Development of a chemiluminescence immunoassay for proGRP in human serum.

Progastrin-releasing peptide is a crucial serum biomarker for the diagnosis, differential diagnosis, therapeutic monitoring, and prognostic evaluation of small cell lung cancer. In this study, a double-antibody sandwich immunoassay for the biomarker was developed. Key factors in the method development were systematically investigated, including magnetic particle coating, conjugate labeling, concentrations of magnetic particles and conjugates, and serum sample volume. The established assay has a total analysis time of approximately 13 min, with a limit of blank of 3.53 pg/mL. The repeatability and within-laboratory precision coefficients of variation were less than 8%. Assay accuracy was unaffected by common endogenous interferents at pathological concentrations or by the presence of gastrin-releasing peptide in the serum. Additionally, thermal accelerated stability testing over 7 days confirmed the robust stability of the reagents. Method comparison further demonstrated that the clinical results obtained by the established method showed high consistency with those of the Roche assay, fully meeting the requirements for clinical application.