CPa9-HNE (NordicCPa9-HNE™)—The Serum Calprotectin

The CPa9-HNE (nordicCPa9-HNE™) biomarker provides a measure of true neutrophil activity by capturing the interplay between two specific key neutrophilic intracellular components; the antimicrobial protein calprotectin and the protease human neutrophil elastase (HNE).

Constant activation and recruitment of neutrophils is a common feature in IBD (Crohn’s disease and ulcerative colitis). Their infiltration into the intestinal tissue has been correlated to disease activity, where they induce mucosal damage through the release of neutrophil extracellular traps (NETosis). Therefore, measuring neutrophil activity using CPa9-HNE provides valuable insight into disease progression and inflammatory burden, potentially guiding the development and evaluation of novel therapeutic interventions, as further encouraged by the Letter of Support from the FDA.

The CPa9-HNE assay measures a specific calprotectin fragment, CPa9-HNE, that serves as a biomarker for activated neutrophils. While full-length calprotectin can be passively released by resting or inactive neutrophils, CPa9-HNE is released exclusively when neutrophils become activated, often in response to infection or inflammation. This specificity allows the assay to distinguish between baseline neutrophil presence and active inflammatory processes, making it a valuable tool for detecting active inflammation and monitoring immune response.

CPa9-HNE provides added clinical value over measuring the full-length calprotectin protein alone. In patients achieving remission with the anti-TNF therapy adalimumab, levels of CPa9-HNE show a continuous reduction from baseline through week 52, reflecting a sustained decrease in neutrophil activation. This reduction serves as a marker of effective therapeutic response, offering insight into both the extent and duration of inflammation control in patients undergoing treatment.