Background/Purpose: Lupus nephritis (LN) is a serious complication of systemic lupus erythematosus (SLE), often leading to chronic kidney disease (CKD) and end-stage renal disease (ESRD). Belimumab, a B-lymphocyte stimulator (BLyS) inhibitor, was FDA-approved for LN in 2020, offering a targeted approach to reduce B-cell activity. This study aims to compare renal outcomes in LN patients treated with Belimumab versus Mycophenolate Mofetil (MMF) using real-world data, providing insights into their relative effectiveness and safety.

Methods: This multicenter retrospective cohort study utilized data from the TriNetX network, comprising electronic health records from 104 healthcare organizations. Adult patients (≥18 years) with lupus nephritis (LN) were identified using ICD-10 codes. Two cohorts were defined: patients receiving Belimumab (n=1,052) and those receiving mycophenolate mofetil (MMF) (n=7,740) between December 2020 and February 2025. To eliminate potential confounding, patients receiving concurrent use of both Belimumab and MMF were excluded from the analysis.Propensity score matching (PSM) was applied to adjust for demographics, comorbidities, and laboratory values, achieving balanced baseline characteristics between the two groups. Outcomes were compared between the matched cohorts over a follow-up period of five years. The primary outcomes were end-stage renal disease (ESRD), dialysis, and renal transplant. Secondary outcomes included opportunistic infections, hospitalization, and all-cause mortality.

Results: After propensity score matching, 1,036 patients were included in each group. The Belimumab cohort had significantly lower odds of dialysis (OR 0.36, 95% CI 0.28–0.45, p < 0.001), ESRD (OR 0.50, 95% CI 0.36–0.68, p = 0.001), and renal transplant (OR 0.17, 95% CI 0.09–0.31, p < 0.001) compared to MMF. Additionally, Belimumab was associated with reduced hospitalization (OR 0.65, 95% CI 0.47–0.89, p = 0.02) and fewer opportunistic infections (OR 0.35, 95% CI 0.23–0.53, p < 0.001). No statistically significant difference was observed in all-cause mortality (OR 0.82, 95% CI 0.61–1.10, p = 0.38).

Conclusion: This real-world analysis suggests that Belimumab may provide superior renal outcomes compared to MMF in lupus nephritis, with reduced risks of dialysis, ESRD, and renal transplant. The findings support the potential of Belimumab as an alternative or adjunct to conventional therapy. Further prospective studies are necessary to confirm long-term efficacy and safety.

Comparative Outcomes in Belimumab vs. MMF for Lupus Nephritis

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/belimumab-versus-mycophenolate-mofetil-in-lupus-nephritis-a-real-world-comparative-analysis/