Subcutaneous Belimumab Demonstrates Consistent Steady-State Pharmacokinetics and is Well Tolerated in Paediatric...

This study assessed pharmacokinetics and safety of subcutaneous (SC) belimumab in Chinese paediatric patients with systemic lupus erythematosus (cSLE) who previously received intravenous (IV) belimumab; only the IV form is approved for cSLE in China.

This single-arm, open-label, 12-week bridging study (GSK Study 217091) characterised belimumab 200 mg SC exposure in Chinese paediatric patients (5-17 years) with cSLE who completed the 48-week IV belimumab Phase 4 trial (GSK Study 213560). Safety and tolerability of SC belimumab on-treatment and in a 16-week follow-up period were also assessed. Patients were categorised based on weight; data were summarised using descriptive statistics.

Overall, 16 patients were enrolled (≥ 15- < 30 kg, n = 1; ≥ 30- < 50 kg, n = 5; ≥ 50 kg, n = 10) with a mean age of 12.9 years. The geometric mean approximate C_max (3 days post-administration) after the first and last dose were 92.44, 63.41 and 68.87 μg/mL, and 28.01, 85.11 and 88.61 μg/mL for the three weight groups, respectively. The geometric mean C_trough at steady state were, 20.44, 71.57 and 85.55 μg/mL for the ≥ 15- < 30 kg, ≥ 30- < 50 kg and ≥ 50 kg weight groups, respectively. Thirteen patients (81%) reported ≥ 1 AE. No SAEs, severe AEs, AESIs, AEs resulting in belimumab discontinuation, deaths, or local injection site reactions were reported.

SC belimumab demonstrated expected steady-state exposure and tolerability in Chinese paediatric patients with SLE, supporting its use in this patient population.

GSK Study 217091; NCT05917288.