Belimumab prevention against organ damage over 8 years and safety up to 13 years: three pooled open-label, long-term extension SLE studies

Objective Examine long-term glucocorticoid usage, safety and prevention of organ damage in patients with SLE treated with belimumab plus standard therapy (ST). Methods This post hoc analysis from three global long-term extension (LTE) studies (BEL112233, BEL112234 and BEL112626) included patients who completed parent studies BLISS-52, BLISS-76 or LBSL02. All patients in the LTEs received open-label belimumab (10 mg/kg) intravenously every 28 days plus ST. Endpoints included long-term SLE medication use any time after first belimumab dose (in parent or LTE study), organ damage accrual (up to 8 years) and safety (up to 13 years). Results Altogether, 1304 patients enrolled in the LTE studies; 1299 received ≥1 dose of belimumab and were included in the modified intent to treat population. Of these, 1221 (94%) patients were female and at enrolment had a mean (SD) age and disease duration of 39.7 (11.6) and 7.2 (6.7) years, respectively. Mean (SD) baseline Safety of Estrogens in Lupus Erythematosus National Assessment-SLE Disease Activity Index (SELENA-SLEDAI) and Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI) scores were 8.2 (4.3) and 0.7 (1.2), respectively. The most frequently used SLE concomitant medications at any time after first dose of belimumab were glucocorticoid (GC) (94.1%), antimalarials (74.6%) and immunosuppressants (56.4%). Approximately 50% of patients reduced their GC dose to ≤7.5 mg/day in the first 3 years, increasing to 73.6% by the end of year 8. Mean (SD) changes in SDI score to year 8 did not exceed 0.3 (0.6). Overall, 97.5% of patients had ≥1 adverse event (AE) up to 13 years. While 40.4% had ≥1 serious AE, the incidence of AEs leading to belimumab discontinuation generally remained low over time (10.7%). Conclusions Patients with SLE treated with belimumab reduced GC use and had minimal to no organ damage progression over 8 years. Robust and consistent safety data up to 13 years support the well-established favourable safety profile of belimumab, with no new safety concerns.