Extracellular matrix turnover biomarkers reflect pharmacodynamic effects and treatment response of adalimumab in patients with axial spondyloarthritis-results from two randomized controlled trials

To investigate if extracellular matrix (ECM) blood-based biomarkers reflect the pharmacodynamic effect and response to TNF-α inhibitor therapy (adalimumab, ADA), in patients with axial spondyloarthritis (axSpA). We investigated ECM biomarkers in two randomized, double-blind, placebo-controlled trials of axSpA patients (DANISH and ASIM, n = 52 and n = 49, respectively) receiving ADA 40 mg or placebo every other week for 12 and 6 weeks, respectively, and thereafter ADA to week 48. Serum concentrations of degraded type I (C1M), II (C2M, T2CM), III (C3M), IV (C4M), VI (C6M), type X (C10C) collagen; metabolite of C-reactive protein (CRPM), prolargin (PROM), citrullinated vimentin (VICM), calprotectin (CPa9-HNE); and formation of type II (PRO‑C2), III (PRO‑C3), and VI (PRO‑C6) turnover of type IV collagen (PRO-C4) were measured at baseline and weeks 6 or 12, 24, and 48. The pharmacodynamic effect and treatment response to ADA was evaluated by linear mixed models, and correlations between biomarkers and clinical scores were assessed by Spearman's correlation. C1M, C3M, C4M, C6M, CRP, PRO-C4, and CPa9-HNE levels declined after 6 or 12 weeks in patients receiving ADA compared to placebo (all p