Lateral flow immunoassay detection of soluble AXL for pancreatic ductal adenocarcinoma diagnosis.

Pancreatic ductal adenocarcinoma (PDAC) ranks as the third leading cause of cancer-related death worldwide. Its high mortality is largely due to the absence of sensitive and specific biomarkers for early detection, as most patients are diagnosed at advanced stages when curative surgery is no longer feasible. Soluble AXL (sAXL), a cleaved form of the AXL receptor tyrosine kinase, has recently emerged as a promising circulating biomarker for PDAC. In this study, we developed and optimized a quantitative colorimetric lateral flow immunoassay (LFIA) employing anti-biotin gold nanoparticle conjugates for sAXL detection in plasma samples. A systematic evaluation of immunoreagents, antibody concentrations, buffer composition, and membrane type improved assay sensitivity, reproducibility, and signal clarity while minimizing background noise. Clinical evaluation demonstrated that the LFIA accurately discriminated PDAC patients from healthy controls, consistent with elevated plasma sAXL levels in PDAC. LFIA measurements were validated against enzyme-linked immunosorbent assay (ELISA), demonstrating statistical significance and confirming diagnostic relevance. The assay's portability, rapid readout, and minimal equipment requirements support its potential as a point-of-care diagnostic tool (POCT). This work represents the first application of a quantitative LFIA for sAXL detection in plasma. The method provides a rapid, cost-effective, and accessible approach for PDAC detection, with potential to improve early diagnosis and patient outcomes. Future studies will focus on expanding the patient cohort and further improving system performance to enhance sensitivity and clinical applicability.