A-347 MMP-7 as an effective biomarker for ruling out biliary atresia

Abstract

The nephrology clinical lab at Cincinnati Children’s Hospital Medical Center has recently validated a diagnostic test to quantify matrix metalloproteinase-7 (MMP-7) in human serum/plasma. MMP-7 also known as uterine metalloproteinase is an enzyme that is key in the breakdown of extracellular macromolecules and has shown promise as a biomarker for the detection of several pathologies. In infants, MMP-7 is has been demonstrated as a potential biomarker for biliary atresia (BA). BA is a liver disorder occurring in babies where bile ducts become blocked and prevent appropriate excretion from the liver. BA must be treated with a hepatoportoenterostomy (Kasai procedure) to fix the blockage. Early detection and surgery have been correlated with improved clinical outcomes and longer life of their natural liver. Currently, biopsy is the gold standard for detection of BA. MMP-7 offers a non-invasive alternative to rule out BA when evaluated in a high-risk patient population. Validation was completed on the fully automated DZ-Lite MMP-7 chemiluminescent immunoassay (CLIA) kit on the Diazyme DZ-Lite 3000 Plus for determination of MMP-7 concentration. This kit uses an ABEI labeled anti-MMP-7 polyclonal antibody and magnetic microbeads coated with anti-MMP-7 monoclonal antibody for capturing. Specimens are mixed with the capturing and detecting reagents to form a sandwich complex at 37 ° C. After sedimentation, the sample is washed to remove unbound substances. Starter reagents containing diluted NaOH and H2O2 are added and begin the flash chemiluminescent reaction. The light signal produced is directly proportional to the concentration of MMP-7 in the sample. Statistical analysis was performed in EP evaluator. All performance metrics were evaluated against a total allowable error of 4 ng/mL or 20 %. The analytical measuring range was determined to be 0.4 ng/mL to 26.4 ng/mL. Age dependent reference ranges were determined from peer-reviewed publication or manufacturer claim, and each range was verified by assaying normal serum samples. The normal MMP-7 concentration range for ages 0-30 days was 4.6-23.8 ng/mL based on 36 samples tested, for 31-150 days the normal range was determined to 3.4-14.3 ng/mL based on 22 samples, and for =151 days the normal ranges was 0.2-5.4 ng/mL based on 116 samples. The cutoff for BA was determined from an ROC analysis using 8 confirmed positive BA cases obtained via the Kasai biopsy procedure. MMP-7 concentrations below the established cutoff of 28.8 ng/mL for the age range between 0-30 days and MMP-7 concentrations under the cutoff of 18.5 ng/mL for ages between 30-150 days effectively ruled out BA. MMP-7 is an effective screening test for BA in newborns and infants. Having an automated, clinically validated CLIA kit available as a screening test allows for an efficient, non-invasive and cost-effective methodology to rule out BA.