Rituximab for Steroid-Dependent or Frequently Relapsing Idiopathic Nephrotic Syndrome in Adults: A Retrospective, Multicenter Study in Spain.

Background: Patients with difficult-to-treat idiopathic nephrotic syndrome (INS), steroid-dependent nephrotic syndrome (SDNS), or frequently relapsing nephrotic syndrome (FRNS) require long-term immunosuppressive therapy. Rituximab offers an alternative treatment for patients with disease that has not responded to multiple therapies.

Objective: Our objective was to determine the efficacy and safety of rituximab in adult patients with difficult-to-treat (SDNS or FRNS) INS.

Methods: We performed a retrospective multicenter study that included 50 adults with difficult-to-treat INS in six Spanish centers. All patients were treated with steroids in combination with another immunosuppressant: 28 patients received rituximab as the additional treatment (rituximab group), and the other 22 patients not treated with rituximab served as the control group.

Results: Of the patients treated with rituximab, 23 (82%) experienced complete remission, 20 (71%) had no relapses after receiving rituximab, and 13 (46%) did not receive any immunosuppressant. Of those in the control group, 14 (63%) experienced complete remission, including eight without immunosuppressants (29%). The rituximab group experienced highly significant reductions in total number of relapses per year (p < 0.001), proteinuria (p = 0.03), steroid doses (p = 0.002), and tacrolimus doses (p = 0.001). Mean follow-up after rituximab was 31 ± 26 months (range 8-86). The need for steroids and other immunosuppressants to achieve sustained remission was lower in the rituximab group than in the control group.

Conclusions: Rituximab treatment was safe and well tolerated. It effectively reduced the incidence of relapses and need for maintenance immunosuppressive therapy in adults with difficult-to-treat INS.