[Association of anti-rituximab antibodies with relapse after therapy in children with frequently relapsing or steroid-dependent nephrotic syndrome].

Objective

To investigate the association between anti-rituximab antibodies (ARA) and relapse after rituximab (RTX) therapy in children with frequently relapsing or steroid-dependent nephrotic syndrome (FRNS or SDNS).

Methods

A retrospective cohort study was conducted. Clinical and laboratory data were collected from 48 FRNS or SDNS children treated with RTX in the Department of Pediatrics, General Hospital of Eastern Theater Command, between April 2024 and October 2024. Data included RTX dosing frequency, relapse events, peripheral CD20⁺ B-cell counts, and ARA levels. With a 6-month observation period after the last RTX therapy, the children were divided into an ARA-positive group and an ARA-negative group based on ARA test results. Chi-square test, independent sample t-test, or Mann-Whitney U test were used to compare relapse rates and laboratory indicators between the two groups. The predictive value of ARA levels for relapse was evaluated using univariate receiver operating characteristic (ROC) curve analysis.

Results

Among the 48 children (36 males, 12 females), the age of disease onset was 3.5 (2.0, 6.0) years, the ages at the first and last RTX treatments were 7.0 (5.0, 12.0) years and 9.5 (7.0, 13.0) years, respectively. The overall ARA positive rate was 29% (14/48). The relapse rate in the ARA-positive group was significantly higher than that in the negative group (P<0.05). The ARA level was 0.01 (0.01, 5.88) μg/L, and all 12 children with ARA levels >5.88 μg/L relapsed. ROC curve analysis showed that ARA levels predicted relapse after RTX treatment in FRNS or SDNS children with an area under the curve (AUC) of 0.73, sensitivity of 0.50, specificity of 1.00, and an optimal cut-off value of 5.02 μg/L. All children received single-dose RTX therapy, with no significant difference in treatment frequency between the two groups (P>0.05). At 3 months after the last rituximab therapy, CD20⁺ B cell counts were significantly higher in the ARA-positive group (P<0.05). During follow-up, 15% (7/48) of the children experienced infusion-related adverse reactions, with no significant difference in incidence between the two groups (P>0.05).

Conclusion

ARA is significantly associated with relapse in FRNS or SDNS children after RTX therapy.