Improved clinical outcomes of tocilizumab versus cyclophosphamide for IgG4-related disease: insights from a prospective IgG4-related disease registry.

Objective To compare the clinical outcomes of patients with active immunoglobulin G (IgG) 4 related disease (IgG4-RD) receiving tocilizumab versus those receiving cyclophosphamide (CYC). Methods This IgG4-RD registry study was a prospective cohort study conducted among patients with active IgG4-RD hospitalized at Zhongshan Hospital, Fudan University. Patients who were treated with tocilizumab or CYC along with glucocorticoids (GCs) were enrolled. All participants were followed up at the hospital clinic at 3 and 6 months after discharge. Primary clinical outcomes were measured via the IgG4-RD responder index (RI), complete response (CR), and partial response (PR), as well as side effects. Results From January 2015 to June 2020, 29 patients enrolled. Fourteen and 15 patients were treated with tocilizumab and CYC, respectively. At the 6-month follow-up, disease activity parameters including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), IgG4, and IgG4-RD RI, decreased significantly in both groups. At 6 months, tocilizumab demonstrated its superiority, with 50% of patients achieving CR in the Tocilizumab group versus 20% in the CYC group. However, no statistical significance was identified (p = 0.128). The GC dosage at 6 months was significantly lower in the tocilizumab group than in the CYC group [10 (9.4-15) mg/d versus 15 (15-15) mg/d, p = 0.025]. In the CYC group, two patients experienced lumbar vertebral compression fractures related to GCs. Other patients in both groups showed mild adverse effects. Conclusions Tocilizumab could be a better steroid-sparing agent, with a comparable curative effect and tolerance, than CYC, in the treatment of IgG4-RD.