B-067 Performance Assessment of a Newly Developed Lateral Flow Assay for the Quantification of Faecal Pancreatic Elastase

Abstract

Abstract Background Pancreatic exocrine insufficiency (PEI) can be defined as an insufficient secretion of pancreatic enzymes and bicarbonate to maintain a normal digestion (1). PEI is associated to fat malabsorption, weight loss and malnutrition-related complications. Due to its important role in the digestive process, as a proteolytic enzyme and the high stability of the enzyme during intestinal transit, fecal pancreatic elastase (fPELA) is an ideal biomarker for the assessment of pancreatic function in patients suffering from PEI. The aim of this work was to develop and optimize a new rapid test for the quantification of fPELA. Methods A quantitative lateral flow assay was designed for the selective measurement of elastase antigen concentrations from stool extracts. The BÜHLMANN Quantum Blue® fPELA is a sandwich immunoassay. A monoclonal detection antibody is conjugated to gold nanoparticles. Elastase present in the sample binds to this gold conjugate. A polyclonal capture antibody, highly specific for elastase, is immobilized on the analytical membrane and captures the complex of elastase bound to the anti-elastase gold conjugate, resulting in a coloring of the test line. The remaining free anti-elastase gold conjugate binds to the control line. The signal intensities of the test line and the control line are measured quantitatively by the Quantum Blue® Reader. Pancreatic elastase is quantified in extracts of human stool samples collected with the BÜHLMANN CALEX® Cap device. Several analytical studies, such as sensitivity, linearity, High Dose Hook Effect (HDHE), were performed during optimization phase to assess the performance of the assay. Moreover, a method comparison with the commercially available high throughput turbidimetric BÜHLMANN fPELA® turbo assay was also performed. Results Both analytical and clinical performance were evaluated. Preliminary results of the assay performance were obtained during the optimization phase. Analytical sensitivity was determined as 12.8 µg/g LoB, 16.6 µg/g LoD and 17.2 µg/g LoQ. The linearity evaluation revealed a linear range of 10 to 472 µg/g. No HDHE was observed in native samples up to 4000 µg/g. Method comparison of the new lateral flow assay with BÜHLMANN fPELA® turbo assay, with 80 clinical samples, revealed good analytical agreement with a slope of 1.04 (Passing-Bablok) and a bias at cutoff (200 µg/g) of 5.6%. Relative bias (Bland-Altman) of the two assays was 6.9%. Considering the turbidimetric assay as the reference method, the sensitivity and specificity were 92% and 83%, respectively. Conclusion The newly developed quantitative lateral flow assay, BÜHLMANN Quantum Blue® fPELA, is an accurate, non-invasive and rapid test to determine fPELA levels in fecal extracts. The lateral flow assay is an attractive alternative to ELISA with a turn-around time of only 15 minutes enabling patients’ management in a more patient near clinical environment.