Long-term safety and efficacy of belimumab in Japanese patients with SLE: A 7-year open-label continuation study.

Objectives: Evaluate long-term safety, tolerability, and efficacy of belimumab in Japanese patients with systemic lupus erythematosus (SLE).

Methods: This was a subgroup analysis of Japanese patients who completed studies BEL113750 or BEL112341 and were enrolled in a Phase 3, open-label extension study (BEL114333; NCT01597622). Eligible patients received intravenous belimumab 10 mg/kg every 28 days for ≤7 years. Primary endpoint: safety and tolerability. Secondary endpoints included SLE Responder Index (SRI)-4 response rate, SRI-4 components, severe SLE flare, and use of corticosteroids/other SLE-related treatments. Analyses were based on observed data from first belimumab dose received in either parent or current study through to study end.

Results: Of 71 Japanese patients enrolled, 69.0% completed the study. Overall, 98.6% patients had adverse events (AEs); 32.4% had serious AEs. The proportion of SRI-4 responders increased progressively (Year 1, Week 24: 40.9% [27/66]; Year 7, Week 48: 84.6% [11/13]) as did the proportion of Safety of Estrogens in Lupus Erythematosus National Assessment-SLE Disease Activity Index responders. The proportion of patients with no worsening in PGA (91.2-100.0%) and no new organ damage (92.6-100.0%) remained stable over time. Severe SLE flare was experienced by 11.3% (8/71) of patients. Corticosteroid and immunosuppressant use decreased over time.

Conclusions: Favourable safety profile and treatment responses with belimumab were maintained for ≤7 years in Japanese patients with SLE.