#2457 Effect of belimumab in renal function and proteinuria in patients with lupus nephritis (LN): our experience
Authors: Liébana Marc Patricio , Romeo Maria José Soler , Hernández Josefina Cortés , Gabaldón María Alejandra , Carrillo Jorge Ivan Zamora , Lopez Marina , Borda Jhusel Rosas , Garcia Sheila Bermejo , Berna Gerson , Leon Juan Carlos , Matamoros Oriol Bestard , Pamplona Irene Agraz 
Published: May 2024

Abstract

Background and Aims
Belimumab was approved for systemic lupus erythematosus (SLE) after demonstrating its security and effectiveness in patients without renal activity. Recently it has been approved to treat LN [1, 2]. In this study, we analyse the experience of our centre with patients treated with Belimumab with any of the indications and renal SLE affectation.

Method
We retrospectively reviewed the clinical and analytical presentations and outcomes in patients diagnosed with SLE and treated with belimumab in our centre no matter the indication of the latest. We collected clinical, analytical, therapeutic and histological data of patients diagnosed with biopsy-proven LN and at least 6 months of follow-up and analyzed the evolution after belimumab was initiated. We excluded hemodialysis patients when analyzed renal function. We also reviewed clinical histories seeking potential complications related to belimumab.

Results
Our cohort includes 14 patients, 71% women, 71% Caucasian, 64% presented HTA and 14% were diabetic. Belimumab was initiated because of extrarenal manifestations in 43% of patients. The mean age at SLE and LN diagnosis was 31 and 36 years respectively, with a mean treatment length of 2.3 years; 71% of patients had class III or IV LN, 14% had V LN and 14% had III+V LN. Before its initiation, our cohort presented a mean SCr 0.8 mg/dL, 2g/g proteinuria, anti-DNA 172 UI/mL, C3 91 mg/dL, C4 21 mg/dL, mean SLEDAI 28.3. Of patients, 71% were under chloroquine, 93% under oral steroids (mean dose 10 mg/day), 93% under MPA (mean dose 1004 mg/day) and 43% under calcineurin inhibitors (CNI). After 6 months mean creatinine was 0.7 mg/dL, proteinuria diminished to 1.5 g/g (p &lt; 0.025), anti-dsDNA were 87UI/mL, C3 was 88.5 and C4 32.7 mg/dL respectively; and after 12 months, creatinine was 0.87 mg/dL, proteinuria was 1.44g/g, anti-dsDNA were 148UI/mL, C3 was 99 and C4 24.7 mg/dL respectively and mean SLEDAI score was 7.1. After one year 66.67% of patients were under chloroquine, 88.89% under corticosteroids (mean dose 6 mg/day), 77.8% under MPA and 33.3% under CNI. After follow up we had 1 death with no secondary effects related to belimumab and reduction in proteinuria kept a trend but was no longer significative (p = 0.052). Belimumab was stopped in 5 patients, 2 of them before their inclusion in a CAR-T programme, 2 of them temporally when diagnosed with endocarditis and 1 of them after the finish of the protocol.

Conclusion
Our study has several limitations, mostly its reduced sample size. In our cohort, belimumab initiation is related only to a reduction of proteinuria after 6 months, but the most important aspect of this analysis may be that it proved to be safe and allowed clinicians to withdraw or reduce other immunosuppressive drugs to avoid their chronic toxicity with no undesirable side effects.