Calprotectin (S100A8/9) as serum biomarker for clinical response in proof-of-concept trials in axial and peripheral spondyloarthritis
1 Department of Clinical Immunology and Rheumatology, Academic Medical Center/University of Amsterdam, Amsterdam, The Netherlands
2 Laboratory of Experimental Immunology, Academic Medical Center/University of Amsterdam, Amsterdam, The Netherlands
3 Department of Rheumatology and Clinical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
Arthritis Research & Therapy 2014, 16:413 doi:10.1186/s13075-014-0413-4Published: 19 August 2014
IntroductionBiomarkers complementing clinical evaluations may help to reduce the length and size of proof-of-concept (PoC) trials aimed to obtain quick ?go/no go? decisions in the clinical development of new treatments. We aimed to identify and validate serum biomarkers with a high sensitivity to change upon effective treatment in spondyloarthritis (SpA) PoC trials.MethodsThe candidate biomarkers high sensitive-C-reactive protein (hs-CRP), interleukin-6 (IL-6), pentraxin-3 (PTX-3), alpha-2-macroglobulin (alpha-2-MG), matrix metalloproteinase-3 (MMP-3), calprotectin, and vascular endothelial growth factor (VEGF) were determined by enzyme-linked immunosorbent assay in healthy controls (n?=?20) and SpA patients before and after 2?weeks of infliximab (n?=?18) or placebo (n?=?19) treatment in cohort 1. Clinical outcome was evaluated at week 12. Results were validated in ankylosing spondylitis (AS) with infliximab (cohort 2, n?=?21) and peripheral SpA with etanercept (cohort 3, n?=?20).ResultsSerum levels of calprotectin, hs-CRP, PTX-3, VEGF (all P?<?0.001) and MMP-3 (P?=?0.062), but not IL-6 and alpha-2-MG, were increased in SpA versus healthy controls. Treatment with infliximab, but not placebo, significantly decreased calprotectin (P?<?0.001) and hs-CRP (P?<?0.001) levels, with a similar trend for MMP-3 (P?=?0.063). The standardized response mean (SRM), which reflects the ability to detect changes over time, was high for calprotectin.(?1.26), good for hs-CRP (?0.96) and moderate for MMP-3 (?0.52). Calprotectin and hs-CRP, but not MMP-3, were good biomarkers for treatment response in axial and peripheral SpA as evaluated and confirmed in cohort 2 and 3 respectively.ConclusionsCalprotectin and hs-CRP are good serum biomarkers with high sensitivity to change upon effective treatment at the group level in small-scale, short term PoC trials in SpA.