Recurrent IgG4-related Tubulointerstitial Nephritis Successfully Treated With Obinutuzumab: A Case Report and Literature Review.

Currently, Immunoglobulin G4 (IgG4)-related disease is treated with glucocorticoids alone or in combination with other immunosuppressants. Although the initial response rate is substantial, the remission rate is suboptimal, and the recurrence rate following rituximab therapy remains high. Here, we report the first patient with IgG4-related tubulointerstitial nephritis who was treated with obinutuzumab after relapse, providing additional insights for future treatment strategies. This case demonstrates that the obinutuzumab induction and maintenance regimen in patients with IgG4-related tubulointerstitial nephritis can maintain prolonged B-cell depletion, rapidly and persistently reduce inflammation and serum IgG4 levels, and reverse functional impairment in some affected organs.