Utilizing IgG Autoantibodies As Biomarkers In IgA Nephropathy

Abstract IgA nephropathy (IgAN) is the most common primary glomerulonephritis and an important cause of kidney failure. It is a mesangioproliferative glomerular disease defined by characteristic IgA1 mesangial deposits. These mesangial deposits likely originate from circulating immune complexes that contain IgA1 with Galactose (Gal)-deficient O-glycans (Gd-IgA1) that are bound by IgG autoantibodies. The pathogenesis model describing IgAN as an autoimmune disease was based on the discovery of IgG autoantibodies that bind Gd-IgA1 in the laboratory of Dr. Jan Novak at the University of Alabama at Birmingham (UAB). As part of these studies, Dr. Novak's laboratory developed assays for the detection and quantitative assessment of both Gd-IgA1 and IgG autoantibodies. The use of these assays for analysis of serum samples from several cohorts of IgAN patients has been published; both the Gd-IgA1 assay and the IgG autoantibody (IgG-AA) assay have potential as markers for preclinical detection of IgAN, prediction of outcome, and monitoring the response to therapy. The established pathogenesis model of IgAN enabled pharmaceutical industry to start developing and testing treatment for the disease. However, only secondary markers (e.g., proteinuria and estimated glomerular filtration rate [eGFR]) are currently used as the endpoints, adding to the time and cost of clinical trials. Thus, clinical-grade tests that assess primary causative markers are urgently needed. To address this requisite, we have licensed the intellectual property from UAB that surrounds the IgAN assays developed in Dr. Novak's laboratory. In Phase I, we transferred the IgG-AA assay to a contract research organization laboratory setting to perform standardization of the protocol, fully characterize the components of the assay, and perform a detailed qualification study on its performance as an initial step in the commercialization process. In Phase II, we will complete the development of the IgAN IgG-AA test, including development of serum controls, reagent sourcing, large-scale printing of ELISA plates, and standardized assay instructions for use by partner and/or Clinical Laboratory Improvement Amendments (CLIA)-certified laboratories. We will perform a series of internal and external validation studies with key opinion leaders and other accessible bio-repositories. By the end of Phase II, we will be ready to introduce our IgAN IgG-AA test into the clinic through CLIA lab partnerships.