# Effectiveness and safety analysis of initial treatment with belimumab in childhood-onset systemic lupus erythematosus

## TL;DR

Belimumab, when used early in treating childhood lupus, helps control the disease faster and reduces steroid use without increasing infections.

## Contribution

Belimumab added to initial therapy improves disease control and reduces glucocorticoid use in childhood-onset systemic lupus erythematosus.

## Key findings

- Belimumab group achieved higher rates of LLDAS and DORIS at 12 months compared to the control group.
- Belimumab group reached disease control faster and used lower prednisone doses after 7 months.
- Belimumab reduced B cells and IgG levels without causing infusion-related adverse reactions.

## Abstract

A retrospective cohort study to analyze the effectiveness and safety of belimumab using in the initial treatment of childhood-onset systemic lupus erythematosus (cSLE).

We collected clinical data from all children with a first diagnosis of cSLE admitted to our center between 1 April 2021 and 1 November 2024. Patients who initiated belimumab within 1 month of diagnosis were assigned to the belimumab group, and those who did not receive belimumab comprised the control group. Propensity score matching (PSM) was applied to balance baseline characteristics between the groups. The proportion of lupus low disease activity status (LLDAS) and remission (Definitions of Remission in Systemic Lupus Erythematosus, DORIS), the disease activity scores, laboratory tests, glucocorticoid dosage, and adverse effects during the courses of treatment in two groups were analysis.

There were 39 cases in both the belimumab group and the control group. The belimumab group exhibited a higher proportion of patients achieving LLDAS (31/39 vs. 14/39, p < 0.001) and DORIS (18/39 vs. 5/39, p =0.002) compared to the control group at 12 months after treatment. Additionally, the time to achieve LLDAS and DORIS was significantly shorter in the belimumab group (log-rank p< 0.001). However, no statistical variances were observed between the two groups in Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, physician global assessment (PGA) scores, complement levels, negative rates of anti-double-stranded DNA (anti-dsDNA) antibodies at each follow-up interval. From the 7th to the 12th month of treatment, the daily prednisone dose in the belimumab group was lower than in the control group. After 12 months of treatment with belimumab, B cells (p< 0.001) and immunoglobulin G (IgG) (p< 0.001) showed a significant decrease from baseline. No infusion-related adverse reactions were observed in children receiving belimumab, and the infection rate did not differ significantly from the control group.

Adding belimumab to initial therapy facilitates quicker disease control and expedites glucocorticoid tapering in children, which can be a new treatment strategy for cSLE.