Novel antibody biomarkers in early axial spondyloarthritis

Axial spondyloarthritis (axSpA) is a chronic immune-mediated rheumatic disease, predominantly characterized by inflammation of the sacroiliac joints and the spine. At present, it is challenging to distinguish axSpA patients from persons with chronic low back pain (CLBP) at an early stage, as diagnostic criteria for axSpA are lacking. In addition, no appropriate serological test is available resulting in a diagnostic delay of 5-10 years. Emerging evidence supports the involvement of autoantibodies or antibodies against self-proteins in axSpA1. In order to identify novel antibody biomarkers in axSpA patients, we recently screened an axSpA cDNA phage display library for reactivity with immunoglobulin G (IgG) antibodies in plasma of early axSpA patients. This resulted in 9 novel Hasselt University (UH) antibody biomarkers for axSpA.

The aim of this study was to determine the diagnostic potential of the 9 UH antibody biomarkers in axSpA patients and controls from 2 independent cohorts.

Using ELISA, presence of the UH antibodies was determined in plasma of 76 early axSpA patients, 75 CLBP patients, 60 rheumatoid arthritis patients (RA) and 94 healthy controls (HC) from the UH cohort. Antibody reactivity was further validated in 174 patients from the Leuven Spondyloarthritis (Biologics) Cohort ((Bio)SPAR), including 79 early axSpA patients.

The 3 UH antibodies with the highest potential to distinguish axSpA patients from persons with CLBP were combined into a panel with a sensitivity of 14% and a corresponding specificity of 95% in persons with CLBP. Combined with the presence of inflammatory back pain, and the currently used laboratory markers human leukocyte antigen B27 (HLA-B27) and C-reactive protein (CRP), the 3 UH antibody biomarkers increase the probability of correct axSpA diagnosis from 79% to 91%.

With a compound annual growth rate (CAGR) of 7% for the therapeutic market, better and earlier diagnosis is key. Using our biomarkers, axSpA patients can be diagnosed better and earlier, resulting in earlier and correct treatment.

1. Quaden, D.H., et al., Autoimmun Rev, 2016.

Authors

Quaden D. (1), Vandormael P. (1), Ruytinx P. (1), Geusens P. (1,2), Vanhoof J. (2), de Vlam K. (3) and Somers V. (1)

Organisations

1 Department of Immunology and Infection, Biomedical Research Institute, Hasselt University, Hasselt, Belgium; 2 ReumaClinic, Genk, Belgium; 3 Division of Rheumatology, University Hospitals Leuven, Belgium

Presenting author

Pieter Ruytinx, Postdoctoral researcher , Hasselt University
pieter.ruytinx@uhasselt.be
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