Gangetic belt in India. While the first-line chemotherapy (CT1) has been established as gemcitabine-platinum doublet in advanced GBC, there is no standard recommendation or guidelines regarding feasibility of second-line therapy.

METHODS

We performed a retrospective analysis of all patients who received second-line of chemotherapy (CT2) at our institution from July 2012 to December 2014. Patient records were examined for efficacy and toxicity of administered CT2, along with response rates (RR) and survival. Potential prognostic factors were also evaluated.

RESULTS

Eighty-seven patients received CT2 in the predefined period. Ninety-nine percent of patients had received a gemcitabine-based regimen as CT1 with a median progression-free survival (PFS) of 5 months before CT2. 51.7 % patients had undergone surgery prior with 5.7 % patients having received radiotherapy previously. Prior to beginning CT2, PS was 0/1 in 67.8 % patients, albumin was >4 g% in 40.2 % and CA 19.9 was raised in a majority (66.7 %) patients, respectively. As per institution protocol, a majority of patients (89.6 %) were administered CAP-IRI regimen. Overall RR and disease control rates (DCR) were 21.8 % and 41.3 %, respectively. Median progression-free survival (PFS) and overall survival (OS) were 6 and 8 months, with no significant differences between CAP-IRI and other regimens. Adverse effects were tolerable, with dose reduced upfront in 23 % patients and 11.5 % patients during subsequent cycles of CT. ECOG Performance Status (PS) of 0/1 was a significant prognostic variable for OS on multivariate analysis (p = 0.003).

CONCLUSION

CAP-IRI is a well-tolerated second-line chemotherapeutic regimen in patients with advanced GBC. Careful selection of patients is required when administering second-line chemotherapy to advanced GBC patients, with particular emphasis on ECOG PS.

Mutation analysis and copy number changes of KRAS and BRAF genes in Taiwanese cases of biliary tract cholangiocarcinoma

BACKGROUND/PURPOSE

Cholangiocarcinoma (CC) is a fatal malignancy originating from biliary tracts and constitutes approximately 10-20% of hepatobiliary cancers. CC is characterized by a very poor prognosis. The definite molecular mechanisms leading to oncogenesis remain unclear. This study aimed to perform mutation analysis and copy number changes of KRAS and BRAF genes of CC in Taiwan.

METHODS

A total of 182 cases of biliary tact CC were studied for point mutation and quantitative real-time polymerase chain reaction analysis of KRAS and BRAF genes. The obtained data were analyzed with clinical and histopathological variables and survival.

RESULTS

KRAS point mutations were detected in intrahepatic CC (7.6%), common bile duct cancer (13.3%), and gallbladder carcinoma (3.3%). BRAF gene amplifications were demonstrated in intrahepatic CC (4.3%), common bile duct cancer (3.3%), and gallbladder cancer (5%). No association was observed between mutation patterns and histopathological features. The analyses of risk factors for overall survival in patients with CC revealed no significant association in age, tumor site, genetic mutation, or amplifications. The tumor stage was the significant prognostic factor.

CONCLUSION

Unlike other studies from American, European, or Japanese groups which showed certain levels of gene mutations in CC, our data revealed a rather low frequency of KRAS mutations and BRAF gene amplifications in CC in Taiwan. Tumor TNM stage was the only significant prognostic parameter in this analysis. It is crucial to gain more information of carcinogenesis, molecular mechanisms and therapeutic strategy in biliary tract cholangiocarcinoma.

Molecular profiling of biliary tract cancer: a target rich disease

Biliary tract cancers (BTCs) are relatively uncommon orphan tumors that have an aggressive disease course and a poor clinical outcome. Surgery is the only curative treatment, but most patients present with advanced disease and therefore have a limited survival. Gemcitabine and cisplatin based chemotherapy has been the only widely accepted standard systemic therapy regimen in these patients but these tumors can be chemoresistant, further complicating their management. In recent times, there has been considerable research in the genetics of BTC and with the advent of new, advanced technologies like next-generation sequencing (NGS) we are achieving a greater understanding of its disease biology. With the help of NGS, we have now been able to identify actionable mutations such as in the isocitrate dehydrogenase 1 (IDH1), FGFR2, BRAF and HER2/neu genes for targeted therapeutics and correlate the genetic variations with distinct clinical prognoses. This recent genetic information has the potential to make precision medicine a part of routine clinical practice for the management of BTC patients.

PIK3CA mutation detection in metastatic biliary cancer using cell-free DNA

PIK3CA mutation is considered a good candidate for targeted therapies in cancers, especially biliary tract cancer (BTC). We evaluated the utility of cell free DNA (cfDNA) from serum by using droplet digital PCR (ddPCR) as an alternative source for PIK3CA mutation analysis. To identify matching archival tumour specimens from serum samples of advanced BTC patients, mutation detection using ddPCR with Bio-Rad's PrimePCR mutation and wild type assays were performed for PIK3CA p.E542K, p.E545K, and p.H1047R. Thirty-eight patients with metastatic BTC were enrolled. Only one (BTC 29T) sample (n = 38) was positive for PIK3CA p.E542K and another (BTC 27T) for p.H1047R mutation; none was positive for PIK3CA p.E545K. Matched serum sample (BTC 29P) was positive for PIK3CA p.E542K with 28 mutant copies detected, corresponding to 48 copies/ml of serum and an allelic prevalence of 0.3%. Another matched serum sample (BTC 27P) was positive for PIK3CA p.H1047R with 10 mutant copies detected, i.e. 18 copies/ml and an allelic frequency of 0.2%. High correlation was noted in the PIK3CA mutation status between tumour gDNA and serum cfDNA. Low-level PIK3CA mutations were detectable in the serum indicating the utility of cfDNA as a DNA source to detect cancer-derived mutations in metastatic biliary cancers.

Molecular genetics and targeted therapeutics in biliary tract carcinoma

The primary malignancies of the biliary tract, cholangiocarcinoma and gallbladder cancer, often present at an advanced stage and are marginally sensitive to radiation and chemotherapy. Accumulating evidence indicates that molecularly targeted agents may provide new hope for improving treatment response in biliary tract carcinoma (BTC). In this article, we provide a critical review of the pathogenesis and genetic abnormalities of biliary tract neoplasms, in addition to discussing the current and emerging targeted therapeutics in BTC. Genetic studies of biliary tumors have identified the growth factors and receptors as well as their downstream signaling pathways that control the growth and survival of biliary epithelia. Target-specific monoclonal antibodies and small molecules inhibitors directed against the signaling pathways that drive BTC growth and invasion have been developed. Numerous clinical trials designed to test these agents as either monotherapy or in combination with conventional chemotherapy have been completed or are currently underway. Research focusing on understanding the molecular basis of biliary tumorigenesis will continue to identify for targeted therapy the key mutations that drive growth and invasion of biliary neoplasms. Additional strategies that have emerged for treating this malignant disease include targeting the epigenetic alterations of BTC and immunotherapy. By integrating targeted therapy with molecular profiles of biliary tumor, we hope to provide precision treatment for patients with malignant diseases of the biliary tract.

Microsatellite instability in gallbladder carcinoma

The genetic abnormalities involved in the pathogenesis of gallbladder carcinoma (GBC) remain unclear. Microsatellite instability (MSI) has been described in many carcinomas, but little is known about the significance of mismatch repair in gallbladder carcinogenesis. Additionally, methylation status of long interspersed element-1 (LINE-1), a surrogate marker of global DNA methylation, has defined distinct subsets of other cancer types but has not been explored in GBC. Immunohistochemical expression of MSH2, MSH6, MLH1, and PMS2 and LINE-1 mRNA in situ hybridization was evaluated in 67 primary and 15 metastatic GBCs from 77 patients. Amplification of human epidermal growth factor receptor 2 (HER2) was evaluated by fluorescence in situ hybridization. Genotyping for 24 genes involved in carcinogenesis was performed using a multiplex PCR-based platform. MSI was present in 6 of 77 GBCs (7.8 %). Loss of MSH2/MSH6 was detected in five cases and loss of MLH1/PMS2 in one case. MSI status was not associated with Lynch syndrome, tumor grade, extracellular mucin, or tumor-infiltrating lymphocytes. There was no significant difference in mean overall survival of patients with and without MSI. Strong LINE-1 staining was identified in none of the GBC with MSI and in 36 of 69 (52 %) of those without MSI (p = 0.005), suggesting that LINE-1 in the former cohort was hypermethylated. All MSI tumors were negative for HER2 amplification, and TP53 and NRAS mutations were only found in GBC without MSI. MSI was identified in a minority of GBC cases. The strong correlation between global DNA methylation as measured by LINE-1 and loss of mismatch repair proteins suggests that methylation may account for the loss of these proteins. These hypermethylated tumors appear to represent a genetically unique cohort of gallbladder neoplasms, and the data suggests that demethylating agents may have a therapeutic value in this class of tumors.

Targeting specific molecular pathways holds promise for advanced gallbladder cancer therapy

Gallbladder cancer is the most common and aggressive malignancy of the biliary tract. The complete surgical resection is the only potentially curative approach in early stage; however, most cases are diagnosed in advanced stages and the response to traditional chemotherapy and radiotherapy is extremely limited, with modest impact in overall survival. The recent progress in understanding the molecular alterations of gallbladder cancer has shown great promise for the development of more effective treatment strategies. This has mainly resulted from the identification of molecular alterations in relevant intracellular signaling pathways-Hedgehog, PI3K/AKT/mTOR, Notch, ErbB, MAPK and angiogenesis-which are potential tailored targets for gallbladder cancer patients. This review discusses the recent remarkable progress in understanding the molecular alterations that represent novel prognosis molecular markers and therapeutic targets for gallbladder cancer, which will provide opportunities for research and for developing innovative strategies that may enhance the benefit of conventional chemotherapy, or eventually modify the fatal natural history of this orphan disease.

Screening for the FIG-ROS1 fusion in biliary tract carcinomas by nested PCR

ROS1 rearrangements have been detected in a variety of tumors and are considered as suitable targets of anticancer therapies. We developed a new, quick, specific, and sensitive PCR test to screen for the FIG-ROS1 fusion and applied it to a series of Italian patients with bile duct carcinoma (BTC). Formalin-fixed, paraffin-embedded tissues, derived from 65 Italian BTC patients, and six cell lines were analyzed by nested PCR to investigate the prevalence of a previously reported FIG-ROS1 fusion. The specificity and sensitivity of nested PCR were investigated in FIG-ROS1 positive U118MG cells in reconstitution experiments with peripheral blood mononuclear cells. We found that six out of 65 (9%) BTC patients were positive for the FIG-ROS1 fusion, comprising two out of 14 (14%) gallbladder carcinoma (GBC) patients and four out of 25 (16%) extrahepatic cholangiocarcinoma (ECC) patients. None of the 26 intrahepatic cholangiocarcinoma cases harbored the FIG-ROS1 fusion. All the cell lines were negative for this variant. In conclusion, 14-16% of GBC and ECC were positive for FIG-ROS1. This may have clinical implications, since these patients will potentially benefit from the treatment with specific ROS1 inhibitors.

BRAF V600E-specific immunohistochemistry reveals low mutation rates in biliary tract cancer and restriction to intrahepatic cholangiocarcinoma

BRAF mutations have emerged as an important predictive biomarker for metastasized melanoma. Other types of cancer may also benefit from BRAF mutation-targeted therapies. In biliary tract cancer, reported BRAF mutation rates are highly controversial, ranging from 0 to 33% in adenocarcinoma of the gallbladder and 0 to 22% in cholangiocarcinoma. We here analyzed tissue microarrays of a large cohort of biliary tract cancer (n=377) including 159 intrahepatic cholangiocarcinomas, 149 extrahepatic cholangiocarcinomas, and 69 adenocarcinomas of the gallbladder for BRAF V600E mutation using a highly sensitive immunohistochemical screening approach implementing the BRAF V600E protein-specific antibody VE1. All VE1-positive cases as well as 42 VE1-negative cases were additionally analyzed by Sanger sequencing. In total, only 5 VE1-positive cases were detected (5/377; 1%). BRAF V600E mutation was confirmed by direct sequencing in all cases. All 5 mutated cases were intrahepatic cholangiocarcinomas (5/159; 3%). None of the extrahepatic cholangiocarcinomas and adenocarcinomas of the gallbladder were VE1 positive. Apart from the subtype restriction of BRAF V600E mutation to intrahepatic cholangiocarcinoma and a female predominance (4 female, 1 male), no significant correlation with clinicopathological data and patient outcome was detected. In conclusion, we demonstrate that BRAF V600E mutation is a rare event in biliary tract cancer, accounting for only 1% of all subtypes, and is restricted to intrahepatic cholangiocarcinoma. In addition, we demonstrate that VE1 immunohistochemistry is a feasible approach to routinely screen for BRAF V600E mutation in biliary tract cancer patients, thereby facilitating the detection of rare patients who may benefit from BRAF mutation-targeted therapies.

The analysis of microsatellite instability in extracolonic gastrointestinal malignancy

Microsatellite instability (MSI) is a genetic feature of sporadic and familial cancers of multiple sites and is related to defective mismatch repair (MMR) protein function. Lynch syndrome (LS) is a familial form of MMR deficiency that may present with a spectrum of MSI positive cancers including gastrointestinal (GI) malignancies. The incidence of high level MSI (MSI-H) in colorectal carcinoma is well defined in both familial and sporadic cases and these tumours portend a better overall prognosis in colorectal carcinoma (CRC). There are certain morphological features that suggest MSI-H CRC and international guidelines have been established for the evaluation of MSI in CRC. The prevalence and morphological features of extracolonic GI MSI-H tumours are less well documented. Furthermore, it is unclear whether the guidelines for the assessment of MSI in CRC are appropriate for application to extracolonic GI malignancies. This review aims to summarise the recent literature on MSI in extracolonic LS-related GI tract malignancies with special attention to the assessment of the MMR system by evaluation of specific microsatellite markers and/or immunohistochemical evaluation of MMR protein expression. The reported prevalence of sporadic and LS-related MSI-H tumours along with their associated unique morphological patterns and related prognostic or therapeutic implications will be discussed.

Clinicopathological relevance of BRAF mutations in human cancer

BRAF represents one of the most frequently mutated protein kinase genes in human tumours. The mutation is commonly tested in pathology practice. BRAF mutation is seen in melanoma, papillary thyroid carcinoma (including papillary thyroid carcinoma arising from ovarian teratoma), ovarian serous tumours, colorectal carcinoma, gliomas, hepatobiliary carcinomas and hairy cell leukaemia. In these cancers, various genetic aberrations of the BRAF proto-oncogene, such as different point mutations and chromosomal rearrangements, have been reported. The most common mutation, BRAF V600E, can be detected by DNA sequencing and immunohistochemistry on formalin fixed, paraffin embedded tumour tissue. Detection of BRAF V600E mutation has the potential for clinical use as a diagnostic and prognostic marker. In addition, a great deal of research effort has been spent in strategies inhibiting its activity. Indeed, recent clinical trials involving BRAF selective inhibitors exhibited promising response rates in metastatic melanoma patients. Clinical trials are underway for other cancers. However, cutaneous side effects of treatment have been reported and therapeutic response to cancer is short-lived due to the emergence of several resistance mechanisms. In this review, we give an update on the clinical pathological relevance of BRAF mutation in cancer. It is hoped that the review will enhance the direction of future research and assist in more effective use of the knowledge of BRAF mutation in clinical practice.

Targeted therapy for biliary tract cancers

Biliary tract cancers (BTCs) are a heterogeneous group of malignancies, with a historically poor prognosis as a whole. Until recently, the development of effective therapeutics was hampered by the relatively low incidence, heterogeneity in patients and tumors, and correspondingly poor clinical trial enrollments. With the publication of the landmark phase III ABC-02 trial demonstrating the superiority of gemcitabine and cisplatin combination chemotherapy, the landscape changed for the development of new agents. Despite this progress, there are currently no approved targeted agents for BTC. This review will focus on recent developments in targeted therapeutics, directed against several key signaling pathways in BTC, including epidermal growth factor receptor, angiogenesis, and the mitogen-activated protein kinase pathway. Data from recent phase I and II trials will be discussed, along with a preview of upcoming trials involving targeted therapies.

Biliary tract carcinomas: from chemotherapy to targeted therapy

Biliary tract carcinomas (BTC) are a group of tumours arising from the epithelial cells of intra- and extra-hepatic biliaryducts and the gallbladder, characterised by a poor prognosis. Surgery is the only curative procedure, but the risk of recurrence is high and furthermore, the majority of patients present with unresectable disease at the time of diagnosis. Systemic therapy is the mainstay of treatment for patients who present recurrent or metastatic disease. Progress has been made in the last decade to identify the most effective chemotherapy regimens, with the recent recommendation of the combination of gemcitabine-cisplatin as the standard schedule. Comprehension of the molecular basis of cholangiocarcinogenesis and tumour progression has recently led to the experimentation of targeted therapies in patients with BTC, demonstrating promising results. In this review we will discuss the clinical experience with systemic treatment for BTC, focusing on future directions with targeted therapies.

Comprehensive review of the diagnosis and treatment of biliary tract cancer 2012. Part II: multidisciplinary management

Biliary tract cancers (gallbladder cancer, intra- and extra-hepatic cholangiocarcinoma and selected periampullary cancers) accounted for 12,760 new cases of cancer in the USA in 2010. These tumors have a dismal prognosis with most patients presenting with advanced disease. Early, accurate diagnosis is essential, both for potential cure where possible and for optimal palliative therapy in all others. This review examines the currently available and emerging technologies for diagnosis and treatment of this group of diseases.

Frequent mutation of isocitrate dehydrogenase (IDH)1 and IDH2 in cholangiocarcinoma identified through broad-based tumor genotyping

Cancers of origin in the gallbladder and bile ducts are rarely curable with current modalities of cancer treatment. Our clinical application of broad-based mutational profiling for patients diagnosed with a gastrointestinal malignancy has led to the novel discovery of mutations in the gene encoding isocitrate dehydrogenase 1 (IDH1) in tumors from a subset of patients with cholangiocarcinoma. A total of 287 tumors from gastrointestinal cancer patients (biliary tract, colorectal, gastroesophageal, liver, pancreatic, and small intestine carcinoma) were tested during routine clinical evaluation for 130 site-specific mutations within 15 cancer genes. Mutations were identified within a number of genes, including KRAS (35%), TP53 (22%), PIK3CA (10%), BRAF (7%), APC (6%), NRAS (3%), AKT1 (1%), CTNNB1 (1%), and PTEN (1%). Although mutations in the metabolic enzyme IDH1 were rare in the other common gastrointestinal malignancies in this series (2%), they were found in three tumors (25%) of an initial series of 12 biliary tract carcinomas. To better define IDH1 and IDH2 mutational status, an additional 75 gallbladder and bile duct cancers were examined. Combining these cohorts of biliary cancers, mutations in IDH1 and IDH2 were found only in cholangiocarcinomas of intrahepatic origin (nine of 40, 23%) and in none of the 22 extrahepatic cholangiocarcinomas and none of the 25 gallbladder carcinomas. In an analysis of frozen tissue specimens, IDH1 mutation was associated with highly elevated tissue levels of the enzymatic product 2-hydroxyglutarate. Thus, IDH1 mutation is a molecular feature of cholangiocarcinomas of intrahepatic origin. These findings define a specific metabolic abnormality in this largely incurable type of gastrointestinal cancer and present a potentially new target for therapy.

Multi-institutional phase II study of selumetinib in patients with metastatic biliary cancers

PURPOSE

Biliary cancers (BCs) carry a poor prognosis, but targeting the RAS/RAF/mitogen-activated protein kinase kinase (MEK)/extracellular signal-related kinase (ERK) pathway is of significance. Selumetinib is an inhibitor of MEK1/2, so this trial was designed to determine the safety and efficacy of selumetinib in BC.

PATIENTS AND METHODS

This was a multi-institutional phase II study of selumetinib at 100 mg given orally twice per day to patients with advanced BC. The primary end point was response rate. All patients were required to provide tissue before enrolling. The levels of phosphorylated ERK (pERK) and AKT (pAKT) were assessed by immunohistochemistry. Tumors were genotyped for the presence of BRAF- and/or RAS-activating mutations.

RESULTS

Twenty-eight eligible patients with a median age of 55.6 years were enrolled. Thirty-nine percent of patients had received one prior systemic therapy. Three patients (12%) had a confirmed objective response. Another 17 patients (68%) experienced stable disease (SD), 14 of whom (56%) experienced prolonged SD (> 16 weeks). Patients gained an average nonfluid weight of 8.6 pounds. Median progression-free survival was 3.7 months (95% CI, 3.5 to 4.9) and median overall survival was 9.8 months (95% CI, 5.97 to not available). Toxicities were mild, with rash (90%) and xerostomia (54%) being most frequent. Only one patient experienced grade 4 toxicity (fatigue). All patients had tissue available for analysis. No BRAF V600E mutations were found. Two patients with short-lived SD had KRAS mutations. Absence of pERK staining was associated with lack of response.

CONCLUSION

Selumetinib displays interesting activity and acceptable tolerability in patients with metastatic BC. Our results warrant further evaluation of selumetinib in patients with metastatic BC.

Multi-institutional phase II study of selumetinib in patients with metastatic biliary cancers

PURPOSE

Biliary cancers (BCs) carry a poor prognosis, but targeting the RAS/RAF/mitogen-activated protein kinase kinase (MEK)/extracellular signal-related kinase (ERK) pathway is of significance. Selumetinib is an inhibitor of MEK1/2, so this trial was designed to determine the safety and efficacy of selumetinib in BC.

PATIENTS AND METHODS

This was a multi-institutional phase II study of selumetinib at 100 mg given orally twice per day to patients with advanced BC. The primary end point was response rate. All patients were required to provide tissue before enrolling. The levels of phosphorylated ERK (pERK) and AKT (pAKT) were assessed by immunohistochemistry. Tumors were genotyped for the presence of BRAF- and/or RAS-activating mutations.

RESULTS

Twenty-eight eligible patients with a median age of 55.6 years were enrolled. Thirty-nine percent of patients had received one prior systemic therapy. Three patients (12%) had a confirmed objective response. Another 17 patients (68%) experienced stable disease (SD), 14 of whom (56%) experienced prolonged SD (> 16 weeks). Patients gained an average nonfluid weight of 8.6 pounds. Median progression-free survival was 3.7 months (95% CI, 3.5 to 4.9) and median overall survival was 9.8 months (95% CI, 5.97 to not available). Toxicities were mild, with rash (90%) and xerostomia (54%) being most frequent. Only one patient experienced grade 4 toxicity (fatigue). All patients had tissue available for analysis. No BRAF V600E mutations were found. Two patients with short-lived SD had KRAS mutations. Absence of pERK staining was associated with lack of response.

CONCLUSION

Selumetinib displays interesting activity and acceptable tolerability in patients with metastatic BC. Our results warrant further evaluation of selumetinib in patients with metastatic BC.

Mutational profiling reveals PIK3CA mutations in gallbladder carcinoma

Background

The genetics of advanced biliary tract cancers (BTC), which encompass intra- and extra-hepatic cholangiocarcinomas as well as gallbladder carcinomas, are heterogeneous and remain to be fully defined.

Methods

To better characterize mutations in established known oncogenes and tumor suppressor genes we tested a mass spectrometric based platform to interrogate common cancer associated mutations across a panel of 77 formalin fixed paraffin embedded archived BTC cases.

Results

Mutations among three genes, KRAS, NRAS and PIK3CA were confirmed in this cohort. Activating mutations in PIK3CA were identified exclusively in GBC (4/32, 12.5%). KRAS mutations were identified in 3 (13%) intra-hepatic cholangiocarcinomas and 1 (33%) perihillar cholangiocarcinoma but were not identified in gallbladder carcinomas and extra-hepatic cholangiocarcinoma.

Conclusions

The presence of activating mutations in PIK3CA specifically in GBC has clinical implications in both the diagnosis of this cancer type, as well as the potential utility of targeted therapies such as PI3 kinase inhibitors.

Development of molecularly targeted therapies in biliary tract cancers: reassessing the challenges and opportunities

Biliary tract cancers (BTCs), which encompass intra- and extrahepatic cholangiocarcinomas as well as gallbladder carcinomas, are a genetically diverse collection of cancers. Most patients with BTC will present with unresectable or metastatic disease. Although the standard systemic chemotherapy approaches are emerging, the prognosis remains poor. Development of molecularly targeted therapies in advanced BTC remains challenging. Recent early-stage clinical trials with targeted therapies appear promising, although the relationships between subsets of patients with positive responses to therapy and tumor genetics remain unexplored. Here we summarize the relevant molecular pathogenesis, recent and ongoing clinical trials with targeted agents, and the key issues in clinical trial design in BTC.

[Chemotherapy in gallbladder carcinoma]

Gallbladder cancer is an aggressive tumor. Its incidence varies according to geography. Surgery is the standard treatment for localized stage but there is no standard treatment in metastatic or locally advanced disease. Because of the rarity of bile tract cancer (BTC) and gallblader carcinoma (GBC), most studies have grouped all BTC and GBC together, and there are very few GBC-specific studies. In addition, there is a paucity of randomized controlled studies in this disease with small numbers of patients and inclusion bias. One randomized trial ABC-02 was well conducted and showed a survival benefit in favor of gemcitabine (GEM)+cisplatin (CDDP), which can be regarded as the standard in locally advanced BTC. Adjuvant therapy after surgical resection is not validated. Understanding the molecular mechanisms of carcinogenesis of GBC has opened the way for the use of targeted therapies. This new treatment would improve survival and quality of life of our patients.

Reduced expression of Raf-1 kinase inhibitory protein is a significant prognostic marker in patients with gallbladder carcinoma

Gallbladder carcinoma is one of the most aggressive malignancies. It is usually diagnosed at an advanced stage, and the prognosis remains poor despite advances in imaging techniques and aggressive surgical treatment. Because of the lack of reliable prognostic markers, the aim of this study was to investigate the prognostic significance of Raf-1 kinase inhibitory protein expression in gallbladder carcinomas. Immunostaining for Raf-1 kinase inhibitory protein was performed on chronic cholecystitis, adenoma, carcinoma in situ, and primary and nodal metastatic gallbladder carcinoma. Raf-1 kinase inhibitory protein expression was reduced in 68.8% (11/16) and 42.3% (44/104) of nodal metastatic and primary gallbladder carcinoma cases, respectively, but in no case of carcinoma in situ, adenoma, or chronic cholecystitis. The differences in Raf-1 kinase inhibitory protein expression in gallbladder carcinoma versus nongallbladder carcinoma tissues (P < .001), and in nodal metastatic gallbladder carcinoma versus primary gallbladder carcinoma (P = .009), were statistically significant. Kaplan-Meier curves showed that patients with Raf-1 kinase inhibitory protein-negative or weakly positive gallbladder carcinoma had a significantly shorter overall survival than did patients with Raf-1 kinase inhibitory protein-positive gallbladder carcinoma (median, 14 versus 120 months; P = .011). Multivariate survival analysis showed that reduced Raf-1 kinase inhibitory protein expression was an independent prognostic predictor for overall survival (P = .020). Our results suggest that reduction in Raf-1 kinase inhibitory protein expression in gallbladder carcinoma contributes to invasion and metastasis and is a significant prognostic marker in patients with gallbladder carcinoma.

Genetics of biliary tract cancers and emerging targeted therapies

Biliary tract cancers (BTC), which encompass intra- and extrahepatic cholangiocarcinomas and gallbladder carcinomas, are a genetically diverse collection of cancers. Evidence suggests distinct models of molecular and pathologic progression, and a growing body of genetics data points to a heterogeneous collection of underlying mutations in key oncogenes and tumor suppressor genes. Although tumor genetics have been used to tailor individual treatment regimens and guide clinical decision making in other cancers, these principles have not been applied in BTC. Recent clinical trials with targeted therapies seem promising, although the relationships between subsets of patients with positive responses to therapy and tumor genetics remain unexplored. Here, we summarize the molecular pathogenesis and genetics of BTCs and animal modeling and relate these to recent and ongoing clinical trials with targeted agents.

Current management of gallbladder carcinoma

Gallbladder cancer (GBC) represents the most common and aggressive type among the biliary tree cancers (BTCs). Complete surgical resection offers the only chance for cure; however, only 10% of patients with GBC present with early-stage disease and are considered surgical candidates. Among those patients who do undergo "curative" resection, recurrence rates are high. There are no established adjuvant treatments in this setting. Patients with unresectable or metastatic GBC have a poor prognosis. There has been a paucity of randomized phase III data in this field. A recent report demonstrated longer overall survival with gemcitabine in combination with cisplatin than with gemcitabine alone in patients with advanced or metastatic BTCs. Molecularly targeted agents are under development. In this review, we attempt to discuss the current status and key issues involved in the management of GBC.

Emerging drugs for biliary cancer

Biliary cancer comprise carcinoma of the gallbladder as well as the intrahepatic, hilar and extrahepatic bile ducts. Furthermore, many different etiologies and risk factors are contributing to the inhomogeneity of this disease. It is often diagnosed at an advanced stage when potentially curative resection is not feasible. Due to the lack of randomised Phase III studies, there is no standard regimen for chemotherapy in biliary cancer. Recent investigations into the underlying molecular mechanisms involved in biliary carcinogenesis and tumour growth have contributed greatly to our understanding of biliary cancer. Through a better understanding of these mechanisms, improved and more specific diagnostic, therapeutic and preventive strategies may be developed. Although fluoropyrimidines and gemcitabine remain the backbone of routine chemotherapy in advanced disease, new agents such as epidermal growth factor receptor blockers and angiogenesis inhibitors may hold promise for improving the outcome for patients with biliary cancer.

Raf kinases: function, regulation and role in human cancer

The Ras-Raf-MAPK pathway regulates diverse physiological processes by transmitting signals from membrane based receptors to various nuclear, cytoplasmic and membrane-bound targets, coordinating a large variety of cellular responses. Function of Raf family kinases has been shown to play a role during organism development, cell cycle regulation, cell proliferation and differentiation, cell survival and apoptosis and many other cellular and physiological processes. Aberrations along the Ras-Raf-MAPK pathway play an integral role in various biological processes concerning human health and disease. Overexpression or activation of the pathway components is a common indicator in proliferative diseases such as cancer and contributes to tumor initiation, progression and metastasis. In this review, we focus on the physiological roles of Raf kinases in normal and disease conditions, specifically cancer, and the current thoughts on Raf regulation.

BRAF and KRAS mutations in prostatic adenocarcinoma

Constitutive activation of the kinase cascade involving RAS, RAF, MEK and ERK is common to human cancers, and mutations of KRAS and BRAF are mutually exclusive and serve as alternatives to activate the RAS/RAF/ERK signaling pathway. RAS mutations are known to occur in prostate adenocarcinomas, but little is known about BRAF mutations in these tumors. In the present study, BRAF and KRAS mutations were characterized in 206 prostate adenocarcinomas by enhanced PCR-RFLP and direct sequencing. The identified KRAS and BRAF mutations were then analyzed with respect to preoperative serum PSA levels, Gleason scores and tumor stages. Mutations in codon 600 of BRAF were identified in 21 (10.2%) of 206 prostate adenocarcinomas. KRAS mutations in codons 12 or 13 were found in 15 (7.3%) of 206 prostate adenocarcinomas. However, no tumor specimen contained both BRAF and KRAS mutations. Prostate adenocarcinomas with a BRAF mutation tended to show higher preoperative serum PSA levels, Gleason scores and tumor stages than prostate adenocarcinomas with a KRAS mutation. The results obtained show that BRAF mutations are as uncommon as KRAS mutations in prostate adenocarcinoma. Although BRAF and KRAS are members of the same RAS/ERK signaling pathway, prostate adenocarcinomas with a BRAF mutation showed clinicopathologic features that differed from those of prostate adenocarcinoma with a KRAS mutation.

Molecular analysis of the EGFR-RAS-RAF pathway in pancreatic ductal adenocarcinomas: lack of mutations in the BRAF and EGFR genes

The vast majority of tumors of the pancreas are ductal adenocarcinomas. This cancer type has an extremely poor prognosis and in many Western countries, it represents the fifth leading cause of cancer-related death. Pancreatic ductal adenocarcinomas exhibit the highest incidence of activating KRAS (Ki-Ras) mutations observed in any human cancer. It was therefore of interest to examine how this pattern would relate to mutations in the BRAF and EGFR genes, which are involved in the same signaling pathway as KRAS. We screened a series of 43 formalin-fixed, paraffin-embedded ductal adenocarcinomas of the pancreas. When DNA was extracted from whole tissue sections, KRAS codon 12 mutations were detected in 67% of the tumors. When cancerous ducts were isolated by laser-assisted microdissection, 91% were positive for KRAS mutations. Although it did not reach statistical significance, there was a trend in our material that survival after diagnosis varied according to KRAS mutation subtype, GTT-positive patients having the best prognosis. No alterations in BRAF exons 11 and 15 or in EGFR exons 18-21 were detected in KRAS-positive or KRAS-negative cases. We therefore conclude that the BRAF and EGFR mutations commonly seen in a variety of human cancers are generally absent from pancreatic ductal adenocarcinomas. Apparently, these tumors depend on no more than one genetic hit in the EGFR-RAS-RAF signaling pathway.