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IL-6 as a therapeutic target in systemic-onset juvenile idiopathic arthritis


To investigate the safety and efficacy of a recombinant human anti-IL-6R monoclonal antibody (MRA) for children with systemic-onset juvenile idiopathic arthritis (So-JIA), a long-term administration of MRA was performed in three children with So-JIA.

Case report

Two boys and one girl with recurrent spiking fever, rash, and arthritis diagnosed as So-JIA (case 1, 7 years old; case 2, 8 years old; case 3, 13 years old) have been treated for 2.6 years, 2.5 years, and 1.9 years, respectively, with MRA after long-term treatment with prednisone and cyclosporin A, being complicated with macrophage activation syndrome during the course of the disease, and resulting in short stature, obesity and destruction of vertebrae. Serum levels of C-reactive protein were persistently high, The white blood cell count was over 15,000/μl with marked neutrophilia, and increased levels of IL-6 were detected. Intravenous administration of MRA was initiated, and prompt responses were obtained in both clinical and laboratory findings. Before accumulation of MRA in serum, fluctuations of C-reactive protein, the erythrocyte sedimentation rate and serum amyloid A levels were observed, but the clinical status of spiking fever, rash, and arthritis became stable. MRA was administered once every other week, and therapeutic effects were persisted during the observation period in all three cases. Around 100 days after the initiation of therapy, the white blood cell count was decreased to a normal number, and they started to grow in height (+18 cm, +13 cm, and +11 cm, respectively). Cyclosporin A was discontinued, and prednisone was tapered and ceased. Increased bone density was demonstrated, and an uptake of the marker isotope in an epiphyseal plate by Gascintigram gradually emerged, suggesting that IL-6 or IL-6/sIL-6R complexes had previously interrupted the bone growth at epiphysis. Three episodes of infection were clearly assessed by increased serum IL-6 levels. JIA core set and C-HAQ scores were remarkably improved. No definite findings of tuberculosis was determined.


For patients with So-JIA, administration of MRA dramatically improved inflammatory disease within 1 week, which indicated a pathogenic role of serum IL-6 and IL-6/sIL-6R complexes in So-JIA. This demonstrated MRA to be the first-line drug for the treatment of the disease.

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Yokota, S., Miyamae, T., Imagawa, T. et al. IL-6 as a therapeutic target in systemic-onset juvenile idiopathic arthritis. Arthritis Res Ther 5 (Suppl 3), 70 (2003).

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