Relevance of circulating Semaphorin 4A for rheumatoid arthritis progression and response to treatment

Abstract Background: The lack of validated tools to predict rheumatoid arthritis (RA) disease course warrants the development of new reliable biomarkers. We have previously detected increased semaphorin 4A (SEMA4A) expression in endothelial cells, synovial tissue, and serum of patients with RA. In addition, SEMA4A serum levels correlated with multiple clinical, biological, and power doppler ultrasound markers of disease activity. Our aim was to evaluate circulating SEMA4A for the prediction of outcomes in patients with RA. Methods: A first cohort included between May 2016 and February 2018 101 consecutive RA patients followed up on an annual basis until August 2021. Baseline SEMA4A concentrations were analyzed according to disease progression defined for the purpose of this study by the occurrence of patient-reported flares and initiation or change of targeted therapy. A second cohort included 40 consecutive RA patients who initiated new therapy because of insufficient disease control. The course of SEMA4A levels was studied between baseline and month 3 according to treatment response. Results: During a follow-up period of 41±15 months, disease progression occurred in 26/101 patients in the first cohort. Increased baseline SEMA4A levels were identified as an independent predictor of disease progression (hazard ratio, HR: 2.71, 95%CI 1.14-6.43). The highest predictive value of disease progression was obtained with the combination of increased circulating SEMA4A and/or DAS28-CRP>3.2 and/or synovial hyperemia on doppler ultrasound (HR: 10.42, 95%CI 1.41-76.94). SEMA4A was also predictive of disease progression in patients with a DAS28 <3.2 at baseline.In the second cohort, baseline SEMA4A levels were significantly higher in patients who further experienced none or moderate response, and SEMA4A concentrations were markedly decreased in the group of patients with good clinical response as compared to non-responders. Conclusion: circulating SEMA4A appears as an appealing biomarker in RA with ability to predict disease progression, and with association with response to therapy.