Nicola O'Connell

Development and application of a new electronic nose instrument for the detection of colorectal cancer

Colorectal cancer is a leading cause of cancer death in the USA and Europe with symptoms that mimick other far more common lower gastrointestinal (GI) disorders. This difficulty in separating colorectal cancer from these other diseases has driven researchers to search for an effective, non-invasive screening technique. Current state-of-the-art method of Faecal Immunochemical Testing achieving sensitivity ~90%, unfortunately the take-up in the western world is low due to the low patient acceptability of stool samples. However, a wide range of cancers have been distinguished from each-other and healthy controls by detecting the gas/volatile content emanating patient biological media. Dysbiosis afforded by certain disease states may be expressed in the volatile content of urine - a reflection of the gut bacterias metabolic processes. A new electronic nose instrument was developed at the University of Warwick to measure the gas/volatile content of urine headspace, based on an array of 13 commercial electro-chemical and optical sensors. An experimental setup was arranged for a cohort of 92 urine samples from patients of colorectal cancer (CRC), irritable bowel syndrome (IBS) and controls to be run through the machine. Features were extracted from response data and used in Linear Discriminant Analysis (LDA) plots, including a full 3-disease classification and one focussing on distinguishing CRC from IBS. The latter case was tested by the success of re-classification using an (n-1) K-nearest neighbour algorithm, showing 78% sensitivity and 79% specificity to CRC.

Detection of Colorectal Cancer (CRC) by Urinary Volatile Organic Compound Analysis

Colorectal cancer (CRC) is a leading cause of cancer related death in Europe and the USA. There is no universally accepted effective non-invasive screening test for CRC. Guaiac based faecal occult blood (gFOB) testing has largely been superseded by Faecal Immunochemical testing (FIT), but sensitivity still remains poor. The uptake of population based FOBt testing in the UK is also low at around 50%. The detection of volatile organic compounds (VOCs) signature(s) for many cancer subtypes is receiving increasing interest using a variety of gas phase analytical instruments. One such example is FAIMS (Field Asymmetric Ion Mobility Spectrometer). FAIMS is able to identify Inflammatory Bowel disease (IBD) patients by analysing shifts in VOCs patterns in both urine and faeces. This study extends this concept to determine whether CRC patients can be identified through non-invasive analysis of urine, using FAIMS. 133 patients were recruited; 83 CRC patients and 50 healthy controls. Urine was collected at the time of CRC diagnosis and headspace analysis undertaken using a FAIMS instrument (Owlstone, Lonestar, UK). Data was processed using Fisher Discriminant Analysis (FDA) after feature extraction from the raw data. FAIMS analyses demonstrated that the VOC profiles of CRC patients were tightly clustered and could be distinguished from healthy controls. Sensitivity and specificity for CRC detection with FAIMS were 88% and 60% respectively. This study suggests that VOC signatures emanating from urine can be detected in patients with CRC using ion mobility spectroscopy technology (FAIMS) with potential as a novel screening tool.

Application of a Novel Tool for Diagnosing Bile Acid Diarrhoea

Bile acid diarrhoea (BAD) is a common disease that requires expensive imaging to diagnose. We have tested the efficacy of a new method to identify BAD, based on the detection of differences in volatile organic compounds (VOC) in urine headspace of BAD vs. ulcerative colitis and healthy controls. A total of 110 patients were recruited; 23 with BAD, 42 with ulcerative colitis (UC) and 45 controls. Patients with BAD also received standard imaging (Se75HCAT) for confirmation. Urine samples were collected and the headspace analysed using an AlphaMOS Fox 4000 electronic nose in combination with an Owlstone Lonestar Field Asymmetric Ion Mobility Spectrometer (FAIMS). A subset was also tested by gas chromatography, mass spectrometry (GCMS). Linear Discriminant Analysis (LDA) was used to explore both the electronic nose and FAIMS data. LDA showed statistical differences between the groups, with reclassification success rates (using an n-1 approach) at typically 83%. GCMS experiments confirmed these results and showed that patients with BAD had two chemical compounds, 2-propanol and acetamide, that were either not present or were in much reduced quantities in the ulcerative colitis and control samples. We believe that this work may lead to a new tool to diagnose BAD, which is cheaper, quicker and easier that current methods.

Mo1019 Breathomics - Distinguishing Minimal From Overt Hepatic Encephalopathy by Volatile Organic Compound Detection in Breath: A Pilot Study

: Hepatic encephalopathy (HE) is a neurological manifestation of decompensated liver disease. It develops in approximately 50% of cirrhotic patients. The current challenge with the diagnosis of Hepatic encephalopathy is distinguishing those with minimal HE as opposed to the more clinically apparent covert and overt HE. Rifaximin, licensed for overt HE, is an effective therapy for these more easily diagnosed patients, but earlier identification and treatment of HE could prevent liver disease progression and hospitalisation. We conducted a pilot study to analyse the breath samples of patients with different HE grades, alongside the breath of healthy controls, using a portable type electronic nose (uvFAIMS). Methods: 42 patients were enrolled; 22 with HE and 20 healthy controls. Breath samples were captured at the bedside using a Warwick designed breath capture device. The samples were then analysed using a ultra violet FAIMS machine. This uses ultra violet light to energise electrons rather than ionising radiation in the traditional FAIMS devices. West Haven criteria were applied and MELD scores calculated. Results: Applying linear discriminant analysis, we could distinguish those with HE from controls with a sensitivity and specificity of 95% respectively. Minimal HE was distinguishable from covert/overt HE with sensitivity of 75% and specificity of 50% Conclusions: This pilot study has affirmed the potential of breath analysis to identify VOCs signatures in HE patients. Importantly this was performed utilising a non-invasive, portable bedside device and holds potential for future early diagnosis of minimal or covert HE.

PWE-136 The non-invasive detection of non-alcoholic fatty liver disease using urinary volatile organic compound analysis: a pilot study

Introduction Non Alcoholic Fatty Liver Disease (NAFLD) is the commonest cause of chronic liver disease in the western world. Current diagnostic methods, including that of the Fibroscan, have limitations, thus there is a clinical need for more robust, non-invasive screening tools. The gut microbiome is altered in several gastrointestinal and hepatic disorders resulting in altered, unique gut fermentation patterns. These patterns are detectable by analysis of volatile organic compounds (VOCs) in urine, breath and faeces. We aimed to determine if progressive fatty liver disease produced an altered VOC pattern in urine; specifically NAFLD and Non-Alcoholic Steatohepatitis (NASH). Method 34 patients were recruited; 8 NASH cirrhotics (NASH-C); 7 non-cirrhotic NASH; 4 NAFLD and 15 controls. Urine was collected and stored frozen. For assay, the samples were defrosted and aliquoted into vials, which were heated to 40 ± 0.1°C and the headspace analysed by FAIMS (Field Asymmetric Ion Mobility Spectroscopy). A previously used data processing pipeline employing a ‘Random Forrest’ classification algorithm and a 10 fold cross validation method was applied. Results Urinary VOCs could distinguish liver disease patients from controls with a sensitivity of 0.58 (0.33–0.88) but specificity of 0.93 (0.68 – 1.00); Area Under Curve (AUC) 0.73 (0.55 – 0.90). NASH/NASH-C was similarly separated from the NAFLD/control patients with a sensitivity of 0.73 (0.45–0.92), a specificity of 0.79 (0.54–0.94) and AUC of 0.79 (0.64–0.95), respectively. Conclusion This pilot study offers the potential for early non-invasive tracking of liver disease using urinary VOC bio-odorant fingerprints to distinguish patients with a disease within the spectrum of fatty liver disease from healthy controls, but also to distinguish subsets of the spectrum from each other, such as NASH from NAFLD. This may develop into a viable alternative surveillance or diagnostic tool in patients unable or unwilling to undergo liver biopsy. Disclosure of interest None Declared.

PWE-110 Breathomics – distinguishing minimal from overt hepatic encephalopathy using volatile organic compound analysis: a pilot study

Introduction Hepatic encephalopathy (HE) is a neurological manifestation of decompensated liver disease which develops in approximately 50% of patients with cirrhosis. The current diagnostic challenge presented by Hepatic encephalopathy is the detection of minimal HE, as opposed to the more clinically apparent overt HE. Rifaximin, licensed for overt HE, is an effective therapy for these patients, but earlier identification and treatment of HE could prevent liver disease progression and hospitalisation. We conducted a pilot study to analyse the breath samples of patients with different HE grades, alongside the breath of healthy controls, using a portable type electronic nose (uvFAIMS). Method 42 patients were enrolled; 22 with HE and 20 healthy controls. Breath samples were captured at the bedside using a Warwick designed breath capture device. The samples were then analysed using an ultra violet FAIMS machine. This uses ultra violet light to energise electrons rather than ionising radiation in the traditional FAIMS devices. West Haven criteria were applied and MELD scores calculated. Data was analysed using a previously developed pipeline based on a 2D wavelet transform and threshold, removing background noise. Sensitivity, specificity, and Area Under Receiver Operator Curve (AUROC) were calculated in 10-fold cross validation and reported using sparse logistic regression. Results 12 patients had minimal HE and 10 had covert/overt HE. Classification of HE vs controls showed a sensitivity of 0.88 (0.73 – 0.95) and specificity of 0.68 (0.51 – 0.81), AUROC 0.84 (0.75–0.93). Minimal HE was distinguished from covert/overt HE with a sensitivity of 0.79 (0.49 – 0.95) and specificity of 0.50 (0.37 – 0.63), AUROC 0.71 (0.57–0.84). There was no statistically significant differences between differing HE grades; AUROC 0.61 (0.43 – 0.79). Conclusion This pilot study has confirmed the potential of detection and diagnosis of HE via breath analysis identification of VOCs signatures. Importantly this was performed utilising a non-invasive, portable bedside device and holds potential for future early diagnosis of minimal or covert HE. Disclosure of interest None Declared.

Mo1394 Towards the Detection of Bile Acid Diarrhea: A Novel Non-Invasive Approach Using Electronic Noses (E-Nose) and Field Asymmetric Ion Mobility Spectroscopy (FAIMS)

OBJECTIVES: Colorectal cancer develops through multiple pathways including the adenomacarcinoma sequence and the serrated pathway. Individuals with serrated polyps (SP) are at higher risk of developing synchronous advanced colorectal neoplasia (AN) and cancer, but the molecular pathways underlying this malignancy remain poorly understood in these individuals. In this study, we characterized patients with coexisting colorectal AN and SP by examining the methylation levels of long interspersed nucleotide element-1 (LINE-1) in the adjacent normal mucosal tissues. METHODS: Colorectal ANs were retrospectively collected. The case group included ANs with coexisting SPs, and the control group consisted of ANs without coexisting SPs. Clinicopathological findings were compared between groups. BRAF and KRAS mutations in the ANs and SPs and LINE-1 methylation levels in adjacent mucosa were examined by quantitative bisulfite pyrosequencing. RESULTS: Seventy-five ANs from 40 patients in the case group, and 179 ANs from 119 patients in the control group were collected and analyzed. There were no significant differences in clinicopathological findings between the 2 groups of ANs, except that intraepithelial neoplasia in the case group was more frequently located in the right colon. BRAF mutations were significantly more frequent in the case group, while KRAS mutation showed no significant differences between groups. Most patients with high-grade intraepithelial neoplasia in both groups showed a component of conventional adenoma, while only one patient with high-grade intraepithelial neoplasia in the control group had a component of SP. Individuals with