Belimumab safety in adult and paediatric Chinese patients with systemic lupus erythematosus: A Phase 4, multicentre, observational study.

Objective: Although belimumab has been widely used in patients with systemic lupus erythematosus (SLE) globally, real-world safety data among Chinese patients are limited, particularly for children. This study assessed the safety and tolerability of belimumab in adult and paediatric patients with SLE in China in real-world clinical practice.

Methods: This Phase 4, multicentre, prospective, observational study enrolled patients prescribed intravenous belimumab by their physicians in tertiary hospitals, independent of a clinical study, during routine clinical visits between May 2021 and May 2022. Patients could have been receiving belimumab prior to enrolment. The primary objective was to describe the incidence of adverse events (AEs), serious AEs (SAEs), adverse drug reactions (ADRs) and AEs of special interest (AESIs) over the 24-week follow-up period. Data were collected at enrolment and approximately 4, 12 and 24 weeks post-enrolment, during routine clinical visits. AEs, ADRs and SAEs were collected as independent events. The safety population comprised patients who received ≥1 dose of belimumab and completed ≥1 follow-up visit.

Results: Overall, 417 patients were included in the analysis (safety population); 89.2% were female and mean (standard deviation) age was 35.5 (11.9) years. AEs were reported in 158 patients (37.9%) and were mostly mild (79.1%). The most common AEs were upper respiratory tract infections (n = 19, 4.6%) and hypokalaemia (n = 18, 4.3%; all mild). Among 22 patients (5.3%) with SAEs, four patients (1.0%) had drug-related SAEs (pneumonia, respiratory tract infection, gingivitis and decreased white blood cell and neutrophil count). ADRs were experienced by 25 patients (6.0%), most commonly urinary tract infections (n = 5, 1.2%). There were no fatal SAEs. AESIs occurred in 14 patients (3.4%), including infections of interest (n = 5, 1.2% all herpes zoster), serious selected psychiatric events (n = 3, 0.7%) and infusion-related systemic and anaphylactic reactions (n = 7, 1.7%). Of 14 paediatric patients enrolled, six experienced AEs, zero ADRs, two SAEs and one AESI.

Conclusion: Belimumab was generally well tolerated in adult and paediatric patients with SLE in this real-world setting in China, with no new safety signals identified. Future assessment of long-term belimumab safety in China beyond 24 weeks will extend this current body of evidence.