Belimumab use in paediatric-onset systemic lupus erythematosus: a status report in France from a retrospective multicentre descriptive study.

Abstract

Juvenile-onset systemic lupus erythematosus (jSLE) is a rare autoimmune disease. Belimumab, a monoclonal antibody targeting soluble B-lymphocyte stimulator, has been approved for paediatric use in France since 2020. This retrospective, multicentre study aimed to descriptively evaluate the real-world use, efficacy and safety of belimumab after 6 months of treatment in jSLE patients. Patients were diagnosed with SLE according to the 2019 EULAR/ACR criteria, and belimumab therapy (intravenous or subcutaneous) was initiated before age 18. Efficacy was assessed using clinical (SLEDAI, low disease activity status, corticosteroid dose) and biological parameters (anti-dsDNA, complement, proteinuria), along with qualitative and semi-quantitative symptom analysis. Twenty-one patients were included. The majority received intravenous belimumab (90.5%) for articular (66.7%) or cutaneous (23.8%) manifestations. At 6 months, SLEDAI scores showed no significant reduction, although there was a trend towards lower corticosteroid use (0.53 vs 0.15 mg/kg/day) and an increase in the proportion of patients achieving low disease activity status (6.3% vs 37.5%). Marked improvement was observed in articular manifestations with 77.8% achieving complete resolution. Cutaneous, renal and haematological responses were limited. Overall, treatment was well tolerated, though psychiatric symptoms led to treatment discontinuation in one patient. This retrospective, multicentre study found that belimumab, primarily administered intravenously, was effective for articular involvement and had a corticosteroid-sparing effect in jSLE, with a favourable safety profile. Its efficacy was limited for cutaneous, renal and haematological manifestations. These findings support the potential benefit of belimumab in this population while highlighting the need for prospective, multicentre and long-term studies to confirm these observations.