#2101 Beyond corticosteroids: rituximab in managing minimal change disease and glucocorticoid-related toxicity
Authors: Henriques Andreia Dos Santos , Venda João , Ferreira Emanuel , Escada Luis , Oliveira Nuno , Alves Rui 
Published: May 2024

Abstract

Background and Aims
Minimal Change Disease (MCD) is the primary cause of Nephrotic Syndrome in children, accounting for 10 to 20% of cases in adults. Glucocorticoids (GC) remain the cornerstone of treatment. Despite a positive response in the majority of patients, up to 25% experience frequent relapses, and up to 30% are GC-dependent, exposing them to significant GC-related toxicity. Rituximab has been increasingly used in these patients, although 2021 KDIGO guidelines still points to cyclophosphamide as the preferred second-line therapy. This study aims to describe a single-centre experience with RTX, examining its effectiveness and assessing its potential to reduce GC exposure.

Method
A retrospective cohort study was conducted on 19 patients with MCD who were considered for RTX at adult age at a tertiary hospital centre between 2015 and 2023. Patients who refused treatment, those with MCD associated with other glomerular diseases, and those with less than 6 months of follow-up post-RTX were excluded from the study.

Results
Twelve patients met the inclusion criteria, including 5 diagnosed before the age of 18. The mean age at RTX initiation was 38.8 ± 14.8 years, with 75% being male. The median MCD duration pre-RTX was 140.5 [18.8–353.5] months, and the median follow-up post-RTX was 18.0 [12.5–41] months. All patients had preserved renal function and exhibited GC-dependency and/or frequent relapses, with 8 patients having received prior cyclophosphamide and/or cyclosporine A (CsA) treatment.
At RTX initiation, all patients were on GC therapy (median 11.1 [10–50] mg/day), with 4 also on CsA. 10 patients were in complete remission, while 2 were in a relapse phase, subsequently achieving complete remission. Various induction regimens were employed: 6 patients received 1000 mg of RTX twice within 2 weeks, 1 received a single dose of 1000 mg, and 5 received a single dose of 500 mg. Out of the 12 patients, 5 did not receive RTX maintenance administrations, while 6 received 500 mg of RTX every 6 to 9 months and 1 patient received 1000 mg every 6 months. Only one adverse event was reported, one uncomplicated upper respiratory tract infection.
Regardless of the induction regimen, all patients maintained a sustained response with complete remission for the following 6 months. All the 7 patients who underwent RTX maintenance did not experience disease relapse, although 2 continued GC therapy (one due to an associated autoimmune disease). Among the 5 patients who did not undergo RTX maintenance, 3 maintained complete remission throughout the follow-up, with a mean time free from any immunosuppression of 14.8 ± 10.6 months. The other 2 patients relapsed at a mean time of 27.5 ± 0.7 months. After relapse, 1 patient resumed GC therapy, and both started RTX maintenance with 500 mg every 6 to 9 months, subsequently achieving and maintaining complete remission.
Among the 12 patients, 9 discontinued GC (1 continued CsA) after an average of 5.9 ± 4.2 months post-RTX, with a mean GC-free period of 16.6 ± 13.2 months during the follow-up period.

Conclusion
RTX proved to be safe and effective for steroid-dependent and/or frequently relapsing MCD, even with a low induction single dose of 500 mg. This low induction regimen may be an effective and potentially preferable option to minimize toxicity. RTX can significantly reduce relapse rate and steroid dose, avoiding complications associated with extended and high-dose GC administration. Notably, this outcome was not achieved previously with cyclophosphamide or CsA.
RTX maintenance therapy may not be universally required for all patients with MCD, since a long period without relapse can be observed after induction therapy. Considering the current absence of a marker for disease activity, it should be taken into account individual patient characteristics and disease severity, particularly previous relapses after RTX induction.
Considering the RTX effectiveness, ability to extend remission, safety, and GC sparing ability, it should be seriously considered as the preferred second-line treatment.