Subcutaneous Belimumab Demonstrates Consistent Steady-State Pharmacokinetics and is Well Tolerated in Paediatric Patients with SLE in China: An Open-Label Study

Abstract

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 Cmax (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 Ctrough 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. Belimumab is a treatment for lupus, a disease where the immune system attacks healthy parts of the body. Doctors can give belimumab either as an infusion into a vein or as an injection under the skin. Most patients are happy getting belimumab as an infusion, but self-injection at home with an easy-to-use injection device may be more convenient and provide greater freedom. It also means patients wouldn’t need to go to the hospital for infusion treatments, which can help them stick to their treatment plan better. In China, only the infusion form is approved for children. To understand the safety and effect of the injection version of belimumab in China, this study looked at how the body tolerates belimumab when given as an injection under the skin in Chinese children with lupus who had already been treated with belimumab through infusion. Overall, 16 children between 5 and 17 years of age took part, after finishing almost 1 year of treatment with infusions. Each child got injections for 12 weeks; their weight determined how often they received injections: every week, every 10 days or every 2 weeks. After 10–12 weeks of injections, the amount of medicine in their blood became steady. Most children had at least one mild side effect, but none had serious problems or bad reactions at the injection site. Overall, this study found that giving belimumab as an injection under the skin has few side effects and works as expected in Chinese children with lupus.