MSACL 2025 Abstract

Applying Ambient Ionisation Mass Spectrometry to Identify Colorectal Cancer Biomarkers in Tissue and Extend Their Detection to Faeces

Elmeri Latvanen (1), Maria Sani (1), Yihan Xu (1), Duncan Roberts (1), Petra Paizs (1), James Alexander (1), James Kinross (1), Daniel Simon (1,2), Elizabeth Want (1) Zoltan Takats (1,2), Lauren Ford (1)
(1) Imperial College London, London, United Kingdom, (2) University of Regensburg, Regensburg, Germany

Elmeri Latvanen, BSc Biochemistry MRes Bioengineering (Presenter) Imperial College London

Presenter Bio: I'm a PhD candidate transitioning to a postdoctoral position at Imperial College London with a background in Biochemistry and Bioengineering. My current work is focused on the early detection of colorectal cancer using surface-enhanced ambient mass spectrometry.

Relevant Financial Disclosures (within past 24 months, reported on Apr 22, 2026) No relevant financial relationship(s) to disclose.

INTRODUCTION:
Colorectal Cancer (CRC) is the third most prevalent cancer worldwide, with incidence rates on the rise, especially among younger populations. Global current screening methods, such as the faecal immunochemical test (FIT), which rely on the presence of blood in stool, have demonstrated limited sensitivity for early-stage cancer and adenomas1. To address this limitation, our research aims to develop high-throughput ambient ionisation mass spectrometry (AIMS) to detect metabolites translating from colorectal cancer tissue through to the faeces. Using modified surface chemistry, we also aim to increase the detection sensitivity of these biomarkers in faecal samples.

METHODS:
Colorectal cancer tissue samples were obtained during surgery from patients undergoing colorectal resection at Imperial College NHS Trust hospitals. Tissue was sectioned to a thickness of 10 µm. Imaging was performed on a Waters Xevo QTOF G2S Mass spectrometer in the range of 50 to 1200 m/z. Mass spectrometry imaging data (MSI) were acquired in both positive and negative ionisation mode with a pixel size of 50 µm, at a rate of 250 µm/s with a sprayer angle of 75° 1mm from the inlet capillary. MSI data were analysed using in-house scripts.
Faecal samples were collected from the colorectal cancer clinics at Imperial College NHS Trust hospitals (REC: 14/EE/0024). Samples were collected from 10 CRC, 7 adenoma, and 15 healthy patients and faecal water was prepared and analysed directly using modified surfaces. LD-REIMS data was collected on a Waters Xevo QTOF G2S mass spectrometer in the range of 50 to 1200 m/z at a rate of 1 scan/s; an Opotek Q-switched optical parametric oscillator (OPO) laser source was used for aerosol generation. RP-UPLC-ESI-MS analysis of the same faecal water samples was performed by the National Phenome Centre. Data processing and analysis was performed using in-house scripts.

RESULTS:
Colorectal cancer tissue sections were H&E stained and assessed by an independent histopathologist to distinguish between healthy, adenoma, and cancerous regions of the tissues. Metabolite variations across these tissue types revealed elevated expression of very long-chain fatty acids (VLCFAs) in cancerous tissue compared to healthy tissue. Notably, nervonic acid (FA 24:1) was localised within cancerous regions. Additionally, other VLCFAs within the same metabolic pathway, such as oleic acid (FA 18:1) and lignoceric acid (FA 24:0), were also found at increased abundances in cancer tissue.
Faecal samples collected from right hemicolectomy patients were used to study the metabolite differences in faeces before, during, and after passing the tumour to assess metabolite transfer from tissue to faeces. Importantly, the absence of bowel preparation allowed for the direct collection of faeces from the bowel. Therefore, comparisons of faecal samples distal to the tumour could be made with faecal samples which have had direct contact with the tumour. The data showed a significant increase in nervonic acid levels from pre- to post-tumour, with a p-value of 0.0016, suggesting direct shedding of VLCFA from the tumour into the faeces.
Further analysis of a cohort of faecal samples collected from colorectal cancer clinics assessed the stability of the identified fatty acids through to excretion. Once again, nervonic acid was found at significantly higher levels in patients with colorectal cancer compared to the healthy cohort, with a p-value of 8.5e-7. Tentative annotation of these identified fatty acids was further supported by RP-UPLC-ESI-MS analysis of the faecal samples, with abundance following a similar trend in the UPLC-MS analysis.

CONCLUSION:
Our findings highlight the potential of very long-chain fatty acids (VLCFAs), particularly nervonic acid, as promising biomarkers for colorectal cancer, detectable in both tissue and faeces. The ability to track metabolite migration from tissue to faeces using ambient ionisation mass spectrometry (AIMS) not only underscores its diagnostic potential but also demonstrates the applicability of AIMS in clinical laboratories.

REFERENCES:
1. Niedermaier, T., Weigl, K., Hoffmeister, M. & Brenner, H. Diagnostic performance of flexible sigmoidoscopy combined with fecal immunochemical test in colorectal cancer screening: meta-analysis and modeling. Eur J Epidemiol 32, 481–493 (2017).