Biomarkers

Protein biomarkers in the rectal mucosa: a novel test for colorectal cancer? (2015)

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Type of publication:
Conference abstract

Author(s):
*Lacy-Colson J., Norwood M., Murray C., Booth J.

Citation:
Gut, June 2015, vol./is. 64/(A529-A530)

Abstract:
Introduction: Earlier detection of colorectal cancer is a clinical priority. Currently very high numbers of patients are referred for colonoscopy under the 2 week rule system, with a pick up rate for cancer of 1:20 or less putting a major strain on endoscopy units investigating large numbers of the worried well. The aim of this study was to assess the correlation of protein biomarkers captured from the rectal mucosa with the presence or absence of colorectal cancer. Method We conducted a case control study of 20 patients with colorectal cancer, and 20 controls. All patients had been referred to colorectal outpatients with potentially worrying symptoms; presence or absence of cancer was determined by colonoscopy or CT virtual colonoscopy. A novel sampling device, OriColTM, was employed to collect samples of rectal mucosa for biomarker analysis. The device incorporates a nitrile membrane which, following insertion into the unprepared rectum via a standard proctoscope, is inflated to make contact with the rectal mucosa for a period of 10 s. Upon deflation and retraction of the membrane, a preservation buffer is added to preserve the sample prior to analysis. Sampling can be performed in an outpatient setting in under 2 min and has been shown to be well tolerated in >2500 patients. The levels of various antibodies, haemoglobin and carcinoembryonic antigen were analysed using conventional ELISA techniques. Statistical analysis of the trial results was performed using the Wilcoxon test for non-parametric comparisons with two sided p values. The area under the receiver operating characteristic (ROC) curve for distinguishing between the two diagnostic groups, together with its confidence interval, was calculated for each biomarker. Logistic regression analyses were used to investigate the performance of different combinations of biomarkers. This study was conducted with appropriate research ethics committee approval. Results Univariate analyses identified five candidate predictive biomarkers for colorectal cancer. All combinations of two and three predictors were investigated using logistic regression. The best performing combination of biomarkers was haemoglobin and IgA. The area under the ROC curve for this best linear combination was 0.86. Conclusion We suggest that ELISA analysis protein biomarkers collected with the OriColTM device offers a potentially useful and cost-effective pre-colonoscopy screening tool in patients referred under the 2 week rule criteria. Data from this pilot study suggests that a sensitivity of >95% can be achieved while massively reducing the number of patients requiring urgent colonoscopy to exclude a diagnosis of cancer.

Link to full-text: http://gut.bmj.com/content/64/Suppl_1/A529.2.full.pdf+html

A novel sampling device for collecting mucocellular material from the unprepared rectum (2014)

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Type of publication:
Conference abstract

Author(s):
Booth J., *Lacy-Colson J., Norwood M., Murray C.

Citation:
Gut, June 2014, vol./is. 63/(A124-A125), 0017-5749 (June 2014) (also published in European Journal of Cancer, July 2014, vol./is. 50/(S240), 0959-8049 (July 2014))

Abstract:
Background: In vitro diagnostic tests are being developed to evaluate informative protein or DNA biomarkers in stool or blood samples. Stool samples are inconvenient to collect and handle, and may suffer from contamination that interferes with molecular assays. Blood samples may not be as informative early in the disease process. Studies have shown that significant numbers of exfoliated cells and their products are retained in a muco-cellular layer overlaying the colonic mucosa, but distinct from the stool, and that this material flows toward the rectum, where it can be captured for analysis. Materials and Methods: Origin Sciences (OS) has developed a novel sampling device that incorporates an inflatable nitrile membrane. Following insertion into the unprepared rectum via a standard proctoscope, the membrane is inflated to make contact with the rectal mucosa for 10 seconds. The membrane is then deflated and retracted into the device prior to removal from the patient. Upon retraction the sampled material is retained on the inverted membrane, which acts as a receptacle for the addition of buffer preserving the material for subsequent analysis. Results: The sampler has now been tested in over 2000 patients and healthy volunteers, and has shown excellent acceptability. Tests and in vitro experiments with monolayers of cultured human cells indicate that the membrane captures intact cells, which are easily washed off the membrane for further investigation. Detailed evaluation of the mucous-associated material captured by the device, in both normal and diseased states, shows it to be rich in protein and nucleic acids. Levels of soluble protein present in standard 3 mL capture buffer varied between 90 and 3000 mug/mL, with a mean of 710 mg/muL. OS has detected informative auto-antibodies of isotypes IgA, IgG, and IgM by ELISA in the protein component of these preparations. These preparations are also rich in nucleic acids; DNA was found at levels ranging from 0.5 to 21.9 mg/muL. This DNA appears to retain a high degree of integrity, since a number of informative genes have been detected by quantitative PCR. Conclusions: The sampling device represents a novel and minimally invasive tool for capturing biomarker-rich material from the unprepared rectum. With minimal contamination by stool, the material collected is readily analysable. In principle this device lends itself to point-of-care testing for a range of indications, including infectious and inflammatory diseases of the GI tract, in addition to malignancy.

Link to more details or full-text:
http://gut.bmj.com/content/63/Suppl_1/A124.2