Efficacy and safety of iguratimod plus corticosteroid as bridge therapy in treating mild IgG4‐related diseases: A prospective clinical trial

AIM: The purpose of this study is to evaluate the therapeutic efficacy and safety of iguratimod plus corticosteroid as bridge therapy in the treatment of mild immunoglobulin G4‐related disease (IgG4‐RD). METHODS: Newly diagnosed IgG4‐RD patients, without internal organ involvement were enrolled. Patients were given one dose of diprospan, intramuscular injection, and iguratimod, 25 mg, twice daily, for 24 weeks and were followed up at 0, 12 and 24 weeks. Follow‐up indexes included IgG4‐RD responder index (IgG4‐RD RI), serology and imaging, plasma cytokines and adverse drug effect. Flow cytometry was performed for T, B cell subsets and plasma was collected for liquid chromatography mass spectrometry (LC‐MS)‐based metabolomic profiling and data processing. RESULTS: Thirty patients were enrolled. At week 24, 9 (30.0%) patients achieved complete response, 17 (56.7%) patients with partial response, and 4 (13.3%) patients had no response to treatment. IgG4‐RD RI, serum IgG and IgG4 levels decreased significantly at weeks 12 and 24 after treatment, as well as CD3+ CD8+ T cells, plasmablast/plasma cells and memory B cells. The LC‐MS based plasma metabolomic profiles revealed significant changes between untreated patients and healthy donors, which became much similar to normal states after treatment. CONCLUSION: Iguratimod plus corticosteroid as bridge therapy is effective for the treatment of mild IgG4‐RD, it can improve the clinical symptoms, reduce serum IgG and IgG4 levels, especially plasmablasts/plasma cells and memory B cells. In addition, the metabolite profiling became similar to normal controls after treatment.