A-030 Innovative Design and Evaluation of a BNP Assay with Enhanced Sample Stability

Abstract Background Natriuretic peptides (NPs), including B-type NP (BNP) and N-terminal-proBNP (NT-proBNP), are widely used as cardiac function biomarkers, reflecting cardiac stretching. Both BNP and NT-proBNP measurements are globally accepted and used in clinical practice for the diagnosis of acute and chronic heart failure (HF), risk stratification, and monitoring therapeutic response. Although BNP and NT-proBNP have similar physiological values, they still differ in terms of clinical and laboratory applications. For example, BNP is less susceptible to renal function compared with NT-proBNP, yet it is highly unstable that can be rapidly digested, losing its immunologic activity in blood. Conventional sandwich BNP immunoassays use two antibodies targeting two different epitopes. Longer distances between epitopes increase the probability of proteolytic degradation. Therefore, specifically designing an antibody pair combination that targets the epitope without enzymatic degradation risk is highly valuable for laboratory practice. Methods The new BNP assay was designed based on the SES-BNPTM (Single Epitope Sandwich). Firstly, the stability of BNP molecules in both blood-based matrix and synthetic-based matrix was evaluated. Secondly, sample stability with different patient plasma samples was evaluated under different temperature conditions. Thirdly, a comprehensive evaluation of analytical performance of this new BNP assay was conducted, including the sensitivity (LoB, LoD, LoQ), specificity, precision, etc. Results Different forms of BNP molecules could stay stable under room temperature within eight hours or under 2-8? within 24 hours. Compared with commercial BNP assays, sample stability for plasma samples from different patients increased from four to eight hours under room temperature and from 12 to 24 hours under 2-8C. Furthermore, the new BNP assay demonstrated excellent analytical sensitivity, where the LOB, LOD, LOQ are 1.00, 2.00, 3.00 pg/mL, respectively. Total imprecision near the threshold of non-CHF population (100 ng/L) was < 5%. No cross-reactivity or interference from endogenous interferents was observed. Conclusion By combining with SES-BNPTM, a new BNP assay was developed to improve sample stability during storage. Stability of BNP molecules in both plasma matrix and in synthetic buffer matrix increased, and would be more convenient during laboratory practice. Through a comprehensive evaluation, this new BNP assay was demonstrated to be highly sensitive, specific and with high precision.