Therapeutic efficacy of upadacitinib in refractory juvenile idiopathic arthritis: a case report.

Background: Juvenile idiopathic arthritis (JIA) remains a clinical challenge when conventional and biological therapies fail. Case presentation: This report describes a case of highly refractory JIA and evaluates the efficacy of the Janus kinase (JAK) inhibitor upadacitinib, providing a potential therapeutic reference for difficult-to-treat pediatric autoimmune diseases. A 16-year-old female presented with a 3-year history of polyarticular swelling and pain that worsened over 1 month. Physical examination revealed extensive tenderness in the small joints of the hands, feet, and knees. Functional impairment was noted in the shoulder joints (restricted abduction and lifting) and wrist joints (limited flexion and extension). Laboratory results showed an erythrocyte sedimentation rate of 26 mm/h and a C-reactive protein level of 18.39 mg/L. Musculoskeletal ultrasound indicated grade 1 synovitis with effusion in the bilateral metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints, as well as both wrist joints. Effusion was also observed in the suprapatellar bursae of both knees. The patient's condition was classified as refractory, with prior failure of multiple lines of therapy, including conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), various biologic DMARDs (bDMARDs) (such as TNF, IL-6, and IL-1 inhibitors), and targeted synthetic DMARDs, such as tofacitinib. Following initiation of upadacitinib, the patient achieved marked clinical remission and improved joint mobility. Conclusions: Upadacitinib demonstrated potent efficacy in a pediatric patient with JIA who was nonresponsive to multiple bDMARDs and tofacitinib. These findings suggest that upadacitinib may be a viable salvage therapy for refractory JIA.