Spanish multicenter registry of belimumab in systemic lupus erythematosus: Data from daily clinical practice

The monoclonal antibody belimumab (BLM) is the first biologic drug approved for the treatment of systemic lupus erythematosus (SLE). While the efficacy and safety profile of BLM has been well documented in clinical trials, both in SLE in general and in lupus nephritis (LN) in particular, it is necessary to obtain data from daily clinical practice.

To describe Spanish experience with BLM for treatment of SLE in daily clinical practice from 2011 until May 2024.

We performed a descriptive, observational, retrospective, and multicenter study of patients diagnosed with SLE based on the classification criteria of EULAR/ACR 2019, SLICC, and/or ACR 1997 who were starting treatment with BLM. Data were collected from the clinical history at 44 hospitals throughout Spain. The primary objective was to analyze laboratory and clinical data, effectiveness and safety. We also assessed the reduction in use of prednisone (or equivalent) and persistence of treatment. The analyses were performed overall and by differentiating between 2 periods (2011-2016 [period 1] and 2017-2024 [period 2]) and according to the subpopulation of patients with LN. Early BLM initiators, patients in monotherapy (HCQ allowed) and patients with prior biologic disease-modifying antirheumatic drugs (bDMARD) treatment were also analyzed.

The registry contains 533 patients (85.7% women, 14.3% men). Mean duration of follow-up was 22.6 months (SD: 21.2). Significant decreases were observed for the dose of prednisone, SLEDAI-2 K score, and anti-dsDNA antibody levels, whereas increases were observed for complement C3 and C4. Kidney biopsy, performed in 114 patients, revealed class IV and class III nephritis to be the most common types (44.7% and 21.2%, respectively). Three-quarters of patients (75%) started treatment in period 2, where the less frequently used drugs were bDMARD, conventional synthetic disease-modifying antirheumatic drugs (csDMARD), and prednisone. In addition, drug persistence was greater than for period 1. Patients treated after bDMARD had a worse survival (p < 0.001) while no differences were observed in patients treated in monotherapy (p = 0.06); in early BLM patients drug survival was similar to those after at least 1 csDMARD (findings were consistent in adjusted multivariable models). A total of 151 patients (28.3%) interrupted treatment, mainly owing to lack of efficacy (56.7%) and infections (12.1%).

We present data on the effectiveness and safety of the largest series to date of SLE patients treated with BLM in daily clinical practice in Spain. Our results show that BLM use was associated with improvements in disease activity and serologic markers, along with prednisone dose reductions, and showed an acceptable safety profile.