RESUMO
OBJECTIVES: Autoreactive memory B cells contribute to chronic and progressive courses in autoimmune diseases like systemic lupus erythematosus (SLE). The efficacy of belimumab (BEL), the first approved biologic treatment for SLE and lupus nephritis (LN), is generally attributed to depletion of activated naïve B cells and inhibition of B cell activation. BEL's effect on memory B cells (MBCs) is currently unexplained. We performed an in-depth cellular and transcriptomic analysis of BEL's impact on the blood MBC compartment in patients with SLE. METHODS: A retrospective meta-analysis was conducted, pooling flow cytometry data from four randomized trials involving 1245 patients with SLE treated with intravenous BEL or placebo. Then, extensive MBC phenotyping was performed using high-sensitivity flow cytometry in patients with mild/moderate SLE and severe SLE/LN treated with subcutaneous BEL. Finally, transcriptomic characterization of surging MBCs was performed by single-cell RNA sequencing. RESULTS: In BEL-treated patients, a significant increase in circulating MBCs, in a broad range of MBC subsets, was established at week 2, gradually returning to baseline by week 52. The increase was most prominent in patients with higher SLE disease activity, serologically active patients, and patients aged ≤18 years. MBCs had a non-proliferating phenotype with a prominent decrease in activation status and downregulation of numerous migration genes. CONCLUSION: Upon BEL initiation, an increase of MBCs was firmly established. In the small cohort investigated, circulating MBCs were de-activated, non-proliferative, and demonstrated characteristics of disrupted lymphocyte trafficking, expanding on our understanding of the therapeutic mechanism of B cell-activating factor inhibition by BEL. TRIAL REGISTRATION: ClinicalTrials.gov NCT00071487, NCT00410384, NCT01632241, NCT01649765, NCT03312907, NCT03747159.
RESUMO
OBJECTIVE: To characterise disease control and remission in patients with SLE receiving belimumab for up to 12 months in the real world. METHODS: This post hoc analysis (GSK Study 213502) used data from the US evaluation Of use of Belimumab in clinical practice SEttings (OBSErve) study (GSK Study 117295), an observational cohort study of adults with SLE initiating and continuing belimumab for ≥6 months. Data were collected every 6 months by physician chart review; details of disease activity using the Safety of Estrogens in Lupus Erythematosus National Assessment-SLE Disease Activity Index (SELENA-SLEDAI) score were collected if routinely used by physicians. Disease control definitions evaluated were SELENA-SLEDAI score of ≤2 at 12 months, SELENA-SLEDAI score of ≤2 and glucocorticoid (prednisone equivalent) dose of ≤5 mg/day at 12 months, SELENA-SLEDAI score of ≤2 and glucocorticoid dose of ≤5 mg/day at both 6 and 12 months. Disease remission definition was SELENA-SLEDAI score=0 at 12 months. Glucocorticoid dose during follow-up was quantified. RESULTS: US OBSErve enrolled 501 patients, 90 of whom had eligible SELENA-SLEDAI scores for inclusion in this analysis. Mean (SD) SELENA-SLEDAI scores were 13.1 (3.0) at baseline and 4.9 (3.4) at 12 months. Disease control at 12 months was achieved by 31.1% of patients when defined as a SELENA-SLEDAI score of ≤2 (95% CI 21.8 to 41.7); this decreased to 25.6% when requiring a SELENA-SLEDAI score of ≤2 and glucocorticoid dose of ≤5 mg/day (95% CI 16.9 to 35.8) and 17.8% when requiring a SELENA-SLEDAI score of ≤2 and glucocorticoid dose of ≤5 mg/day at both 6 and 12 months (95% CI 10.5 to 27.3). No patient achieved remission at 12 months. Glucocorticoids decreased from a baseline median of 20.0 mg/day (IQR 15.0-30.0) to 5.0 mg/day (IQR 0-10.0) at 12 months. CONCLUSION: Improved disease control and reduced glucocorticoid use was achieved for a proportion of patients following up to 12 months of belimumab treatment in a US real-world setting.
