SETD2 histone modifier loss in aggressive GI stromal tumours.

BACKGROUND: GI stromal tumours (GISTs) are clinically heterogenous exhibiting varying degrees of disease aggressiveness in individual patients. OBJECTIVES: We sought to identify genetic alterations associated with high-risk GIST, explore their molecular consequences, and test their utility as prognostic markers. DESIGNS: Exome sequencing of 18 GISTs was performed (9 patients with high-risk/metastatic and 5 patients with low/intermediate-risk), corresponding to 11 primary and 7 metastatic tumours. Candidate alterations were validated by prevalence screening in an independent patient cohort (n=120). Functional consequences of SETD2 mutations were investigated in primary tissues and cell lines. Transcriptomic profiles for 8 GISTs (4 SETD2 mutated, 4 SETD2 wild type) and DNA methylation profiles for 22 GISTs (10 SETD2 mutated, 12 SETD2 wild type) were analysed. Statistical associations between molecular, clinicopathological factors, and relapse-free survival were determined. RESULTS: High-risk GISTs harboured increased numbers of somatic mutations compared with low-risk GISTs (25.2 mutations/high-risk cases vs 6.8 mutations/low-risk cases; two sample t test p=3.1×10-5). Somatic alterations in the SETD2 histone modifier gene occurred in 3 out of 9 high-risk/metastatic cases but no low/intermediate-risk cases. Prevalence screening identified additional SETD2 mutations in 7 out of 80 high-risk/metastatic cases but no low/intermediate-risk cases (n=29). Combined, the frequency of SETD2 mutations was 11.2% (10/89) and 0% (0/34) in high-risk and low-risk GISTs respectively. SETD2 mutant GISTs exhibited decreased H3K36me3 expression while SETD2 silencing promoted DNA damage in GIST-T1 cells. In gastric GISTs, SETD2 mutations were associated with overexpression of HOXC cluster genes and a DNA methylation signature of hypomethylated heterochromatin. Gastric GISTs with SETD2 mutations, or GISTs with hypomethylated heterochromatin, showed significantly shorter relapse-free survival on univariate analysis (log rank p=4.1×10-5). CONCLUSIONS: Our data suggest that SETD2 is a novel GIST tumour suppressor gene associated with disease progression. Assessing SETD2 genetic status and SETD2-associated epigenomic phenotypes may guide risk stratification and provide insights into mechanisms of GIST clinical aggressiveness.

Resected pancreatic adenocarcinoma: An Asian institution's experience.

BACKGROUND: Pancreatic adenocarcinoma (PDAC) is highly lethal. Surgery offers the only chance of cure, but 5-year overall survival (OS) after surgical resection and adjuvant therapy remains dismal. Adjuvant trials were mostly conducted in the West enrolling fit patients. Applicability to a general population, especially Asia has not been described adequately. AIM: We aimed to evaluate the clinical outcomes, prognostic factors of survival, pattern, and timing of recurrence after curative resection in an Asian institution. METHODS AND RESULTS: The clinicopathologic and survival outcomes of 165 PDAC patients who underwent curative resection between 1998 and 2013 were reviewed retrospectively. Median age at surgery was 62.0 years. 55.2% were male, and 73.3% had tumors involving the head of pancreas. The median OS of the entire cohort was 19.7 months. Median OS of patients who received adjuvant chemotherapy was 23.8 months. Negative predictors of survival include lymph node ratio (LNR) of >0.3 (HR = 3.36, P = .001), tumor site involving the body or tail of pancreas (HR = 1.59, P = .046), presence of perineural invasion (PNI) (HR = 2.36, P = .018) and poorly differentiated/undifferentiated tumor grade (HR = 1.86, P = .058). The median time to recurrence was 8.87 months, with 66.1% and 81.2% of patients developing recurrence at 12 months and 24 months respectively. The most common site of recurrence was the liver. CONCLUSION: The survival of Asian patients with resected PDAC who received adjuvant chemotherapy is comparable to reported randomized trials. Clinical characteristics seem similar to Western patients. Hence, geographical locations may not be a necessary stratification factor in RCTs. Conversely, lymph node ratio and status of PNI ought to be incorporated.

Comparison between long and short-term venous patencies after pancreatoduodenectomy or total pancreatectomy with portal/superior mesenteric vein resection stratified by reconstruction type.

BACKGROUND: Venous reconstruction has been recently demonstrated to be safe for tumours with invasion into portal vein and/or superior mesenteric vein. This study aims to compare the patency between various venous reconstructions. METHODS: This is retrospective study of 76 patients who underwent pancreaticoduodenectomy or total pancreatectomy with venous reconstruction from 2006 to 2018. Patient demographics, tumour histopathology, morbidity, mortality and patency were studied. Kaplan-Meier estimates were performed for primary venous patency. RESULTS: Sixty-two patients underwent pancreaticoduodenectomy and 14 underwent total pancreatectomy. Forty-seven, 19 and 10 patients underwent primary repair, end-to-end anastomosis and interposition graft respectively. Major morbidity (Clavien-Dindo >grade 2) and 30-day mortality were 14/76(18.4%) and 1/76(1.3%) respectively. There were 12(15.8%) venous occlusion including 4(5.3%) acute occlusions. Overall 6-month, 1-year and 2-year primary patency was 89.1%, 92.5% and 92.3% respectively. 1-year primary patency of primary repair was superior to end-to-end anastomosis and interposition graft (primary repair 100%, end-to-end anastomosis 81.8%, interposition graft 66.7%, p = 0.045). Pairwise comparison also demonstrated superior 1-year patency of primary repair (adjusted p = 0.037). There was no significant difference between the cumulative venous patency for each venous reconstruction method: primary repair 84±6%, end-to-end anastomosis 75±11% and interposition graft 76±15% (p = 0.561). CONCLUSION: 1-year primary venous patency of primary repair is superior to end-to-end anastomosis and interposition graft.

Whole-Genome and Epigenomic Landscapes of Etiologically Distinct Subtypes of Cholangiocarcinoma.

Cholangiocarcinoma (CCA) is a hepatobiliary malignancy exhibiting high incidence in countries with endemic liver-fluke infection. We analyzed 489 CCAs from 10 countries, combining whole-genome (71 cases), targeted/exome, copy-number, gene expression, and DNA methylation information. Integrative clustering defined 4 CCA clusters-fluke-positive CCAs (clusters 1/2) are enriched in ERBB2 amplifications and TP53 mutations; conversely, fluke-negative CCAs (clusters 3/4) exhibit high copy-number alterations and PD-1/PD-L2 expression, or epigenetic mutations (IDH1/2, BAP1) and FGFR/PRKA-related gene rearrangements. Whole-genome analysis highlighted FGFR2 3' untranslated region deletion as a mechanism of FGFR2 upregulation. Integration of noncoding promoter mutations with protein-DNA binding profiles demonstrates pervasive modulation of H3K27me3-associated sites in CCA. Clusters 1 and 4 exhibit distinct DNA hypermethylation patterns targeting either CpG islands or shores-mutation signature and subclonality analysis suggests that these reflect different mutational pathways. Our results exemplify how genetics, epigenetics, and environmental carcinogens can interplay across different geographies to generate distinct molecular subtypes of cancer.Significance: Integrated whole-genome and epigenomic analysis of CCA on an international scale identifies new CCA driver genes, noncoding promoter mutations, and structural variants. CCA molecular landscapes differ radically by etiology, underscoring how distinct cancer subtypes in the same organ may arise through different extrinsic and intrinsic carcinogenic processes. Cancer Discov; 7(10); 1116-35. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 1047.

The Singapore Liver Cancer Recurrence (SLICER) Score for relapse prediction in patients with surgically resected hepatocellular carcinoma.

BACKGROUND AND AIMS: Surgery is the primary curative option in patients with hepatocellular carcinoma (HCC). Current prognostic models for HCC are developed on datasets of primarily patients with advanced cancer, and may be less relevant to resectable HCC. We developed a postoperative nomogram, the Singapore Liver Cancer Recurrence (SLICER) Score, to predict outcomes of HCC patients who have undergone surgical resection. METHODS: Records for 544 consecutive patients undergoing first-line curative surgery for HCC in one institution from 1992-2007 were reviewed, with 405 local patients selected for analysis. Freedom from relapse (FFR) was the primary outcome measure. An outcome-blinded modeling strategy including clustering, data reduction and transformation was used. We compared the performance of SLICER in estimating FFR with other HCC prognostic models using concordance-indices and likelihood analysis. RESULTS: A nomogram predicting FFR was developed, incorporating non-neoplastic liver cirrhosis, multifocality, preoperative alpha-fetoprotein level, Child-Pugh score, vascular invasion, tumor size, surgical margin and symptoms at presentation. Our nomogram outperformed other HCC prognostic models in predicting FFR by means of log-likelihood ratio statistics with good calibration demonstrated at 3 and 5 years post-resection and a concordance index of 0.69. Using decision curve analysis, SLICER also demonstrated superior net benefit at higher threshold probabilities. CONCLUSION: The SLICER score enables well-calibrated individualized predictions of relapse following curative HCC resection, and may represent a novel tool for biomarker research and individual counseling.

Biliary-enteric transanastomotic stenting with Intestofix.

BACKGROUND: Biliary-enteric transanastomotic stenting is useful under adverse local conditions or when small-calibre bile ducts are encountered. METHODS: A commercially available feeding jejunostomy kit, Intestofix, was inserted transjejunally through the blind loop of a Roux-en-Y hepatico-jejunostomy. CONCLUSIONS: The stent splinted the anastomosis to reduce biliary leaks and may help to prevent subsequent stricture formation.

Preclinical evaluation of transcriptional targeting strategy for human hepatocellular carcinoma in an orthotopic xenograft mouse model.

Gene regulation of many key cell-cycle players in S-, G(2) phase, and mitosis results from transcriptional repression in their respective promoter regions during the G(0) and G(1) phases of cell cycle. Within these promoter regions are phylogenetically conserved sequences known as the cell-cycle-dependent element (CDE) and cell-cycle genes homology regions (CHR) sites. Thus, we hypothesize that transcriptional regulation of cell-cycle regulation via the CDE/CHR region together with liver-specific apolipoprotein E (apoE)-hAAT promoter could bring about a selective transgene expression in proliferating human hepatocellular carcinoma. We show that the newly generated vector AH-6CC-L2C could mediate hepatocyte-targeted luciferase gene expression in tumor cells and freshly isolated short-term hepatocellular carcinoma cultures from patient biopsy. In contrast, normal murine and human hepatocytes infected with AH-6CC-L2C expressed minimal or low luciferase activities. In the presence of prodrug 5-fluorocytosine (5-FC), AH-6CC-L2C effectively suppressed the growth of orthotopic hepatocellular carcinoma patient-derived xenograft mouse model via the expression of yeast cytosine deaminase (yCD) that converts 5-FC to anticancer metabolite 5-fluoruracil. More importantly, we show that combination treatment of AH-6CC-L2C with an EZH2 inhibitor, DZNep, that targets EpCAM-positive hepatocellular carcinoma, can bring about a greater therapeutic efficacy compared with a single treatment of virus or inhibitor. Our study showed that targeting proliferating human hepatocellular carcinoma cells through the transcriptional control of therapeutic gene could represent a feasible approach against hepatocellular carcinoma.

Ampullary carcinoma: effect of preoperative biliary drainage on surgical outcome.

AIM: To evaluate the influence of preoperative biliary drainage on morbidity and mortality after surgical resection for ampullary carcinoma. METHODS: We analyzed retrospectively data for 82 patients who underwent potentially curative surgery for ampullary carcinoma between September 1993 and July 2007 at the Singapore General Hospital, a tertiary referral hospital. Diagnosis of ampullary carcinoma was confirmed histologically. Thirty-five patients underwent preoperative biliary drainage (PBD group), and 47 were not drained (non-PBD group). The mode of biliary drainage was endoscopic retrograde cholangiopancreatography (n = 33) or percutaneous biliary drainage (n = 2). The following parameters were analyzed: wound infection, intra-abdominal abscess, intra-abdominal or gastrointestinal bleeding, septicemia, biliary or pancreatic leakage, pancreatitis, gastroparesis, and re-operation rate. Mortality was assessed at 30 d (hospital mortality) and also long-term. The statistical endpoint of this study was patient survival after surgery. RESULTS: The groups were well matched for demographic criteria, clinical presentation and operative characteristics, except for lower hemoglobin in the non-PBD group (10.9 +/- 1.6 vs 11.8 +/- 1.6 in the PBD group). Of the parameters assessing postoperative morbidity, incidence of wound infection was significantly less in the PBD than the non-PBD group [1 (2.9%) vs 12 (25.5%)]. However, the rest of the parameters did not differ significantly between the groups, i.e. sepsis [10 (28.6%) vs 14 (29.8%)], intra-abdominal bleeding [1 (2.9%) vs 5 (10.6%)], intra-abdominal abscess [1 (2.9%) vs 8 (17%)], gastrointestinal bleeding [3 (8.6%) vs 5 (10.6%)], pancreatic leakage [2 (5.7%) vs 3 (6.4%)], biliary leakage [2 (5.7%) vs 3 (6.4%)], pancreatitis [2 (5.7%) vs 2 (4.3%)], gastroparesis [6 (17.1%) vs 10 (21.3%)], need for blood transfusion [10 (28.6%) vs 17 (36.2%)] and re-operation rate [1 (2.9%) vs 5 (10.6%)]. There was no early mortality in either group. Median survival was 44 mo (95% CI: 34.2-53.8) in the PBD group and 41 mo (95% CI: 27.7-54.3; P = 0.86) in the non-PBD group. CONCLUSION: Biliary drainage before surgery for ampullary cancer significantly reduced postoperative wound infection. Overall mortality was not influenced by preoperative drainage.