Serum biomarkers associated with baricitinib response in patients with juvenile idiopathic arthritis: a post-hoc analysis of the phase 3 JUVE-BASIS trial

Background
Baricitinib has previously been shown to improve clinical response in patients with juvenile idiopathic arthritis (JIA) in the JUVE-BASIS trial. In this post-hoc analysis we aimed to identify whether pharmacodynamic changes in serum biomarkers in response to baricitinib treatment could help reaffirm the clinical utility of baricitinib in patients with JIA.
Methods
JUVE-BASIS was a randomised, double-blind, placebo-controlled, withdrawal, efficacy, safety, phase 3 trial, done in 75 centres in 20 countries. Eligible patients were children and adolescents (aged 2 to <18 years), with polyarticular JIA (positive or negative for rheumatoid factor), extended oligoarticular JIA, enthesitis-related arthritis, or juvenile psoriatic arthritis, as per the International League of Associations for Rheumatology criteria and an inadequate response (≥12 weeks) or intolerance to one or more conventional synthetic or biological disease-modifying antirheumatic drugs (DMARDs). Here we report post-hoc analyses of serum samples from patients who received open-label baricitinib in the 12-week lead-in period of the JUVE-BASIS trial. Samples were assessed using an Olink Explore 3072 panel at baseline and week 12. Baricitinib-mediated pharmacodynamic changes in serum protein markers were measured as changes from baseline to week 12 derived from a mixed model with repeated measurement. Pearson correlations of the change in serum biomarkers and clinical disease activity (JADAS-27 scores) comparing baseline with week 12 were examined. Proportional changes in biomarkers were classified into three response subsets based on JIA-ACR response rates: JIA-ACR <30% (non-responders), JIA-ACR 30–70% (responders), and JIA-ACR 70–100% (super-responders). People with lived experience of JIA were not involved in the design or conduct of this study. The JUVE-BASIS trial was registered with ClinicalTrials.gov, NCT03773978, and is completed.FindingsBetween Dec 17, 2018 and March 3, 2021, 220 patients were enrolled in JUVE-BASIS and received at least one dose of baricitinib in the open-label lead-in period. In this post-hoc analysis, 168 serum samples from 84 patients were analysed: 67 (80%) of 84 patients were female, 17 (20%) were male, 67 (80%) were White and the mean age was 14 years (SD 2). 10 (12%) of 84 were non-responders, 27 (32%) were responders, and 47 (56%) were super-responders based on clinical response. Several serum biomarkers showed significant changes following 12 weeks of baricitinib treatment for all patients with higher magnitude changes seen in responders and super-responders. Changes in biomarkers associated with macrophage activation (CCL7, CCL18, and IL-6) and regulation of matrix composition (matrix metalloproteinase-3) were positively correlated with clinical response.InterpretationTo our knowledge, this is the first study measuring serum protein markers in the context of an intervention trial with baricitinib in patients with JIA. Associated biomarker changes with clinical response might allow physicians to potentially identify patients who are most likely to be responsive to baricitinib treatment.