Membranous nephropathy associated with immunoglobulin G4-related disease successfully treated with obinutuzumab

Abstract

Immunoglobulin G4 (IgG4)-releated disease is typically associated with interstitial nephritis, but rare cases of idiopathic membranous nephropathy as a renal manifestation have been described. Obinutuzumab was successfully used in refractory membranous nephropathy, but evidence for the treatment of IgG4-related disease with obinutuzumab is lacking. We report one patient's case with membranous nephropathy associated with IgG4-related disease who was treated with obinutuzumab following an anaphylactic reaction to rituximab. Obinutuzumab treatment resulted in a sustained complete remission of membranous nephropathy and a decrease of IgG4 to the normal range. This case demonstrates that membranous nephropathy associated with IgG4-related disease can be treated successfully with obinutuzumab.

Keywords: B lymphocytes; IgG4-related disease; kidney disease; membranous nephropathy.

FIGURE 1:

Histopathologic evaluation and laboratory findings of our patient. Histopathologic evaluation of the kidney shows (a) perimembranous nephropathy in periodic acid–Schiff–stained kidney sections with (b) IgG, (c) IgG4 and (d) PLA-2R positivity. Representative pictures are shown. Magnification ×200. (e) IgG and (f) IgG4 staining of lymph nodes show massive infiltration of IgG4-positive plasma cells and an IgG4⁺:IgG⁺ plasma cell ratio >40%. Representative pictures are shown. Magnification ×100. (g) Urinary albumin:creatinine ratio and serum IgG4 levels over the course of the disease are shown. The therapy was started using a CNI and prednisolone, followed by the first rituximab dose (RTX I, 860 mg) and the second reduced dose (RTX II, 430 mg), which needed to be stopped due to an anaphylactic reaction. We then continued with steroid monotherapy slowly tapering the dosage. 1 g obinutuzumab (Obi) was given twice, on day 1 and 15.