Full Papers

Serum ferritin predicts response to tocilizumab in glucocorticoid-resistant adult-onset Still's disease: a prospective real-world cohort study

D. Ma¹, H. Yao², X. Zhang³, Y. Wang⁴, M. Shao⁵, H. Zhu⁶, Y. Gan⁷, X. Sun⁸, Y. Yang⁹, Y. An¹⁰, Y. Jia¹¹

Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing; and Department of Rheumatology and Immunology, Peking University Shougang Hospital, Beijing, China.
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China. yaohaihong@pku.edu.cn
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China.
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China.
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China.
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China.
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China.
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China.
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China.
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China.
Department of Rheumatology and Immunology, Peking University People’s Hospital, Beijing, China. jiayuan1023@bjmu.edu.cn

CER19705
Full Papers

Received: 19/01/2026
Accepted : 28/04/2026
In Press: 22/10/2026

Abstract

OBJECTIVES:
To evaluate the real-world effectiveness and safety of tocilizumab (TCZ) in glucocorticoid (GC)-resistant adult-onset Still’s disease (AOSD) and explore predictors of clinical response.
METHODS:
This prospective, single-centre cohort study enrolled consecutive eligible patients with GC-resistant AOSD who initiated intravenous TCZ (4-8 mg/kg every four weeks) between June 2021 and June 2024. The primary outcome was clinical remission at 12 months per 2024 EULAR/PReS criteria (clinically inactive disease [CID] lasting ≥6 months). Secondary outcomes included CID rate at 6 months, laboratory and clinical activity scores, GC dose reduction, TCZ retention, and safety.
RESULTS:
Forty patients (median age 35.5 years; 80% female) were included. Clinical remission at 12 months was 55.0% (22/40); CID at 6 months was 62.5% (25/40). Significant improvements were observed in C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), serum ferritin (SF), and Pouchot scores (all p<0.001). Median daily prednisone dose decreased by 91%, from 50.0 mg to 4.4 mg (p<0.001). Baseline SF levels ≥ 2500 μg/L were independently associated with lower remission rates (adjusted odds ratio 0.19, 95% CI 0.04 - 0.94; p=0.042) and higher GC requirements at 12 months (β=5.55, 95% CI 1.16 - 9.94; p=0.015). The 12-month TCZ retention rate was 65.0%. Serious adverse events included macrophage activation syndrome (MAS, 7.5%) and lymphoma (2.5%).
CONCLUSIONS:
TCZ is effective and steroid-sparing in GC-resistant AOSD. Baseline hyperferritinaemia (SF ≥2500 μg/L) is a potential biomarker for poorer outcomes, suggesting a need for tailored management.