EFFECTIVENESS AND SAFETY OF BARICITINIB IN CHILDREN WITH ACTIVE JUVENILE IDIOPATHIC ARTHRITIS: A SINGLE-CENTER RETROSPECTIVE COHORT STUDY

Abstract

Baricitinib, a selective Janus kinase 1 and Janus kinase 2 (JAK1/JAK2) inhibitor, was approved by the European Medicines Agency (EMA) in 2023 for the treatment of juvenile idiopathic arthritis (JIA) in children aged 2 years and older. Data on its use in routine clinical practice at Russian pediatric centers remain scarce. Objective: To retrospectively assess the effectiveness and safety of baricitinib in patients with JIA treated at a Russian rheumatology center. Materials and Methods: We conducted a retrospective cohort study at Morozov Children’s City Clinical Hospital. The safety analysis included 41 patients, and the effectiveness analysis included 40 patients. Follow-up lasted up to 12 months, with a median duration of 5.5 months. The primary endpoint was the change in the clinical Juvenile Arthritis Disease Activity Score based on 10 joints (cJADAS10) after 3 months of treatment (visit M3). Assessments were performed at baseline (T0) and at 3 (M3) and 6 (M6) months. Statistical analysis included nonparametric tests for paired comparisons with adjustment for multiple hypothesis testing; confidence intervals for proportions were calculated using the Wilson method. Results: The cohort included 29 girls (71%) and 12 boys (29%). The median age at treatment initiation was 11.9 years [6.2–16.1]; total follow-up was 16.0 patient-years, with a median of 5.5 months [3.2–6.2]. The cJADAS10 decreased from 13.5 [9.2–19.0] at T0 to 8.0 [4.2–11.8] at M3 (n=38; median change, –5.0 [–8.0; –2.0]; p<0.001) and to 2.0 [1.0–10.0] at M6 (n=25; median change, −9.0 [–12.0; –4.0]; p<0.001). Clinically inactive disease was documented in 27 of 36 children (75%) at M3 and in 19 of 28 (68%) at M6. Infections (≥1 episode) occurred in 13 of 41 patients (32%; at least 24 events). No serious adverse events, herpes zoster, or adverse events of special interest were recorded (0/41). Conclusion: Baricitinib treatment was associated with a marked reduction in disease activity and achievement of inactive disease in most patients. No serious adverse events or adverse events of special interest were recorded during follow-up; infections were the most common adverse events. Baricitinib may be an effective and safe treatment option for children with active JIA, although these findings require confirmation in prospective controlled studies.