SERUM IL-37 AS AN EFFICIENT BIOMARKER OF DISEASE ACTIVITY IN PATIENTS WITH ANKYLOSING SPONDYLITIS: POST- HOC ANALYSIS OF PLANETAS STUDY

Abstract

Background IL-37 is an anti-inflammatory cytokine which belongs to IL-1 cytokine superfamily. Patients with ankylosing spondylitis (AS) also had a higher serum IL-37 concentration than controls, and were also associated with other inflammatory markers such as CRP, ESR, and BASDAI levels.1 However, the relationship between serum IL-37 and disease activity after anti-TNF treatment has not been reported.

Objectives To investigate the association of serum IL-37 level with disease activity in AS patients who were treated with infliximab.

Methods Patients were recruited from the PLANETAS study (NCT01220518). Patients with active AS were treated with CT-P13 or infliximab originator. The serum levels of IL-37 were measured at week 0 and week 30 with specific ELISA. Other demographic, laboratory and clinical variables were evaluated simultaneously.

Results Fifty patients with active AS (BASDAI >4) were analysed. The median age of patients was 40 years old [Interquartile range (IQR), 33.8–49.5), and the median BASDAI score was 6.7 (IQR 5.3–7.9). Compared to baseline, all measured clinical and laboratory parameters and serum IL-37 were significantly reduced. There was a statistically significant correlation between IL-37 and CRP, BASDAI at baseline, but not at week 30. Additionally, the differences (Δ) of parameters at baseline and at week 30 were assessed on their associations with other disease activity parameters. Delta IL-37 was significantly correlated with ΔCRP, ΔBASFI and ΔBASDAI. The ROC curves of serum biomarkers for ASAS 20 achievement revealed that AUC value for ΔIL-37 (AUC=0.74) was similar with ΔESR (AUC=0.71, p=0.64) and superior than ΔCRP (AUC=0.54, p<0.01). AUC value for ΔIL-37 of ASAS 40 achievement was 0.66, which was similar with ΔESR (AUC=0.60, p=0.38) and superior than ΔCRP (0.46, p<0.01).