Genome-wide association studies in oesophageal adenocarcinoma and Barrett's oesophagus: a large-scale meta-analysis

Background: Esophageal adenocarcinoma (EA) is one of the fastest rising cancers in western countries. Barrett’s Esophagus (BE) is the premalignant precursor of EA. However, only a subset of BE patients develop EA, which complicates the clinical management in the absence of valid predictors. Genetic risk factors for BE and EA are incompletely understood. This study aimed to identify novel genetic risk factors for BE and EA.Methods: Within an international consortium of groups involved in the genetics of BE/EA, we performed the first meta-analysis of all genome-wide association studies (GWAS) available, involving 6,167 BE patients, 4,112 EA patients, and 17,159 representative controls, all of European ancestry, genotyped on Illumina high-density SNP-arrays, collected from four separate studies within North America, Europe, and Australia. Meta-analysis was conducted using the fixed-effects inverse variance-weighting approach. We used the standard genome-wide significant threshold of 5×10-8 for this study. We also conducted an association analysis following reweighting of loci using an approach that investigates annotation enrichment among the genome-wide significant loci. The entire GWAS-data set was also analyzed using bioinformatics approaches including functional annotation databases as well as gene-based and pathway-based methods in order to identify pathophysiologically relevant cellular pathways.Findings: We identified eight new associated risk loci for BE and EA, within or near the CFTR (rs17451754, P=4·8×10-10), MSRA (rs17749155, P=5·2×10-10), BLK (rs10108511, P=2·1×10-9), KHDRBS2 (rs62423175, P=3·0×10-9), TPPP/CEP72 (rs9918259, P=3·2×10-9), TMOD1 (rs7852462, P=1·5×10-8), SATB2 (rs139606545, P=2·0×10-8), and HTR3C/ABCC5 genes (rs9823696, P=1·6×10-8). A further novel risk locus at LPA (rs12207195, posteriori probability=0·925) was identified after re-weighting using significantly enriched annotations. This study thereby doubled the number of known risk loci. The strongest disease pathways identified (P<10-6) belong to muscle cell differentiation and to mesenchyme development/differentiation, which fit with current pathophysiological BE/EA concepts. To our knowledge, this study identified for the first time an EA-specific association (rs9823696, P=1·6×10-8) near HTR3C/ABCC5 which is independent of BE development (P=0·45).Interpretation: The identified disease loci and pathways reveal new insights into the etiology of BE and EA. Furthermore, the EA-specific association at HTR3C/ABCC5 may constitute a novel genetic marker for the prediction of transition from BE to EA. Mutations in CFTR, one of the new risk loci identified in this study, cause cystic fibrosis (CF), the most common recessive disorder in Europeans. Gastroesophageal reflux (GER) belongs to the phenotypic CF-spectrum and represents the main risk factor for BE/EA. Thus, the CFTR locus may trigger a common GER-mediated pathophysiology.

Inverse Association Between Gluteofemoral Obesity and Risk of Barrett's Esophagus in a Pooled Analysis

BACKGROUND & AIMS: Gluteofemoral obesity (determined by measurement of subcutaneous fat in hip and thigh regions) could reduce risks of cardiovascular and diabetic disorders associated with abdominal obesity. We evaluated whether gluteofemoral obesity also reduces risk of Barrett's esophagus (BE), a premalignant lesion associated with abdominal obesity.

METHODS: We collected data from non-Hispanic white participants in 8 studies in the Barrett's and Esophageal Adenocarcinoma Consortium. We compared measures of hip circumference (as a proxy for gluteofemoral obesity) from cases of BE (n=1559) separately with 2 control groups: 2557 population-based controls and 2064 individuals with gastroesophageal reflux disease (GERD controls). Study-specific odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using individual participant data and multivariable logistic regression and combined using random effects meta-analysis.

RESULTS: We found an inverse relationship between hip circumference and BE (OR per 5 cm increase, 0.88; 95% CI, 0.81-0.96), compared with population-based controls in a multivariable model that included waist circumference. This association was not observed in models that did not include waist circumference. Similar results were observed in analyses stratified by frequency of GERD symptoms. The inverse association with hip circumference was only statistically significant among men (vs population-based controls: OR, 0.85; 95% CI, 0.76-0.96 for men; OR, 0.93; 95% CI, 0.74-1.16 for women). For men, within each category of waist circumference, a larger hip circumference was associated with decreased risk of BE. Increasing waist circumference was associated with increased risk of BE in the mutually adjusted population-based and GERD control models.

CONCLUSIONS: Although abdominal obesity is associated with increased risk of BE, there is an inverse association between gluteofemoral obesity and BE, particularly among men.

Epirubicin, oxaliplatin, and capecitabine with or without panitumumab for patients with previously untreated advanced oesophagogastric cancer (REAL3): a randomised, open-label phase 3 trial.

BACKGROUND: EGFR overexpression occurs in 27-55% of oesophagogastric adenocarcinomas, and correlates with poor prognosis. We aimed to assess addition of the anti-EGFR antibody panitumumab to epirubicin, oxaliplatin, and capecitabine (EOC) in patients with advanced oesophagogastric adenocarcinoma. METHODS: In this randomised, open-label phase 3 trial (REAL3), we enrolled patients with untreated, metastatic, or locally advanced oesophagogastric adenocarcinoma at 63 centres (tertiary referral centres, teaching hospitals, and district general hospitals) in the UK. Eligible patients were randomly allocated (1:1) to receive up to eight 21-day cycles of open-label EOC (epirubicin 50 mg/m(2) and oxaliplatin 130 mg/m(2) on day 1 and capecitabine 1250 mg/m(2) per day on days 1-21) or modified-dose EOC plus panitumumab (mEOC+P; epirubicin 50 mg/m(2) and oxaliplatin 100 mg/m(2) on day 1, capecitabine 1000 mg/m(2) per day on days 1-21, and panitumumab 9 mg/kg on day 1). Randomisation was blocked and stratified for centre region, extent of disease, and performance status. The primary endpoint was overall survival in the intention-to-treat population. We assessed safety in all patients who received at least one dose of study drug. After a preplanned independent data monitoring committee review in October, 2011, trial recruitment was halted and panitumumab withdrawn. Data for patients on treatment were censored at this timepoint. This study is registered with ClinicalTrials.gov, number NCT00824785. FINDINGS: Between June 2, 2008, and Oct 17, 2011, we enrolled 553 eligible patients. Median overall survival in 275 patients allocated EOC was 11.3 months (95% CI 9.6-13.0) compared with 8.8 months (7.7-9.8) in 278 patients allocated mEOC+P (hazard ratio [HR] 1.37, 95% CI 1.07-1.76; p=0.013). mEOC+P was associated with increased incidence of grade 3-4 diarrhoea (48 [17%] of 276 patients allocated mEOC+P vs 29 [11%] of 266 patients allocated EOC), rash (29 [11%] vs two [1%]), mucositis (14 [5%] vs none), and hypomagnesaemia (13 [5%] vs none) but reduced incidence of haematological toxicity (grade ≥ 3 neutropenia 35 [13%] vs 74 [28%]). INTERPRETATION: Addition of panitumumab to EOC chemotherapy does not increase overall survival and cannot be recommended for use in an unselected population with advanced oesophagogastric adenocarcinoma. FUNDING: Amgen, UK National Institute for Health Research Biomedical Research Centre.

Biomarker analysis in oesophagogastric cancer: Results from the REAL3 and TransMAGIC trials.

BACKGROUND: REAL3 (Randomised ECF for Advanced or Locally advanced oesophagogastric cancer 3) was a phase II/III trial designed to evaluate the addition of panitumumab (P) to epirubicin, oxaliplatin and capecitabine (EOC) in untreated advanced oesophagogastric adenocarcinoma, or undifferentiated carcinoma. MAGIC (MRC Adjuvant Gastric Infusional Chemotherapy) was a phase III study which demonstrated that peri-operative epirubicin, cisplatin and infused 5-fluorouracil (ECF) improved survival in early oesophagogastric adenocarcinoma. PATIENTS AND METHODS: Analysis of response rate (RR; the primary end-point of phase II) and biomarkers in the first 200 patients randomised to EOC or modified dose (m) EOC+P in REAL3 was pre-planned to determine if molecular selection for the on-going study was indicated. KRAS, BRAF and PIK3CA mutations and PTEN expression were assessed in pre-treatment biopsies and results correlated with response to mEOC+P. Association between these biomarkers and overall survival (OS) was assessed in MAGIC patients to determine any prognostic effect. RESULTS: RR was 52% to mEOC+P, 48% to EOC. Results from 175 assessable biopsies: mutations in KRAS (5.7%), BRAF (0%), PIK3CA (2.5%) and loss of PTEN expression (15.0%). None of the biomarkers evaluated predicted resistance to mEOC+P. In MAGIC, mutations in KRAS, BRAF and PIK3CA and loss of PTEN (phosphatase and tensin homolog) were found in 6.3%, 1.0%, 5.0% and 10.9%, respectively, and were not associated with survival. CONCLUSIONS: The RR of 52% in REAL3 with mEOC+P met pre-defined criteria to continue accrual to phase III. The frequency of the mutations was too low to exclude any prognostic or predictive effect.

Transformation to "high grade" neuroendocrine carcinoma as an acquired drug resistance mechanism in EGFR-mutant lung adenocarcinoma.

Several different acquired resistance mechanisms of EGFR mutant lung adenocarcinoma to EGFR-tyrosine kinase inhibitor (TKI) therapy have been described, most recently transformation to small cell lung carcinoma (SCLC). We describe the case of a 46-year-old female with relapsed EGFR exon 19 deletion lung adenocarcinoma treated with erlotinib, and on resistance, cisplatin-pemetrexed. Liver rebiopsy identified an afatinib-resistant combined SCLC and non-small cell carcinoma with neuroendocrine morphology, retaining the EGFR exon 19 deletion. This case highlights acquired EGFR-TKI resistance through transformation to the high-grade neuroendocrine carcinoma spectrum and that that such transformation may not be evident at time of progression on TKI therapy.

ALK translocation is associated with ALK immunoreactivity and extensive signet-ring morphology in primary lung adenocarcinoma.

BACKGROUND: ALK rearrangement is particularly observed in signet-ring sub-type adenocarcinoma. Since fluorescence in situ hybridization (FISH) is not suitable for mass screening, we aimed to characterize the predictive utility of tumour morphology and ALK immunoreactivity to identify ALK rearrangement, in a primary lung adenocarcinoma dataset enriched for signet-ring morphology, compared with that of other morphology. METHODS: 7 adenocarcinomas from diagnostic archives reported with signet-ring morphology were assessed and compared with 11 adenocarcinomas without signet-ring features over the same time period. Growth patterns were reviewed, ALK expression was assessed by standard immunohistochemistry using ALK1 clone and Envision detection (Dako), and ALK rearrangement was assessed by FISH (Abbott Molecular). Associations between groups and predictive utility of tumour morphology and ALK expression using FISH as gold standard were calculated. RESULTS: 2 excision lung biopsy cases with pure (100%) signet-ring morphology and solid patterns demonstrated diffuse moderate cytoplasmic ALK immunoreactivity (2+) and harboured ALK rearrangements (p=0.007), unlike 5 mixed-signet-ring and 11 non-signet-ring adenocarcinomas, which showed negative or 1+ immunoreactivity; and did not harbour ALK rearrangements (p>0.1). ALK expression was not associated with ALK copy number. 6 of 7 cases with signet ring morphology stained for TTF-1. Pure signet-ring morphology and moderate ALK expression were both associated with ALK rearranged tumours. CONCLUSION: ALK rearrangement is strongly associated with ALK immunoreactivity, and was seen only in tumours with pure signet-ring morphology and solid growth pattern. Tumour morphology, growth pattern and ALK immunoreactivity appear to be good indicators of ALK rearrangement, with TTF-1 positivity aiding in proving primary pulmonary origin.