Efficacy of tocilizumab in conventional treatment-refractory adult-onset Still's disease: multicenter retrospective open-label study of thirty-four patients.

Objective: Adult-onset Still's disease (AOSD) is frequently refractory to standard therapy. Tocilizumab (TCZ) has demonstrated efficacy in single cases and in small series of patients with AOSD. The aim of this multicenter study was to assess the efficacy of TCZ in patients with AOSD refractory to conventional treatment.

Methods: This was a retrospective open-label study of TCZ treatment in 34 patients with AOSD who had experienced an inadequate response to corticosteroids and at least 1 standard synthetic immunosuppressive drug and also, in many cases, biologic agents.

Results: The mean ± SD age of the patients (8 men and 26 women) was 38.7 ± 16.1 years. The median duration of AOSD before TCZ was initiated was 4.2 years (interquartile range [IQR] 1-9 years). The initial dosages of intravenous TCZ were 8 mg/kg every 4 weeks in 22 patients, 4 mg/kg every 4 weeks in 2 patients, and 8 mg/kg every 2 weeks in 10 patients. TCZ treatment resulted in rapid and maintained improvement in both clinical and laboratory parameters. After 1 year of TCZ therapy, the incidence of joint manifestations had decreased from 97.1% at baseline to 32.4%, the incidence of both cutaneous manifestations and fever had decreased from 58.8% to 5.9%, and the incidence of lymphadenopathy had decreased from 29.4% to 0%. A dramatic reduction in laboratory markers of inflammation, including the C-reactive protein level, the erythrocyte sedimentation rate, and the ferritin level, was achieved. The median dosage of prednisone was also reduced, from 13.8 mg/day (IQR 5-45) at the initiation of TCZ to 2.5 mg/day (IQR 0-30) at 12 months. After a median followup of 19 months (IQR 12-31 months), only 2 patients required permanent discontinuation of TCZ therapy because of severe infections.

Conclusion: TCZ treatment was associated with rapid and maintained clinical and laboratory improvement in patients with AOSD refractory to standard treatment. However, joint manifestations seem to be more refractory to treatment compared with systemic manifestations.