Validation of APF as a Urinary Biomarker for Interstitial Cystitis

The purpose of this study is to develop and characterize a surface plasmon resonance (SPR)- based assay that can specifically detect binding of APF to its cellular receptor, cytoskeleton associated protein 4 (CKAP4), immobilized on a sensor chip surface and to test the ability of this SPR-based assay to discriminate and measure the concentration of APF in urine from well-defined IC patients vs. age-matched, asymptomatic controls. In the first year of study, we completed all of the pre-clinical study components for Aim 2 and received all of the necessary regulatory approvals. The infrastructure for the study was established, including hiring relevant personnel as well as establishing SOPs and procuring supplies to ensure consistency across sites. Patient recruitment has begun and is on track. Considerable progress has been made toward the development, characterization, and eventual testing of clinical samples by the SPR assay. The focus in year one has been on development of the SPR assay using CKAP4 as a biosensor to detect APF. Our results demonstrate that we have successfully optimized rCKAP4 activity and immobilization with sufficient binding efficiency to detect and quantitate APF in a purified system. A parallel approach using an APF mAb as a biosensor was pursued to enhance sensitivity of the assay; it offers an alternate strategy to specifically measure APF in urine with the goal of developing a non-invasive, point-of-care diagnostic test for IC. The original document contains color images.